Thread: Internal Medicine - 25 MCQ's

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

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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


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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


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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

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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


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6.A previously healthy 37-year-old woman comes to the physician because of recurrent episodes of double vision and drooping of her eyelids for the last month. Such episodes occur without apparent reason, last for hours, and resolve spontaneously. She also reports occasional hoarseness and difficulty in swallowing, which also come and go. Vital signs and physical examination are normal. Which of the following is the most appropriate next step in diagnosis?
a) Blood, urine, and CSF analysis
b)MRI of the head
c)EEG recording
d)Electromyography under repetitive stimulation
e) Muscle biopsy


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7. During the month of December, a middle-aged patient with chronically dry skin develops widespread coin-shaped lesions. The lesions begin as itchy patches of vesicles and papules. These later ooze serum and crust over. The lesions are most numerous on the extensor surfaces of the extremities and on the buttocks. The patient says that some of the lesions have appeared to heal and then reappear at the same sites. Which of the following is the most likely diagnosis?
a) Nummular dermatitis
b)Pompholyx
c)Psoriasis
d)Seborrheic dermatitis
e)Stasis dermatitis

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8.Which of the following medical interventions is an example of a primary preventive measure?
a)Isolation of disease contacts
b)Mammography
c)Routine immunization
d)Screening for visual acuity
e) Testing of stool for occult blood

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9. A 17-year-old boy presents with chronic low back pain for the past 8 months. He was the most promising member of the high school swim team but was forced to quit because of his back pain. The pain begins frequently at night, radiates down the thighs, and is accompanied by pronounced stiffness of the lumbar spine. He denies any gastrointestinal or genital infections. His temperature is 37.0 C (98.6 F). Examination reveals moderate limitation of back motion and tenderness of the lower spine. A diastolic murmur along the left sternal border is heard on chest examination. Laboratory investigation shows an elevated erythrocyte sedimentation rate (ESR) and negative rheumatoid factor. X-ray films of the vertebral column and pelvic region show flattening of the lumbar curve and subchondral bone erosion involving the sacroiliac joints. Which of the following is the most likely diagnosis?
a) Ankylosing spondylitis
b)Degenerative join disease
c) Reiter syndrome
d)Seronegative rheumatoid arthritis
e) Still disease

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10. A 56-year-old man has been admitted to the medical intensive care unit in respiratory distress. An endotracheal tube is placed for mechanical ventilation at a tidal volume of 900 mL, a rate of 12 breaths/min, and a fraction of inspired oxygen of 50%. The positive end expiratory pressure is 10 cm of water. Medications include subcutaneous heparin and aspirin. He now develops tachycardia and a blood pressure of 70/palpation mm Hg. Cardiac examination reveals multiple premature contractions. His arterial blood gas reveals a PO2 of 40 mm Hg. Which of the following is the most likely cause of this condition?
a) Cardiac arrhythmia
b)Bronchial secretions
c)Myocardial infarction
d)Pneumothorax
e) Pulmonary embolus

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11. A 45-year-old alcoholic man with cirrhosis is transferred to the intensive care unit after developing esophageal varices complicated by shock. A screening battery of tests is ordered, revealing a total thyroxine (T4) of 3.8 mg/dL. Physical examination of the thyroid gland is unremarkable. Follow-up studies showed a total triiodothyronine (T3) of 30 ng/dL and TSH (third-generation test) of 0.7 mIU/mL. Which of the following is the most likely diagnosis in this patient?
a) Euthyroid sick syndrome
b)Graves disease
c) Hashimoto disease
d)Medullary carcinoma of the thyroid
e) Silent lymphocytic thyroiditis


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12.A 29-year-old man presents to the clinic complaining of generalized fatigue. The patient is new to the clinic and reports that, over the past few weeks, he has been feeling much more tired than usual. He also reports that this happens to him just about every year, and that other physicians have told him that he is "overworked." His review of symptoms is notable for frequent sneezing, post-nasal drip, eye watering, and a itch of his posterior pharynx. These symptoms tend to be worse in the spring and summer and have been bothering him since mid-April, about 1 month ago. His past medical history is remarkable only for mild asthma induced by being outdoors. He takes no regular medications but does take diphenhydramine on occasion. He denies tobacco, ethanol, or illicit substance use. Which of the following is the most appropriate diagnostic test at this time?
a) Blood radioallergosorbent test
b)None, the diagnosis is based solely on the history and physical examination
c)Intradermal testing
d)Serum protein electrophoresis
e)Skin-prick testing

