Medical Cases and Answers

Diarrhea Case 6

2011-06-20T06:00:00.000-07:00

A 45-year-old man presents to a physician because of severe chronic diarrhea accompanied by a 18 kg (40 Ib) weight loss. The diarrhea began several years ago, and has become steadily worse. It is often accompanied by excessive flatulence, and the man notes that his stools usually float. The man additionally has felt generally poorly and sometimes has experienced joint symptoms. Intestinal biopsy demonstrates

Iarge numbers of foamy macrophages distending the lamina propria. A periodic acid-Schiff (PAS) stain shows granules within the macrophages.

Q 1

Which of the following is the most likely diagnosis?

/ A. Celiac sprue

/ B. Intestinal lymphangiectasia

/ C. Lactase deficiency

/ D. Tropical sprue

/ E. Whipple disease

This patient disease has been etiologically related to infection with which of the following?

/ A. Bartonella

/ B. Borrelia

/ C. Francisella

/ D. tropheryma

/ E. Vibrio

Excessive flatulence suggests which of the following problems :

/ A. Colon obstruction

/ B. GI hypermotility

/ C. GI hypomotility

/ D. Malabsorption

/ E. Small intestinal obstruction

Q 4

BIood studies on this patient demonstrate a microcytic hypochromic anemia. The nutrient whose deficiency would most likely account for the patient's anemia is primarily absorbed in which of the following sites?

/ A. Colon

/ B. Duodenum

/ C. Esophagus

/ D. IIeum

/ E. Stomach

Q 5

This patient's illness is most effectively treated with which of the following?

/ A. Antibiotics

/ B. Chemotherapy

/ C. Radiation therapy

/ D. Steroid therapy

/ E. Surgery

____________________________________________________________________________

Diarrhea Case 6 Answers

The correct answer is E. This patient has Whipple disease, which is a rare illness characterized by diarrhea, often severe malabsorption, and weight loss. The condition most commonly affects men aged 30 to 60. The disease may present either abruptly or insidiously. If it develops insidiously, non-gastrointestinal manifestations may bring the patient to medical attention. These may include pleuritic pain, pleural effusion, anemia, joint problems, cardiac problems, neuropsychiatric problems, eye problems, or hepatic dysfunction.

All of the other diseases listed can also cause chronic diarrhea.

Celiac sprue (choice A) shows villous atrophy on biopsy, and is related to gluten sensitivity.

Intestinal lymphangiectasia (choice B) shows dilated lymphatic channels on biopsy.

Lactase deficiency (choice C) is due to an enzymatic abnormality and is characterized by a histologically normal intestinal epithelium.

Tropical sprue (choice D) usually shows moderate broadening and shortening of villi, and an often intense inflammatory reaction.

The correct answer is D. Electron microscopy of the intestinal mucosa shows that the PAS-positive granules in macrophages in Whipple disease are actually bacterial forms. The causative organism is Tropheryma whippelii, and, if necessary, its DNA can be identified with PCR technology. This is necessary because attempts to culture the organism have not, to date, been successful. At the moment, this test is available only through reference laboratories. In patients who have extraintestinal manifestations, macrophages containing the bacteria may be found in extraintestinal sites.

Bartonella(choice A) species can cause cat scratch disease, trench fever, and disseminated infections.

Borrelia(choice B) causes Lyme disease.

Francisella(choice C) causes tularemia.

Vibrio(choice E) causes cholera and other diarrheal illnesses.

The correct answer is D. When a patient complains of excessive flatulence, the first step is to ask them to describe the amount and frequency of the flatulence, since some people with normal intestinal gas production have unrealistic expectations about the possibility of completely eliminating flatulence. In cases in which excessive flatulence really is present, you should think of gastrointestinal disorders that can cause malabsorption, since many cases of excessive flatulence are related to bacterial digestion of unabsorbed nutrients (notably carbohydrates) with resultant gas production as a by-product. These disorders may include a wide variety of underlying conditions including pancreatic disease, liver disease, genetic enzymatic abnormalities of the intestinal mucosa, and acquired intestinal tract disease.

Colonic obstruction (choice A), small intestinal obstruction (choice E), and GI hypomotility (choice C) can also cause gas to be retained in the bowel and be visible on abdominal x-ray films, but do not, by themselves, increase gas production.

GI hypermotility (choice B) often accompanies acute diarrheal illness, but the excessive flatulence that may also be present in that setting is secondary to malabsorption rather than the hypermotility.

The correct answer is B. Microcytic, hypochromic anemia suggests iron deficiency. Patients with Whipple disease frequently develop anemia related to poor duodenal absorption of either folate (producing a macrocytic anemia) or iron. Other substances absorbed in the duodenum include water, calcium, fats, sugars, proteins, many vitamins, magnesium, and sodium.

The colon (choice A) absorbs water and electrolytes.

The esophagus (choice C) does not absorb nutrients.

The ileum (choice D) can absorb bile salts, vitamin B12, and chloride.

The stomach (choice E) can absorb water and alcohol.

The correct answer is A. The symptoms of Whipple disease often dramatically improve after antibiotic therapy, although the therapy must often be continued for prolonged intervals to prevent relapse and the microscopic intestinal changes may not resolve for 2 years. Many antibiotics are effective, including chloramphenicol, tetracycline, ampicillin, penicillin, and trimethoprim-sulfamethoxazole. The other therapies listed in the choices are not usually employed with Whipple disease.

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Diarrhea Case 5

2011-06-20T05:52:00.000-07:00

An 11-month-old girl who attends a day care center develops vomiting and severe, watery diarrhea. The child is taken to an emergency department on the third day of the illness, because the mother is concerned that she has not been able to hold any food or liquids down without vomiting. Physical examination demonstrates an obviously ill child with listless behavior, Ioss of skin turgor, dry mucous membranes, and weight 3 pounds less than 1 week previously. Her blood pressure is 64/40 mm Hg.

Q 1

Which of the following is the most common cause of viral gastroenteritis in children under the age of three?

/ A. Astrovirus

/ B. Calicivirus

/ C. Enteric adenovirus

/ D. Norwalk virus

/ E. Rotavirus

Q 2

In the United States, this virus tends to cause illness during which of the following periods?

/ A. Predominately fall months

/ B. Predominately spring months

/ C. Predominately summer months

/ D. Predominately winter months

/ E. Year-Iong with no seasonal preference

Q 3

The virus is predominately spread by which of the following routes?

/ A. Contaminated blood

/ B. Contaminated food

/ C. Contaminated water sources

/ D. Direct fecaI-oral route

/ E. Inhaled aerosols

Q 4

This child's poor skin turgor, dry mucus membranes, significant weight loss, and low blood pressure all suggest which of the following?

/ A. Dehydration

/ B. Disseminated intravascular coagulation

/ C. IIeus

/ D. Sepsis

/ E. Starvation

Q 5

In 1989, the FDA Iicensed a live attenuated vaccine against the causative agent of this disease for use in infants. It was later withdrawn for

which of the following reasons?

/ A. Data suggested a link between the vaccine and intussusception in some infants during the first 1-2 weeks following vaccination.

/ B. It was questioned if there was association between the vaccine and the development of autism.

/ C. Seizures occurred in a significant number of recipients.

/ D. The vaccine was not widely used because it was too expensive.

/ E. The vaccine was thought to be associated with the development of arthritis in recipients.

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Diarrhea Case 5 Answers

The correct answer is E. The most common cause of severe dehydrating diarrhea in infants and young children is Group A rotavirus. The peak incidence of infection occurs from 3 to 15 months. After age three, severe diarrhea is rare, but mild disease can occur. This virus accounts for about half of the cases of diarrhea requiring hospitalization in children in the United States. Rotaviruses are in the Reoviridae family and have a genome consisting of 11 double-stranded RNA segments. The other agents listed can also cause viral gastroenteritis in children and/or adults.

The correct answer is D. In temperate climates, rotavirus has a winter seasonal pattern. In the United States, epidemics occur from November to April. In tropical climates, disease caused by rotavirus occurs year round.

The correct answer is D. Rotavirus is a notoriously contagious virus, and the infective dose is thought to be as small as 10-100 infectious viral particles. While the initial yearly source of the virus may be from contaminated estuary waters (choice C), the vast majority of cases are spread from person to person via direct contact with stool on diapers, objects such as toys, or fingers. While not always necessary, the presence of rotavirus can be confirmed by using enzyme immunoassay on stool specimens. Day care centers are notorious sources of minor epidemics of the virus, and day care workers should be encouraged to be very careful. Reasonable precautions include removal of kids with diarrhea from the day care environment, prompt diaper changing before the children have a chance to touch the stool, and routine use of fresh disposable gloves during diapering.

Contaminated blood (choice A) and inhaled aerosols (choice E) are not usual routes of infection.

Contaminated food (choice B), typically contaminated by food handlers who have recently changed an infected child's diapers, is an uncommon source of infection.

The correct answer is A. These findings strongly suggest that the child is severely dehydrated and in need of intravenous fluid replacement. Approximately 500,000 children are seen in emergency room and outpatient clinic visits for rotavirus infection yearly, and of these, about 50,000 hospitalizations (usually to correct dehydration) and 20 deaths (usually caused by failure to correct the dehydration in a timely fashion) occur yearly in the United States. World-wide, rotavirus infection is thought to cause around 600,000 deaths, primarily in young children. This child with severe dehydration should at least be given IV fluids, and might require hospitalization.

Disseminated intravascular coagulation (choice B) would cause multiple petechiae and purpura, and does not usually complicate rotavirus infection.

Ileus (choice C) is a paralyzed bowel, which is the opposite of the problem seen in gastroenteritis.

Sepsis (choice D) is not usually diagnosed in viral infections, but is seen in severe bacterial infections, often with bacteremia.

Three or four days of not eating is not long enough to induce starvation (choice E).

The correct answer is A. The live attenuated rotavirus vaccine was a virus mixture of reassorted strains that were primarily animal viruses except for one human-virus gene segment. The vaccine had a 49-68% efficacy against any diarrhea due to rotavirus and a 61-100% efficacy against severe disease. However, during the first 11 months of use, post-licensure studies identified intussusception, a form of intestinal obstruction in which a segment of the bowel prolapses into a more distal segment, as an uncommon but potentially life-threatening side effect. Follow up studies estimated that 1 additional case of intussusception occurred for every 5,000- 10,000 vaccinees. The vaccine has currently been withdrawn from use in the US.

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Diarrhea Case 4

2011-06-20T05:46:00.000-07:00

A 17-year-old boy is seen in an emergency department with severe acute abdominal symptoms that suggest appendicitis. The patient had a similar episode previously that led to an appendectomy, but the appendix was free of inflammation at pathologic examination. On questioning,

the boy reports having had intermittent diarrhea with moderate chronic abdominal pain for several years, which he had been afraid to tell anyone about after having had a "normaI" appendix removed. On physical examination, the boy is noted to be thin, with short stature, and have a palpable fullness in the right lower quadrant of his abdomen. UItrasound examination of the abdomen shows some thickening of bowel mesentery, but no distinct masses. Colonoscopy demonstrates sharply demarcated segments of diseased bowel with patchy mucosal ulcersseparated by adjacent normal bowel involving both the distal ileum and right side of the colon.

Q 1

Which of the following is the most likely diagnosis?

/ A. Colon cancer

/ B. Crohn disease

/ C. Hirschsprung disease

/ D. Pseudomembranous colitis

/ E. UIcerative colitis

Q 2

Which of the following findings on right colon mucosal biopsy would be most suggestive of the patient's likely diagnosis?

/ A. Absence of nerve cell bodies in submucosa

/ B. Bacteria-Iaden pseudomembrane

/ C. Crypt abscesses

/ D. Neoplastic epithelial cells

/ E. Small granulomas

Q 3

The patient is treated initially with corticosteroids, and then these are tapered and he is switched to a maintenance therapy with sulfasalazine.

Sulfasalazine is an unusual medication that combines which of the following?

/ A. A histamine derivative and a beta blocker

/ B. A Iipoxygenase inhibitor and a penicillin derivative

/ C. A mast cell degranulation inhibitor and an anticoagulant

/ D. A salicylate derivative and a sulfonamide derivative

/ E. A serotonin antagonist and a proton pump inhibitor

Q 4

Several years later, the patient develops recurrent urinary tract infections with mixed flora bacteria isolated from the urine. This pattern

suggests that which of the following may have developed?

/ A. BIadder stone

/ B. Fistula

/ C. Kidney stone

/ D. Systemic immunosuppression

/ E. Urethral strictures

Q 5

At a still later date, the patient develops chronic lower back pain and is diagnosed with ankylosing spondylitis. Which HLA type has been

associated with this extracolonic manifestation?

/ A. HLA-B27

/ B. HLA-B35

/ C. HLA-Cw6

/ D. HLA-DR3

/ E. HLA-DR5

Q 6

Examination of the patient's legs reveals necrotic ulcers with ragged bluish-red overhanging edges together with areas containing plaques

with pustules. Which of the following is the most likely diagnosis?

/ A. Eruptive xanthomata

/ B. Lupus vulgaris

/ C. Raynaud's phenomenon

/ D. Psoriasis

/ E. Pyoderma gangrenosum

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Diarrhea Case 4 Answers

The correct answer is B. This patient most likely has Crohn disease, as indicated by his chronic abdominal complaints and the distal small intestinal and colonic ulceration with skip lesions (normal bowel separating involved areas). In addition to the distal small intestine and colon, Crohn disease can affect the perianal area, entire small intestine, stomach, and esophagus. Crohn disease may present with chronic diarrhea with systemic complaints, acute abdomen, or extraintestinal manifestations. The peak incidence for onset of symptoms occurs between 14 to 24 years. Crohn disease is thought to be due to a genetic predisposition that leads to an autoimmune reaction in the intestine that may be triggered in response to an environmental, dietary, or infectious agent. About 1 in 6 people with Crohn disease have a relative with Crohn disease, or, less commonly, ulcerative colitis.

Colon cancer (choice A) would be highly unlikely in a 17-year-old, and usually causes a single mass lesion or stricture.

Hirschsprung disease (choice C) causes megacolon in young children.

Pseudomembranous colitis (choice D) is due to overgrowth of Clostridium difficile and is usually seen following treatment with broad-spectrum antibiotics.

Ulcerative colitis (choice E) usually extends from the rectum proximally and does not have skip lesions.

The correct answer is E. Microscopic features of Crohn disease include transmural inflammation, small granulomas (most characteristic, but only present in about 50% of cases), and variable degrees of inflammation.

Absence of nerve cell bodies in submucosa (choice A) suggests Hirschsprung disease.

A bacteria-laden pseudomembrane (choice B) suggests pseudomembranous colitis;

Crypt abscesses (choice C) suggest ulcerative colitis.

Neoplastic epithelial cells (choice D) suggest colon cancer or neoplastic polyps.

The correct answer is D. Acute exacerbations of Crohn disease can be treated with corticosteroids, but then the patient is usually switched to maintenance therapy with immunomodulating drugs, such as azathioprine and 6-mercaptopurine, or sulfasalazine or related drugs. Sulfasalazine has a sulfapyrine component, which is a sulfonamide derivative and a 5-aminosalicyclic acid (5-ASA) component, which is a salicylate derivative. Most of the drug activity appears to be related to the 5-ASA component, and most of the toxicity is related to the sulfapyrine, so alternatives to sulfasalazine, such as mesalamine, are being developed that preserve the 5-ASA activity without retaining the sulfapyrine component. The other answers are distracters.

The correct answer is B. The patient has probably developed a fistula between the intestine and the bladder. Fistulas are a relatively common complication of Crohn disease. Surgery is used to correct recurrent intestinal obstruction and intractable fistulas, but may be unsatisfactory because of disease recurrence.

The other choices do not commonly complicate Crohn disease and would not specifically predispose for mixed flora infections.

The correct answer is A. Ankylosing spondylitis is one of the seronegative spondyloarthropathies. It should be suspected in any young person complaining of chronic lower back pain and can be confirmed by radiographs or CT scans of sacroiliac joints. The disease usually progresses to involve the whole vertebral column, producing ankylosis and respiratory failure secondary to restrictive lung disease. HLA-B27 positivity has been associated with Crohn disease patients who develop extracolonic manifestations including ankylosing spondylitis, sacroiliitis, uveitis, and primary sclerosing cholangitis.

You should associate HLA-B35 (choice B) with vitiligo, duodenal ulcer, and subacute thyroiditis.

You should associate HLA-Cw6 (choice C) with psoriasis.

You should associate HLA-DR3 (choice D) with celiac disease, Goodpasture syndrome, type I diabetes mellitus, and systemic lupus erythematosus.

You should associate HLA-DR5 (choice E) with juvenile rheumatoid arthritis and pernicious anemia.

The correct answer is E. Pyoderma gangrenosum can precede the onset of chronic inflammatory bowel disease. It is treated by systemic and topical corticosteroids. It may also be associated with myeloproliferative disorders and rheumatoid arthritis.

Xanthomata (choice A) may be located on the tendons on the back of the hands, the Achilles tendon and patellar tendon, buttocks, and back. They are usually yellow papules up to 5 mm in diameter. They suggest familial hypercholesterolemia.

Lupus vulgaris (choice B) is a progressive form of cutaneous tuberculosis occurring in a person with a moderate or high degree of immunity. The two types are the plaque form (a tiny reddish-brown, flat plaque that extends gradually) or the ulcerative form (scarring and ulceration over the areas of necrosis).

Raynaud's phenomenon (choice C) presents as cold and cyanotic digits along with atrophy of the finger pulp and, in severe cases, gangrene. It is an exaggerated physiological response wherein the fingers turn white, and then when rewarmed, will turn blue, and then red as part of rebound hyperemia. It may be associated with underlying connective tissue diseases such as systemic sclerosis.

Psoriasis (choice D) presents as a thick plaque-like scale that is usually silver or salmon-pink in color. It is usually well defined on the extensor surfaces of elbows or knees. It is often associated with asymmetrical arthropathy mainly involving the terminal interphalangeal joints.

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Diarrhea Case 3

2011-06-20T05:40:00.000-07:00

A 25-year-old woman is hospitalized for multiple injuries to her arms and legs from an automobile accident. She is treated with several intravenous broad-spectrum antibiotics because of significant concern that her wounds are becoming infected with a mixed flora of organisms. She responds over the next several days to the antibiotics with an initial decrease in fever. However, on the fourth day after her accident, she develops severe diarrhea with fever, vomiting, cramping abdominal pain, tenesmus, abdominal distension, and fluid losses severe enough to require IV fluids.

Proctoscopic examination demonstrates discrete yellow plaques up to 2 cm diameter which are scattered over the colonic mucosa. Which of the following would most likely be demonstrated on colonic biopsy?

/ A. Acid fast bacteria

/ B. Neoplastic polyps

/ C. Parasitic eggs

/ D. Pseudomembrane formation

/ E. Small granulomas

Which of the following organisms has been implicated in this disease?

/ A. Clostridium botulinum

/ B. Clostridium difficile

/ C. Clostridium perfringens

/ D. Clostridium septicum

/ E. Clostridium tetani

Q 3

Which of the following tests would be most helpful in confirming the diagnosis?

