Question 1.A 31-year-old homosexual man presents complaining of pain with defecation. He denies any symptoms of diarrhea, abdominal pain, or fevers. Six months earlier, he developed traveler's diarrhea while vacationing
in Mexico. On physical examination, he is afebrile and has an
unremarkable abdominal examination. On examination of the perianal area,
there is a group of five clustered ulcers adjacent to the anal orifice
and extending into the anal canal. A sigmoidoscopy reveals normal
rectosigmoid mucosa. Which of the following is the most likely
diagnosis?
A)Cytomegalovirus infection
B)Herpes infection
C)Neisseria gonorrhea
D)Shigella dysenteriae
E)Ulcerative colitis
Explanation:
The correct answer is B. This patient is complaining of pain with defecation without any associated abdominal or bowel symptoms. The reference to traveler's diarrhea is a red herring. The grouped ulcers are characteristic of a herpetic infection. The ulcers begin as vesicular lesions and then painfully ulcerate. The perineal region is frequently involved, and the lesions may spread into the anal canal but do not usually cause any evidence of proctosigmoiditis. These symptoms are often accompanied by neuropathic symptoms, as the herpes resides in the dorsal ganglia.
Cytomegalovirus infection (choice A) may involve the colon in a severely immunocompromised HIV patient whose CD4 count is less than 50. This man has no evidence of HIV and furthermore has no colitic symptoms. In addition, cytomegalovirus will not cause ulceration on the exterior perianal skin.
Neisseria gonorrhea(choice C) may be the cause of a sexually transmitted proctitis but will present with a mucopurulent discharge and perhaps symptoms of mild proctitis but without ulceration.
Shigella dysenteriae(choice D) will present as an invasive type of diarrhea with bloody, mucoid stools and may cause ulceration in the colon or small bowel but does not cause ulcerations in the anal canal or perianal region.
Ulcerative colitis (choice E) would have an abnormal sigmoidoscopic appearance and present with bloody diarrhea. Ulcerations of the perineal region are not characteristic of ulcerative colitis.
Question 2. An elderly diabetic consults a physician because of severe and persistent earache. Otoscopic examination demonstrates foul-smelling purulent otorrhea and a red mass lesion of the external ear canal. Biopsy of the mass demonstrates granulation tissue rather than tumor. Which of the following is the most likely causative organism?
a)Escherichia coli
b)Haemophilus influenzae
c)Proteus vulgaris
d)Pseudomonas aeruginosa
e)Staphylococcus aureus
Explanation:
The correct answer is D. External otitis, or infection of the external ear canal, can be caused by a variety of organisms, notably including Escherichia coli, Pseudomonas aeruginosa, Proteus vulgaris, and Staphylococcus aureus. There is, however, a severe subtype of external otitis, malignant external otitis, of which you should be aware. This form is specifically caused by Pseudomonas aeruginosa, and tends to affect elderly diabetics and AIDS patients, causing the findings illustrated in the question stem. It is particularly worrisome both because the Pseudomonas organism is so tissue destructive and because it is often highly resistant to most intravenous antibiotics. (Consult your local microbiology or pharmacology departments for advice about local sensitivities if you encounter the condition.) Complications can be devastating, including deafness, facial nerve paralysis, osteomyelitis, and meningitis.
Escherichia coli(choice A) can cause both external otitis and acute otitis media, but does not usually cause malignant external otitis.
Haemophilus influenzae(choice B) is an important cause of acute otitis media.
Proteus vulgaris(choice C) can cause external otitis, but does not usually cause the malignant form.
Staphylococcus aureus(choice E) can cause external otitis, but does not usually cause the malignant form.
Question 3.A 74-year-old woman presents complaining of very severe abdominal pain, which began abruptly 8 hours ago. She describes the pain as "the worst I've ever had." On questioning, she is unable to give a precise location but indicates that her entire mid-abdomen is extremely painful. She has been followed for the past 10 years for symptoms of congestive heart failure after she had an anterior wall myocardial infarction. She has remained relatively well controlled with only occasional dyspnea on exertion. Her medications include captopril, furosemide, digoxin, isosorbide dinitrate, and aspirin. She has not had any prior surgery. On physical examination, she appears extremely uncomfortable.
Her temperature is 38.9 C (101.9 F), blood pressure is 174/102 mm Hg, and pulse is 118/min and irregularly irregular. On cardiac examination, there is a regular heart rhythm with a II/VI holosystolic murmur heard best at the apex and radiating to the axilla. She has an irregularly irregular S1 and S2, and scattered bibasilar rales.