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13.A 58-year-old man with known hepatitis C and cirrhosis complains of worsening fatigue and confusion over the past 5 days. He has been admitted three times in the past 4 months for variceal bleeding and has had ascites that has been refractory to high-dose oral diuretic use. He also reports that over the past 48 hours he has had a declining urinary output. On physical examination, he is gaunt and jaundiced. He has tense ascites and a liver span of 7 cm in the midclavicular line. Laboratory results reveal a white blood cell count of 4600/mm3, a hemoglobin of 9.4 g/dL, and a hematocrit of 29%. His electrolytes reveal a BUN of 34 mg/dL and a creatinine of 3.1 mg/dL. A urinary sodium is less than 10 mEq/L. Which of the following is the most appropriate treatment for his elevated BUN and creatinine?
a)Large volume paracentesis
b)Hemodialysis
c)Mesocaval shunt
d)Kidney transplantation
e)Liver transplantation

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14. A 54-year-old, malnourished man is admitted for evaluation of jaundice, ascites, and tenderness in the right upper abdomen. His temperature is 38 C (100.4 F). Physical examination reveals mild hepatomegaly and splenomegaly, as well as generalized muscle wasting. Ultrasound examination confirms the presence of an enlarged liver and a small amount of ascitic fluid. Laboratory studies show: Serum albumin...........................2.5 g/dL
Globulin.....................................3.8 g/dL
Bilirubin:
Total........................................3.5 mg/dL
Direct......................................1.7 mg/dL
AST.........................................300 U/L
ALT.........................................120 U/L
Amylase...................................100 U/L
Alkaline phosphatase................100 U/L
Hematologic hemoglobin...........10 g/dL
Mean corpuscular volume.........100 µm
Leukocyte count.......................4000/mm3
Segmented neutrophils..............66%
Bands......................................7%
Prothrombin time......................18 sec
Which of the following is the most likely diagnosis?
a) Acute pancreatitis
b)Alcoholic hepatitis
c)Cholecystitis
d)Duodenal peptic ulcer
e)Viral hepatitis

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15. A 28-year-old man who recently emigrated from Italy returns to the physician's office for a follow up visit to evaluate his anemia. Four days ago, he presented with fatigue and dyspnea on exertion, and was found to have a hematocrit of 22%.
At that time he was admitted to the local hospital for evaluation. Laboratory analysis shows:
Hematocrit........................................ 23%
Mean corpuscular volume (MCV)......59 µm3
Reticulocyte count.............................4.3%
Serum iron........................................160 µg/dL
Total iron binding capacity (TIBC).....230 µg/mL
Serum ferritin...................................80 ng/mL
Hemoglobin electrophoresis:..............Absent beta bands Which of the following is the most likely diagnosis?
a) Alpha-thalassemia
b)Beta-thalassemia
c)Iron deficiency anemia
d)Megaloblastic anemia
e)Sickle cell disease

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16. A 25-year-old man has had type 1 diabetes mellitus for 5 years. His physician is concerned about the possibility of permanent renal damage. Which of the following is the best early indicator for diabetic nephropathy?
a)Albuminuria
b)Hypertension
c)Rising blood urea nitrogen
d)Rising creatinine
e) Urinary tract infection

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17. A 40-year-old woman presents with complaints of burning and tingling sensations in the left hand for several months. She relates that she has been frequently awakened at night by aching pain in the same hand. She is otherwise in good health. Examination fails to detect any impairment in sensation, but pain is elicited by extreme dorsiflexion of the wrist. The patient is unable to correctly identify different clothes by rubbing between the left thumb and index finger. Which of the following is the most likely diagnosis?
a)Angina pectoris
b)Carpal tunnel syndrome
c)Dupuytren contracture
d)Fibrositis
e)Reflex sympathetic dystrophy

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18.A 50-year-old man develops a mass on the back of his hand. The lesion somewhat resembles a "volcano" and consists of a round, firm, flesh colored, 1-cm nodule with sharply rising edges and a central crater. Keratotic debris can be expressed from the central crater. The lesion has developed very rapidly over about a three-month period. Which of the following is the most likely diagnosis?
a)Keratoacanthoma
b)Lipoma
c)Malignant melanoma
d)Pyogenic granuloma
e) Seborrheic keratosis

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19. A physician is called to see a 69-year-old woman who underwent cardiac catheterization via the right femoral artery earlier in the morning. She is now complaining of a cool right foot. Upon examination she has a pulsatile mass over her right groin with loss of her distal pulses, and auscultation reveals a bruit over the point at which the right femoral artery was entered. Which of the following is the most likely diagnosis?
a)Cholesterol emboli syndrome
b)Femoral aneurysm
c)Femoral hernia
d)Femoral pseudoaneurysm
e)Retroperitoneal hematoma