/ A. CT scan

/ B. MRI scan

/ C. "Scotch tape" test

/ D. Specific toxin in stool

/ E. Stool for ova and parasites

Q 4

This patient should not undergo barium contrast studies because of the increased risk in her disease of which of the following

/ A. AIIergic reaction

/ B. Gut perforation

/ C. Predisposition for cancerous transformation

/ D. Secondary appendicitis

/ E. Trapping of dye in diverticula

Q 5

Which of the following drugs is most likely to be effective in this case?

/ A. 3rd generation cephalosporin

/ B. Amoxicillin

/ C. Ampicillin

/ D. CIindamycin

/ E. Vancomycin

____________________________________________________________________________

Diarrhea Case 3 Answers

The correct answer is D. This patient's history and proctoscopic examination are typical of severe pseudomembranous colitis (also sometimes called antibiotic associated colitis). Patients with milder disease may have only diarrhea. On pathologic examination, pseudomembranes composed of fibrin, neutrophils, necrotic material, and bacteria are seen overlying partially disrupted glands with prominent submucosal edema.

Acid fast bacteria (choice A) would suggest tuberculosis or atypical mycobacterial infection.

Neoplastic polyps (choice B) are seen as isolated findings or as part of familial polyposis syndromes.

Pseudomembranous colitis is not related to parasitic infection (choice C).

Small granulomas (choice E) could suggest either Crohn disease or tuberculosis.

The correct answer is B. The clostridia are gram-positive, anaerobic, spore-forming rods that can produce a variety of nasty diseases. This patient's disease, pseudomembranous colitis, is due to bacterial gut overgrowth with Clostridium difficile, usually in the aftermath of broad-spectrum antibiotic therapy. Both children and adults may become infected. Probably in most cases, the patients already had small numbers of the organisms in their guts before antibiotic therapy, although isolated examples of transmission within wards have also been documented.

Clostridium botulinum(choice A) causes botulism.

Clostridium perfringens(choice C) and Clostridium septicum(choice D) cause gas gangrene.

Clostridium tetani(choice E) causes tetanus.

The correct answer is D. Clostridium difficile produces toxins A and B, which can now be rapidly identified in stool samples. This is the best confirmatory test following proctoscopy, as the results will be back much faster than the pathology report on a tissue sample. The toxins cause necrosis of the superficial gut mucosa that, in turn, leads to pseudomembrane formation. True infection of the gut wall by the bacteria does not occur. (The bacteria like to live in and eat the necrotic material and fibrin of the pseudomembrane.)

CT scan (choice A) and MRI scan (choice B) are expensive tests that will not contribute to the diagnosis.

The "Scotch tape" test (choice C) involves using tape to collect pinworm eggs from the perirectal skin.

Clostridium difficile is a bacterium rather than a larger parasite, so stool for ova and parasites (choice E) would not be helpful.

The correct answer is B. In addition to the immediate risks related to hypotension, dehydration, and electrolyte imbalance in these sometimes critically ill patients, complications that can incur include colonic perforation (which may be induced by barium contrast studies) and toxic megacolon.

Pseudomembranous colitis does not alter allergic reactions (choice A), predispose for appendicitis (choice D) or cancer (choice C), or induce formation of diverticula (choice E).

The correct answer is E. Clostridium difficile is resistant to most antibiotics, which is why it tends to cause a bowel bacterial overgrowth when broad-spectrum antibiotics are used. The two antibiotics to which it is usually sensitive, and that are consequently most often used to treat pseudomembranous colitis, are vancomycin and metronidazole. The other agents listed in the choices are frequently reported causes of pseudomembranous colitis.

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Diarrhea Case 2

2011-06-20T05:33:00.000-07:00

A 32-year-old woman goes to an emergency department because she has developed severe, watery diarrhea. On questioning, she reports that three days previously, she spent the weekend along the Gulf of Mexico, and ate at a raw oyster bar. About 36 hours later, she developed vomiting and an abrupt, painless, watery diarrhea. The volume of diarrhea has been copious, and she has subsequently developed intense thirst, oliguria, muscle cramps, and weakness. At the time of being seen in the emergency department, she is noted to have marked loss of tissue turgor, sunken eyes, and wrinkling of the skin of her fingers. Laboratory studies demonstrate hemoconcentration and severe metabolic acidosis with potassium depletion.

Q 1

Which of the following is the most likely cause of the woman's problems?

/ A. Amoeba infection

/ B. Bacterial infection

/ C. Food poisoning

/ D. Irritable bowel syndrome

/ E. Viral infection

Q 2

An organism cultured from the patient's stool is subsequently characterized as an oxidase-positive, gram-negative curved rod with polar

flagella that shows "shooting star" mobility and grows best on TCBS medium. Which of the following is the most likely pathogen?

/ A. Escherichia

/ B. Pseudomonas

/ C. Salmonella

/ D. Shigella

/ E. Vibiro

This organism is most likely classified as which of the following types ?

/ A. O1

/ B. O2

/ C. O5

/ D. O105

/ E. O139

Q 4

In the United States, approximately what percentage of patients who acquire this infection subsequently die?

/ A. 1% or less

/ B. 5-10%

/ C. 20-30%

/ D. 50-70%

/ E. 90% or more

Q 5

The patient responds with IV fluids, and is very much better within 24 hours. While this woman did not require antibiotic therapy, which of the

following antibiotics is used for this disease?

/ A. First generation cephalosporin

/ B. Metronidazole

/ C. Penicillin

/ D. Tetracycline

/ E. Third generation cephalosporin

____________________________________________________________________________

Diarrhea Case 2 Answwers

The correct answer is B. This patient is severely ill and dehydrated. Severe watery diarrhea that persists is most likely to be due to a bacterial infection.

Amoeba infection (choice A) usually produces a bloody diarrhea that does not have the watery characteristic of cholera.

Food poisoning (choice C) usually begins within the first eight hours after ingestion of contaminated food, and is often over within 24 hours.

Irritable bowel syndrome (choice D) is usually a chronic, but relatively mild, problem.

Viral infection (choice E) can cause gastroenteritis, but it is not usually as debilitating as this patient's disease.

The correct answer is E. The features noted are those of Vibrio cholerae, the causative organism of the severe diarrheal disease, cholera. The diarrhea is the result of the action of the cholera enterotoxin, which acts by ADP-ribosylating adenylate cyclase, leading to increased cyclic AMP with secondary increased efflux of Cl^- and H₂O. World-wide, cholera is usually spread by fecally contaminated water, but in areas such as Europe and the United States, where the general level of hygiene, sewage control, and water supply is good, the occasional cases seen are often the result of contaminated food. Some of the shellfish from the Gulf of Mexico naturally contain the organism, and ingestion of these shellfish in raw or poorly cooked form has caused cholera.

Escherichia(choice A) is oxidase-negative.

Pseudomonas(choice B) is an oxidase-positive, gram-negative rod that characteristically produces the blue pigment, pyocyanin.

Salmonella(choice C) is a motile, gram-negative rod that is a non-lactose fermenter that produces H₂S.

Shigella(choice D) are non-motile gram-negative rods.

The correct answer is A. Vibrio cholera serogroup O1 is the major cause of epidemic cholera, and up until 1992 was the only cause. Since then, the O139 serogroup (choice E) has been an important pathogen in India and Bangladesh, but has not yet become important outside Asia. No other serotypes are known to cause epidemic cholera.

The correct answer is A. The mortality of cholera varies markedly depending upon the general health of the individuals who become infected and the availability of adequate medical care. In extreme situations, such as in refugee camps with little sanitation, little food, and no available medical facilities, case fatality rates of 25-50% are encountered. In Europe, the Americas, and more recently Asia, case fatality rates in most situations are kept at 1% or less. A major reason for the decreased fatality rates in most parts of the world is that the World Health Organization has been encouraging endemic areas to pre-plan for epidemics and have available large numbers of previously prepared packages of oral rehydration salts.

The correct answer is D. Most patients with cholera in this country who have disease severe enough to cause significant dehydration are rehydrated initially with IV fluids, and are then switched to oral fluids several hours later. In countries with more likelihood of having an epidemic and poorer medical availability, packages of oral rehydration salts to which water is added are commonly (and very effectively) used to treat cholera. Antibiotics are often not employed in milder cases. In severe cases, antibiotic therapy can reduce the volume and duration of the diarrhea experienced by the patient. The usual antibiotic of choice is tetracycline, although some resistant strains are emerging. Useful alternative drugs include ciprofloxacin, erythromycin, doxycycline, and furazolidone. No vaccine against cholera is presently available in the United States, although two vaccines (which are not completely effective) are available elsewhere in the world. The other agents listed in the choices are not used to treat cholera.

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Diarrhea Case 1

2011-06-20T05:02:00.000-07:00

A 52-year-old woman consults a physician because she has been having increasingly frequent episodes of abdominal cramps and diarrhea.

These episodes are accompanied by an uncomfortable flushing of her skin. She thinks they are sometimes precipitated by eating, alcohoI, or emotional distress, but she has also recently been having episodes that had no obvious trigger.

Q 1

Her physician suspects that she may have a hormone-secreting tumor. Ectopic secretion of which of the following substances would be most

Iikely to cause diarrhea?

/ A. Gastrin

/ B. GIucagon

/ C. Histamine

/ D. Insulin

/ E. Serotonin

Which of the following laboratory tests would be most appropriate to test for excess secretion of the hormone causing the diarrhea?

/ A. Dexamethasone test

/ B. Hemoglobin A1C

/ C. Urinary 5-hydroxyindoleacetic acid

/ D. Urinary aminolevulinic acid

/ E. Urinary porphobilinogen

Q 3

CT scan demonstrates several probable metastatic tumors in the patient's liver. These are most likely which of the following histologic types?

/ A. Burkitt lymphoma

/ B. Carcinoid tumor

/ C. Hepatocellular carcinoma

/ D. Kaposi sarcoma

/ E. Squamous cell carcinoma

Q 4

The metastases most likely originated from which of the following?

/ A. Central nervous system

/ B. Gastrointestinal tract

/ C. Reproductive tract

/ D. Respiratory tract

Q 5

These tumors are thought to be derived from which of the following cell lines?

/ A. Endothelial cells

/ B. Enterochromaffin cells

/ C. Fibroblasts

/ D. Lymphocytes

/ E. Smooth muscle cells

____________________________________________________________________________

Diarrhea Case 1 Answers

The correct answer is E. Excess serotonin can act on smooth muscle to produce diarrhea, colic, and malabsorption.

Excess gastrin secretion (choice A) can cause peptic ulceration secondary to stimulation of gastric glands.

Excess glucagon secretion (choice B) can cause rash and impaired glucose tolerance.

Excess histamine secretion (choice C), as well as excess bradykinin secretion, can coexist with excess serotonin secretion, and can contribute to the flushing seen in this patient.

Excess insulin secretion (choice D) can cause hypoglycemia.

The correct answer is C. 5-hydroxyindoleacetic acid is the major urinary metabolite of serotonin.

The dexamethasone test (choice A) is used to screen for Cushing syndrome.

Hemoglobin A1c (choice B) is a marker for long-term glycemic control.

Urinary porphobilinogen (choice E) and urinary aminolevulinic acid (choice D) are used in the diagnosis of the porphyrias.

The correct answer is B. The patient's clinical presentation is typical for carcinoid syndrome, which is a clinical manifestation of hormone-secreting carcinoid tumors. It is usually seen in the presence of metastatic disease involving the liver. None of the other tumors listed would be expected to secrete hormones.

The correct answer is B. Approximately 90% of carcinoid tumors occur in the gastrointestinal tract, with the most common site in the gastrointestinal tract being the small intestine (39%, data from www.carcinoid.org web site). Involvement of the appendix (26%) and rectum (15%) is also fairly common. Other sites include colon (5-7%), stomach (2-4%), pancreas (2-3%), liver (less than 1%), bronchial system (10%, choice D), and rarely gonads (choice C), gallbladder and bile ducts, urinary bladder and kidneys (choice E), prostate, breast, and thymus. The central nervous system (choice A) does not appear to be a significant site of origin.

The correct answer is B. Carcinoid tumors are thought to be derived from the glandular endocrine hormone-producing cells, known as enterochromaffin cells, which are widely distributed through the body. They occupy a borderline category between benign and malignant, because only a fairly small percentage of them eventually metastasize, and pathologists are unable, histologically, to tell which ones will or will not. Most of the malignant ones are derived from the small intestine (1/5 metastasize and 1/3 of those cause carcinoid syndrome), and they tend to produce the clinical symptoms of carcinoid syndrome illustrated in the case history only when they have metastasized to the liver. The tumors probably secrete hormones prior to metastasis; the absence of carcinoid syndrome in these patients is attributed to the fact that the venous drainage of the gut passes through the liver via the portal system, clearing the blood of excess vasoactive substances. Also, some of the tumors do not secrete clinically significant amounts of hormones. Serotonin, histamine, and bradykinin are the most common hormones secreted that produce symptoms. Carcinoid tumors are found incidentally in approximately 0.5% of appendectomy specimens; appendiceal carcinoids only rarely metastasize. The tumors may also be a component of the multiple endocrine neoplasia (MEN) syndromes. Tumors that are identified incidentally before metastasis can be cured surgically. No effective chemotherapy or radiotherapy is available for metastatic disease, but the tumors grow so slowly that 10-15 year survival times are not unusual. The somatostatin analog octreotide can help control symptoms.

Endothelial cells (choice A) give rise to vascular tumors such as Kaposi sarcoma and angiosarcoma.

Fibroblasts (choice C) can give rise to a variety of fibromas and fibrosarcomas.

Lymphocytes (choice D) can give rise to leukemias and lymphomas.

Smooth muscle cells (choice E) can give rise to leiomyomas and leiomyosarcomas.

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Abdominal Pain Case 5

2011-01-02T13:40:00.000-08:00

A 17-year-old boy is taken to the emergency department because he has developed severe abdominal pain. The pain began abruptly several hours previously, and was felt initially in the periumbilical region, but later shifted to the right lower quadrant. The boy had initially felt somewhat nauseous, but this has passed. On physical examination, he is noted to have localized pain on cough and to be running a low-grade fever.

Q 1

Examination of the abdomen demonstrates right lower quadrant tenderness at the junction of the middle and outer thirds of the line joining the umbilicus to the anterior superior spine of the iliac. This location is known as which of the following?

/ A. Gubernaculum

/ B. Langer's line

/ C. Linea alba

/ D. McBurney's point

/ E. Tunica albuginea

Q 2

Which of the following is the most likely diagnosis?

/ A. Appendicitis

/ B. Diverticulitis

/ C. Gallstones

/ D. Rectal ulcer

/ E. Renal colic

Q 3

The patient also exhibits an increase in pain in the right lower quadrant from the passive extension of the right hip joint. This finding suggests that the inflammation also involves which of the following?

/ A. BIadder

/ B. External oblique muscle

/ C. Femur

/ D. IIiopsoas muscle

/ E. Transverse abdominal muscle

Q 4

The patient is prepared for immediate surgery. Cefotaxime is administered before, during, and after surgery. The specimen, once removed, is sent to the laboratory for pathology and bacteriologic culture. A malodorous pus surrounds the serosa of the surgical specimen, and a mixed gram-negative flora is cultured. Rapid enzyme tests for beta-Iactamase production are positive. Which of the following drugs should be added to the initial cefotaxime regimen?

/ A. Bacitracin

/ B. CIavulanic acid

/ C. CIindamycin

/ D. Isoniazid

/ E. Vancomycin

Q 5

The patient's postoperative recovery is uneventfuI, but 10 days after discharge, he returns to his physician complaining of continuous low-grade fever. An abscess is drained transrectally, and organisms are cultured from the pus. Which of the following is an attribute of this organism that makes it an important abscess former?

/ A. It is an anaerobe

/ B. It is an intracellular pathogen

/ C. Its endotoxin lacks 2,3-ketodeoxyoctonate

/ D. Mycolic acid

/ E. Prodigious capsule

_____________________________________________________________________

Abdominal Pain Case 5 Answers

The correct answer is D. The point described is McBurney's point, which overlies the location of the appendix in most individuals.

The gubernaculum (choice A) is the fibrous cord that connects the primordial testis or ovary to the anterolateral abdominal wall.

Langer's lines (choice B) are the cleavage lines of the skin.

The linea alba (choice C) is a sheet-like aponeurosis that covers the anterior abdominal wall.

The tunica albuginea (choice E) is a tough fibrous coat that covers the testis.

The correct answer is A. This patient has a typical presentation for appendicitis, and the diagnosis is confirmed by the presence of localized tenderness at McBurney's point.

Diverticulitis (choice B) is usually a disease of middle-aged or older individuals and most commonly affects the left-lower quadrant.

Symptomatic gallstone disease (choice C) causes pain and tenderness in the right upper quadrant.

Rectal ulcer (choice D) causes pain with stool movement, but does not usually produce tenderness identifiable on abdominal examination.

Renal colic (choice E) usually produces flank or lower back pain.

The correct answer is D. This patient has a "positive psoas sign," which is an increase in pain from passive extension of the right hip joint. This maneuver stretches the iliopsoas muscle, which lies behind the appendix and can become secondarily inflamed when the appendiceal inflammation extends through the serosa. The psoas sign is clinically useful in both confirming the appendix as the probable origin of the patient's pain, and indicating that the inflammation is transmural and that the risk of rupture and peritonitis is increased.

The bladder (choice A) is located more medially, and is usually not affected by appendicitis.

The external oblique (choice B) and transverse abdominal (choice E) muscles are in the anterior and lateral abdominal walls, and do not usually become inflamed with appendicitis.

The femur (choice C) is moved during the extension of the right hip joint, but is not the source of the pain.

The correct answer is B. Clavulanic acid is a beta-lactamase inhibitor, which when administered with beta lactam agents, irreversibly binds and inactivates bacterial beta-lactamases, thereby permitting the companion drug to disrupt bacterial cell wall synthesis. Suspected appendicitis is usually treated with prompt appendectomy, since delay is associated with increased risk of potentially life-threatening peritonitis and sepsis.

Bacitracin (choice A) is not correct, since this drug inhibits bacterial cell wall synthesis by binding to and inhibiting the dephosphorylation of a membrane-bound lipid pyrophosphate. Gram-negative bacteria are resistant to this agent, and it would not have a synergistic effect if administered with a third generation cephalosporin.

Clindamycin (choice C) is not correct, because this drug blocks protein elongation by binding to the 50S ribosome. Although it is effective against anaerobic gram-negative bacilli, it would not have a complementary effect when administered with a third generation cephalosporin.

Isoniazid (choice D) is not correct because it inhibits the synthesis of mycolic acids for the cell wall of actively dividing Mycobacteria. It would not be effective in the flora of this patient's gut, nor would it act synergistically with third generation cephalosporins.

Vancomycin (choice E) is not correct because it disrupts cell wall synthesis in growing gram-positive bacteria. It would not be effective against the flora of this patient's gut, nor would it act synergistically with third generation cephalosporins.

The correct answer is E. Prevotella (Bacteroides) is a frequent cause of abscesses in the intestinal tract because it is a normal flora organism and produces a large capsule, which impedes phagocytosis.

Although the genus is anaerobic (choice A), it is not this attribute which causes its formation of abscesses.

Prevotella is extracellular, not an intracellular pathogen (choice B).

Although Prevotella does indeed have this type of endotoxin (choice C), the absence of this molecule decreases the toxicity of the toxin, and does not contribute to its proclivity toward abscess formation.

Mycobacteria, and not other genera such as Prevotella, are known for their long-chain fatty acids (mycolic acids; choice D).

