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

USMLE USMLE-STEP-2 Online Questions & Answers

• Question 261:

  A 7-year-old boy presents with a rash. His mother states that he was well until 3 days ago when he developed fever and malaise. The next day, the rash started as papules on the trunk, which rapidly changed to vesicles. The lesions have spread all over the body. On physical examination, he has no fever and seems well. You note numerous vesicles all over the body, some of which have crusted over.

  Which of the following is the most likely diagnosis?

  A. chicken pox
  B. Kawasaki disease
  C. measles
  D. rubella
  E. staphylococcal scalded skin syndrome
  A. chicken pox

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  Explanation

  This is a typical presentation of chicken pox. A prodrome of fever and malaise is followed by the rapid eruption of papules that turn to vesicles and crust over. The rash in measles, rubella, and Kawasaki disease are macular or maculopapular. In staphylococcal scalded skin syndrome, a diffuse, tender erythroderma develops

• Question 262:

  A 3-year-old boy presents to the physician's office with an asymptomatic neck mass located in the midline, just below the level of the thyroid cartilage. The mass moves with deglutition and on protrusion of the tongue. For the above patient with a neck mass, select the most likely diagnosis.

  A. thyroid carcinoma
  B. cystic hygroma
  C. acute suppurative lymphadenitis
  D. thyroglossal duct cyst
  E. lipoma
  F. carotid artery aneurysm
  G. mixed parotid tumor (pleomorphic adenoma)
  H. laryngeal carcinoma
  I. parathyroid adenoma
  J. branchial cleft cystK. tuberculosis
  D. thyroglossal duct cyst

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  Explanation

  Athyroglossal duct cyst represents the remnants of the thyroglossal duct tract left over from descent of the thyroid gland from the foramen cecum. It is located in the midline and moves superiorly as the tongue protrudes because the tract communicates with the foramen cecum.

• Question 263:

  A 39-year-old woman presents to the physician's office for evaluation of a palpable nodule in the neck of 2 years' duration. Her past history is pertinent for Hashimoto's disease diagnosed 5 years ago, for which she takes thyroid hormone. She has a history of low-dose chest irradiation for an enlarged thymus gland during infancy. On examination, a 2.5-cm nodule is palpable in the left lobe of the thyroid and is firm and nontender.

  Which of the following is the most appropriate next step in her management?

  A. ultrasound of the neck
  B. thyroid scintiscan
  C. MRI of the neck
  D. CT scan of the neck and chest
  E. FNA of the nodule
  E. FNA of the nodule

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  Explanation

  Factors that increase the risk for carcinoma include exposure to low-dose irradiation, age under 20 or over 60, male gender (especially over age 40), and recent onset. An increased incidence of thyroid carcinoma in patients with Hashimoto's thyroiditis has not been substantiated. For diagnosis, FNA is highly accurate and has become the preferred diagnostic modality. FNA is the most important diagnostic test for selecting patients for operation, supplanting all other diagnostic tests.

• Question 264:

  A10-year-old boy comes to the office with fever and chills for 5 days and myalgia. He has recently returned from a 2-week vacation to New England with his family. On physical examination he has mild splenomegaly. Which of the following is the most likely cause of his symptoms?

  A. Kawasaki disease
  B. pneumococcus
  C. babesiosis
  D. leptospirosis
  E. psittacosis
  C. babesiosis

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  Explanation

  Kawasaki disease is an acute vasculitis of unknown etiology. Humans contract brucellosis by direct contact with infected animals or by drinking unpasteurized milk. Babesiosis is transmitted by ticks. Leptospirosis is obtained from exposure to the urine of infected animals. Psittacosis is obtained from exposure to bird feces.

• Question 265:

  A 4-year-old child presents to his pediatrician with a complaint of a mild rash and fevers. His travel history is positive for a camping trip 2 weeks prior. The parents do not recall a tick bite on the child and do not remember if there were ticks in the area. No other members of the family complain of similar symptoms and the child does not attend day care. Physical examination is positive for a temperature of 100.9°F with an erythematous rash noted over the child's trunk. Which of the following factors would significantly increase the possibility that the child has Lyme disease?

  A. The camping trip occurred in an area endemic for the tick Ixodes dentatus.
  B. The camping trip occurred in Texas.
  C. The camping trip occurred in an area with a high indigenous population of lizards.
  D. The camping trip occurred in an area endemic for the white-footed mouse.
  E. The camping trip occurred in an area which had recently been sprayed with pesticides.
  D. The camping trip occurred in an area endemic for the white-footed mouse.

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  Explanation

  The principal risk factor for Lyme disease in the United States is residence in an area with high infestation rates of infected ticks. In the coastal northeastern United States, the whitefooted mouse is the most competent vertebrate reservoir of B. burgdorferi, the organism responsible for Lyme disease, with infection rates of up to 80%. Therefore, residence in an area where there is a large population of whitefooted mice will also increase the likelihood ofexposure to Lyme disease. The tick species I. dentatus has maintained cryptic cycles of B. burgdorferi, but it is not considered to be a public health risk because it rarely feeds on humans. Texas is not one of the endemic areas for Lyme disease. Lizards are actually considered to be a zooprophylactic host because they are an incompetent reservoir of B. burgdorferi, and they are also a preferential feeding source for immature stages of the tick. Pesticide spraying is actually protective against tick infestation and therefore will reduce the chances of tick exposure.