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20. A patient complains to a physician of chronic pain and tingling of the buttocks. The pain is exacerbated when the buttocks are compressed by sitting on a toilet seat or chair for long periods. No lumbar pain is noted. Pain is elicited when the physician performs Freiberg's maneuver, in which there is a forceful internal rotation of the extended thigh. Which of the following is the most likely diagnosis?
a)Disk compression of the sciatic nerve
b)Fibromyalgia
c)Piriformis syndrome
d)Popliteus tendinitis
e)Posterior femoral muscle strain

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21. A 74-year-old woman, who has been followed for the past 25 years for chronic obstructive pulmonary disease (COPD) presents complaining of 48 hours of temperatures to 38.6 C (101.4 F) and worsening shortness of breath. She has a chronic productive cough, which has become more copious. On physical examination, she has rhonchi and increased fremitus in the posterior mid-lung field. A Gram's stain reveals many epithelial cells and multiple gram-positive and gram-negative organisms; no neutrophils are seen. Which of the following is the most likely organism causing the symptoms?
a)Escherichia coli
b)Haemophilus influenzae
c)Klebsiella pneumoniae
d)Mycobacterium tuberculosis
e)Mycoplasma pneumonia

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22. A 53-year-old man comes to the physician because of progressive weakness and weight loss over the past 2 months. He says that he also began noticing areas of his skin getting darker even though it is winter and he is never in the sun. He takes no medications and has no other medical conditions. Physical examination shows no abnormalities except for orthostatic hypotension and hyperpigmentation of his skin. Laboratory studies show:
Sodium........................130 mEq/L
Chloride ......................95 mEq/L
Potassium...................6.5 mEq/L
Bicarbonate................20 mEq/L
Leukocyte count..............5000/mm3
Segmented neutrophils......40%
Band forms ......................4%
Lymphocytes...................40%
Monocytes .....................6%
Eosinophils......................9.5%
Basophils........................0.5%
Which of the following is the most likely diagnosis?
a)Addison's disease
b) Conn's syndrome
c)Cushing's disease
d)Cushing's syndrome
e) Syndrome of inappropriate antidiuretic hormone secretion

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23. A 35-year-old HIV-positive man comes to medical attention with a 6-month history of progressive memory loss and incontinence. He is taking zidovudine and a protease inhibitor. He first noticed difficulties with handwriting. Neurologic examination demonstrates deficits in cognitive and fine motor control functions. Laboratory investigations show a CD4 cell count of 25/mm3. MRI studies reveal moderate brain atrophy but no focal lesions. A lumbar puncture shows no CSF abnormalities. Which of the following is the most likely diagnosis?
a) CMV encephalitis
b)Cryptococcal meningoencephalitis
c)HIV encephalitis
d) HIV myelopathy
e)Primary brain lymphoma
f)Progressive multifocal leukoencephalopathy
g)Toxoplasmosis

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24. A 57-year-old woman presents with progressive shortness of breath over the past 2 days. The woman was admitted to the medical service 6 days ago after a fall and has been on bed rest for a nondisplaced pubic ramus fracture. She has been on deep vein thrombosis prophylaxis with subcutaneous heparin. Her past medical history is significant for type 2 diabetes and dialysis-dependent renal failure secondary to diabetic nephropathy. She makes no urine at baseline. Her last dialysis run was 4 days ago, though she usually undergoes dialysis 3 times per week. She has no chest pain. On physical examination, she appears anxious. Her blood pressure is 160/105 mm Hg, pulse is 110/min, and respirations are 22/min. Her oxygen saturation is 80% on room air, and she appears cyanotic. She has a jugular venous pressure of 10 cm and inspiratory crackles half way up from the bases on auscultation of the lungs. An ECG reveals a rate-related right bundle branch block but no ischemic changes. A chest x-ray film obtained yesterday revealed interstitial edema and vascular redistribution to the apices. Which of the following is the most appropriate initial therapy?
a) An anti-hypertensive agent to decrease her blood pressure to normal
b)A beta blocker to better control her pulse
c)IV morphine to decrease her respirations to normal
d)Oxygen by endotracheal intubation to maximize the oxygen concentration
e) Oxygen by face mask to increase her oxygen saturation

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25. A 37-year-old accountant presents to ask for advice regarding the future management of his ulcerative colitis. He has had pancolitis for the past 19 years and has been told that he is at an increased risk for developing colorectal cancer. He asks for the physician's recommendation regarding appropriate surveillance. Which of the following is the most appropriate response?
a)Annual stool guaiac testing
b)Barium enema
c)Colonoscopy
d)Colonoscopy and multiple biopsies
e)Flexible sigmoidoscopy with multiple biopsies

[HIDE]
1)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.
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2) 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.
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3) 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.
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4) 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.
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5) 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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6) Explanation:
The correct answer is
D. The clinical manifestations are highly characteristic of myasthenia gravis. This disorder has three general features: the fluctuating nature of muscle weakness, predominant involvement of ocular muscles (with diplopia and ptosis), and positive clinical response to administration of cholinergic agents. Crisis of weakness involving respiratory muscles was the most frequent cause of death before the advent of positive pressure respirators. The disease is autoimmune-mediated and results from autoantibodies to the muscular nicotinic receptors. Besides the pharmacologic test, a progressive decrease in the amplitude of muscle potential is the diagnostic feature of myasthenia gravis. Electromyography is therefore very useful in the diagnosis of this condition.