Abdominal Pain Case 4

2011-01-02T13:34:00.000-08:00

A 45-year-old man goes to an emergency department because he is experiencing severe abdominal pain, which is radiating straight through to his back. The pain began several hours after an admitted alcoholic binge, and has not changed in position, although it has become worse.

Q 1

Which of the following would be the most likely cause of this type of pain?

/ A. Acute appendicitis

/ B. Acute hepatitis

/ C. Acute pancreatitis

/ D. Chronic hepatitis

/ E. Myocardial infarction

Q 2

In addition to alcohol use, which of the following is a common predisposing factor for this patient's disease?

/ A. Biliary tract stones

/ B. Duodenal cancer

/ C. Gastric carcinoma

/ D. Kidney stones

/ E. Peptic ulcer

Q 3

Marked serum elevation of which of the following markers would most strongly substantiate the likely diagnosis?

/ A. Acid phosphatase

/ B. Amylase

/ C. Aspartate aminotransferase

/ D. AIkaline phosphatase

/ E. Creatinine kinase

Q 4

The patient has a severe course that requires treatment in an ICU. CIinically, he appears similar to patients with sepsis, with fever, elevated white count, hypotension, increased pulse rate, shallow and rapid breathing, oliguria, and a blunted sensorium, in addition to his pain and abdominal tenderness. These clinical findings are most likely related to which of the following?

/ A. Activation of the inflammatory cascade

/ B. AIcohol withdrawal symptoms

/ C. AIIergic reaction to alcohol

/ D. Drug toxicity effect

/ E. Secondary infection with mixed flora gut bacteria

Q 5

The patient's condition resolves in about two weeks, but he continues to drink after leaving the hospitaI. When seen several years later, he has had a number of similar episodes, and now has chronic severe abdominal pain. CT scan demonstrates a single, smooth-walled, fluid filled space in the tail of the pancreas, which can be reached by the radiologist for CT-guided aspiration with an approach from the back. The fluid aspirated is yellowish, clear, and acellular. Which of the following is the most likely diagnosis?

/ A. Pancreatic microcystic adenoma

/ B. Pancreatic mucinous cystadenocarcinoma

/ C. Pancreatic mucinous cystadenoma

/ D. Pancreatic pseudocyst

/ E. Pancreatic solid-cystic tumor

____________________________________________________________________

Abdominal Pain Case 4 Answers

The correct answer is C. The typical pain described occurs in approximately 50% of patients with acute pancreatitis. Other patients may have milder pain or even, uncommonly, pain first felt in the lower abdomen.

The pain of acute appendicitis (choice A) is often felt first as referred pain near the umbilicus, with tenderness on palpation in the left lower quadrant.

Acute hepatitis (choice B) can cause pain referred to the right shoulder.

Chronic hepatitis (choice D) does not usually cause pain.

Myocardial infarction (choice E) can cause substernal pain and pain radiating to the left shoulder.

The correct answer is A. The overwhelmingly most common predisposing factors for acute pancreatitis are gallstones (more specifically tiny ones that lodge in the extrahepatic bile duct system) and alcohol abuse.

Rarely, nearby cancers (choices B and C) can occlude the pancreatic duct system and cause a secondary acute pancreatitis.

Kidney stones (choice D) have no relationship with pancreatitis.

Peptic ulcers (choice E) that erode into the pancreas can uncommonly secondarily inflame the pancreas

The correct answer is B. The usual markers for pancreatitis are amylase and lipase. Marked elevation of amylase usually means either pancreatic disease or salivary gland disease; lipase will be elevated in pancreatic disease but not salivary gland disease. If you see elevated amylase on a USMLE question, you should think of pancreatitis or salivary gland disease (mumps, salivary gland stone). However, you should be aware, for your general medical knowledge, that modest elevations of amylase can be seen in a much wider variety of settings (often reflecting either subclinical pancreatic damage or hemoconcentration of pancreatic enzymes), including GI obstruction, mesenteric thrombosis and infarction, macroamylasemia (a genetic condition with abnormal amylase), renal disease, ruptured tubal pregnancy, lung cancer, acute alcohol ingestion, and following abdominal surgery.

Associate acid phosphatase (choice A) with diseases involving the prostate and, to lesser degrees, bone, the heart, platelets, and the liver.

Associate aspartate aminotransferase (choice C) with diseases of the heart, muscle, liver, pancreas (though not as important for diagnosis as amylase and lipase), and brain.

Associate alkaline phosphatase (choice D) with diseases of bone, liver, and to lesser degrees, lung and heart.

Associate creatinine kinase (choice E) with diseases of the heart, muscle, brain, and the general body (trauma, surgery).

The correct answer is A. Acute pancreatitis can either be relatively mild, or a severe condition that may cause death. It is thought that, in severe cases, leakage of enzyme-containing pancreatic secretions into the tissues/and or blood stream causes cleavage of precursors, thus strongly activating the complement and inflammatory cascades. These, in turn, produce abundant cytokines, which worsen the symptoms. The clinical result is similar to sepsis, with risk of multi-organ failure and death. The treatment of acute pancreatitis is primarily supportive, and may include careful attention to fluid resuscitation, oxygen supplementation, cardiovascular support, dialysis, management of electrolyte abnormalities, pain control, and total parenteral nutrition.

Alcohol allergy (choice C) or withdrawal (choice B) do not play any additional part in most of these symptoms once the pancreatitis has developed.

Infection (choice E) and drug toxicity (choice D) are also not a necessary part of the clinical picture, although physicians may worry that the patient's general clinical status is masking other, potentially more treatable, problems.

The correct answer is D. Pancreatic pseudocyst is a fairly common complication of both acute and chronic pancreatitis, and appears to develop when trapping of pancreatic digestive juices (containing amylase, lipase, and proteases) causes a "digestion" of part of the pancreas, leaving a fluid filled cystic space. The term "pseudocyst", rather than "cyst", is used by purists because the space does not have an epithelial lining, and is hence not a "true cyst". Pseudocysts are usually solitary and typically measure 5-10 cm in diameter. They can be surgically excised (and the surrounding tissue will typically show evidence of chronic pancreatitis in long-standing cases) or sometimes, if the anatomy is favorable, drained into adjacent hollow viscera. Some are medically managed if small.

Most true neoplasms of the pancreas contain (often large numbers of) smaller, multiple, cysts. These tumors can be benign or malignant, and the ones with mucus-secreting epithelium (choices B and C) are more common than those with a serous lining (choices A and E).

Abdominal Pain Case 3

2011-01-02T13:29:00.000-08:00

A 64-year-old man with a history of coronary artery disease (CAD) comes to the emergency department with the acute onset of severe, constant, Lower abdominal pain and rectal bleeding. He reports that he previously has had several episodes of similar, but less severe pain.

About 12 hours after the onset of pain, the patient began passing copious bright red blood per rectum. He denies nausea, vomiting, sick contacts, or foreign traveI. Initial physical examination reveals a distressed man, who is afebrile, but tachypneic, with scant diffuse abdominal tenderness to palpation. Rectal examination is positive for blood. Laboratory studies reveal a metabolic acidosis with an elevated serum Iactate.

Q 1

Which of the following is the most likely diagnosis?

/ A. Colon carcinoma

/ B. Infectious colitis

/ C. Inflammatory bowel disease

/ D. Ischemic colitis

/ E. Necrotizing enterocolitis

Q 2

The lactate produced from the anaerobic metabolism in the infarcted gut will likely be which of the following?

/ A. Exhaled as a fruity odor

/ B. Incorporated into glycogen in the liver

/ C. Incorporated into myoglobin in muscle

/ D. Incorporated into urea in the urine

/ E. Secreted by the kidneys unchanged

Q 3

If this patient's disease were drug-induced, which of the following agents would most likely be responsible?

/ A. Acetaminophen

/ B. Amiodarone

/ C. Cocaine

/ D. Dexamethasone

/ E. Nitroglycerin

Q 4

While the patient is in the emergency department, the pain becomes increasingly severe. Several hours after his initial examination, the patient becomes febrile and is now exquisitely tender to palpation. He writhes in pain when the physician jostles the bed. Air is seen under the diaphragm in an upright chest x-ray film. These new findings suggest which of the following?

/ A. Abdominal aortic aneurysm

/ B. Bowel obstruction

/ C. Cholecystitis

/ D. Hypovolemia

/ E. Perforation with peritonitis

Q 5

Upon surgical exploration of the abdomen, the colon is dull and dusky from the mid transverse colon to the rectum. The patient has occluded

which of the following vessels?

/ A. Celiac trunk

/ B. Cystic artery

/ C. External iliac artery

/ D. Inferior mesenteric artery

/ E. Superior mesenteric artery

____________________________________________________________________________

Abdominal Pain Case 3 Answers

The correct answer is D. A patient with severe abdominal pain and rectal bleeding with an unremarkable physical examination is likely suffering from ischemic colitis. "Pain out-of-proportion to examination" is a classic finding for ischemic colitis. The previous episodes of less severe pain represent ischemic angina. An infarction has occurred, as indicated by the rise in serum lactate secondary to the colon's anaerobic metabolism. The history of coronary artery disease also suggests this diagnosis, as the atherosclerotic processes that contribute to his CAD are also likely present in his abdominal vasculature.

Colon cancer (choice A) would produce less acute symptoms, but occasionally, colon cancer may present acutely with obstructive symptoms. Patients may have bleeding and abdominal pain, but the pain is typically intermittent and accompanied by nausea, vomiting, abdominal distention, and absence of flatus.

Infectious colitis (choice B) is incorrect. While patients may have bleeding and abdominal pain, nothing in the history suggests a disease of infectious origin (no sick contacts or foreign travel). The acute onset also suggests a vascular event, rather than an infectious one.

Inflammatory bowel disease (IBD) (choice C) is incorrect because while the patient reports previous episodes, an elderly man with IBD would likely have a chronic history of abdominal pain and bleeding.

Necrotizing enterocolitis (choice E) affects premature infants and would not be relevant in this setting.

The correct answer is B. Lactate is converted into glucose, and then glycogen in the liver by a process know as the Cori cycle.

Choice A is incorrect, as lactate would not be exhaled. A fruity odor on the breath would be a sign of ketoacidosis.

While some of the carbon from the lactate may be incorporated into peptides via Krebs intermediates (e.g., choice C), the vast majority would be left as carbohydrate.

Urea (choice D) represents a means of eliminating nitrogenous waste.

Choice E is wrong, as the kidneys would retain the lactate, rather than excreting it.

The correct answer is C. Cocaine is a sympathomimetic drug that indirectly acts on both the alpha and beta adrenergic receptors on the vasculature. As such, cocaine may cause vasospasm in the abdominal vasculature leading to infarction and ischemic colitis. Similar vasospastic events may occur in the coronary vasculature, leading to myocardial infarction.

Acetaminophen (choice A) is an analgesic, and would not play a role in producing ischemic colitis.

Amiodarone (choice B) is an antiarrhythmic, and would not contribute to ischemic colitis.

Dexamethasone (choice D) is a steroidal anti-inflammatory drug. Not only would this medication not cause ischemic colitis, it might mask the symptoms due to its potent anti-inflammatory properties.

Nitroglycerin (choice E) is a venodilator, and would not contribute to ischemic colitis. As a venodilator, nitroglycerin is used to treat coronary ischemia by reducing cardiac preload.

The correct answer is E. This patient has experienced a bowel perforation. Air under the diaphragm in an upright chest film provides definitive evidence that a hollow viscus has ruptured. Air near the liver on a left lateral decubitus (patient lays with the left side down) is an alternative study to demonstrate perforation. Spillage from the perforated bowel has irritated and inflamed the peritoneum, resulting in peritonitis. Symptoms of peritonitis include extreme, sharp pain exacerbated by jostling (patients often report that the bumpy ride to the emergency department caused extreme pain). Patients will be exquisitely tender to palpation and percussion and may have abdominal rigidity. Fever typically accompanies peritonitis.

While an abdominal aortic aneurysm or AAA (choice A) presents as acute abdominal pain, this pain is described as tearing and may radiate to the back. A pulsatile abdominal mass may be palpated. The air on the chest film is also inconsistent with AAA.

This patient does not have bowel obstruction (choice B). Signs and symptoms of bowel obstruction include: nausea, vomiting, intermittent abdominal pain, hypovolemia, abdominal distention, absence of flatus, and a "step ladder" bowel pattern on abdominal films.

Cholecystitis (choice C) typically presents as right upper quadrant (RUQ) pain, fever, and jaundice. Patients usually have a history of colicky RUQ pain.

While the patient is at risk for hypovolemia (choice D), none of the symptoms listed typify hypovolemia. Signs and symptoms of mild to moderate hypovolemia include malaise, dry mouth, thirst, decreased skin turgor, tachycardia, hypotension, and decreased urine output.

The correct answer is D. The inferior mesenteric artery distributes blood to the embryologic hindgut. This includes the distal 1/3 of the transverse colon to the rectum. The rectum is spared because it receives circulation from the inferior rectal artery (not mesenteric).

The celiac trunk (choice A) supplies the embryologic foregut. The first three branches include the splenic artery, the left gastric artery, and the common hepatic artery. This patient has no findings in this distribution.

The cystic artery (choice B) supplies the gall bladder. There are no gall bladder findings in this case.

The external iliac artery (choice C) gives rise to the vessels of the lower extremity. Symptoms of occlusion or stenosis might include buttock and thigh pain exacerbated by walking. Severe stenosis might give patients buttock and thigh pain, even at rest.

The superior mesenteric artery (choice E) supplies the embryologic hindgut. This extends from the duodenum to the proximal 2/3 of the transverse colon

Abdominal Pain Case 2

2011-01-02T13:17:00.000-08:00

A 47-year-old woman presents to the emergency department with cra mping/colicky abdominal pain. The current episode of pain began several hours ago, following a fatty meaI. The pain began slowly, and rose in intensity to a plateau over the course of several hours. The patient reports that she had had several other episodes of similar pain during the past several months, with long intervening periods of freedom from pain. On physical examination, she is noted to have tenderness to deep palpation in the right upper quadrant of the abdomen near the rib cage. The patient also reports that she is experiencing shoulder/back pain at a site she identifies near the right lower scapula, but no tenderness can be elicited during the back and shoulder examination.

Q 1

Which of the following organs is the most likely source of this woman's pain?

/ A. Appendix

/ B. Diaphragm

/ C. Esophagus

/ D. Gallbladder

/ E. Stomach

Q 2

Which of the following techniques would be most appropriate to demonstrate the patient's most likely diagnosis?

/ A. Colonoscopy

/ B. CT scan of the abdomen

/ C. Esophagoduodenoscopy

/ D. MRI scan of the abdomen

/ E. UItrasonography

Q 3

Following appropriate diagnostic studies, the patient is taken to the surgical suite. During the surgery, the surgeon inserts his fingers from

right to left behind the hepatoduodenal ligament. As he does so, his fingers enter which of the following?

/ A. Ampulla of Vater

/ B. Common bile duct

/ C. Epiploic foramen

/ D. Greater peritoneal sac

/ E. Portal vein

Q 4

During the cholecystectomy, the surgeon ligates the cystic artery. This is typically a branch of which of the following?

/ A. Gastroduodenal artery

/ B. Left gastroepiploic artery

/ C. Right gastroepiploic artery

/ D. Right hepatic artery

/ E. Superior pancreaticoduodenal artery

Q 5

Pathologic examination of the specimen removed by the surgeon demonstrates the presence of numerous yellow stones (shown above).

These are most likely composed primarily of which of the following?

/ A. Bilirubinate

/ B. Calcium phosphate

/ C. Cholesterol

/ D. Cystine

/ E. Struvite

Q 6

If this patient had a small stone lodge near the ampulla of Vater, which of the following complications would be most likely to occur?

/ A. Crohn disease

/ B. Diabetes mellitus

/ C. Pancreatitis

/ D. Peptic ulcer

/ E. Polyarteritis nodosa

Q 7

If this patient had refused surgical treatment, which of the following would be the most appropriate pharmacotherapy to provide definitive

treatment and thereby relieve associated pain?

/ A. Ampicillin

/ B. CIofibrate

/ C. Meperidine

/ D. Oxycodone

/ E. Ursodiol

_____________________________________________________________________

Abdominal pain Case 2 Answers

The correct answer is D. This woman most likely has gallstones. Cholelithiasis, or the formation of calculi (gallstones) within the gallbladder, is very common in the United States, with over 500,000 cholecystectomies being performed yearly. While many cases of gallstone disease are symptomatic, right upper quadrant pain with referral of the pain to the lower right scapula should specifically suggest gallbladder disease. The pattern of episodes of several hours of pain followed by long periods of freedom from pain is also typical of symptomatic gallstone disease.

The appendix (choice A) would most likely cause lower abdominal pain.

Pain from irritation of the diaphragm (choice B) can cause right upper quadrant pain and referred pain in the supraclavicular area (rather than the subscapular pain of biliary colic). The absence of right upper quadrant tenderness to palpation, and the history of pain after a fatty meal also argue against this diagnosis.

Esophageal pain (choice C) related to regurgitation of gastric contents (heartburn) can occur postprandially, but tends to radiate into the neck, throat, or even face.

Peptic ulcer pain of gastric origin (choice E) is usually described as causing burning, gnawing, or hunger, and may be relieved by eating.

The correct answer is E. Real-time ultrasonography, with 98% sensitivity and 95% specificity, is considered the method of choice for diagnosing possible gallbladder stones.

Colonoscopy (choice A) and esophagoduodenoscopy (choice C) might be helpful for excluding alternative diagnoses, but would not themselves establish a diagnosis of gallstone disease.

CT (choice B) and MRI (choice D) scans of the abdomen are expensive tests whose use is not warranted, since real-time ultrasonography performs as well or better.

The correct answer is C. The space behind the stomach, hepatoduodenal ligament, and hepatogastric ligament is the omental bursa. This space can be entered by passing through the epiploic foramen of Winslow, as described in the question stem.

The common bile duct enters the duodenum through the ampulla of Vater (choice A).

The hepatoduodenal ligament contains the common bile duct (choice B), the portal vein (choice E), and the hepatic artery.

The greater peritoneal sac (choice D) lies anterior to the stomach and hepatoduodenal ligament.

The correct answer is D. The cystic artery is generally a branch of the right hepatic artery.

The gastroduodenal artery (choice A) is a branch of the (common) hepatic artery.

The left gastroepiploic artery (choice B) is a branch of the splenic artery.

The right gastroepiploic artery (choice C) is a branch of the gastroduodenal artery.

The superior pancreaticoduodenal artery (choice E) is a branch of the gastroduodenal artery.

The correct answer is C. The stones are gallstones, and their yellow color indicates that they are composed of cholesterol. Cholesterol stones are the most common form of gallstones. Risk factors include female sex, multiparity, obesity, increased age (female, fat, forty, and fertile) and North American Indian race.

Bilirubinate (choice A) gallstones, which are usually associated with hemolytic anemias, are less common, brown, rather than yellow, and often faceted.

Calcium phosphate (choice B), cystine (choice D), and struvite (choice E) composition can be seen in kidney stones

The correct answer is C. A small gallstone obstructing the pancreatic outflow is a well-known cause of acute pancreatitis. The other conditions listed are not caused by gallstones

The correct answer is E. The question is asking, "Which of the following will eradicate a gallstone?" When a gallstone is eliminated the pain will subsequently be eliminated. This question is NOT asking, "which of the following is the most appropriate form of pain control?". Ursodiol (ursodeoxycholic acid) is a hydrophilic bile acid that is used to dissolve small (<>

Analgesics and antibiotics, such as ampicillin (choice A), are administered when appropriate, but do not help eradicate the stones.