An abdominal examination reveals mild distention and no hepatosplenomegaly. The abdomen is diffusely soft but very tender to palpation. A rectal examination reveals brown, guaiac-positive stool. She has no audible bowel sounds. Which of the following is the most likely diagnosis?
a) Diverticulitis
b)Ischemic colitis
c) Mesenteric ischemia
d)Pancreatitis
e)Small bowel obstruction
Explanation:
The correct answer is
C. This patient has symptoms of congestive heart failure and possible atrial fibrillation, as demonstrated by her irregularly irregular heartbeat. In addition, she is on digoxin and is at high risk for the development of an embolic occlusion of the superior mesenteric artery. These patients will present with severe pain out of proportion to their objective physical findings. The diagnosis should be suspected clinically, and immediate superior mesenteric arteriogram should be performed. If evidence of ischemia is confirmed, the patient should proceed to exploratory laparotomy to evaluate for intestinal ischemia and possible gangrenous bowel.
Diverticulitis (choice A) may present with severe abdominal pain but is generally lower abdominal and is often localized in the left lower quadrant, the site of sigmoid diverticulitis. Patients will often give a history of chronic crampy, postprandial pain in the left lower quadrant.
Ischemic colitis (choice B) will usually present as diarrhea, often bloody, in elderly patients with known atherosclerotic heart disease.
Although pancreatitis (choice D) may develop abruptly, particularly with gallstone pancreatitis, the symptoms are usually localized to the epigastric lesion, with radiation to the back and associated nausea and vomiting. Furthermore, chronic pancreatitis does not cause heme-positive stools, as in this patient.
A small bowel obstruction (choice E) is unlikely in the absence of prior abdominal surgery, and associated adhesions and will generally present with abdominal distension in association with high-pitched hyperactive bowel sounds, as well as nausea and vomiting.
Qusetion 4. A 22-year-old man comes to the emergency department because of dyspnea, palpitations, and a headache. These symptoms came on soon after he took trimethoprim-sulfamethoxazole for a urinary tract infection. Laboratory studies show a normochromic, normocytic anemia. A peripheral blood smear reveals Heinz bodies. Which of the following is the most likely cause of this patient's anemia?
a) Lead poisoning
b)Folate deficiency
c)Glucose-6-phosphate dehydrogenase deficiency
d)Hereditary spherocytosis
e) Occult blood loss
Explanation:
The correct answer is
C. This patient has glucose-6-phosphate dehydrogenase (G6PD) deficiency, which is an X-linked disorder that leads to hemolytic crises within hours of exposure to oxidant stress. The most common stressors are viral and bacterial infections, sulfa drugs, quinines, and fava beans. During an acute hemolytic crisis, hemoglobin becomes denatured and leads to the formation of Heinz bodies. The diagnosis is made by the demonstration of Heinz bodies during an acute crisis, and low levels of G6PD during normal times. The treatment includes maintaining adequate urine output and the prevention of future episodes.
Lead poisoning (choice A) leads to a normochromic, normocytic anemia with basophilic stippling. The clinical features include abdominal pain, headache, irritability, and peripheral motor neuropathy. Treatment includes the use of chelating agents.
Folate deficiency (choice B) leads to megaloblastic anemia and is most common in alcoholics.
Hereditary spherocytosis (choice D) is an inherited membrane disorder that leads to hemolytic anemia and red blood cell swelling. Small, round, hyperchromatic red cells without a central area of pallor are seen on blood smears.
Occult blood loss (choice E) leads to chronic iron loss and microcytic anemia. The symptoms include a gradual onset of weakness and fatigue. Management includes the diagnosis and control of the underlying disorder.
Question 5.A 54-year-old obese man presents for a routine physical examination. He was diagnosed with type 2 diabetes 1 year earlier. He has been moderately compliant with dietary precautions and his morning glucose has been persistently between 150 and 200 mg/dL. He is therefore started on glipizide. One month later, metformin is added because of continued poor control. His other medications are propranolol and nifedipine for hypertension, and naproxen, which he began approximately 2 weeks ago for severe knee pain due to osteoarthritis. On physical examination his blood pressure is 154/92 mm Hg, and he has a soft fourth heart sound. The remainder of the physical examination is normal. His routine electrolytes are checked and reveal a BUN of 29 mg/dL and a creatinine of 1.8 mg/dL; both had been normal 1 year earlier. Which of his medications is most likely responsible for the increase in BUN and creatinine?
a) Glipizide
b)Metformin
c)Naproxen
d)Nifedipine
e) Propranolol
Explanation:
The correct answer is
C. The use of nonsteroidal anti-inflammatory drugs (NSAIDs), such as naproxen, may cause a usually mild renal insufficiency, possibly related to a mild interstitial nephritis or glomerulonephritis. Risk of NSAID-induced renal damage is increased in the elderly and in patients with underlying renal disease.
Glipizide (choice A), a second-generation sulfonylurea, may predispose patients to hypoglycemia but is not associated with renal toxicity.