Blood, urine, and CSF analysis (choice A) are entirely within normal limits in myasthenia gravis, although they are indeed frequently performed in the initial screening.

MRI of the head (choice B) and EEG recording (choice C) would be entirely useless in this setting.

Since the disorder is due to impaired cholinergic transmission at the neuromuscular junction, skeletal muscle biopsy (choice E) is within normal limits at the light microscopic level. Occasionally muscle biopsy is performed to rule out other causes of muscle weakness, such as myopathic processes.
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7) Explanation:
The correct answer is
A. The patient most likely has nummular dermatitis, which is a chronic inflammation of the skin, the etiology of which is still unknown. The presentation illustrated in the question stem is typical. This condition should be in your differential diagnosis whenever the terms "coin-shaped" or "discoid" are used to describe a patient's skin lesions in a question. Microscopically, the dominant feature is a localized spongiosis (corresponding to edema) of the epidermis, which may also contain minute fluid-filled holes that correspond to the tiny vesicles seen clinically in early lesions. Treatment of these patients is problematic, and numerous regimens involving corticosteroids or antibiotics have been recommended, each of which appears to work with some but not all patients.

Pompholyx (choice B) produces deep-seated pruritic vesicles on the palms, fingers, and soles. Psoriasis (choice C) can produce coin-shaped lesions, but they are covered with silvery scale.

Seborrheic dermatitis (choice D) produces hyperkeratosis on the scalp and face.

Stasis dermatitis (choice E) can produce discoloration and ulceration of the lower legs near the ankles.
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8) Explanation:
The correct answer is
C. Primary prevention requires implementation of a procedure when the disease is not present even in a presymptomatic phase. Routine immunization of individuals at risk, whether children or adults, is primary prevention.

Isolation of disease contacts is tertiary prevention (choice A).

Mammography is a form of secondary prevention (choice B) where the early or presymptomatic recognition of disease is involved.

Visual screening is a screening test and a form of secondary prevention (choice D).

Occult blood testing in stool is a form of secondary prevention as well (choice E).
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9)Explanation:
The correct answer is
A. The patient's young age, occurrence of pain at night, negativity of rheumatoid factor, and especially, bilateral involvement of sacroiliac joints are consistent with ankylosing spondylitis. This is one of the seronegative spondyloarthropathies, characterized by onset before 40 years of age, absence of circulating autoantibodies, frequent association with HLA-B27 histocompatibility antigen, and common involvement of the spinal column. Ankylosing spondylitis should be suspected in any young person complaining of chronic lower back pain and 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. Uveitis and aortic insufficiency are additional manifestations.

Degenerative joint disease (choice B) would be exceptional at such a young age, unless predisposing conditions were present. Degenerative joint disease is not associated with systemic signs and symptoms. Radiographs of affected joints show narrowed interarticular spaces, osteophytes, and increased density of subchondral bone. Sacroiliac joints are not involved.

Reiter syndrome (choice C) is one of the seronegative spondyloarthropathies. It develops as a sequela of gastrointestinal infections due to Salmonella, Shigella, or Campylobacter, or after sexually transmitted infection caused by Chlamydia or Ureaplasma. Arthritis of large joints (knee and ankle), conjunctivitis, and skin vesicular eruption are the hallmarks of this condition.

Seronegative rheumatoid arthritis (choice D) refers to those cases in which a typical picture of rheumatoid arthritis is associated with negative rheumatoid factor. Rheumatoid arthritis involves small joints, especially those of the hands.

Still disease (choice E) is a rare systemic form of arthritis with onset before age 17. It manifests with spiking fever and systemic symptoms that usually antedate arthritis. Associated manifestations include a morbilliform rash, hepatosplenomegaly, serositis, anemia, and leukocytosis.
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10) Explanation:
The correct answer is
D. The sudden onset of tachycardia and hypotension indicates an acute process. Since the patient is being mechanically ventilated with positive pressure, he is at increased risk of a bullous rupture from barotrauma, leading to a pneumothorax.

Cardiac arrhythmia (choice A) could lead to tachycardia and hypotension. Ventricular tachycardia and atrial fibrillation with a rapid ventricular response may cause this from decreased ventricular filling. An ECG would aid in this diagnosis. In the setting of mechanical ventilation, however, a pneumothorax must be excluded first.