Clofibrate (choice B) is an antihyperlipidemic that is associated with the development of gallstones. High-risk patients, such as diabetics and the elderly, should be watched closely.

As a side note, if this question were asking: "which of the following is the most appropriate form of pain control in this patient", the most appropriate answer would be meperidine. Meperidine (choice C) is the narcotic of choice since it causes the least amount of spasm of the sphincter of Oddi. In other words, meperidine is preferred over oxycodone (choice D).

Abdominal Pain Case 1

2011-01-02T13:09:00.000-08:00

A 27-year-old woman goes to an emergency room with severe abdominal pain. She had previously experienced similar episodes of pain that Iasted several hours to a few days, but this episode is the most severe. She has also been experiencing nausea, vomiting, and constipation.

The physician is left with the impression that she is agitated and somewhat confused, and an accurate history is difficult to elucidate. The patient is sent for emergency laparotomy, but no pathology is noted at surgery. Following the unrevealing surgery, an older surgeon comments that he had once seen a similar case that was actually due to porphyria.

Q 1

The porphyrias are biochemical abnormalities in which of the following pathways?

/ A. GIycogen degradation

/ B. Heme synthesis

/ C. Lipoprotein degradation

/ D. Nucleotide degradation

/ E. Urea cycle

Q 2

Following the surgery, the decision is made to screen for the porphyrias that cause acute neurovisceral symptoms. Which of the following

tests would be most likely to be used?

/ A. Erythrocyte porphyrins

/ B. Total fecal porphyrins

/ C. Total plasma porphyrins

/ D. Total urinary porphyrins

/ E. Urinary porphobilinogen

Q 3

Which of the following are the three most common forms of porphyria?

/ A. Acute intermittent porphyria, erythropoietic protoporphyria, and porphyria cutanea tarda

/ B. Acute intermittent porphyria, hepatoerythropoietic porphyria, and variegate porphyria

/ C. Congenital erythropoietic porphyria, delta-aminolevulinic acid dehydratase-deficient porphyria, and hepatoerythropoietic porphyria

/ D. Erythropoietic protoporphyria, hereditary coproporphyria, and porphyria cutanea tarda

/ E. Hereditary coproporphyria, variegate porphyria, and X-Iinked sideroblastic anemia

Q 4

This patient is found to have increased levels of both delta-aminolevulinic acid (ALA) and porphobilinogen (PBG) in blood. Follow-up studies demonstrate low PBG deaminase in erythrocytes. AIso, additional history is elicited, revealing that the woman had started a very low carbohydrate diet about one week before being admitted to the hospitaI. Which of the following is the most likely diagnosis?

/ A. Acute intermittent porphyria

/ B. Congenital erythropoietic porphyria

/ C. Erythropoietic protoporphyria

/ D. Porphyria cutanea tarda

/ E. X-Iinked sideroblastic anemia

Q 5

Which of the following drugs would be most likely to induce an attack of abdominal pain in this patient?

/ A. Acetaminophen

/ B. Aspirin

/ C. Barbiturate

/ D. GIucocorticoid

/ E. Insulin

____________________________________________________________________________

Abdominal Pain Case 1 Answers:

The correct answer is B. The porphyrias are a group of rare, related diseases that have in common a block in the heme synthesis pathway. The block is usually partial rather than complete, and thus many of these patients have only intermittent symptoms. Most cases of porphyria present with either a neurovisceral pattern (including both psychiatric symptoms and abdominal pain) or with photosensitive skin lesions. These two patterns are associated with different forms of porphyria.

Associate abnormalities of glycogen degradation (choice A) with the glycogen storage diseases, such as von Gierke disease, Pompe disease, and Forbes disease.

Associate abnormalities of lipoprotein degradation (choice C) with some forms of hyperlipoproteinemia (notably Type I).

Associate abnormalities of nucleotide degradation (choice D) with gout and Lesch-Nyhan syndrome.

Associate abnormalities of the urea cycle (choice E) with congenital hyperammonemia, citrullinemia, and argininosuccinic academia

The correct answer is E. The acute neurovisceral porphyrias are those that tend to present with severe abdominal pain, often accompanied by neuropsychiatric symptoms. The best tests to use for screening of these diseases are urinary porphobilinogen (PBG, either random or 24 hour) and urinary delta-aminolevulinic acid (ALA, either random or 24 hour).

Erythrocyte porphyrins (choice A) are used for follow-up in the photosensitive types of porphyria.

Total fecal porphyrins (choice B) are used for follow-up evaluation after screening tests for either the photosensitive porphyrias or the acute neurovisceral porphyrias are positive.

Total plasma porphyrias (choice C) are useful for first line screening of the photosensitive porphyrias, and are used for further evaluation after screening in the acute neurovisceral porphyrias.

Total urinary porphyrins (choice D) are used for further evaluation after screening for acute neurovisceral porphyries

The correct answer is A. The porphyrias are complex diseases that can easily appear overwhelming. A very useful point to know (both clinically and for the USMLE) is that the three most common forms are acute intermittent porphyria, erythropoietic protoporphyria, and porphyria cutanea tarda. Acute intermittent porphyria tends to present with acute neurovisceral symptoms. Erythrocytic protoporphyria tends to present acutely with painful skin lesions. Porphyria cutanea tarda tends to present with chronic blistering skin lesions. The other types listed in various choices are also porphyrias, but are less common.

The correct answer is A. These laboratory findings are most consistent with acute intermittent porphyria, which is due to PBG deaminase deficiency. Patients usually, but not always, have a deficiency of erythrocyte PBG deaminases. (Some cases have also been described in which the enzyme deficiency is limited to liver.) The condition is an autosomal dominant disorder that typically becomes symptomatic in women after puberty, and then often only if a precipitating event (dieting, use of certain drugs, premenstrual) is also present. Symptoms during the attacks can include abdominal symptoms (pain, nausea, vomiting, constipation, diarrhea, abdominal distension, ileus), which are thought to be due to the effects of this condition on visceral nerves. Other symptoms that may be mediated neurologically include incontinence, urinary retention, tachycardia, diaphoresis, hypertension, muscle weakness, psychiatric symptoms, seizures, and rarely, severe paralysis, respiratory insufficiency, and death. Both intravenous glucose (oral is often inadequate due to poor intestinal function) and exogenous heme supplementation can suppress the heme biosynthetic mechanism, and tend to ameliorate the acute attack. Patients should be cautioned to diet gently, as intense dieting can precipitate attacks.

Congenital erythropoietic porphyria (choice B) is characterized by severe skin blistering that usually begins after birth, pink to dark-brown urine, normal ALA and PBG, and increased porphyrins (primarily uroporphyrin I and coproporphyrin I) in urine, plasma, and erythrocytes.

Erythropoietic protoporphyria (choice C) is characterized by cutaneous photosensitivity that begins early in life and high protoporphyrin in erythrocytes and bone marrow.

Porphyria cutanea tarda (choice D) is characterized by photosensitivity with skin blistering, elevated plasma porphyrins, and elevated urine porphyrins (mostly uroporphyrin and heptacarboxylporphyrin).

The very rare X-linked sideroblastic anemia (choice E), due to a deficiency of delta-aminolevulinic acid synthase, can clinically resemble acute intermittent porphyria, and is characterized by elevated levels of urinary ALA and coproporphyrin.

The correct answer is C. Some symptomatic episodes of acute porphyria (including acute intermittent porphyria, hereditary coproporphyria, variegate porphyria, and aminolevulinic acid dehydratase porphyria) are triggered by drug ingestion, and administration of drugs to undiagnosed patients can cause an acute exacerbation of an ongoing attack of acute porphyria. Drugs considered unsafe for use in these patients notably include alcohol, anticonvulsants, barbiturates, many other sedatives, and sulfonamide antibiotics. Of particular concern are the sedative agents, since it may be very tempting to give an obviously agitated patient a sedative to allow easier examination of the patient. Many other drugs are also on the lists of potentially dangerous drugs in these patients. Once the diagnosis is established, the patient should be instructed to always inform her/his physician of her condition, and ask that the safety of drugs prescribed in patients with porphyria be checked. Many of the drugs that can induce or exacerbate an attack of porphyria do so by increasing the activity of the cytochrome P450 system, which indirectly triggers an increase in heme biosynthesis. The other medications listed in the choices are "safe" in these patients.

Gastrointestinal Bleeding case 6

2010-07-01T10:49:00.000-07:00

A 2-year-old child is seen in the emergency department because of bright red blood per rectum. This is the third time this has happened, and on the previous episode, no lesion was identified on colonoscopy. During this visit, the child is scheduled for small bowel barium studies,

which show an outpouching of the distal ileum about 2 feet proximal to the cecum.

Q 1

Which of the following is the most likely diagnosis?

/ A. Abnormally located appendix

/ B. Crohn disease

/ C. Diverticulosis

/ D. Meckel diverticulum

/ E. Potter syndrome

Q 2

The prevalence of this patient's anatomic anomaly in the US population is which of the following?

/ A. 2%

/ B. 6%

/ C. 15%

/ D. 40%

/ E. 80%

Q 3

This patient's anatomic anomaly is thought to be embryologically derived from which of the following?

/ A. Mesonephric duct

/ B. Mullerian duct

/ C. Paramesonephric duct

/ D. Vitelline duct

/ E. Wolffian duct

Q 4

Which of the following is the most common type of ectopic tissue seen in this patient's anatomic anomaly?

/ A. Endometrial tissues

/ B. Gastric mucosa

/ C. Jejunal mucosa

/ D. Pancreatic tissue

/ E. Rectal mucosa

Q 5

The ulceration that was the source of bleeding in this patient is most likely related to acid secretion by which of the following cell types?

/ A. Chief cells

/ B. Mucous neck cells

/ C. Parietal cells

/ D. Surface epithelial cells

/ E. Zymogenic cells

Q 6

The acid-secreting cells are stimulated by which of the following hormones?

/ A. Cholecystokinin

/ B. Gastric inhibitory peptide

/ C. Gastrin

/ D. Secretin

/ E. Vasoactive intestinal polypeptide

Q 7

Stimulation of which receptor on the acid-secreting cell leads to increased acid secretion?

/ A. Epinephrine receptor

/ B. Histamine-1 receptor

/ C. Histamine-2 receptor

/ D. Prostaglandin E2 receptor

/ E. Somatostatin receptor

______________________________

______________________________________

Gastrointestinal Bleeding case 6 answers

The correct answer is D. This patient has a Meckel diverticulum. Meckel diverticula can be asymptomatic through life, or may come to medical attention because of a bleeding peptic ulcer, acute inflammation, rupture, strangulation, or intussusception of the Meckel diverticulum. Diagnosis, as in this case, may be difficult because the ileum is difficult to visualize. In some cases, small bowel barium studies may successfully identify the lesion.

While the appendix (choice A) can have variations in location, these tend to involve the side of the cecum into which it opens. Also, the appendiceal lumen remains narrow in aberrant locations.

Crohn disease (choice B) can involve the distal ileum and cause gastrointestinal bleeding, but would not cause an isolated outpouching of the ileum.

Diverticulosis (choice C) refers to acquired diverticula, and is usually a disease of older individuals.

Potter syndrome (choice E) refers to the cluster of bilateral renal agenesis, oligohydramnios, limb deformities, facial deformities, and pulmonary hypoplasia.

The correct answer is A. The usually cited prevalence for Meckel diverticulum is 2%, although it actually varies from 0.2% to 4%. Many medical students remember five "2s" associated with Meckel diverticulum: 2 inches long, 2 feet from the ileocecal valve, 2% of the population, commonly presents in the first 2 years of life, and may have 2 types of epithelium.

The correct answer is D. The vitelline duct or yolk stalk embryologically connects the midgut to the yolk sac. The duct usually disappears by the seventh gestational week, but if it fails to obliterate, several lesions can be produced, including Meckel diverticulum, a persistent vitelline duct that drains as a fistula through the anterior abdominal wall at the umbilicus, a fibrous band, or a vitelline duct cyst. The other ducts are genital ducts.

The mesonephric (wolffian) duct (choices A and E) develops into seminal vesicles, epididymis, ejaculatory duct, and ductus deferens; the paramesonephric (mullerian) duct (choices B and C) develops into the fallopian tube, uterus, and part of the vagina.

The correct answer is B. Meckel diverticula often have ectopic tissues in them, the most common of which is heterotopic gastric mucosa. The tissues listed in the other choices can also be seen, as well as colonic mucosa.

The correct answer is C. In gastric mucosa, whether in the stomach, or in an ectopic location, it is the parietal cells that secrete acid. This acid secretion is particularly likely to cause peptic ulceration in a Meckel diverticulum or the adjacent ileum, because the secretion of protective mucus is likely to be markedly inadequate in this setting, and the distal small intestinal mucosa is not equipped to handle an acid environment.

The chief cells, also called zymogenic cells (choices A and E) secrete pepsinogen.

The mucous neck cells and surface epithelial cells (choices B and D) secrete mucus.

The correct answer is C. The polypeptide hormone gastrin is secreted by the duodenum and pyloric antrum. Its release is stimulated by the presence of digested protein in the stomach and duodenum. Gastrin stimulates acid secretion from the parietal cells of the gastric glands and pepsinogen secretion from the chief cells.

Cholecystokinin (choice A) is secreted by the endocrine cells of the duodenum and proximal jejunum, and stimulates pancreatic enzyme synthesis and secretion, increases gall bladder emptying, and decreases gastric emptying.

Gastric inhibitory peptide (choice B) inhibits gastrin release and gastric acid secretion, and causes insulin release from the endocrine pancreas.

Secretin (choice D) is produced in the crypts of Lieberkühn of the duodenum, and stimulates pepsinogen secretion from the stomach, and fluid and bicarbonate release from the pancreas.

Vasoactive intestinal polypeptide (choice E) induces smooth muscle relaxation, modifies the composition of pancreatic juice and bile, and inhibits gastric acid secretion and absorption from the intestinal lumen.

The correct answer is C. Acid secretion by parietal cells can be stimulated by the gastrin receptor, the histamine-2 (H2) receptor, and the acetylcholine receptor. Drugs with anti-H2 receptor activity are used to treat peptic ulcer disease. The histamine that stimulates the H2 receptors is probably derived from enterochromaffin cells.

Epinephrine and histamine-1 receptors (choices A and B) do not appear to have a physiologic role in gastric acid secretion.

Substances capable of reducing gastric acid secretion include prostaglandin E₂(choice D), secretin, and somatostatin (choice E).

Gastrointestinal Bleeding case 5

2010-07-01T10:45:00.000-07:00

A 47-year-old, darkly pigmented man with a known history of alcohol abuse begins vomiting large quantities of blood and is brought by ambulance to the emergency department.

Q 1

In the emergency department, the man is found to have a temperature of 36.7 C (98.1 F), blood pressure of 65/40 mm Hg and dropping rapidly, a weak pulse of 130/min, and respirations of 29/min. These vital signs suggest that which of the following is developing?

/ A. Congestive heart failure

/ B. Meningitis

/ C. Pneumonia

/ D. Septicemia

/ E. Shock

Q 2

A blood sample is drawn and an IV Iine is started. While the patient is being cross-matched, the physical examination is continued. The patient's sclerae are noted to be icteric and his nail beds and palms have a yellowish hue. A caput medusa

is noted. Which of the following is the most accurate description of a caput medusa?

/ A. Ecchymoses over the mastoid process

/ B. Paradoxical increase in venous distension and pressure during inspiration

/ C. Reflex movement of the eyes in the opposite direction to that in which the head is moved

/ D. Small bony masses found on the terminal phalanges

/ E. Varicose veins radiating from the area of the umbilicus

Q 3

Caput medusa specifically suggests which of the following diagnoses?

/ A. BIadder infection

/ B. Duodenal ulcer

/ C. Gastric ulcer

/ D. Pancreatitis

/ E. Portal hypertension

Q 4

Which of the following is the most common cause of this patient's disorder in the United States?

/ A. Hepatic cirrhosis

/ B. Hepatic vein thrombosis

/ C. Hepatocellular carcinoma

/ D. Metastatic disease to the liver

/ E. Portal vein thrombosis

Q 5

Endoscopic studies demonstrate that this patient has bleeding esophageal varices, and the bleeding is successfully stopped with

sclerotherapy. What percentage of patients with bleeding esophageal varices have another episode of variceal bleeding at a subsequent

time?

/ A. 5%

/ B. 25%

/ C. 40%

/ D. 70%

/ E. 95%

Q 6

Following blood transfusions and sclerotherapy, the patient initially feels reasonably well and is able to converse with medical personneI. Over

the next 12 hours, while he does not begin to rebleed, his mental status deteriorates. Arterial blood levels of which of the following would be

most helpful in confirming the likely diagnosis?

/ A. Ammonia

/ B. Angiotensin l

/ C. Calcitonin

/ D. Carbon monoxide

/ E. Ceruloplasmin

____________________________________________________________________

Gastrointestinal Bleeding case 5 answers

The correct answer is E. The patient's low and dropping blood pressure, tachycardia, high respiratory rate, and slightly below normal body temperature are all consistent with impending shock. At this point, the other conditions listed in the choices have not yet been ruled out, but clinically, the patient should begin to be immediately treated for the shock, even if the therapeutic workup for underlying conditions must be temporarily deferred

The correct answer is E. Medusa was a goddess with snakes instead of hair on her head. The caput medusa (Medusa's head) is an old term still in fairly common use for numerous varicose veins radiating over the abdomen from the area of the umbilicus.

Choice A describes Battle's sign, which is suggestive of basal skull fracture.

Choice B describes Kussmaul's sign, which is seen in constrictive pericarditis.

Choice C describes the doll's eye sign, which is looked for in the evaluation of comatose patients and suggests functional integrity of the brainstem tegmental pathways and cranial nerves involved in eye movement.

Choice D describes Heberden's nodules, which are seen in osteoarthritis.

The correct answer is E. The caput medusa develops when severe portal hypertension induces dilation of the anastomotic channels between the portal venous system and the systemic venous system, some of which involve the superficial veins near the umbilicus. The other answers are distracters.

The correct answer is A. The overwhelmingly most common cause of portal hypertension in the United States is hepatic cirrhosis, which is usually due to either alcoholism or hepatitis viral infection. In this patient's case, the diagnosis of cirrhosis is further clinically substantiated by his jaundice, as evidenced by his sclera, nail beds, and palms. (Look in these areas on individuals in whom dark skin pigmentation may mask the jaundice generally.) The other entities listed are occasional causes of portal hypertension.

The correct answer is D. Patients who have had one episode of bleeding from esophageal varices have an approximately 70% chance of developing a second incident of bleeding, and one third of these episodes of rebleeding is fatal.

The correct answer is A. Hepatic encephalopathy is seen in end-stage cirrhosis patients, and can either present or worsen in the presence of gastrointestinal bleeding. The blood in the upper gastrointestinal tract behaves essentially as a high protein load, and increases the absorption of ammonia and nitrogen, which cannot be appropriately metabolized by the liver. GI bleeding may also predispose for inadequate renal function secondary to hypotension.

Angiotensin I (choice B) is part of the renin-angiotensin-aldosterone system for blood pressure and sodium ion control.