Metformin (choice B) does not induce renal damage but should be used cautiously in patients with underlying renal damage because of the possibility of developing lactic acidosis.
Neither nifedipine (choice D) nor propranolol (choice E) has a tendency to adversely affect the kidneys.
A)Cytomegalovirus infection
B)Herpes infection
C)Neisseria gonorrhea
D)Shigella dysenteriae
E)Ulcerative colitis
Explanation:
The correct answer is B. This patient is complaining of pain with defecation without any associated abdominal or bowel symptoms. The reference to traveler's diarrhea is a red herring. The grouped ulcers are characteristic of a herpetic infection. The ulcers begin as vesicular lesions and then painfully ulcerate. The perineal region is frequently involved, and the lesions may spread into the anal canal but do not usually cause any evidence of proctosigmoiditis. These symptoms are often accompanied by neuropathic symptoms, as the herpes resides in the dorsal ganglia.
Cytomegalovirus infection (choice A) may involve the colon in a severely immunocompromised HIV patient whose CD4 count is less than 50. This man has no evidence of HIV and furthermore has no colitic symptoms. In addition, cytomegalovirus will not cause ulceration on the exterior perianal skin.
Neisseria gonorrhea(choice C) may be the cause of a sexually transmitted proctitis but will present with a mucopurulent discharge and perhaps symptoms of mild proctitis but without ulceration.
Shigella dysenteriae(choice D) will present as an invasive type of diarrhea with bloody, mucoid stools and may cause ulceration in the colon or small bowel but does not cause ulcerations in the anal canal or perianal region.
Ulcerative colitis (choice E) would have an abnormal sigmoidoscopic appearance and present with bloody diarrhea. Ulcerations of the perineal region are not characteristic of ulcerative colitis.
Question 2. An elderly diabetic consults a physician because of severe and persistent earache. Otoscopic examination demonstrates foul-smelling purulent otorrhea and a red mass lesion of the external ear canal. Biopsy of the mass demonstrates granulation tissue rather than tumor. Which of the following is the most likely causative organism?
a)Escherichia coli
b)Haemophilus influenzae
c)Proteus vulgaris
d)Pseudomonas aeruginosa
e)Staphylococcus aureus
Explanation:
The correct answer is D. External otitis, or infection of the external ear canal, can be caused by a variety of organisms, notably including Escherichia coli, Pseudomonas aeruginosa, Proteus vulgaris, and Staphylococcus aureus. There is, however, a severe subtype of external otitis, malignant external otitis, of which you should be aware. This form is specifically caused by Pseudomonas aeruginosa, and tends to affect elderly diabetics and AIDS patients, causing the findings illustrated in the question stem. It is particularly worrisome both because the Pseudomonas organism is so tissue destructive and because it is often highly resistant to most intravenous antibiotics. (Consult your local microbiology or pharmacology departments for advice about local sensitivities if you encounter the condition.) Complications can be devastating, including deafness, facial nerve paralysis, osteomyelitis, and meningitis.
Escherichia coli(choice A) can cause both external otitis and acute otitis media, but does not usually cause malignant external otitis.
Haemophilus influenzae(choice B) is an important cause of acute otitis media.
Proteus vulgaris(choice C) can cause external otitis, but does not usually cause the malignant form.
Staphylococcus aureus(choice E) can cause external otitis, but does not usually cause the malignant form.
Question 3.A 74-year-old woman presents complaining of very severe abdominal pain, which began abruptly 8 hours ago. She describes the pain as "the worst I've ever had." On questioning, she is unable to give a precise location but indicates that her entire mid-abdomen is extremely painful. She has been followed for the past 10 years for symptoms of congestive heart failure after she had an anterior wall myocardial infarction. She has remained relatively well controlled with only occasional dyspnea on exertion. Her medications include captopril, furosemide, digoxin, isosorbide dinitrate, and aspirin. She has not had any prior surgery. On physical examination, she appears extremely uncomfortable.
Her temperature is 38.9 C (101.9 F), blood pressure is 174/102 mm Hg, and pulse is 118/min and irregularly irregular. On cardiac examination, there is a regular heart rhythm with a II/VI holosystolic murmur heard best at the apex and radiating to the axilla. She has an irregularly irregular S1 and S2, and scattered bibasilar rales.