Bronchial secretions (choice B) usually have a progressively worsening presentation. Furthermore, the patient would exhibit desaturation, but not necessarily hypotension.

Myocardial infarction (choice C) may lead to cardiogenic shock from failure. However, this would most likely be a bit more progressive and less acute. Infarction must remain high on the differential diagnosis, and the patient may require vasopressors because of the shock. In the immediate setting, the pneumothorax is more likely, given the acuity of onset.

Pulmonary embolus (choice E) is on the differential diagnosis of electromechanical dissociation. This patient's risk of an embolus is increased because of prolonged immobilization. However, the subcutaneous heparin should be adequate prophylaxis against an embolism.
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11) Explanation:
The correct answer is
A. This patient is seriously ill, with low T4 and low T3, but normal TSH. This is typical for euthyroid sick syndrome, which occurs in many seriously ill patients who do not have clinical hypothyroidism. It can be enough of a diagnostic problem that some references suggest that thyroid hormones not be measured in patients in the intensive care unit unless they are strongly clinically suspected of having thyroid disease. The TSH level is usually most helpful in distinguishing euthyroid sick syndrome from true hypothyroidism, as it often above 30 mU/mL in true hypothyroidism and may be below normal, normal, or minimally elevated in euthyroid sick syndrome. Disproportionately decreased T3 is also typical of euthyroid sick syndrome, and T4 may be normal or decreased.

Graves disease (choice B) produces hyperthyroidism.

Hashimoto disease (choice C) typically produces a rubbery goiter.

Medullary carcinoma of the thyroid (choice D) is rare and would probably not affect the serum thyroid hormone levels unless it was very extensive.

Silent lymphocytic thyroiditis (choice E) can cause hypothyroidism that typically occurs in the postpartum period.
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12) Explanation:
The correct answer is
B. This patient most likely has seasonal allergic rhinitis. It has been shown quite convincingly that the diagnosis is based on the history and physical alone and that further work-up is not cost-effective and should be reserved for refractory cases.

The blood radioallergosorbent test (choice A) reliably detects allergen-specific IgE antibodies in the serum and quantifies their concentrations.

Intradermal testing (choice C) involves the introduction of a measurable amount of allergen into the dermal layer of the skin.

Serum protein electrophoresis (choice D) is not routinely used to aid in the diagnosis of rhinitis. It is commonly used in the diagnosis of sickle cell disease and multiple myeloma.

Skin-prick testing (choice E) involves the application of a small amount of concentrated allergen to the skin; it is then "pricked" through to the epidermal layer. This type of testing is less sensitive than intradermal testing.
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13) Explanation:
The correct answer is
E. This patient with well advanced cirrhosis and portal hypertension has developed the onset of renal insufficiency consistent with hepatorenal syndrome. This occurs during the end stages of cirrhosis and is characterized by diminished urine output and low urinary sodium. In the setting of end-stage liver disease, renal vasoconstriction occurs, and the distal convoluted tubule responds by conserving sodium. Unless the renal function is allowed to deteriorate further, liver transplantation will reverse this vasoconstriction and kidney function will return to normal.

A large volume paracentesis (choice A) may relieve the ascites but will have no significant benefit on the impaired renal function.

There are no indications in this question to suggest that the patient requires acute hemodialysis (choice B).

A mesocaval shunt (choice C) is a surgical procedure that may decompress the portal pressure but will not have any benefit on renal function.

Renal transplantation (choice D) is of no value in this patient since the underlying lesion is in the liver; the kidneys will return to normal function if there is improvement in hepatic function.
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14) Explanation:
The correct answer is
B. This patient's symptomatology is consistent with acute hepatitis. Although alcoholic hepatitis may be indistinguishable from other forms of acute hepatitis, an alcoholic etiology is favored by prevalent elevation of AST (more than two times) compared with ALT. All the remaining laboratory findings, e.g., neutropenia with relative granulocytosis, hypoalbuminemia with hypergammaglobulinemia, and prolonged PT, may be present in many other forms of acute hepatitis, including viral hepatitis (choice E). Evidence of malnourishment is also consistent with alcoholism. Macrocytic anemia is a frequent coexisting finding due to vitamin B12 and folic acid deficiency. In short, only the presence of AST elevation greater than 2 times that of ALT is highly suggestive of alcoholic hepatitis. None of the remaining symptoms or laboratory changes is pathognomonic of this condition. Alcoholic injury is, however, the most likely etiology in consideration of the whole clinical picture.

Acute pancreatitis (choice A) most frequently develops in patients with a history of alcoholism or cholelithiasis. It presents with a dramatic picture of extremely severe, deep abdominal pain often radiating to the back. The patient is restless and diaphoretic. Serum levels of amylase and lipase are usually markedly elevated. Mild elevations of the latter enzymes are often seen in alcoholic hepatitis.