Calcitonin (choice C) is a hormone secreted by the thyroid, which may be increased in medullary carcinoma of the thyroid.

Carbon monoxide (choice D) increases in the blood in smokers.

Ceruloplasmin (choice E) is a copper-carrying protein monitored in patients with Wilson disease.

Gastrointestinal Bleeding case 4

2010-07-01T10:36:00.000-07:00

A 25-year-old man presents to the emergency department complaining of passing bright red blood per rectum. He reports no prior episodes of gastrointestinal bleeding, but he has had occasional lower abdominal pain and diarrhea for the past ten months. He reports a 7 kg weight Ioss since the onset of these symptoms. He denies sick contacts. On examination, he is febrile with moderate, diffuse abdominal pain to palpation and percussion. Rectal examination is positive for blood.

Q 1

Which of the following is the most likely diagnosis?

/ A. Chronic pancreatitis

/ B. Duodenal ulcer

/ C. Infectious colitis

/ D. Inflammatory bowel disease

/ E. Ischemic colitis

Q 2

A colonoscopy is performed and mucosal ulceration with bleeding extending continuously from the rectum to the cecum is seen. The terminal

ileum is spared. Had the terminal ileum been affected, the patient would have been at risk for which of the following conditions?

/ A. Diabetes mellitus

/ B. Folate deficiency

/ C. Iron deficiency anemia

/ D. Kwashiorkor

/ E. Pernicious anemia

Q 3

At colonoscopy the colonic mucosa appears granular, and is ulcerated. Numerous crypt abscesses and pseudopolyps are observed. Which of

the following is the most likely diagnosis?

/ A. Celiac disease

/ B. Clostridium difficile colitis

/ C. Crohn disease

/ D. Rectal diverticulosis

/ E. Ulcerative colitis

Q 4

Several months pass and this patient's symptoms progress. He continues to have frequent bloody diarrhea and abdominal pain. Abruptly, this

patient experiences the acute onset of severe abdominal pain and is taken to the emergency department by friends. In the emergency

department, he is febrile, and his abdomen is rigid, with severe pain to palpation and percussion. Laboratory findings are consistent with

dehydration. Amylase and lipase are normaI. Which of the following most likely explains this patient's new findings?

/ A. Abdominal aortic aneurysm rupture

/ B. Acute pancreatitis

/ C. Bowel perforation and peritonitis

/ D. Sepsis from fulminant infectious colitis

/ E. Severe ischemic colitis

____________________________________________________________________

Gastrointestinal Bleeding case 4 answers

The correct answer is D. Patients with inflammatory bowel disease can present with a variety of symptoms. While ulcerative colitis and Crohn disease patients may have distinct presentations, mixed presentations are common. Distinguishing Crohn disease and ulcerative colitis is difficult, based on clinical findings. Symptoms typical for Crohn disease include: abdominal pain, fever, diarrhea, weight loss, and anal disease. Symptoms typical for ulcerative colitis include: bloody diarrhea, fever, and weight loss.

Chronic pancreatitis (choice A) presents as epigastric pain that radiates to the back, weight loss, and steatorrhea. In many cases, a history of alcoholism is present. Thus the location of this patient's pain and his lower GI bleeding are not consistent with chronic pancreatitis.

Duodenal ulcer (choice B) may present as epigastric pain, and with severe disease, severe bleeding may be present. Patients with duodenal ulcer rarely have diarrhea and weight loss. Thus this diagnosis is unlikely.

Infectious colitis (choice C) presents as abdominal pain and bleeding. Many infectious agents may cause GI bleeding, including Salmonella, Shigella, Campylobacter jejuni, and E. coli. The chronic nature of this patient's complaints and the lack of sick contacts suggests a different diagnosis.

Ischemic colitis (choice E) presents as acute onset of severe abdominal pain often with copious bright red blood per rectum. On examination, they display the classic finding of "pain out of proportion to examination." They are typically elderly patients with a history of atherosclerotic or embolic disease.

The correct answer is E. Pernicious anemia is a hypochromic, megaloblastic anemia that may be associated with neurologic complications. It occurs as a result of a lack of vitamin B 12. The B12/intrinsic factor complex is absorbed in the terminal ileum by active transport. If this patient's ulcerative colitis extended into the terminal ileum, this condition could complicate his disease. Crohn disease almost invariably affects the terminal ileum, and this malabsorptive condition is more common in that setting. Ulcerative colitis usually affects only the colon, but ileal extension has been observed.

Diabetes mellitus (choice A) is an endocrine condition, and is unrelated to the absorptive capacity of the terminal ileum.

Folate (choice B) is absorbed in the proximal small intestine. Ileal involvement would not affect its absorption.

Iron (choice C) is also absorbed in the proximal small intestine. Ileal involvement would not affect its absorption.

Kwashiorkor (choice D) is protein malnutrition. Protein is absorbed throughout the small intestine. Ileal involvement would not affect its absorption.

The correct answer is E. Granular, flat mucosa with ulcers, crypt abscesses, and pseudopolyps are characteristic findings in ulcerative colitis.

Celiac disease (choice A) is a disease of the intestine resulting from a hypersensitivity to the protein gluten. The intestinal mucosa is smooth and atrophic.

Clostridium difficile colitis (choice B) or "pseudomembranous colitis" is a colonic infection seen after extensive antibiotic use, which disturbs the colonic flora, promoting overgrowth of C. difficile. Fibrinous pseudomembranes are seen in the colon at colonoscopy.

Endoscopic evaluation of Crohn disease (choice C) reveals swollen mucosa with transverse fissures and linear ulcers. Biopsy findings demonstrate transmural involvement with granuloma formation.

Diverticula are outpouchings of the intestinal mucosa. They may bleed, or they may become infected, leading to a painful condition, diverticulitis. The findings here do not suggest diverticulosis (choice D).

The correct answer is C. This patient's chronic course with acute exacerbation suggests that this patient has viscus perforation with peritonitis secondary to exacerbation of his ulcerative colitis. The inflammatory processes in ulcerative colitis can be so severe that erosion from inflammation can cause colonic perforation. Bowel contents then leak into the peritoneal cavity, causing peritonitis. Peritonitis is characterized by fever, severe abdominal pain, abdominal tenderness to palpation and percussion, and rigidity of the abdominal wall.

Abdominal aortic aneurysm rupture (choice A) presents as abdominal pain that radiates to the back. It is accompanied by hemodynamic instability that may deteriorate to shock. This presentation is not consistent with findings in this patient.

Acute pancreatitis (choice B) can cause severe abdominal pain and fever. The pain, however is usually epigastric and radiating to the back. Typically nausea and vomiting accompany pancreatitis. Amylase and lipase are elevated.

This patient does not display the symptoms of sepsis (choice D). In sepsis, patients are febrile with hemodynamic instability.

Ischemic colitis (choice E) can lead to perforation and peritonitis, and if the patient had symptomatology consistent with ischemic colitis, it could be the source of this patient's peritonitis. This patient did not report bright red blood per rectum, or "pain out of proportion to examination," making ischemic colitis less likely.

Gastrointestinal Bleeding case 3

2010-07-01T10:31:00.000-07:00

A 55-year-old man with a history of coronary artery disease and alcoholism presents to the emergency department complaining that he vomited bright red blood twice this morning. He denies previous episodes of bleeding or abdominal pain. On examination, he is a malnourished man in acute distress. His blood pressure is 90/50 mm Hg and his pulse is 110/min. His mucous membranes are dry and his sclera are icteric. Abdominal examination reveals a distended abdomen with an enlarged, palpable spleen. Purplish striae are seen around the umbilicus. On rectal examination, Iarge hemorrhoids are seen, but the stool is negative for blood.

Q 1

Which of the following is the most likely diagnosis?

/ A. Erosive gastritis

/ B. Esophageal varices

/ C. Infectious enteritis

/ D. Mallory Weiss tear

/ E. Peptic ulcer disease

Q 2

Which of the following coagulation factors would most likely be unaffected in this patient?

/ A. Factor ll

/ B. Factor VII

/ C. Factor IX

/ D. Factor XIII

/ E. Von Willebrand's factor

Q 3

Which of the following anatomic relationships provides the basis for the patient's hemorrhoids?

/ A. Coronary vein anastomosis with the esophageal plexus

/ B. Inferior rectal vein anastomosis with the iliac vein

/ C. Paraumbilical vein anastomosis with the inferior epigastric vein

/ D. Superior mesenteric vein anastomosis with the splenic vein

/ E. Superior rectal vein anastomosis with the inferior and middle rectal vein

Q 4

Which of the following structures are found in the portal triad?

/ A. Hepatic vein, common hepatic artery, common bile duct

/ B. Portal vein, celiac artery, common bile duct

/ C. Portal vein, common hepatic artery, common bile duct

/ D. Portal vein, falciform ligament, common bile duct

/ E. Portal vein, sinusoids, bile canaliculi

____________________________________________________________________________

Gastrointestinal Bleeding case 3 answers

The correct answer is B. While all of the answer choices listed must be considered in the differential, upper gastrointestinal bleeding from esophageal varices is most likely. This patient displays many of the stigmata of hepatic disease and portal hypertension: icteric sclera, hemorrhoids, distended umbilical veins (caput medusae), and a history of alcoholism. In this setting, esophageal varices would be the most likely. To make this diagnosis definitively, however, one needs to examine the gastrointestinal tract endoscopically.

Erosive gastritis (choice A) is a source of upper gastrointestinal hemorrhage, but it seldom bleeds so profusely that the patient becomes hemodynamically unstable.

Infectious disease in the gastrointestinal tract (choice C) may produce hemorrhage, but it tends to produce lower GI bleeding.

Mallory Weiss tears (choice D) produce upper GI bleeding. This tearing of the gastroesophageal junction occurs in alcoholics, but usually a history of retching precedes bleeding. No such history is elicited here.

Peptic ulcer disease (choice E) can produce brisk upper GI bleeding. It is less likely in this case because this patient has no history of GI pain.

The correct answer is E. Von Willebrand's factor is a coagulation factor produced by the vascular endothelium and megakaryocytes. It is the only protein in the cascade that is not synthesized in the liver. vWF mediates the adhesion of platelets to the vessel wall basement membrane after vascular injury. Patients with a deficiency of von Willebrand's factor have a tendency to bleed. It is an autosomal dominant disease, and the ristocetin cofactor activity test is the best way to clinically assess vWF function.

Factor II (choice A) is produced in the liver. Deficiency is very rare, but can produce spontaneous or posttraumatic bleeding.

Factor VII (choice B) is produced in the liver.Severe factor VII deficiency is a very rare cause of bleeding.

Factor IX (choice C) is produced in the liver. A factor IX deficiency is known as hemophilia B, which is an X-linked disease.

Factor XIII (choice D) is produced in the liver. A deficiency of factor XIII produces delayed bleeding and poor wound healing.

The correct answer is E. The patient's hemorrhoids are a consequence of his portal hypertension. The patient has a cirrhotic liver, which impedes circulation in the portal system. As the pressure rises in the portal system, blood in the portal circulation begins to backflow into the caval circulation. At the sites at which the portal system anastomoses with the caval circulation, venous engorgement occurs. At one such site, the confluence of the superior rectal vein (portal) with the middle and inferior rectal vein (caval), this venous engorgement leads to hemorrhoids.

The coronary vein anastomosis with the esophageal venous plexus (choice A) provides the anatomic basis for the esophageal varices seen in portal hypertension. As pressure builds in the portal system, venous engorgement occurs, and varices are produced in the distal esophagus. These varices can be the site of life-threatening upper GI bleeding.

The anastomosis of the inferior rectal vein with the iliac vein (choice B) is a caval-caval anastomosis and would not be affected by portal hypertension.

The anastomosis of the paraumbilical vein and the inferior epigastric vein (choice C) is the portal-caval anastomosis responsible for the purplish striae or caput medusae seen on this patient's abdomen. This circulatory route is an embryologic remnant, and is only patent when portal pressure rises high enough to re-open this pathway.

The anastomosis of the superior mesenteric vein and the splenic vein (choice D) marks the origin of the portal vein. It may have an elevated pressure, but it is not the basis for hemorrhoids.

The correct answer is C. The portal triad contains the portal vein, common hepatic artery, and common bile duct. It is found in the fold of peritoneum, called the hepatoduodenal ligament, that separates the greater and lesser abdominal sacs.

None of the other choices offer a complete answer:

The hepatic vein (choice A) drains the liver into the inferior vena cava (IVC).

The celiac artery (choice B) supplies blood to the anatomic foregut. One of its branches, the common hepatic artery, travels in the porta hepatis.

The falciform ligament (choice D) is the remnant of the umbilical vein that passes from the anterior abdominal wall to the superior surface of the liver.

Bile canaliculi (choice E) are microscopic channels that drain bile from the hepatocytes.

Gastrointestinal Bleeding case 2

2010-07-01T10:26:00.000-07:00

A 9-day-old baby is noted to be lethargic and has been feeding poorly. Over the next day, the baby develops bilious vomiting, a distended tender abdomen, and bloody stools.

Q 1

Which of the following diseases would most likely cause gastrointestinal bleeding in a neonate?

/ A. Crohn disease

/ B. Cystic fibrosis

/ C. Diverticulitis

/ D. Necrotizing enterocolitis

/ E. UIcerative colitis

Q 2

Which of the following is considered the most important risk factor for this patient's disease?

/ A. Perinatal asphyxia

/ B. Polycythemia

/ C. Prematurity

/ D. Respiratory distress syndrome

/ E. Shock

Q 3

A plain radiograph of the abdomen demonstrates gas within the bowel walI (pneumatosis). Which of the following would most likely be

associated with this finding?

/ A. Air in the biliary tract

/ B. BIood in the biliary tract

/ C. Gas in the hepatic veins

/ D. Gas in the mediastinum

/ E. Gas in the portal vein

Q 4

The baby's condition continues to deteriorate, and the decision is made to surgically resect the affected GI segment. Resection of which of the

following areas of the gastrointestinal tract would most likely produce severe long-term malabsorption?

/ A. Ascending colon

/ B. Duodenum

/ C. Jejunum

/ D. Stomach

/ E. Terminal ileum

Q 5

The baby's resected gastrointestinal segment would be most likely to show which of the following on pathologic examination?

/ A. Distended macrophages with PAS-positive granules in the submucosa

/ B. Gangrenous intestinal wall

/ C. Granuloma formation

/ D. Neoplastic epithelial proliferation

/ E. Outpouching of intestinal mucosa through the muscular layer

____________________________________________________________________

Gastrointestinal Bleeding case 2 answers

The correct answer is D. Necrotizing enterocolitis is a feared complication of infancy. It has an incidence of 1 to 5% in neonatal intensive care unit admissions. The condition is a necrotizing disease of the small intestine, and sometimes, the colon. The pathogenesis is still not clear, but may involve an ischemic insult leaving the bowel susceptible to bacterial overgrowth. Necrotizing enterocolitis may develop suddenly, with features suggesting neonatal sepsis, or more slowly, over a period of one or two days. The case description illustrates typical features.

Crohn disease (choice A) and ulcerative colitis (choice E) may present as early as in the teenage years, but not usually in infancy.

Cystic fibrosis (choice B) is a cause of meconium ileus and later malabsorption, but does not typically present with gastrointestinal bleeding.

Diverticulitis (choice C) is usually a disease of middle-aged to older adults.

The correct answer is C. Prematurity is the most important risk factor for necrotizing enterocolitis, although term infants also sometimes develop the condition. Clinical series have reported that between 60 and 95% of affected babies are premature, and the incidence is markedly increased in babies born at lower gestational ages.

Many other purported risk factors have also been cited but seem to have a lesser effect, including perinatal asphyxia (choice A), respiratory distress syndrome (choice D), umbilical catheterization, hypothermia, shock (choice E), patent ductus arteriosus, cyanotic congenital heart disease, polycythemia (choice B), thrombocytosis, anemia, exchange transfusion, congenital GI anomalies, chronic diarrhea, non-breast milk formula, nasojejunal feedings, hypertonic formula, and colonization with necrogenic bacteria. It may simply be that any already fragile baby, particularly if premature, who has other significant underlying disease, is at increased risk for developing necrotizing enterocolitis.

The correct answer is E. Portal venous gas is seen in association with pneumatosis intestinalis, most commonly with necrotizing enterocolitis. The physiology of this is that the portal vein, via the mesenteric veins, drains nutrient-rich blood from the gut to the liver. In the case of necrosis with air in the bowel wall, air migrates into the portal venous system and to the liver. On CT, this has the characteristic appearance of peripheral lucencies following the portal venous system intrahepatically. In cases of more severe pneumatosis, the bowel may rupture and lead to pneumoperitoneum.

Note: Although this item may have seemed difficult, it was, in essence, a straightforward pathophysiology question, i.e., "Where would gas in the wall of the intestine go?" The distracter explanations give additional information concerning the radiographic appearance of the other conditions (the following will most likely NOT be tested on Step I of the USMLE).

Pneumobilia, or air in the biliary tract (choice A), would be seen after instrumentation of the biliary system, such as after an endoscopic retrograde cholangiopancreatogram (ERCP). Other causes include a gas-forming infection within the biliary tree or previous sphincterotomy (endoscopic opening of the sphincter of Oddi). Pneumobilia has a distinct appearance on CT: there is gas located centrally in the liver within the ducts.

Hemobilia, or blood in the biliary tract (choice B), would be seen after instrumentation of the biliary system, such as after an endoscopic retrograde cholangiopancreatogram (ERCP), from a biliary or hepatic tumor, or secondary to a hypocoagulable state. Hemobilia is found at endoscopy, and is generally not visible on plain radiographs. High attenuation material may be seen within the bile ducts on a CT scan, suggesting hemobilia.

Hepatic venous gas (choice C) would not be seen with pneumatosis because the hepatic veins drain the liver into the inferior vena cava (IVC). Gas from the bowel wall gets trapped in the portal veins and does not traverse the liver to get into the hepatic veins.

Pneumomediastinum (choice D) is usually from thoracic trauma causing rupture of the esophagus or pneumothorax. Gas within the soft tissues of the head and neck may dissect to the mediastinum. Rarely, pneumoperitoneum may lead to secondary pneumomediastinum. Pneumatosis without pneumoperitoneum would not lead to pneumomediastinum.

The correct answer is E. Babies with early necrotizing enterocolitis are sometimes successfully managed medically with fluids, bowel rest, and correction of anemia and thrombocytopenia that may have developed secondary to the gastrointestinal bleeding. Surgical resection may be necessary in more severe cases of necrotizing enterocolitis, but may have a mortality of 30-40% in these deathly ill infants. Unfortunately, necrotizing enterocolitis most often affects the terminal ileum, which is also the site most necessary to prevent long-term malnutrition. In practice, more than 50% of the bowel must usually be removed before substantial malabsorption occurs. The ileum is the site that is most active in nutrient (particularly fats) absorption, vitamin B12 absorption, and conjugated bile salt absorption.

The ascending colon (choice A) is good at absorbing water and has a small capacity for absorbing carbohydrates.

The duodenum (choice B) and jejunum (choice C) are also important absorptive sites, but are less of a long-term problem because the ileum appears to usually have the capacity to replace their absorptive function after proximal small intestine resection.

Nutrient absorption does not usually occur in the stomach (choice D).

