USMLE USMLE Certifications USMLE-STEP-2 Questions & Answers

• Question 731:

  A 59-year-old woman had a left modified radical mastectomy for intraductal carcinoma 2 years previously. She presents with confusion, lethargy, and thigh pain. X-rays reveal a lytic lesion in the shaft of the femur. Which of the following blood abnormalities is most likely?

  A. high glucose

  B. low calcium

  C. high potassium

  D. high calcium

  E. low magnesium

  Correct Answer: D

  Hypercalcemia is a common complication of malignancy. Mechanisms include bone metastases, humoral secretion (e.g., osteoclast-activating factor), prostaglandin, or ectopic parathormone production and immobilization. Hypercalcemia is often manifested by confusion and lethargy. The other metabolic abnormalities usually are not associated with confusion. Therapy is directed at increasing renal calcium clearance and inhibiting further bone resorption. Saline infusion raises the glomerular filtration rate and decreases calcium reabsorption in the proximal tubule. Under life-threatening circumstances, the infusion may need to be aggressive, as much as 6 L of saline daily plus furosemide. Radiotherapy will do nothing for the calcium. Tamoxifen is an antiestrogen used in the treatment of breast carcinoma and other malignancies. When used in the presence of bone metastases, it may contribute to hypercalcemia. Chemotherapy will not decrease the calcium levels. Glucocorticoids have an antitumor effect and reduce tumor production of humoral mediators, but act slowly.

• Question 732:

  A 23-year-old woman presents with "skipped heartbeats" and on cardiac examination is found to have a midsystolic click followed by a late systolic murmur. Echocardiogram shows prolapse of the mitral valve. Which of the following is true about this condition?

  A. Mitral valve prolapse is present in up to 10% of the population.

  B. Mitral valve prolapse is more common in men.

  C. Prophylaxis against bacterial endocarditis is never recommended.

  D. Risk of pulmonary embolism is high.

  E. Ventricular arrhythmias do not occur.

  Correct Answer: A

  Mitral valve prolapse can be diagnosed by auscultation and echocardiogram in as much as 10% of the population. They may be asymptomatic or complain of atypical chest pain, palpitation, shortness of breath, or weakness. An increasing number of complications are being recognized. Although they occur infrequently, they may be life threatening and demand careful evaluation of individuals at risk. Both supraventricular and ventricular arrhythmias occur, as may sudden death. Mitral insufficiency, if present, is usually insignificant but may progress and require valve replacement. There is an increased risk of infective endocarditis. Intraatrial thrombus formation may occur, predisposing to cerebral and peripheral embolism. Because the clot originates in the left atrium, however, pulmonary embolism does not occur more frequently in these patients.

• Question 733:

  A 19-year-old high school senior complains of feeling "fat and ugly" despite being extremely thin. She takes small amounts of food at meals and occasionally gags herself to induce vomiting after meals. Which of the following is commonly associated with this disorder?

  A. menorrhagia

  B. metrorrhagia

  C. loss of body hair

  D. bradycardia

  E. thrombocytopenia

  Correct Answer: D

  The history of severe, self-induced weight loss with an abnormal attitude toward food, weight, and body image in an adolescent female strongly suggests anorexia nervosa. Common symptoms are amenorrhea, not menorrhagia or metrorrhagia, constipation, and cold intolerance. Examination frequently reveals cachexia, hypothermia, bradycardia, hypotension, percarotenemic skin, and increased lanugo-like body hair. Decreased thyroid and pituitary function are evident on laboratory tests, but thrombocytopenia and anemia are not common

• Question 734:

  A 59-year-old woman complains of shortness of breath and aching left-sided chest pain that radiates to the left shoulder. Physical examination shows no abnormalities; her CXRs are shown in Figure below. Which of the following statements is true concerning this disease?

  

  A. This tumor frequently metastasizes to distant sites.

  B. Direct exposure to asbestos is required.

  C. Most cases are associated with recent, massive exposure to asbestos.

  D. Diffuse forms may be cured by chemotherapy alone.

  E. Localized forms may be cured by surgery alone.

  Correct Answer: E

  The x-ray in Figure shows a large, pleural based tumor in the left upper chest; this is most likely a mesothelioma. The tumor is locally invasive, so there are no signs of extrathoracic disease. Direct exposure or contact with asbestos is not required-tumors have occurred in families of asbestos workers. The exposure may be brief and mild, and there is typically a long latent period before appearance of the tumor, about 2040 years. Surgery is curative in local cases. Diffuse malignant mesothelioma responds poorly to all treatments (surgery, radiotherapy, and chemotherapy).