Cholecystitis (choice C) is usually secondary to a stone impacted in the cystic duct, resulting in distention of the gallbladder and colicky pain. Fever and mild jaundice may be present, but usually AST and ALT are normal or slightly elevated.

Duodenal peptic ulcer (choice D) is accompanied by epigastric pain or discomfort. If perforation occurs, the pain begins suddenly and is associated with abdominal guarding. Jaundice, laboratory evidence of liver damage, and ascites are absent.
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15) Explanation:
The correct answer is
B. This is a patient of Mediterranean descent who has a microcytic anemia with an appropriate reticulocyte count, normal iron studies and a hemoglobin electrophoresis with an increased alpha chain component of hemoglobin. The thalassemias are a heterogeneous group of inherited disorders characterized by the underproduction of either the alpha or the beta chains of the hemoglobin molecule. In beta thalassemia, a reduced production of beta chains occurs with normal amounts of alpha production.

Alpha-thalassemia (choice A) is not supported by the presence of alpha chains on the electrophoretic pattern.

Iron deficiency anemia (choice C) although a microcytic anemia, is not supported by the normal iron studies.

Megaloblastic anemia (choice D) is not supported by the low MCV.

Sickle cell disease (choice E) is not supported by any of the data. It is usually diagnosed by sickle cells on the peripheral smear and the presence of hemoglobin S on electrophoresis.
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16) Explanation:
The correct answer is
A. Permanent renal damage can develop in as little as 5 years after diabetes mellitus. Diabetic nephropathy complicates about one third of cases of type 2 diabetes mellitus, and a smaller proportion of type 2 cases. One of the problems is that diabetic nephropathy tends to be asymptomatic until end-stage disease develops, so there has been considerable interest in identifying early markers for significant renal disease. The spilling of albumin into the urine and, more specifically, the spilling of very small levels of albumin ("microalbuminuria") are the best markers to date for significant diabetic nephropathy.

Hypertension (choice B) often coexists with, and apparently favors the development of, microalbuminuria, but is not a specific marker for renal damage.

Rising blood urea nitrogen (choice C) and rising creatinine (choice D) occur a little later, when there is already a very significant decrease in glomerular filtration rate.
Urinary tract infection (choice E) can permanently damage the kidneys but does not always do so.
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17) Explanation:
The correct answer is
B. The symptomatology is classic for carpal tunnel syndrome, which is a form of neuropathy resulting from anatomic compression of the median nerve. Pain, tingling sensations, and hypoesthesia in the distribution of the median nerve are the cardinal manifestations. These often undergo exacerbations at nighttime. A shock-like pain upon percussion on the volar aspect of the wrist (Tinel sign) is an additional characteristic sign. Carpal tunnel syndrome is most often idiopathic, but may represent a manifestation of underlying disorders such as rheumatoid arthritis, sarcoidosis, amyloidosis, acromegaly, and leukemia.

Carpal tunnel syndrome may be confused with angina pectoris (choice A) when located on the left side. However, angina pectoris typically manifests with physical or emotional stress and very rarely results in pain limited to the hand.

Dupuytren contracture (choice C) is a relatively common disorder characterized by fibrous thickening of the palmar fascia. Contracture and nodule formation ensue. This condition is most common in Caucasian men over 50.

Fibrositis (choice D), also known as fibromyalgia, refers to a poorly understood syndrome of widespread musculoskeletal pain associated with tenderness in multiple trigger points. Fatigue, headache, and numbness are also common. Women between 20 and 50 years of age are most commonly affected. Neck, shoulders, low back and hips are usually involved.

Reflex sympathetic dystrophy (choice E) describes a syndrome of pain and swelling of one extremity (most commonly a hand), associated with skin atrophy. It is thought to be secondary to vasomotor instability. Sometimes, it follows injuries to the shoulder (shoulder-hand variant).
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18)Explanation:
The correct answer is
A. This is a keratoacanthoma. These lesions have the distinctive appearance described in the question stem, and tend to occur on sun-exposed areas including the face, the forearm, and the dorsum of the hand. These lesions microscopically closely resemble squamous cell carcinoma, but are now considered benign. They may resolve spontaneously, and some authors suggest that they may not need resection. However, they are usually resected since both patient and physician often feel uncomfortable with neglecting them without having a definitive diagnosis and being absolutely certain they will spontaneously regress.

Lipoma (choice B) causes a soft subcutaneous mass.

Malignant melanoma (choice C) usually causes a pigmented lesion, often with feathery edges suggesting invasion.

Pyogenic granuloma (choice D) causes a red mass, often at a site of previous injury.

Seborrheic keratosis (choice E) causes a warty lesion most often found on the temple or trunk.
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19) Explanation:
The correct answer is
D. Femoral pseudoaneurysms represent an important vascular complication of cardiac catheterization. The combination of a pulsatile mass, femoral bruit, and compromised distal pulses make this diagnosis likely. The diagnosis can be confirmed by ultrasound of the groin.