The correct answer is B. The intestinal wall in early necrotizing enterocolitis shows edema, hemorrhage, and necrosis. In more advanced disease, gangrenous necrosis of the full bowel thickness is seen, and necrotic inflammatory debris may adhere to the mucosal surface. Some cases show evidence of reparative change, such as epithelial regeneration and granulation tissue formation, suggesting that the lesion may have evolved over several days before becoming clinically obvious.

Choice A is a feature of Whipple disease.

Choice C is a feature of Crohn disease.

Choice D is a feature of colonic polyps and cancers.

Choice E is a feature of diverticulitis.

Gastrointestinal Bleeding case 1

2010-07-01T10:19:00.000-07:00

A 60-year-old man comes to the emergency department complaining of bright red blood per rectum. The bleeding began abruptly several hours prior to his visit. He has light-headedness when he stands up rapidly, but has no abdominal pain, cramping, fever, nausea, or vomiting. He has no history of previous episodes of bleeding or abdominal pain, but has a history of coronary artery disease and takes aspirin as a "blood thinner." He is afebrile, slightly hypotensive and tachycardic, but stable. On examination, he has decreased skin turgor, and dry mucous membranes. He has no abdominal tenderness. Rectal examination is positive for gross blood.

Q 1

Which of the following is the most likely diagnosis?

/ A. Arteriovenous malformation

/ B. Diverticulitis

/ C. Infectious colitis

/ D. Ischemic colitis

/ E. UIcerative colitis

Q 2

After the patient has stabilized, a colonoscopy is performed to elucidate the origin of the bleeding. Several star-shaped branching vessels

measuring 0.2 to 1.0 cm are seen in the colonic submucosa. BIeeding is stopped by electrocoagulation. A diagnosis of lower gastrointestinal

bleeding is given. Which anatomic landmark demarcates upper gastrointestinal bleeding from lower gastrointestinal bleeding?

/ A. IIeocecal valve

/ B. Ligament of Treitz

/ C. Papilla of Vater

/ D. Pylorus

/ E. Splenic flexure of the colon

Q 3

The aspirin taken by this patient represents a contributor to his condition. Which of the following best describes the mechanism of action of

aspirin?

/ A. Aspirin decreases the serum level of factor VIII

/ B. Aspirin decreases the serum level of factor IX

/ C. Aspirin irreversibly inhibits platelets

/ D. Aspirin irreversibly inhibits thrombin

/ E. Aspirin reversibly inhibits platelets

/ F. Aspirin reversibly inhibits thrombin

Q 4

Which of the following is an important mechanism in short-term blood pressure maintenance?

/ A. BIood pressure regulation occurs slowly by endocrine mechanisms only

/ B. Decreased stretch in the carotid bodies decreases sympathetic and increases parasympathetic discharge to the heart

/ C. Decreased stretch in the carotid bodies increases sympathetic and decreases parasympathetic discharge to the heart

/ D. Decreased stretch in the carotid sinus decreases sympathetic and increases parasympathetic discharge to the heart

/ E. Decreased stretch in the carotid sinus increases sympathetic and decreases parasympathetic discharge to the heart

Q 5

Normal saline is administered to this patient and his blood pressure and heart rate normalize. One of the goals in fluid resuscitation is to

optimize cardiac parameters according to Starling's Law. Starling's Law describes which of the following?

/ A. The relationship between end diastolic volume and contractility

/ B. The relationship between heart rate and stroke volume

/ C. The relationship between preload and afterload

/ D. The relationship between stroke volume and end systolic volume

/ E. The relationship between systemic vascular resistance and cardiac output

____________________________________________________________________________

Gastrointestinal Bleeding case 1 answers

The correct answer is A. Painless hematochezia or bright red lower GI bleeding can come from many sources. While bright red lower GI bleeding tends to indicate lower GI bleeding (bleeding distal to the ligament of Treitz), brisk upper GI bleeding can also be the source. The clinical manifestations of such bleeding range from negligible to hemodynamic instability, depending upon the rate of bleeding. The differential diagnosis for painless hematochezia includes AV malformations, gastric erosions, esophageal varices, esophagitis, duodenal or gastric ulcer, hemorrhoids, diverticulosis, and colonic neoplasm.

Diverticulitis (choice B) occurs when a colonic outpouching or diverticulum becomes inflamed. Patients tend to be elderly and present with fever, abdominal pain, and abdominal tenderness on examination. While painful, these lesions do not bleed significantly (unlike their uninflamed counterparts in diverticulosis).

Infectious colitis (choice C) may present as rectal bleeding, but this bleeding is typically accompanied by pain, cramping, and fever. Causative organisms may include Salmonella, Shigella, Campylobacter jejuni, E. coli, and Entamoeba histolytica.

Ischemic colitis (choice D) may have rectal bleeding, but the hallmark of ischemic colitis is severe abdominal pain out of proportion to examination findings.

Ulcerative colitis (choice E) presents as abdominal pain and diarrhea, which may be bloody or nonbloody. In addition, the onset of the disease tends to be earlier, so this patient would likely have had previous episodes of pain

The correct answer is B. The ligament of Treitz, or the peritoneal ligament, which separates the third (retroperitoneal) portion of the duodenum from the fourth (peritoneal) portion of the duodenum, traditionally demarcates upper GI bleeding from lower GI bleeding. Bleeding proximal to this landmark tends to produce melena or black tarry stools. Bleeding distal to this landmark tends to produce hematochezia or red blood per rectum.

The ileocecal valve (choice A) separates the terminal ileum from the cecum.

The papilla of Vater (choice C) is where the pancreatic duct and common bile duct empty into the duodenum.

The pylorus (choice D) is the sphincter separating the stomach from the duodenum.

The splenic flexure of the colon (choice E) marks the transition from transverse colon to the descending colon.

The correct answer is C. Patients with gastrointestinal bleeding must be assessed for anatomic as well as physiologic and pharmacologic sources of bleeding. Aspirin acts as an anticoagulant by irreversibly inhibiting platelets, preventing the formation of a clot by blocking platelet adhesion and aggregation. Since this platelet mass acts as a matrix for fibrin clot formation, blocking platelets prevents clot formation. This mechanism has been utilized in patients with atherosclerotic disease to prevent intravascular clot formation, but may aggravate bleeding conditions such as this.

Aspirin does not decrease the serum level of factor VIII (choice A). Factor VIII deficiency is the pathophysiology behind hemophilia A.

Factor IX deficiency (choice B) is associated with hemophilia.

Aspirin does not inhibit thrombin (choices D and F). Thrombin is the enzyme responsible for cleaving fibrinogen to fibrin.

Aspirin's effects on platelets are not reversible (choice E), and a new population of functional platelets must replace the inhibited platelets before coagulation is fully restored.

The correct answer is E. As blood pressure falls in this patient with hypovolemia, many short term and long term mechanisms work to raise the falling pressure. In the short term, the baroreceptors found in the carotid sinus and aortic arch regulate blood pressure by modulating the autonomic nervous system. As pressure falls in this patient, the baroreceptors sense this change as a decrease in stretch in the vessel walls. Afferent fibers from the baroreceptors then "report" this change to the medullary cardiovascular center. This center responds by increasing sympathetic discharge and decreasing parasympathetic discharge to the heart and resistance vessels. This acts to restore the blood pressure by increasing heart rate, stroke volume, and vascular resistance.

While endocrine mechanisms (choice A) restore mean arterial pressure for the long term, the sympathetic mechanisms outlined above restore pressure toward baseline much more rapidly.

Choices B and C are incorrect. The carotid bodies contain chemoreceptors (not stretch receptors) that detect changes in PO₂, PCO₂, and pH. They restore these parameters to normal by acting through the medullary centers to change heart rate, stroke volume, vascular resistance, and ventilatory parameters.

The decrease in pressure triggers an increase in sympathetic discharge and decrease in parasympathetic discharge (compare with choice D).

The correct answer is A. Starling's law of the heart describes the relationship between end diastolic volume or preload and cardiac contractility. It states that cardiac contractility is maximized at a particular preload. It also states that cardiac contractility declines as the preload is increased or decreased from this optimum. The basis for this principle is that at a particular preload, the myocardium is "stretched" to a point that maximizes the number of actin and myosin units that may interact in a given contraction.

Choice B is incorrect. Heart rate x stroke volume = cardiac output

Choice C is incorrect. Preload is related to end diastolic volume and passive wall tension exerted on the diastolic ventricle.

Choice D is incorrect. End diastolic volume - end systolic volume = stroke volume

Choice E is incorrect. Mean arterial pressure = cardiac output x total peripheral resistance.

Hemoptysis Case 3

2010-06-10T08:26:00.000-07:00

A 53-year-old man consults a physician because he has begun coughing up sputum tinged with fresh blood. He does not initially report any other symptoms to his physician. When his physician comments on his hoarseness and cough, the patient discounts these symptoms and attributes them to his long smoking history. He cannot say when they began or became worse.

Q 1
The chronic hoarseness suggests dysfunction of which of the following?
/ A. Palate
/ B. Pharynx
/ C. Tongue
/ D. Trachea
/ E. Vocal cords

Q 2
Laryngoscopy reveal a fungating tumor of the larynx that is located between the false and true vocal cords. This tumor is in which of the following sites?
/ A. Aryepiglottic fold
/ B. Infraglottic compartment
/ C. Piriform recess
/ D. Supraglottic compartment
/ E. Ventricle

Q 3
Biopsy of the mass demonstrates a malignancy. Which of the following is the most likely diagnosis?
/ A. Adenocarcinoma
/ B. Lymphoma
/ C. Oat cell carcinoma
/ D. Sarcoma
/ E. Squamous cell carcinoma

Q 4
In addition to smoking, which of the following is an accepted risk factor for this patient's tumor?
/ A. Alcohol use
/ B. Cocaine use
/ C. Coffee use
/ D. Marijuana use
/ E. Tea use

Q 5
The patient returns to clinic three weeks after receiving the news that his cancer is inoperable. His wife reports that he has been more withdrawn, eating and sleeping poorly and "just seems to have lost all hope." On examination, the patient moves very little, never makes eye contact, and admits to "some" depressed mood, Ioss of appetite, and sleep disruption. Which of the following symptoms is of most concern regarding his risk of suicide?
/ A. Decreased appetite
/ B. Decreased energy
/ C. Diminished concentration
/ D. Guilty and worthless feelings
/ E. Hopelessness

Q 6
Some patients present with hoarseness due to a tumor at the lung apex that involves a nerve that is a branch of which of the following?
/ A. Accessory nerve
/ B. Glossopharyngeal nerve
/ C. Hypoglossal nerve
/ D. Phrenic nerve
/ E. Vagus nerve

____________________________________________________________________
Hemoptysis Case 3 Answers
A1
The correct answer is E. Hoarseness specifically suggests dysfunction of the vocal cords, which produce the sounds that are then articulated to speech with the pharynx (choice B), palate (choice A), tongue (choice C), teeth, and lips. While vocal cord dysfunction is specifically suggested by hoarseness, the anatomic lesion may or may not be present at the level of the vocal cords. Vocal paralysis may be the result of local tumor or trauma, intracranial lesions affecting the nucleus ambiguus or its supranuclear tracts, and lesions at the base of the skull, neck, or upper portion of the thorax that involve either the vagus nerve or the recurrent laryngeal nerves.
Air from the trachea (choice D) passes into the larynx to reach the vocal cords, but tracheal dysfunction does not produce hoarseness.

A2
The correct answer is E. The interior of the larynx is divided into 3 compartments: the supraglottic compartment (choice D) above the false vocal cords, the ventricle between the false and true vocal cords, and the infraglottic compartment (choice B) below the true vocal cords.
The aryepiglottic fold (choice A) is the upper free border of the quadrangular membrane found in the supraglottic compartment.
The piriform recess (choice C) lies behind the thyroid laminae and the lateral wall of the supraglottic compartment.

A3

The correct answer is E. The epithelial lining of the larynx is squamous epithelium, and the vast majority of cancers of the larynx are squamous cell carcinomas. Squamous cell carcinoma can present with hoarseness, cough, hemoptysis, or difficulty swallowing. If the symptoms develop insidiously (as in the case), the patient may not seek medical attention until late in the course. While very small laryngeal cancers can be treated successfully with surgery and/or radiation, larger ones are much more problematic, in large part because complete resection of the cancer and any lymph node metastases can be difficult to impossible to perform without compromising the many vital neck structures. Patients treated with partial laryngectomy may retain some speech ability. Patients treated with total laryngectomy can often learn to speak again using esophageal speech (gradual belching of air through the pharyngoesophageal junction), a tracheoesophageal fistula (one way valve between the trachea and the esophagus which makes a sound when air is forced across it), or an electrolarynx (sound source held against the neck). With all three techniques, the sound produced is then turned into articulation by the patient's pharynx, palate, tongue, teeth, and lips. The other tumors listed in the choices are very uncommon in the larynx.

A4
The correct answer is A. The only two risk factors that you will need to associate with laryngeal carcinoma are smoking and alcohol use. Cocaine (choice B), coffee (choice C), and tea (choice E) have not been linked to laryngeal cancer.
Marijuana (choice D) has been suggested as a risk factor for oral cancer in a few cases, but a causal association has not been established.

A5
The correct answer is E. Hopelessness is an ominous sign and is associated with a higher risk for suicide.
Decreased appetite (choice A), decreased energy (choice B), and diminished concentration (choice C) are symptoms indicating the presence of a major depressive episode, or are the result of the medical illness.
Guilty and worthless feelings (choice D) are symptoms of depression. They do not predict risk for suicide.

A6
The correct answer is E. The larynx has complex innervation. The vocal cords and most of the area of the larynx below them are supplied by the recurrent laryngeal nerve, which is a branch of the vagus nerve that passes beneath the subclavian artery before returning to the neck to innervate the larynx. From above the larynx, the superior laryngeal nerve arises from the vagus and divides into the internal laryngeal nerve and the external laryngeal nerve. The innervation above the vocal cords is by the internal laryngeal branch of the vagus nerve. The cricothyroid muscle (the only muscle of the larynx not supplied by the recurrent laryngeal nerve) is supplied by the external laryngeal branch of the superior laryngeal, which also branches off the vagus, but which contains motor fibers originally derived from the accessory nerve (choice A).
The glossopharyngeal nerve (choice B) supplies the pharynx.
The hypoglossal nerve (choice C) supplies the tongue.
The phrenic nerve (choice D) supplies the diaphragm.

Hemoptysis Case 2

2010-06-10T08:14:00.000-07:00

A fifty-year-old man presents to his primary care doctor complaining of chronic cough with hemoptysis, weakness, frequent urination, thirst, and a decreased ability to concentrate. Review of systems reveals fever, chills, night sweats, and a twenty-pound weight loss. He has a
seventy pack-year smoking history. On examination, his lungs are clear to auscultation, but neurologic examination reveals global hyporeflexia.
A chest x-ray film reveals a 4-cm hilar non-cavitary opacity in the left lung. Serum electrolytes show K+ = 2.3 mEq/L. Calcium is within normal limits.

Q 1
Which of the following is the most likely diagnosis?
/ A. Adenocarcinoma
/ B. Bronchioloalveolar carcinoma
/ C. Mesothelioma
/ D. Small cell carcinoma
/ E. Squamous cell carcinoma

Q 2
Which of the following substances secreted from the lesion is the most likely cause of this patient's electrolyte disturbance?
/ A. ACTH
/ B. Aldosterone
/ C. Angiotensin ll
/ D. Epinephrine
/ E. PTH

Q 3
As the patient's condition progresses, the patient grows increasingly hoarse. Which of the following is the most likely reason for the patient's hoarseness?
/ A. Enlargement of the mass has severely decreased inspiratory volume.
/ B. Extension of the mass into the larynx
/ C. Impingement on cranial nerve XII
/ D. Impingement on the recurrent laryngeal nerve
/ E. Metastasis into the speech centers of the brain

Q 4
This patient is given cisplatin as part of his chemotherapeutic regimen. Which of the following is a known adverse effect of cisplatin?
/ A. Cardiotoxicity
/ B. Hemorrhagic cystitis
/ C. Nephrotoxicity
/ D. Profound myelosuppression
/ E. Pulmonary fibrosis

Q 5
In addition, this patient is given etoposide. Which of the following best describes the mechanism of action of etoposide?
/ A. Etoposide cross-Iinks DNA
/ B. Etoposide induces single- and double-stranded breaks in DNA
/ C. Etoposide inhibits dihydrofolate reductase
/ D. Etoposide inhibits microtubule formation
/ E. Etoposide inhibits topoisomerase ll

Q 6
The patient has been aware of his diagnosis and prognosis for several weeks now. He makes the statement "I had successes and failures but I'm pretty sure l got as much living out of the last 50 years as anybody could." This statement suggests that the patient is experiencing which of the following of Erikson's stages?
/ A. Ego integrity vs. despair
/ B. Generativity vs. self absorption
/ C. Identity vs. role confusion
/ D. Industry vs. inferiority
/ E. Intimacy vs. isolation

____________________________________________________________________
Hemoptysis Case 2 Answers
A1
The correct answer is D. This patient has classic findings for small cell carcinoma of the lung (also known as oat cell carcinoma). Patients with small cell carcinoma typically present with constitutional symptoms, cough, and hemoptysis. Paraneoplastic syndromes are common with this cancer, and may often be the first symptoms to present. This patient has hypokalemia and many of the symptoms that accompany it: muscular weakness, frequent urination, thirst, and decreased ability to concentrate. This patient's radiographic findings (non-cavitary hilar mass) also support the diagnosis of small cell carcinoma.
Adenocarcinomas (choice A) tend to present as peripheral masses, and paraneoplastic syndromes are rare.
Bronchioloalveolar carcinoma (choice B) is a subtype of adenocarcinoma. It arises from the peripheral airways, and while it can present as a discrete mass, it typically is indistinct radiographically as it grows down the airway surfaces. Again, paraneoplastic syndromes are rare.
Mesothelioma (choice C) is a pleural malignancy associated with asbestos exposure. They do not present as hilar masses. 50% metastasize, but death usually results from local extension. They tend to produce large effusions that may obscure the mass on chest x-ray films.
Squamous cell carcinoma (choice E), like small cell carcinoma, has a strong association with smoking. These tumors may present in a similar fashion, with a more central lung lesion, but paraneoplastic syndromes with squamous cell carcinoma tend to be related to the secretion of a PTH-like substance, resulting in hypercalcemia. Thus the diagnosis of small cell carcinoma is more likely.

A2
The correct answer is A. ACTH is often secreted by small cell lung carcinoma. The clinical results are those seen from uninhibited ACTH secretion: the adrenal gland increases the production of glucocorticoids and mineralocorticoids. Thus, patients experience hypokalemia, hyperglycemia, and hypertension. The chronic sequelae of this process (Cushingoid symptoms) are not usually seen, due to the metabolic demands of the neoplasm and the short survival of affected individuals.
None of the other hormones listed above are commonly secreted by small cell cancers.