• Question 266:

  It is reported that an alarming number of fractures are occurring among the elderly in your community. You are contacted by a local radio station for an interview on this subject. You explain that which of the following is the most likely cause of the high number of fractures?

  A. Alzheimer's disease
  B. osteoporosis
  C. obesity
  D. Parkinson's disease
  E. deteriorating eyesight
  B. osteoporosis

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  Explanation

  There are many intrinsic factors that lead to falls in the elderly. Iatrogenic causes from medication prescribed commonly impair stability of gait. However, it is osteoporosis, particularly in the elderly female that results in the excess fractures, usually of the femur. Alow BMI is associated with a higher risk of osteoporosis and therefore, fractures. Although the elderly are more likely to have Alzheimer's and Parkinson's diseases, and poor eyesight, these are not as important as osteoporosis in fractures among the elderly

• Question 267:

  Doing a retrospective chart review of unmatched cases and controls, you calculate an OR to make an initial assessment of whether women who have had induced abortions are more likely to develop breast cancer. Twenty of 100 women with breast cancer reported a history of induced abortion. Ten of 200 women without breast cancer reported a history of induced abortion.

  What are the exposure odds among cases?

  A. 0.250
  B. 0.500
  C. 2.000
  D. 4.000
  E. 8.000
  A. 0.250

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  Explanation

  The problem can be represented by the following table:

  

  The odds of exposure among cases is calculated by dividing the probability that a case was exposed by the probability that a case was not exposed: (20/100)/(80/100) = 20/80 = 0.25.

• Question 268:

  Apreviously healthy 19-year-old woman has a sudden onset of headache, profound myalgias, profuse vomiting, and diarrhea. The woman is near the end of her menstrual period and is using tampons. She appears to be suffering from toxic shock syndrome (TSS). Which of the following is the most likely skin finding?

  Which of the following is another common finding in TSS and is part of the case definition?

  A. hypertension: systolic BP 160 mmHg
  B. hyperreflexia
  C. fever with temperature 102°F
  D. elevated platelet count 400,000
  E. hypercalcemia
  C. fever with temperature 102°F

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  Explanation

  Toxin-producing S. aureus organisms have been implicated in the pathogenesis of TSS and are frequently cultured from the vagina and cervix of affected women. There is no diagnostic laboratory test, and diagnosis is based on the typical clinical findings. Diffuse macular erythroderma (sunburn-like rash) occurs in the first few days of illness, followed by desquamation, usually of the palms and soles 12 weeks later. Fever, hypotension, and multiorgan-system involvement (GI, CNS, muscular, renal, hepatic, hematologic) are also part of the case definition.

  Platelet counts are usually reduced below 100,000. Disorientation may occur but without such focal neurologic signs as hyperreflexia. Complications include shock, arrhythmias, renal failure, respiratory failure, and coagulopathy. Hypercalcemia is not a part of the picture

• Question 269:

  A 65-year-old woman presents to the physician's office for her yearly physical examination. She has no complaints except for a recent 10-lb weight loss. Past history is pertinent for a 40 pack-year smoking history, hypertension, asthma, and hypothyroidism. Examination reveals a thin woman with normal vital signs and unremarkable heart and abdominal examinations. Lung examination reveals mild wheezing and a few bibasilar rales. A chest x-ray is obtained and is shown in Figure. Achest x-ray obtained 3 years ago was normal. Yearly laboratory tests including a CBC, electrolytes, and lipid panels are normal.

  

  Which of the following is the most appropriate next diagnostic test?

  A. percutaneous needle biopsy
  B. CT scan
  C. pulmonary function tests
  D. mediastinoscopy
  E. bronchoscopy
  B. CT scan

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  Explanation

  The finding of a new, irregular lesion in a patient with a long smoking history must be considered a lung carcinoma and should be managed accordingly. Nonsmall cell carcinoma is the most common lung neoplasm. Small cell carcinomas usually grow rapidly and disseminate widely by the time of diagnosis. Tuberculosis would present with systemic symptoms and apical disease on chest x-ray. Likewise, a lung abscess would be accompanied by systemic symptoms and may show air-fluid levels in the abscess cavity. A hamartoma presents as an extremely slowly growing nodule that may contain popcorn calcifications. The most appropriate test following suspicious findings on a chest x-ray would be a CT scan to evaluate further the nodule, evaluate the lymph node status, and triage subsequent diagnostic tests. If enlarged mediastinal nodes are seen, then mediastinoscopy may be indicated. Bronchoscopy may be helpful to assess for endobronchial lesions and to obtain tissue for diagnosis. Pulmonary function tests are necessary once a decision is made to consider operation. Percutaneous needle biopsy may be required to obtain tissue once CT scanning is performed

• Question 270:

  Identify the following personality disorders with the symptoms listed below. Unwilling to take personal risks; perceives self as inept, unappealing, inferior

  A. antisocial
  B. avoidant
  C. borderline
  D. dependent
  E. histrionic
  F. narcissistic
  G. obsessive-compulsive
  H. paranoid
  I. schizoid
  J. schizotypal
  B. avoidant

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  Explanation

  Persons with personality disorders are rigidly bound to the use of patterns of defense and various traits that distinguish the disorders. All have problems with interpersonal relationships