Cholesterol emboli syndrome (choice A) is also an important complication to recognize in the post-catheterization patient. It usually presents, however, with skin findings in the distal extremities of livedo reticularis, ischemic ulcerations, cyanosis, gangrene, or subcutaneous nodules.

Femoral aneurysms (choice B), like the more common aortic and popliteal aneurysms, are true aneurysms that represent a dilation of the arterial wall itself, often associated with an underlying connective tissue disorder or atherosclerotic disease. While true aneurysms may also present as pulsatile masses in the groin and may be associated with distal embolization of clots, the proximity to cardiac catheterization makes pseudoaneurysm likelier.

Femoral hernias (choice C) occur when abdominal contents pass through the femoral canal, with the hernia sac lying below Poupart's ligament. While it may present as a mass in the groin, a femoral hernia would unlikely be associated with a bruit or arterial vascular compromise.

Another important complication of cardiac catheterization via the femoral artery is a retroperitoneal bleed (choice E). This complication presents, however, as either new back pain, an unexplained drop in the hematocrit, or purpura over the flanks.
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20) Explanation:
The correct answer is
C. This is piriformis syndrome. As you may recall from your anatomy, the piriformis is the small muscle that crosses the greater sciatic foramen, cutting it into two spaces as the muscle passes from the edge of the sacrum to the greater trochanter. The sciatic nerve comes out of the greater sciatic foramen below the piriformis, and is liable to compression by the muscle. Symptoms are as described above; bicycle riding and running may also set off the symptoms, which may take the form of chronic nagging ache, pain, tingling, or numbness. Treatment is usually to teach the patient to avoid maneuvers that set off the symptoms. Some patients have been helped by corticosteroid injection near the site where the piriformis muscle crosses the sciatic nerve; this therapy is thought to work by reducing the fat around the muscle and thereby increasing the available space in the area.

Disk compression of the sciatic nerve (choice A) can also produce sciatic pain, but there is almost always lumbar as well as buttock pain.

Fibromyalgia (choice B) causes achy pain, tenderness, and stiffness of involved sites, including muscles, tendon insertions, and nearby soft tissues. Sites commonly involved include head, neck, shoulders, thorax, low back, and thighs.

Popliteus tendinitis (choice D) is inflammation of the tendon of the popliteus muscle of the knee.

Posterior femoral muscle strain (choice E) produces pain in the posterior thigh on jumping.
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21) Explanation:
The correct answer is
B. This patient, with a long history of chronic obstructive pulmonary disease (COPD), has evidence of a community-acquired pneumonia. The common organisms causing pneumonias in patients with COPD are Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis.

This patient has no other history suggestive of Escherichia coli(choice A) infection elsewhere (such as in the urinary tract), and primary
E. coli pneumonia is rare.

Klebsiella pneumoniae(choice C) is typically found in alcoholic patients and it may cavitate.

There is no evidence of tuberculosis (choice D) by history. Tuberculosis usually presents with a more chronic presentation. Furthermore, it would generally be found as an upper lobe infiltrate, consistent with reactivation tuberculosis. Much less commonly, tuberculosis may present as a primary infection, but this is generally seen in patients with an underlying immunocompromised state. In the setting of primary tuberculosis, a lower lung field pneumonia is in fact possible.

Mycoplasma pneumonia(choice E) does not present with a lobar consolidation and is generally a disease of younger people who present with fever, malaise of at least several days duration, and a nonproductive cough. The chest x-ray film in a patient with Mycoplasma pneumonia would classically reveal faint bilateral interstitial infiltrates.
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22) Explanation:
The correct answer is
A. This patient most likely has Addison's disease, which is primary adrenocortical deficiency. It is a rare disease that is caused by a progressive destruction of the adrenal glands, usually due to idiopathic atrophy, surgery, infection, or hemorrhage. The clinical symptoms include weakness, weight loss, hyperpigmentation, nausea and vomiting, and hypotension. Laboratory findings include hyponatremia (due to aldosterone deficiency), hyperkalemia, and normocytic anemia with eosinophilia and lymphocytosis. The diagnosis is made with the ACTH stimulation test. Cortisol and aldosterone levels do not increase when the ACTH is given. The treatment is glucocorticoid and mineralocorticoid replacement.

Conn's syndrome (choice B) is primary aldosteronism due to an aldosterone-producing adenoma. Symptoms include headaches and hypertension. Laboratory findings include hypokalemia and hypernatremia. Metabolic alkalosis is common.