A3
The correct answer is D. As seen with many hilar masses, impingement on the recurrent laryngeal nerve produces hoarseness. The recurrent laryngeal nerve courses inferiorly to the aortic arch and then turns superiorly to innervate the intrinsic muscles of the larynx (except the cricothyroid muscle). When this nerve sustains unilateral damage, hoarseness results, as patients have difficulty abducting the vocal cords. Bilateral damage results in acute breathlessness, because both of the vocal cords move to the midline and block the airway.
Enlargement of the mass (choice A) to a size that would affect speech would likely produce pulmonary collapse, not hoarseness.
Extension of the mass from the hilum of the lung to the larynx (choice B) would be unlikely. Many critical structures are in this course, and the patient would likely not survive long enough to become hoarse from direct extension.
Impingement on cranial nerve XII (choice C) would affect movement of the tongue. Not only would metastasis or direct extension to the anatomic site of this nerve be unlikely, this event would not make a patient hoarse.
Metastasis to the speech centers (choice E) would produce more profound speech difficulties. The characteristics of the aphasia would depend upon which speech center is affected ( i.e., fluent vs. expressive aphasia).

A4
The correct answer is C. Cisplatin is a heavy metal compound used in the treatment of small cell carcinoma of the lung. Cisplatin cross-links DNA, though it is not a true alkylating agent. The dominant adverse effect seen with its administration is nephrotoxicity, as it is toxic to both proximal and distal renal tubule epithelium. It produces only modest myelosuppression.
Doxorubicin causes cardiotoxicity (choice A) and congestive heart failure may result.
Cyclophosphamide is a chemotherapeutic agent known to cause hemorrhagic cystitis (choice B).
The myelosuppression with cisplatin is modest. Many other chemotherapeutic agents are known to severely suppress the marrow (choice D).
Bleomycin is known to cause pulmonary fibrosis (choice E).

A5
The correct answer is E. Etoposide acts by inhibiting the enzyme topoisomerase II. Topoisomerases are enzymes that create and repair breaks in DNA during replication. This enzyme is needed to relieve topologic and conformational changes as the DNA is "unzipped" during replication and transcription.
Alkylating agents, such as cyclophosphamide, cross-link DNA (choice A).
The antitumor antibiotics, such as bleomycin, act by inducing breaks in DNA (choice B).
Methotrexate is an antimetabolite chemotherapeutic agent that inhibits dihydrofolate reductase (choice C), an enzyme needed to produce purine nucleotides. Thus the "purine shortage" produced hinders cell replication.
The Vinca alkaloids exert their effects by inhibiting microtubule formation (choice D). Without microtubules, cells cannot mobilize their chromosomes, and thus mitosis is inhibited.

A6
The correct answer is A. In the ego integrity vs. despair stage, individuals reconcile their achievements and failures and face the fact that any human life is limited. Persons completing this task find self-worth in reviewing their life events. Persons stuck at this task cannot admit that time has run out.
Generativity vs. self-absorption (choice B) usually occurs from age 30-65. It involves noting ones contributions as a parent (in the broadest sense) and eventually "passing the torch" to the next generation. Persons stuck in this phase refuse to give up any power to their successors, and maintain ultimate authority without making a place for the next generation.
Identity vs. role confusion (choice C) occurs during adolescence, and is usually defined by emotional and or geographic separation from the actual parents, with an internal identity based on both similarities and differences from parental traits and values.
Industry vs. inferiority (choice D) is a stage in which school age (6-12) children explore peer groups and learn that industry (hard work) generally pays off.
Intimacy vs. isolation (choice E) is the stage, in the early twenties, when young adults connect to their peers and significant others in a meaningful and mature way, putting aside fear and inhibitions.

Hemoptysis Case 1

2010-06-10T07:59:00.000-07:00

A 28-year-old man is evacuated by ambulance from his work to the emergency department of a local hospital after he abruptly develops massive hemoptysis. When seen in the emergency department, he is already hypotensive and requires transfusion to maintain blood
pressure. Emergency department personnel perform intubation with assisted ventilation to maintain his respiratory function. A chest x-ray film shows diffuse bilateral alveolar infiltrates. According to the patient's wife, the man had a number of minor episodes of hemoptysis with blood- tinged sputum during the past year, but discounted them and refused to seek medical attention.

Q 1
Which of the following is the most likely diagnosis?
/ A. Bronchogenic carcinoma
/ B. Goodpasture syndrome
/ C. Idiopathic pulmonary fibrosis
/ D. Pneumonia
/ E. Tuberculosis

The man is admitted to the hospitaI, and during his hospitalization, is also found to have hematuria, proteinuria, red cell casts in the urine, and rising serum creatinine. A hematoxylin and eosin stained section of a renal biopsy is shown above. Which of the following is the most likely diagnosis?

/ A. End-stage renal disease
/ B. Glomerulonephritis
/ C. Kimmelstiel-Wilson nodules
/ D. Pyelonephritis
/ E. Tubulointerstitial nephritis

A second section from the renal biopsy was stained with immunofluorescent antibodies to human lgG (and human complement) with the result shown. Which of the following is most likely the antigen against which the lgG antibody is directed?
/ A. Collagen
/ B. EIastin
/ C. Fibronectin
/ D. Laminin
/ E. Vitronectin

Q 4
The antigenic determinant against which the lgG is specifically directed is located in the C-terminal domain of one peptide chain of the
molecule. The nucleotide sequence encoding this region is known, and a small portion of the intron (Iower case) and exon (UPPER CASE)
sequence of this region is shown below:
c a t t a g G A A C T C T T G
How many amino acids of the this antigen are translated from the in-frame sequence shown?
/ A. 1
/ B. 2
/ C. 3
/ D. 4
/ E. 5

Q 5
Which of the following would be the most appropriate pharmacotherapy for this patient?
/ A. Erythropoietin
/ B. Famciclovir
/ C. Foscarnet
/ D. Isoniazid
/ E. Methylprednisolone

Q 6
Over the next six months, the patient is treated with repeated plasmapheresis. Which of the following is the rationale of this therapy for this patient?
/ A. Decrease blood clotting factors
/ B. Increase hematocrit
/ C. Increase platelets
/ D. Protect against infection
/ E. Reduce circulating autoantibodies

____________________________________________________________________

Hemoptysis Case 1 Answers

A1
The correct answer is B. Goodpasture syndrome is a hypersensitivity disorder of unknown cause that can cause hemoptysis and dyspnea secondary to bleeding from the alveolar capillary bed. The pulmonary hemorrhage may be mild to massive. Most patients, as in this case, are young men.
Bronchogenic carcinoma (choice A) and tuberculosis (choice E) can cause pulmonary hemorrhage, which is usually not massive, but can be excluded because a mass lesion was not seen on chest x-ray.
Idiopathic pulmonary fibrosis (choice C) and pneumonia (choice D) could both cause diffuse pulmonary changes visible on x-ray, but would be unlikely to cause massive hemoptysis.

A2

The correct answer is B. In addition to lung involvement, Goodpasture syndrome is also characterized by severe renal involvement which may precede, coexist with, or follow lung involvement. Renal biopsy characteristically shows rapidly progressive glomerulonephritis with crescent formation in Bowman's spaces.
End-stage renal disease (choice A) with marked scarring of the renal cortex and loss of glomeruli can be seen after many years of kidney disease of many types.
Kimmelstiel-Wilson nodules (choice C) are characteristic of diabetic nephropathy.
Pyelonephritis (choice D) is an infection of the kidney, and can complicate a urinary tract infection or be due to hematogenous dissemination of bacteria.
Tubulointerstitial nephritis (choice E) can be seen with drug reactions and toxins.

A3
The correct answer is A. The photomicrograph shows the linear immunofluorescence characteristic of Goodpasture syndrome. The antigenic determinant in Goodpasture syndrome is on the alpha-3 chain of type IV (basement membrane type) collagen.
Elastin (choice B), fibronectin (choice C), laminin (choice D) and vitronectin (choice E) are all found in the extracellular matrix. These molecules could conceivably be antigenic, but have not been implicated in Goodpasture syndrome.

A4

The correct answer is C. The intron sequence (lower case) is a non-coding region between exons. Therefore, the intron portion of the sequence above (cattag) does not encode any amino acids in the Goodpasture antigen. The 9 nucleotides of the in-frame exon sequence shown (UPPER CASE) would be translated into 3 amino acids (3 nucleotides/amino acid) of the Goodpasture antigen. None of the 3 codons shown (GAA, CTC, TTG) is a stop codon.
If all the nucleotides shown were part of an exon, the sequence would code for only 1 amino acid (choice A) because the second triplet (tag) is a stop codon.

A5

The correct answer is E. Corticosteroids and cyclophosphamide are used to prevent the formation of new antibodies and control the inflammatory response in Goodpasture syndrome. Intravenous administration of corticosteroids, such as methylprednisolone or prednisone, or immunosuppressive therapy with cyclophosphamide is usually carried out for several days.
Erythropoietin (choice A) is a glycoprotein, normally produced in the kidneys, that stimulates red blood cell production. It is indicated for treatment of anemia associated with chronic renal failure, zidovudine therapy in HIV-infected patients, and for cancer patients on chemotherapy. It is contraindicated in patients with uncontrolled hypertension and hypersensitivity to mammalian cell-derived products or to human albumin.
Famciclovir (choice B) is a synthetic acyclic purine nucleoside analog that interferes with DNA synthesis in herpes simplex virus (types 1 and 2) and varicella zoster virus. It is used in the treatment of genital herpes in patients who are not immunocompromised.
Foscarnet (choice C) is an agent that inhibits the replication of all known herpes viruses, including cytomegalovirus, herpes simplex virus (types 1 and 2), human herpesvirus 6, Epstein-Barr virus and varicella zoster virus. This agent is indicated for the treatment of cytomegalovirus (CMV) retinitis, mucocutaneous herpes simplex virus (HSV), and acyclovir-resistant HSV in immunocompromised patients.
Isoniazid (choice D) is an agent indicated for the treatment of all forms of tuberculosis (TB) as well as the prophylaxis of tuberculosis. This agent is associated with the development of severe and sometimes fatal hepatitis. Peripheral neuropathy is the most common side effect seen with isoniazid therapy and is associated with a symmetrical numbness and tingling of the extremities. Pyridoxine administration can treat/prevent this condition.

A6

The correct answer is E. In plasmapheresis, the patient's blood is removed (in small amounts over time). The blood cells are collected and the plasma is discarded, and then the blood cells are resuspended in someone else's plasma before being returned to the patient's body. Plasmapheresis is a very effective, albeit expensive, way of washing autoantibody out of the patient's body, and together with pharmacologic immunosuppression has markedly changed the formerly dismal prognosis of Goodpasture syndrome. Surviving patients often stop producing clinically significant amounts of autoantibody within 12 to 18 months, although some patients may require longer-term immunosuppressive therapy.

Cough Case 5

2010-05-02T15:39:00.000-07:00

A 14-year-old girl receives a bone marrow transplant as part of her treatment for acute lymphoblastic lymphoma. During the period of profound immunosuppression before the marrow engrafts, she develops nonproductive cough, fever, mild hemoptysis, and pleuritic chest pain. A plain chest x-ray film shows a pleuraI-based wedge-shaped lesion with focal cavitation. Open chest lung biopsy reveals necrosis and hemorrhage.
Septate fungal forms with dichotomous 45-degree branching are seen in the necrotic areas and involving the walls of several blood vessels.
When the fungus is cultured, it is found to be a monomorphic fungus.

Q 1

Which of the following is a monomorphic filamentous fungus?

/ A. Aspergillus
/ B. Blastomyces
/ C. Coccidides
/ D. Histoplasma
/ E. Sporothrix

Q 2
Two commonly encountered invasive fungi are Aspergillus and Candidia. In tissue specimens, which of the following features is often helpful in distinguishing these organisms?

/ A. Aspergillus has both hyphae and pseudohyphae
/ B. Aspergillus has budding yeasts
/ C. Aspergillus has germ tubes
/ D. Aspergillus shows dichotomous branching
/ E. Aspergillus shows generally obtuse angles of branching

Q 3

Involvement by this patient's infection of which of the following is considered to have the worst prognosis?
/ A. Brain
/ B. Lung
/ C. Middle ear
/ D. Sinus
/ E. Skin

Q 4
Which of the following is the most appropriate pharmacotherapy for this patient?
/ A. Amphotericin B
/ B. Clotrimazole
/ C. Fluconazole
/ D. Flucytosine
/ E. Griseofulvin

Q 5

Which of the following best describes the mechanism of action of the most appropriate medication for this patient's disease?
/ A. Forms pores in fungal membranes
/ B. Inhibits the demethylation of lanosterol
/ C. Inhibits squalene epoxidase
/ D. Inhibits thymidylate synthase
/ E. Interferes with the synthesis of ergosterol

Q 6

Toxicity to which of the following organs is most likely to limit the administration of the most appropriate medication for this patient's disease?
/ A. Brain
/ B. Heart
/ C. Kidney
/ D. Liver
/ E. Lung

____________________________________________________________________

Cough Case 5 Answers
A1
The correct answer is A. The fungi that cause "deep infections" in humans are subdivided into the dimorphic forms (which, depending upon temperature, can be either yeast forms or hyphal forms) and the monomorphic forms (which grow in the same general form at different temperatures). Of the fungi listed, only Aspergillus is monomorphic. Aspergillus is a common saprophytic mold found on decaying material in the environment throughout the world. It can cause human diseases, including allergic bronchopulmonary aspergillosis (which is essentially an allergic reaction to inhaled Aspergillus conidia or spores), fungus ball (in which the Aspergillus grows without invading in a preexisting cavitary lesion of the lung), invasive aspergillosis (including pneumonia, meningitis, and other systemic infections), and cellulitis. Invasive aspergillosis is most often seen in severely immunocompromised patients with severe neutropenia, notably including those with a history of transplantation, chronic granulomatous disease, and leukemia. This patient's presentation is typical for invasive pulmonary aspergillosis. The other fungi listed (choices B, C, D, and E) are all dimorphic.

A2
The correct answer is D. Aspergillus has hyphae, but not pseudohyphae, budding yeasts, or germ tubes. The branching is dichotomous and at an acute (often about 45 degrees) angle (opposite of choice E).
Characteristics to look for with Candida include both pseudohyphae and true hyphae (choice A), budding yeasts (choice B), and occasionally germ tubes (choice C, better seen with some culture methods).

A3
The correct answer is A. Cerebral aspergillosis is a feared complication of other forms of aspergillosis because most patients die despite appropriate antifungal therapy. Of the other sites listed in the question choices, true invasive infection of the lung (choice B), as opposed to a fungus ball, is considered the most serious site of infection, though less so than infection of the brain.
Middle ear and sinus involvement (choices C and D) become clinically worrisome when dissemination or extension to the brain occurs.
Skin involvement (choice E) is worrisome if dissemination occurs.

A4
The correct answer is A. Amphotericin B is the mainstay of therapy of invasive aspergillosis. This medication has a wide fungicidal spectrum and remains either the drug of choice or the co-drug of choice for severe infections caused by Aspergillus, Candida, Cryptococcus, Histoplasma, Mucor, and Sporothrix. Alternative antifungal agents that are not the preferred therapy but do have some activity against aspergillus include itraconazole, flucytosine (choice D), and voriconazole.
Clotrimazole (choice B) is used topically for candidal and dermatophytic infections.
Fluconazole (choice C) is the drug of choice for esophageal and invasive candidiasis and coccidioidomycosis, and is used for prophylaxis and suppression in cryptococcal meningitis.
Flucytosine (choice D) is also synergistic with amphotericin B in candidiasis and cryptococcosis.
Griseofulvin (choice E) is given orally, but is active only against dermatophytes.

A5
The correct answer is A. The polyene anti-fungal amphotericin B is an amphoteric compound, with both polar and non-polar structural elements, that interacts with ergosterol in fungal membranes to form artificial "pores," which disrupt membrane permeability. Resistant fungal strains are those that appear to have low ergosterol content in their cell membranes. Amphotericin B is given by slow IV infusion and penetrates poorly into the central nervous system (intrathecal injections can be used). It has a half-life of more than 2 weeks and is removed by both metabolism and renal elimination.
Antifungal agents in the azole class (including ketoconazole, fluconazole, and itraconazole) interfere with the synthesis of ergosterol (choice E) by inhibiting the P450-dependent 14-alpha-demethylation of its precursor molecule, lanosterol (choice B).
Flucytosine is activated by fungal cytosine deaminase to 5-fluorouracil (5-FU), which can be incorporated into fungal RNA and can be also used to form 5-fluorodeoxyuridine monophosphate, which in turn inhibits thymidylate synthase (choice D) and the synthesis of thymine.
The anti-dermatophytic drug terbinafine inhibits squalene epoxidase (choice C) and thus decreases ergosterol synthesis (choice E).

A6
The correct answer is C. Nephrotoxicity is most likely to be dose-limiting, and may force amphotericin treatment to end prematurely. This is an important problem, since we have so few drugs with wide spectrum activity against invasive fungal organisms. An amphotericin B lipid complex (ABLC, Abelcet) that may be less nephrotoxic in those patients who cannot tolerate conventional amphotericin is available. Amphotericin B also causes infusion-related reactions including fever, chills, nausea, vomiting, headache, generalized malaise, hypotension, and arrhythmias.
Major problems encountered less commonly than renal toxicity include anaphylaxis, generalized pain, bone marrow toxicity, rash, a variety of cardiac problems including cardiac arrest (choice B), liver failure (choice D), pulmonary edema (choice E), and convulsions (choice A).

Cough Case 4

2010-05-02T15:33:00.000-07:00

A 72-year-old woman presents to the emergency department with cough, fever, and shortness of breath. The woman lives alone at home, but spends part of each day shopping and riding public buses. Approximately 4 days previously she had developed an upper respiratory infection.
Approximately 2 days ago, she abruptly became much more ilI, and her symptoms started worsening, beginning with a single, Iong, shaking chill. Since that time, she has had fever, pain with breathing, cough, and dyspnea. She decided to come to the emergency department when
her temperature at home was 103.4 F. In the emergency department, her temperature is 39.9 C (103.8 F), blood pressure is 90/50 mm Hg, pulse is 120/min, and respirations are 30/min. No breath sounds are heard over her lower left lung field, but they can be heard at other sites.

Q 1

A chest x-ray film would be most likely to demonstrate which of the following:
/ A. A single roughly ovoid white area
/ B. Complete whitening over one lobe of her lungs
/ C. Marked dilation and elongation of bronchial spaces
/ D. Multiple small spotty areas of white found primarily near the bronchi
/ E. No obvious radiologic changes

Q 2
Gram's stain of a smear from a sputum sample demonstrates gram-positive lancet-shaped diplococci in short chains. Which of the following
would most likely be identified after culturing?