An abdominal examination reveals mild distention and no hepatosplenomegaly. The abdomen is diffusely soft but very tender to palpation. A rectal examination reveals brown, guaiac-positive stool. She has no audible bowel sounds. Which of the following is the most likely diagnosis?
a) Diverticulitis
b)Ischemic colitis
c) Mesenteric ischemia
d)Pancreatitis
e)Small bowel obstruction
Explanation:
The correct answer is
C. This patient has symptoms of congestive heart failure and possible atrial fibrillation, as demonstrated by her irregularly irregular heartbeat. In addition, she is on digoxin and is at high risk for the development of an embolic occlusion of the superior mesenteric artery. These patients will present with severe pain out of proportion to their objective physical findings. The diagnosis should be suspected clinically, and immediate superior mesenteric arteriogram should be performed. If evidence of ischemia is confirmed, the patient should proceed to exploratory laparotomy to evaluate for intestinal ischemia and possible gangrenous bowel.
Diverticulitis (choice A) may present with severe abdominal pain but is generally lower abdominal and is often localized in the left lower quadrant, the site of sigmoid diverticulitis. Patients will often give a history of chronic crampy, postprandial pain in the left lower quadrant.
Ischemic colitis (choice B) will usually present as diarrhea, often bloody, in elderly patients with known atherosclerotic heart disease.
Although pancreatitis (choice D) may develop abruptly, particularly with gallstone pancreatitis, the symptoms are usually localized to the epigastric lesion, with radiation to the back and associated nausea and vomiting. Furthermore, chronic pancreatitis does not cause heme-positive stools, as in this patient.
A small bowel obstruction (choice E) is unlikely in the absence of prior abdominal surgery, and associated adhesions and will generally present with abdominal distension in association with high-pitched hyperactive bowel sounds, as well as nausea and vomiting.
Qusetion 4. A 22-year-old man comes to the emergency department because of dyspnea, palpitations, and a headache. These symptoms came on soon after he took trimethoprim-sulfamethoxazole for a urinary tract infection. Laboratory studies show a normochromic, normocytic anemia. A peripheral blood smear reveals Heinz bodies. Which of the following is the most likely cause of this patient's anemia?
a) Lead poisoning
b)Folate deficiency
c)Glucose-6-phosphate dehydrogenase deficiency
d)Hereditary spherocytosis
e) Occult blood loss
Explanation:
The correct answer is
C. This patient has glucose-6-phosphate dehydrogenase (G6PD) deficiency, which is an X-linked disorder that leads to hemolytic crises within hours of exposure to oxidant stress. The most common stressors are viral and bacterial infections, sulfa drugs, quinines, and fava beans. During an acute hemolytic crisis, hemoglobin becomes denatured and leads to the formation of Heinz bodies. The diagnosis is made by the demonstration of Heinz bodies during an acute crisis, and low levels of G6PD during normal times. The treatment includes maintaining adequate urine output and the prevention of future episodes.
Lead poisoning (choice A) leads to a normochromic, normocytic anemia with basophilic stippling. The clinical features include abdominal pain, headache, irritability, and peripheral motor neuropathy. Treatment includes the use of chelating agents.
Folate deficiency (choice B) leads to megaloblastic anemia and is most common in alcoholics.
Hereditary spherocytosis (choice D) is an inherited membrane disorder that leads to hemolytic anemia and red blood cell swelling. Small, round, hyperchromatic red cells without a central area of pallor are seen on blood smears.
Occult blood loss (choice E) leads to chronic iron loss and microcytic anemia. The symptoms include a gradual onset of weakness and fatigue. Management includes the diagnosis and control of the underlying disorder.
Question 5.A 54-year-old obese man presents for a routine physical examination. He was diagnosed with type 2 diabetes 1 year earlier. He has been moderately compliant with dietary precautions and his morning glucose has been persistently between 150 and 200 mg/dL. He is therefore started on glipizide. One month later, metformin is added because of continued poor control. His other medications are propranolol and nifedipine for hypertension, and naproxen, which he began approximately 2 weeks ago for severe knee pain due to osteoarthritis. On physical examination his blood pressure is 154/92 mm Hg, and he has a soft fourth heart sound. The remainder of the physical examination is normal. His routine electrolytes are checked and reveal a BUN of 29 mg/dL and a creatinine of 1.8 mg/dL; both had been normal 1 year earlier. Which of his medications is most likely responsible for the increase in BUN and creatinine?
a) Glipizide
b)Metformin
c)Naproxen
d)Nifedipine
e) Propranolol
Explanation:
The correct answer is
C. The use of nonsteroidal anti-inflammatory drugs (NSAIDs), such as naproxen, may cause a usually mild renal insufficiency, possibly related to a mild interstitial nephritis or glomerulonephritis. Risk of NSAID-induced renal damage is increased in the elderly and in patients with underlying renal disease.
Glipizide (choice A), a second-generation sulfonylurea, may predispose patients to hypoglycemia but is not associated with renal toxicity.
Metformin (choice B) does not induce renal damage but should be used cautiously in patients with underlying renal damage because of the possibility of developing lactic acidosis.
Neither nifedipine (choice D) nor propranolol (choice E) has a tendency to adversely affect the kidneys.
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