Cushing's disease (choice C) is caused by an ACTH-producing pituitary tumor that produces excess aldosterone and adrenal androgen secretion. The symptoms include weakness and fatigue, increased weight, osteoporosis, hypertension, striae, amenorrhea, edema, and impaired glucose tolerance. A high-dose dexamethasone suppression test, CT scans and MRIs are used to make the diagnosis. Treatment is surgery.

Cushing's syndrome (choice D) is similar to Cushing's disease except that it is due to adrenal hyperplasia, an adrenal neoplasm or exogenous, iatrogenic causes.

Syndrome of inappropriate antidiuretic hormone secretion (choice E) is characterized by hyponatremia, anorexia, nausea and concentrated urine. It is caused by head trauma, a tumor or infections. The treatment is fluid restriction.
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23) Explanation:
The correct answer is
C. AIDS may lead to various complications affecting the CNS. Among these, HIV encephalitis, clinically known as AIDS dementia complex, is the most common. The pathologic substrate is a subacute inflammatory infiltration of the brain caused by direct spread of HIV to the CNS. Presence of the HIV genome can be demonstrated by in situ hybridization in microglia and histiocytes. The diagnosis of HIV encephalitis (or AIDS dementia complex) must be reached by exclusion of other infective and neoplastic conditions associated with AIDS. AIDS dementia complex is characterized by cognitive impairment, incontinence, impairment of motor skills, and confusion. MRI studies and CSF analysis are useful in excluding other CNS diseases (see below).

CMV encephalitis (choice A) usually affects the periventricular regions of the brain and the retina. CMV encephalitis is usually associated with disseminated infection. CMV can be isolated in the CS
F. MRI may also demonstrate periventricular white matter abnormalities.

Cryptococcal meningoencephalitis (choice B) is an acute life-threatening disease manifesting with signs and symptoms of increased intracranial pressure and fever. The CSF would show numerous cryptococcal organisms.

HIV myelopathy (choice D) manifests mainly with spastic paraparesis. It is a complication similar in pathologic substrate to vitamin B12 deficiency, i.e., vacuolar degeneration of the posterior and lateral columns of the spinal cord. Its pathogenesis is still unclear, but a direct viral effect is suspected.

Primary brain lymphoma (choice E) is a frequent manifestation of AIDS. The MRI would show a ring-enhancing mass, which is not the typical radiologic presentation of brain lymphomas in immunocompetent hosts.

Progressive multifocal leukoencephalopathy (choice F) consists of multifocal areas of myelin destruction. These changes would be visible on MRI. This complication is due to JC virus, a papovavirus that causes asymptomatic infections in immunocompetent individuals.

Toxoplasmosis (choice G) manifests on MRI in a manner similar to lymphoma, i.e., a ring-enhancing mass. This opportunistic infection is extremely frequent in AIDS patients.
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24)Explanation:
The correct answer is
E. Although the patient clearly has abnormal vital signs that are worrisome, the finding most likely to place the patient in immediate danger is her hypoxia. The patient's oxygen saturation of 80% places her at significant risk for delirium, cardiac arrhythmias, and cardiopulmonary arrest. Oxygen should first be administered noninvasively in this case, starting with a non-rebreather face mask until the clinical picture can be stabilized.

An anti-hypertensive agent (choice A) would be an important therapy if her congestive heart failure and hypoxia were the result of diastolic ventricular dysfunction from a hypertensive emergency. Even if this were the case, however, the initial therapy would still be to initially treat her hypoxia while administering an anti-hypertensive agent.

Beta blockade (choice B) is effective at controlling heart rate through the drug's actions on nodal conduction in the heart. However, there is rarely an indication to treat sinus tachycardia, as the underlying cause (in this case likely anxiety and the increased work of breathing against non-compliant lungs) should be addressed first. Again, the hypoxia takes precedence.

IV morphine (choice C) would have the effect here of diminishing anxiety and decreasing venous return to the heart. Although these effects may be attractive, morphine is also a respiratory depressant, and the patient may require her complete respiratory drive to maintain her blood oxygen levels.

Of all of the ways to administer oxygen, intubation, either endotracheal (choice D) or nasotracheal, is the only means to ensure 100% oxygen delivery to the lungs. This patient may ultimately require intubation, but, given its risks, it is appropriate to attempt noninvasive oxygen delivery first. If the question had suggested that the patient was unable to maintain her airway or that noninvasive methods had failed to correct the hypoxia, this choice would have been correct.
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25) Explanation:
The correct answer is
D. Patients with longstanding extensive ulcerative colitis for at least 10 years' duration are at increased colon cancer risk. Appropriate surveillance involves annual or biannual colonoscopy with multiple biopsies at regular intervals, even of normal appearing mucosa, to check for dysplasia.

None of the other choices allows sampling of the entire colonic mucosa for histologic examination for the precancerous lesion of low- or high-grade dysplasia.

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