• Question 735:

  A70-year-old man presents to urgent care complaining of a painful, swollen left knee. He previously has had no problems with this knee. Three days prior to onset, he went out dancing for 23 hours but recalls no specific injury. Examination of the knee reveals a moderatesized effusion and mild pain with any range of motion. Plain x-ray shows no fracture. Which of the following is the best next management?

  A. MRI of knee

  B. aspiration of effusion fluid

  C. rest, ice, and leg elevation

  D. physical therapy referral

  E. arthroscopy

  Correct Answer: B

  The presence of effusion generally signifies significant disease. Aspiration of the effusion will help in

  evaluation for hemarthrosis, septic arthritis, and inflammatory crystal disease. Each of these is important to

  identify and treat early. An MRI and/or arthroscopy would be later considerations.

  Orthopedic referral likely would be necessary.

• Question 736:

  A 30-year-old woman is visiting you in your primary care office as a new patient. Overall, she is healthy. On taking a family history, you learn that her mother was diagnosed with colorectal cancer at the age of

  50. When should this patient start being screened for colorectal cancer?

  A. there is no proven benefit for colorectal cancer screening

  B. at age 40

  C. at age 50

  D. at age 60

  E. at age 30

  Correct Answer: B

  Screening should begin approximately 10 years before the age of diagnosis of colorectal cancer in a first-degree (parent or sibling) relative. Given that this patient's mother was diagnosed at age 50, this patient should start screening at age 40. The natural history of a colon polyp to develop into cancer is thought to be 10 years. Colorectal cancer screening has proven mortality benefit.

• Question 737:

  You evaluate a 38-year-old man who complains of muscle weakness. Her appearance is remarkable for a periorbital heliotrope rash with edema and erythema on his upper chest, neck, and face. Which of the following is the most likely diagnosis?

  

  Which of the following examination findings would this patient most likely have?

  A. proximal muscle weakness

  B. distal muscle weakness

  C. ataxic gait

  D. hyperactive deep tendon reflexes

  E. inflamed small joints

  Correct Answer: A

  The heliotrope, purple periorbital rash is seen with dermatomyositis and may even precede the muscle involvement. On examination, these patients will usually show proximal muscle weakness and may complain of difficulty getting up from a chair, climbing stairs, and raising the arms over the head. Ataxia may be present with cerebellar lesions. Deep tendon reflexes should be normal and there is no joint inflammation. Polymyalgia rheumatica generally occurs in older people but is not associated with muscle weakness. Spinocerebellar degeneration, vasculitis, and rheumatoid arthritis are not associated with this rash. Creatine phosphokinase is usually markedly elevated and muscle biopsy will confirm the diagnosis. Serum creatinine, sodium, and potassium should be normal, and the rheumatoid factor should not be elevated.

• Question 738:

  You evaluate a 38-year-old man who complains of muscle weakness. Her appearance is remarkable for a periorbital heliotrope rash with edema and erythema on his upper chest, neck, and face. Which of the following is the most likely diagnosis?

  

  A. polymyositis

  B. dermatomyositis

  C. spinocerebellar degeneration

  D. vasculitis

  E. rheumatoid arthritis

  Correct Answer: B

  The heliotrope, purple periorbital rash is seen with dermatomyositis and may even precede the muscle involvement. On examination, these patients will usually show proximal muscle weakness and may complain of difficulty getting up from a chair, climbing stairs, and raising the arms over the head. Ataxia may be present with cerebellar lesions. Deep tendon reflexes should be normal and there is no joint inflammation. Polymyalgia rheumatica generally occurs in older people but is not associated with muscle weakness. Spinocerebellar degeneration, vasculitis, and rheumatoid arthritis are not associated with this rash. Creatine phosphokinase is usually markedly elevated and muscle biopsy will confirm the diagnosis. Serum creatinine, sodium, and potassium should be normal, and the rheumatoid factor should not be elevated.