/ A. Chlamydia pneumoniae
/ B. Haemophilus influenzae
/ C. Legeonella pneumophila
/ D. Staphylococcus aureus
/ E. Streptococcus pneumoniae

Q 3
Which of the following is thought to contribute to the ability of gram-positive organisms to retain the Gram's stain during the decolorization
process?
/ A. Large periplasmic space
/ B. Presence of capsule
/ C. Presence of outer membrane
/ D. Presence of pili
/ E. Thick peptidoglycan layer

Q 4
Which of the following is a characteristic feature on culture of this patient's organism?
/ A. AIpha-hemolytic colonies inhibited by optochin on blood agar and lysed by bile
/ B. Beta-hemolytic colonies that are bacitracin-resistant on blood agar
/ C. Beta-hemolytic colonies that are inhibited by bacitracin on blood agar
/ D. Catalase-negative organisms that hydrolyze esculin in 40% bile and 6.5% NaCI
/ E. Catalase-positive, coagulase-positive organisms that cause beta-hemolytic, yellow colonies on blood agar

Q 5
At this stage of the disease (two days following onset of first symptoms), and before treatment is started, what are the expected histopathologic findings in the affected lung parenchyma?
/ A. Advanced organization with macrophages and fibroblasts
/ B. Interstitial lymphomonocytic inflammatory infiltration
/ C. Intra-alveolar purulent exudate admixed with erythrocytes
/ D. Resolution of inflammatory exudate with semifluid debris
/ E. Vascular congestion without intra-alveolar exudation

Q 6
The patient's infection is treated with parenteral penicillin, to which she promptly responds. This drug acts by which of the following mechanisms?
/ A. Inhibits bacterial protein synthesis
/ B. Inhibits growth of cell walls
/ C. Interferes with bacteriaI DNA synthesis
/ D. Interferes with folate metabolism
/ E. Punches holes in cell membranes

Q 7
A few minutes after the patient receives the antibiotic therapy, she develops an adverse reaction characterized by an itchy skin eruption and
acute respiratory distress. This reaction is most likely attributable to which of the following mechanisms?
/ A. Antibody-mediated cellular dysfunction
/ B. Complement-dependent reaction
/ C. Delayed-type hypersensitivity
/ D. IgE-mediated mast cell degranulation
/ E. Immune-complex deposition

____________________________________________________________________

Cough Case 4 Answers
A1
The correct answer is B. This patient has lobar pneumonia, which is seen radiologically as a complete whitening of one or more lobes of the lungs.
Choice A describes the appearance of a mass lesion of the lung, such as tumor or tuberculosis
Choice C describes the radiologic changes accompanying bronchiectasis.
Choice D describes the radiologic appearance of bronchopneumonia, rather than lobar pneumonia.
While very early in lobar pneumonia, no obvious radiologic changes may be seen (choice E), this patient's lack of breath sounds over the lower left lung field indicates that her pneumonia is past this very early stage.

A2
The correct answer is E. Streptococcus pneumoniae is the most commonly identified causative organism for bacterial pneumonia. Up to two-thirds of bacteremic community-acquired pneumonias are due to this organism. 5-25% of healthy individuals carry S. pneumoniae in their pharynx. The classic description of S. pneumoniae on Gram's stain is that given in the question stem. S. pneumoniae can be verified by the Quellung reaction, or counterimmunoelectrophoresis to determine serotypes of isolated strains or for case detection using sputum specimens (there are more than 80 distinct serotypes based on studies of capsular antigens).
Chlamydia pneumoniae(choice A) is not identified on the basis of Gram's stain, but rather, can be seen with Giemsa or immunofluorescence.
Haemophilus influenzae(choice B) and Legionella pneumophila(choice C) are gram-negative rods.
Staphylococcus aureus(choice D) is also a gram-positive coccus, but the classic description of this organism typically includes a reference to "grape-like clusters."

A3
The correct answer is E. The peptidoglycan layer in the cell wall of gram-positive organisms is much thicker than that in gram-negative organisms, and is thought to contribute to the gram-positive staining reaction.
A large periplasmic space (choice A) and an outer membrane (choice C) are characteristics of gram-negative cell walls.
Capsules (choice B) can be seen in both gram-positive and gram-negative species.
Pili (choice D) are small hair-like structures that are most often seen in gram-negative organisms.

A4
The correct answer is A. These findings are used to identify Streptococcus pneumoniae. Optochin sensitivity is used to differentiate the viridans streptococci (resistant) from S. pneumoniae (sensitive). Another test used to identify S. pneumoniae is the Quellung reaction. The only medically important optochin-sensitive organism that gives a positive Quellung reaction is S. pneumoniae.
Choice B is seen with Streptococcus agalactiae.
Choice C is seen with Streptococcus pyogenes.
Choice D is seen with Enterococcus faecalis.
Choice E is seen with Staphylococcus aureus.

A5
The correct answer is C. Acute lobar pneumonia has classically been subdivided into four pathologic stages. The initial stage of congestion(choice E) lasts less than 24 hours and is characterized by engorgement of vessels, with intra-alveolar fluid containing few cells, but often, numerous bacteria. Over the following few days, an exuberant intra-alveolar exudate of red cells, neutrophils, and fibrin develops, heralding the stage of red hepatization (choice C; so-called because the lung resembles liver at this stage). During the last half of the first week of illness, the red cells begin to break down, but a fibrinous exudate remains in the alveoli; this is the stage of gray hepatization. If death does not supervene, resolution (choice D) occurs in the second week in untreated cases, with digestion of the exudate to leave semifluid debris that are phagocytized, or coughed up. In some cases, the exudate, rather than resolving in this manner, undergoes further organization (choice A).
An interstitial lymphomonocytic infiltrate (choice B) is characteristic of primary atypical pneumonia, caused by Mycoplasma or viruses.

A6
The correct answer is B. The penicillins and cephalosporins both inhibit cell wall synthesis. Penicillin G is the preferred antibiotic for sensitive strains; 25% of strains are resistant and can be treated with cephalosporins, erythromycin, and clindamycin. Pneumococcal pneumonia can be prevented in a number of cases; the pneumococcal vaccine contains 23 specific polysaccharide antigens found in 85-90% of the serious pneumococcal infections.
Inhibitors of bacterial protein synthesis (choice A) include aminoglycosides, chloramphenicol, macrolides, and tetracycline.
Inhibitors of nucleic acid synthesis (choice C) include fluoroquinolones and rifampin.
Inhibitors of folic acid synthesis (choice D) include sulfonamides, trimethoprim, and pyrimethamine.
Agents that disrupt cell membranes (choice E) include azole and polyene antifungal agents.

A7
The correct answer is D. This patient has had an acute allergic reaction to the antibiotic, which can be further classified as an immediate hypersensitivity reaction. These reactions are mediated in a way similar to hay fever, with preformed IgE binding to the antibiotic antigen, and then the antigen-antibody complex triggering degranulation of mast cells with release of histamine and other active substances. These substances then cause both the itchiness of the skin and the bronchospasm that caused the respiratory distress.
An example of a disease caused by antibody-mediated cellular dysfunction (choice A) is Graves disease, in which antibodies to the TSH receptor cause a non-physiologic chronic stimulation of thyroid epithelial cells.
An example of a complement-dependent reaction (choice B) is hemolytic disease of the newborn.
An example of delayed-type hypersensitivity (choice C) is the tuberculin reaction.
An example of an immune complex deposition disease (choice E) is the vasculitis seen in systemic lupus erythematosus.

Cough Case 3

2010-05-02T15:27:00.000-07:00

A 60-year-old man presents to the emergency department complaining of shortness of breath, cough, and copious sputum production. He states that he has been coughing for years, and has had increased sputum production for several months each year. On examination, he is
obese, afebrile, cyanotic, and in acute distress. Coarse rales are auscultated bilaterally at the lung bases. He smokes two packs of cigarettes a day and has a seventy-five pack-year smoking history. A chest x-ray film appears normal, except for slightly enlarged lung fields.

Q 1

Which of the following is the most likely diagnosis?
/ A. Chronic bronchitis
/ B. Emphysema
/ C. Myocardial infarction
/ D. Pneumonia
/ E. Pulmonary embolus

Q 2
As this patient waits in the emergency department, his condition begins to deteriorate. He turns increasingly blue and an arterial blood gas is drawn. His PO2 is 45 mm Hg, which under normal conditions means that his hemoglobin would be 75% saturated. Which of the following
mechanisms could cause a hemoglobin saturation of less than 75% at this pO2?
/ A. Decreased 2,3-DPG Ievels
/ B. Decreased hemoglobin
/ C. Decrease in body temperature
/ D. Decreased PCO2
/ E. Decreased serum pH

Q 3
Why must care be exercised when administering O2 to this patient?
/ A. Administering O2 washes out alveolar CO2 and inhibits respiration
/ B. Chronic hypoxia alters the blood-brain barrier such that CO2 cannot diffuse into the medullary apneustic center
/ C. Chronic hypoxia induces atrophy in the dorsal respiratory group in the medulla
/ D. Increased PO2 worsens CO2 retention by decreasing respiratory drive
/ E. O2 is acutely toxic to the chronically hypoxic alveolar epithelium

Q 4
The mucus seen in this patient is derived from which of the following cell types?
/ A. Alveolar macrophages
/ B. Goblet cells
/ C. Neuroendocrine cells
/ D. Type l pneumocyte
/ E. Type ll pneumocyte

Q 5
Which of the following spirometry profiles would most likely be seen in this patient?
/ A. Decreased TLC, decreased FEV1
/ B. Decreased TLC, decreased RV
/ C. Decreased TLC, increased FEV1
/ D. EIevated TLC, decreased FEV1
/ E. NormaI TLC, decreased FEV1

____________________________________________________________________

Cough Case 3 Answers

A1
The correct answer is A. This patient has findings classic for the "blue bloater" of chronic bronchitis. Patients with chronic bronchitis have excessive tracheobronchial mucus production sufficient to cause cough with expectoration for at least three months of the year for more than two consecutive years. "Blue bloaters" are named for their obese body habitus, copious sputum production, and cyanotic episodes. This condition may occur initially without airway obstruction, but eventually, most patients progress to obstructive disease.
Patients with emphysema (choice B) represent another form of COPD. They are known as "pink puffers" because they do not become cyanotic until they decompensate. They display a thin body habitus and belabored breathing. This patient is not consistent with the pink puffer of emphysema.
This patient does not have the classic findings for myocardial infarction (choice C), which include: chest pressure or pain, shortness of breath, and/or pain that radiates to the jaw or left arm.
It is unlikely that this patient has pneumonia (choice D). Patients with pneumonia have cough with purulent sputum production, but they are usually febrile and have chest x-ray opacities.
While the diagnosis of pulmonary embolus (choice E) is elusive due to its varied presentations, it is unlikely that this patient has a pulmonary embolus. Findings for PE include pleuritic chest pain, shortness of breath, hemoptysis, and a history of calf pain indicative of deep vein thrombosis.

A2
The correct answer is E. A decrease in pH (an increase in H+ concentration) decreases the affinity of hemoglobin for O2. This facilitates unloading of oxygen from hemoglobin to the tissues. Choices A, C, and D increase the affinity of hemoglobin for O2, and thus cause the Hb to retain the O2.
Choice B is a distracter

A3
The correct answer is D. In a patient with normal respiratory function, the PCO2 and pH of cerebrospinal fluid drives the respiratory center in the medulla oblongata. As serum PCO2 rises, increased CO2 diffuses across the blood-brain barrier. When this CO2 is buffered with the high HCO3- of cerebral spinal fluid, the concentration of H+ rises accordingly. The chemosensitive cells in the medulla's respiratory center respond to this localized decrease in pH by stimulating ventilation. The pH in the CSF returns to nearly normal, more quickly than the renal compensation of the arterial pH, which takes 2-3 days. Patients with chronic CO2 retention will have an abnormally low ventilation for their PCO2 because the pH of their CSF is nearly normal. Therefore, in patients with chronic CO2 retention, arterial hypoxemia becomes their primary ventilatory stimulus. When the patient is given supplemental O2, the PO2 rises, and the hypoxic stimulation disappears, and respiration can become markedly depressed. The PCO2-dependent respiratory drive does not revert immediately, and thus the patient hypoventilates and retains CO2, which may precipitate coma, stupor, or death.
Administering O2 at high flow rates (choice A) may wash out alveolar CO2, but this is not the mechanism for hypoventilation of the chronically hypoxic patient.
Chronic hypoxia does not alter the diffusing capacity of the BBB (choice B).
Chronic hypoxia does not cause the respiratory center to atrophy (choice C).
Chronically high O2 concentrations can damage the alveolar epithelium, but in the acute setting, it does not alter its diffusion capabilities (choice E).

A4
The correct answer is B. In chronic bronchitis, goblet cell hyperplasia is seen in the airways. This hyperplasia, caused by chronic irritation (usually by tobacco smoke), results in increased mucus secretion and formation of mucus plugs. These mucus plugs obstruct the airways, and are responsible for part of the obstructive component of chronic bronchitis. Some degree of loss of elastic recoil of the airways is also seen and further adds to the obstructive component of the disease.
Alveolar macrophages (choice A) do not secrete mucus. They have a phagocytic function.
Neuroendocrine cells (choice C) are present in the respiratory tract. They are the cell of origin for oat cell carcinomas, and the neuroendocrine capabilities of these cells become evident with the paraneoplastic syndromes seen in this high-grade carcinoma.
Type I pneumocytes (choice D) comprise the majority of alveolar epithelium. They provide the majority of the surface area on which gas exchange occurs.
Type II pneumocytes (choice E) secrete the alveolar surfactant that allows alveoli of different diameters to inflate at the same pressure.

A5
The correct answer is E. Patients with chronic bronchitis tend to have normal TLC and decreased FEV1. Patients with chronic bronchitis do not typically have the increased TLC that their counterparts with emphysema have. They may however, have a modestly increased residual volume due to air trapping distal to mucus plugs. Similarly these mucus plugs obstruct the airways, creating the obstructive component of chronic bronchitis. Hence a decreased FEV1 is noted.
Choices A and B are not typical of any common pulmonary disorder.
Choice C is consistent with restrictive lung disease. The increased fibroelastic elements in the lung parenchyma decrease the lung capacity, while allowing the airways to remain open at increasingly lower pressures. Thus, a decreased TLC is seen with an increased FEV1.
Choice D is consistent with emphysema. These patients have destruction of the fibroelastic elements of the lung. As a result, the TLC increases. With decreased elastic tissue, the airways collapse at higher airway pressures, and a decreased FEV1 is seen.

Cough Case 2

2010-05-02T15:19:00.000-07:00

A 70-year-old man is seen by his family practice physician during a routine office visit. The man complains of not feeling well for the last three months. Further questioning reveals that the patient has a chronic, unproductive cough that he attributes to an old smoking history. Physical
examination is notable for a 15-pound weight loss since the last office visit three months previously. A multinodular infiltrate is seen in the lung field behind and above the right clavicle.

Q 1

The patient is injected intradermally with PPD. 3 days after the injection, there is a 13-mm diameter area of induration at the injection site. This reaction is an example of which of the following types of immune response?
/ A. Type l hypersensitivity
/ B. Type ll hypersensitivity, cytotoxic subtype
/ C. Type ll hypersensitivity, noncytotoxic subtype
/ D. Type lll hypersensitivity
/ E. Type IV hypersensitivity

Q 2
Which of the following principally mediates this form of hypersensitivity?
/ A. Cytotoxic T cells, TH1 cells, and macrophages
/ B. IgE, basophils, and mast cells
/ C. IgG and complement
/ D. IgG, IgM, neutrophils, and macrophages
/ E. IgG, IgM, neutrophils, macrophages, and natural killer cells

Q 3
The strongest definitive identification of the pathogen responsible for this patient's disease would be provided by a positive result on which of the following biochemical tests?
/ A. Arylsulfatase
/ B. Heat-stable catalase
/ C. Niacin
/ D. Nitrate reductase
/ E. Urease

Q 4
The mass lesion in the patient's lung is evaluated with fiberoptic bronchoscopy with transbronchial biopsy. Sputum collected after the procedure demonstrates acid-fast bacteria with a "beaded" appearance. Giant cells found in the biopsy material would be likely to express
which of the following membrane markers?
/ A. CD4
/ B. CD8
/ C. CD14
/ D. CD16
/ E. CD19

Q 5

The principal drug recommended for treatment of this patient's disease targets which of the following molecules?
/ A. Arabinogalactan
/ B. Dihydrofolate reductase
/ C. Dihydropteroate synthetase
/ D. Mycolic acid
/ E. Peptidoglycan

____________________________________________________________________

Cough Case 2 answers

A1

The correct answer is E. This patient has a positive PPD test, as indicated by an area of induration greater than or equal to 10 mm. PPD is a purified protein derivative of tuberculin, so this finding indicates that the patient has tuberculosis. The PPD reaction is an example of type IV hypersensitivity, also known as delayed-type hypersensitivity.
Type I hypersensitivity (choice A) is immediate hypersensitivity, and can be seen for example, in hay fever and atopic dermatitis.
Cytotoxic type II hypersensitivity (choice B) can be seen in autoimmune hemolytic anemia and transfusion reactions.
Noncytotoxic type II hypersensitivity (choice C) can be seen in myasthenia gravis and Graves disease.
Type III hypersensitivity (choice D) is due to immune complex deposition, and can be seen in systemic lupus erythematosus and rheumatoid arthritis.

A2

The correct answer is A. Cytotoxic T lymphocytes, T helper 1 lymphocytes, and macrophages mediate the delayed-type hypersensitivity reaction, which develops in response to viral, fungal, and intracellular bacterial antigens. Antibodies do not play a significant role in this type of response.
IgE, basophils, and mast cells (choice B) are involved in the production of type I hypersensitivity.
IgG and complement (choice C) is a mechanism of toxicity in type II cytotoxic hypersensitivity.
IgG, IgM, neutrophils, and macrophages (choice D) may be involved in types II or III hypersensitivities.
IgG, IgM, neutrophils, macrophages, and natural killers (choice E) may be involved in types II or III hypersensitivities.

A3

The correct answer is C. Mycobacterium tuberculosis is the only member of the genus Mycobacterium that is a producer of niacin.
Mycobacterium fortuitum and M. chelonae produce arylsulfatase (choice A), but M. tuberculosis does not.
Heat-stable catalase (choice B) is produced by Mycobacterium kansasii, M. avium intracellulare, and M. fortuitum, but not by M. tuberculosis.
Mycobacterium tuberculosis, M. kansasii, and M. fortuitum produce nitrate reductase (choice D), however niacin is more definitive for the identification of M. tuberculosis.

A4

The correct answer is C. CD14, the endotoxin receptor, is a standard marker for macrophages and cells of their lineage. The giant cells in a TB granuloma are histiocytes, which are modified macrophages, so they would bear macrophage cell markers.
CD4 (choice A) is a cell marker for helper T lymphocytes that would be found in the halo of lymphocytes surrounding the Langerhans giant cells, but would not be on the giant cells themselves.
CD8 (choice B) is a cell marker for cytotoxic T lymphocytes that would be present in the halo of lymphocytes surrounding the giant cells, but would not be on the giant cells themselves.
CD16 (choice D) is a cell marker for NK cells, which would not be on the giant cells in a TB granuloma.
CD19 (choice E) is a cell marker for B-lymphocytes, which are not likely to be present in a TB granuloma, a reaction mediated exclusively by cell-mediated immunity.

A5

The correct answer is D. The mainstay of therapy for tuberculosis is treatment with drugs such as isoniazid, rifampin, ethambutol, ethionamide, pyrazinamide, and streptomycin. Both isoniazid and ethionamide target the mycolic acid molecules in the mycobacterial cell wall. A single drug, usually isoniazid, can be used for chemoprophylaxis and when clinical disease is absent. Multiple drugs are usually used in other settings. Mycobacterium tuberculosis resistant to all first-line drugs is being seen with increasing frequency among AIDS patients.
Arabinogalactan (choice A) is the molecule targeted by ethambutol, which is a drug added to the anti-mycobacterial regimen only when drug-resistant strains are implicated.
Dihydrofolate reductase (choice B) is the molecule targeted by trimethoprim, which is not the principal drug recommended for treatment of tuberculosis.
Dihydropteroate synthetase (choice C) is the molecule targeted by dapsone, which is the drug of choice for Mycobacterium leprae, not M. tuberculosis.
Peptidoglycan (choice E) is the molecule targeted by the penicillins, vancomycin, and cycloserine.