USMLE USMLE-STEP-2 Online Practice Questions and Exam Preparation

USMLE USMLE-STEP-2 Online Questions & Answers

• Question 231:

  A70-year-old man with a 60 pack-year smoking history presents with cough and weight loss. He describes recent diffuse darkening of his skin and his CXR shows a mass suspicious for lung cancer in the left hilum. His laboratory tests reveal hypokalemia. Which of the following is the most likely histology of his lung cancer?

  A. adenocarcinoma
  B. small cell
  C. squamous cell
  D. mesothelioma
  E. glioblastoma
  B. small cell

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  Explanation

  Endocrine syndromes are seen in 12% of patients with lung cancer. Squamous cell carcinoma is associated with PTH-related peptide. Adrenocorticotrophic hormone (ACTH) and ADH secretion can be associated with small cell lung carcinoma. ACTH-secreting tumors are associated with darkening of the skin and hypokalemia.

• Question 232:

  A 47-year-old man with diabetes and hypertension travels with his family to Mexico. The next morning after eating out at a local restaurant and despite drinking bottled water, he develops severe crampy abdominal pain and watery, frequent diarrhea. Which of the following is the best approach for his care?

  A. ciprofloxacin . 3 days
  B. penicillin . 5 days
  C. tetracycline . 3 days
  D. observation of symptoms
  E. metronidazole . 10 days
  A. ciprofloxacin . 3 days

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  Explanation

  Ciprofloxacin is the drug of choice in a dose of 500 mg bid for 13 days because most cases of travelers' diarrhea are from E. coli. This patient's symptoms are moderate to severe and warrant antibiotic treatment which will decrease the frequency of bowel movements and duration of illness. Erythromycin and tetracycline are effective for Vibrio which is an uncommon cause of travelers' diarrhea. Metronidazole is used for Clostridium difficile enteritis.

• Question 233:

  For each item, select the ONE best lettered option that is most closely associated with it. Each lettered heading may be selected once, more than once, or not at all. A 42-year-old obese woman complains of hirsutism, amenorrhea, and difficulty becoming pregnant.

  A. Cushing's syndrome
  B. Addison's disease
  C. Klinefelter syndrome
  D. hyperparathyroidism
  E. hypothyroidism
  F. pheochromocytoma
  G. acromegaly
  H. diabetes insipidus
  I. diabetes mellitus
  J. polycystic ovarian disease
  J. polycystic ovarian disease

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  Explanation

  Polycystic ovarian syndrome is characterized by infertility, hirsutism, obesity, and amenorrhea or oligomenorrhea. These patients have chronic anovulation and experience withdrawal bleeding after progestogen administration.

• Question 234:

  A 43-year-old prison cook becomes ill with jaundice, malaise, and fever. Shortly thereafter, multiple prison inmates develop similar symptoms.

  According to the above symptoms, select the most likely type of viral hepatitis.

  A. hepatitis A
  B. hepatitis B
  C. hepatitis C
  A. hepatitis A

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  Explanation

  Hepatitis A is transmitted almost exclusively by the fecal-oral route. Large outbreaks have been linked to contaminated food products. Intrafamily and intrainstitutional spread also is common. Clinical severity usually is mild, and hepatitis A does not progress to chronicity. Hepatitis C more commonly progresses to chronicity (5070% develop chronic hepatitis and 8090% of these patients have evidence for chronic infection). Hepatitis C can lead to cirrhosis and hepatocellular carcinoma. Chronicity occurs in only 110% of patients with hepatitis B

• Question 235:

  Select the appropriate incubation period of the Chicken pox infectious disease of childhood.

  A. 16 days
  B. 78 days
  C. 810 days
  D. 1021 days
  E. 3050 days
  F. 120180 days
  D. 1021 days

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  Explanation

  The incubation period for diphtheria is 17 days. The incubation period for chicken pox is 1021 days, average 14. Infectious mononucleosis, caused by the Epstein-Barr virus, has an estimated incubation period of 3050 days. The incubation period following infection by the mumps virus is usually 1618 days but, like chicken pox, may vary from 14 to 25 days. Pertussis has a shorter incubation period, usually 710 days, with a variation of 421 days. The usual period from contamination with tetanus spores to clinical symptoms is generally 68 days. For rubella, the incubation period is from 14 to 21 days, but usually ranges from 16 to 18 days.

• Question 236:

  A full-term newborn develops cyanosis a few hours after birth. Oxygen administration does not improve color or oxygen saturations. Which of the following is the most likely diagnosis?

  A. atrial septal defect
  B. ventricular septal defect
  C. patent ductus arteriosus
  D. aortic stenosis
  E. pulmonary stenosis
  E. pulmonary stenosis

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  Explanation

  Cyanosis in newborn infants is associated with major right-to-left shunts. Total anomalous pulmonary venous return results in a right-toleft shunting through an interatrial communication, usually a patent foramen ovale. Patent ductus arteriosus and atrial septal defect, when unaccompanied by other cardiovascular abnormalities, cause left-to-right shunts that do not produce cyanosis. Coarctation of the aorta does not typically cause symptoms in the newborn.

  Hypoplastic left heart presents with signs of failure in the newborn period.

• Question 237:

  You make the diagnosis of Marfan syndrome in a very tall 22-year-old man with long, thin extremities. The major cause of morbidity and mortality in Marfan patients is cardiac. Which of the following is a common complication?

  A. pulmonary stenosis
  B. ventricular septal defect (VSD)
  C. pulmonary hypertension
  D. aortic root dilatation
  E. coronary artery disease (CAD)
  D. aortic root dilatation

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  Explanation

  Marfan syndrome is an inherited disorder of connective tissue, but at least one-fourth of patients do not have an affected parent. Abnormal metabolism of collagen or elastin is suspected as the cause. Clinical features involve the eyes (upward subluxation of the lenses, myopia), cardiovascular system (aortic dilation, regurgitation, and aneurysms; mitral valve prolapse), and the skeleton (arachnodactyly, pectus deformity, joint laxity). Mental retardation and malar rash are not associated with Marfan. Afrequent finding is increased length of the limbs as compared with the trunk. Aortic root dilatation is a serious complication that can lead to aortic regurgitation, dissection, and even rupture.

  Mitral valve prolapse is also seen, but pulmonary stenosis, VSD, pulmonary hypertension, and CAD are not increased with Marfan syndrome. Echocardiography should be performed to follow the course of the heart. The other tests will not reveal aortic root dilatation or aneurysm formation.

• Question 238:

  Match the below medication with the potential blood dyscrasia side effect it can be associated with.

  Valproate.

  A. leukocytosis
  B. thrombocytopenia
  C. agranulocytosis
  D. megaloblastic anemia
  E. lymphocytosis
  B. thrombocytopenia

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  Explanation

  Valproate can be associated with thrombocytopenia and platelet dysfunction especially at high doses. Leukocytosis is a common benign effect of lithium. Clozaril can cause agranulocytosis in 12% of patients. Agranulocytosis can be an idiosyncratic adverse event with carbamazepine.

• Question 239:

  A worker complains of paresthesias, numbness, and tingling that started distally in the lower extremities but that is starting to affect his hands. He is developing muscle weakness. He feels tired, and has a headache and complains of memory deficit. Electromyographic abnormalities suggest axonal degeneration and demyelination. Exposure to which of the following is the most suspect cause of this clinical picture?

  A. lead
  B. benzene
  C. zinc
  D. carbon disulfide
  E. vibration
  D. carbon disulfide

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  Explanation

  Carbon disulfide causes sensorimotor peripheral neuropathy. Central nervous system (CNS) effects and optic neuritis are also common. Long-term exposure may increase cardiovascular risk. Lower sperm counts and more abnormal spermatozoa are observed than in unexposed subjects.

• Question 240:

  Among the observational study designs, the prospective cohort design offers which of the following advantages?

  A. It provides a relatively quick answer.
  B. It allows one to take advantage of existing outcome data.
  C. It is easy to assemble a comparison group.
  D. It allows one to measure incidence.
  E. It is relatively cheap.
  D. It allows one to measure incidence.

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  Explanation

  In a prospective cohort design, a group of subjects at risk of developing disease are followed over a specified period of time. This design permits the direct calculation of incidence by dividing the number of subjects who developed the disease of interest during the follow-up period by the population or persontime at risk. In contrast, incidence cannot be calculated directly from the other observational study design.