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

USMLE USMLE-STEP-2 Online Questions & Answers

• Question 271:

  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?

  A. papular rash on the trunk
  B. scaly rash on the face
  C. pustular rash on the extremities
  D. macular erythroderma
  E. heliotrope facial rash
  D. macular erythroderma

  ---

  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 272:

  A 45-year-old woman presents with fever, anorexia, nausea, and diarrhea. Other patients in the community have presented similarly and have a common exposure at a local restaurant. In the above case of hepatitis, select the most likely type of viral hepatitis.

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

  ---

  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 273:

  A 35-year-old woman presents to the physician's office for evaluation of a left neck mass discovered 1 month ago on a routine physical examination. On examination, the mass measures 2 cm and is located anterolateral to the larynx and trachea. It is nontender and moves with swallowing. Past history is pertinent for a 15 pack-year smoking history and occasional alcohol intake. 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
  A. thyroid carcinoma

  ---

  Explanation

  The location of this neck mass and its movement with swallowing is strongly suggestive of a thyroid mass. The most common type of thyroid cancer is papillary carcinoma, which has an excellent prognosis under the age of 40. Needle biopsy should be performed as a diagnostic test, followed by operation.

• Question 274:

  A 24-year-old man runs a marathon on an unusually hot and muggy day. Several hours later he becomes ill with fever, weakness, and painful swollen legs and passes dark brown urine. Which of the following is a common finding with this disorder?

  A. Urine orthotoluidine (Hematest) reaction will be negative.
  B. Serum will be pink.
  C. Serum creatine phosphokinase levels will be elevated.
  D. Serum haptoglobin levels will be elevated.
  E. Serum potassium levels will be lowered.
  C. Serum creatine phosphokinase levels will be elevated.

  ---

  Explanation

  The clinical features of the patient described in the question are characteristic of rhabdomyolysis with myoglobinuria. Skeletal muscle injury releases large amounts of myoglobin into the circulation, and myoglobinuria produces a positive orthotoluidine reaction. Because myoglobin is quickly cleared from serum by the kidneys, the serum does not turn pink, as it does with hemoglobinemia. Muscle damage leads to elevated creatine phosphokinase levels and hyperkalemia. Myoglobin does not bind to

  haptoglobin as does hemoglobin, so serum haptoglobin levels are normal. The major complication of rhabdomyolysis is acute renal failure.

• Question 275:

  A 30-year-old asymptomatic male presents to your office because his father just had a heart attack. He is concerned that he may have inherited his father's condition because a cholesterol level test done at his work site last year was 220 mg/dL. You review his history and find that he smokes 25 cigarettes a day, eats mostly at fast food restaurants, sits at a desk job, and has no regular moderate intensity physical activities. His blood pressure is 130/85 mmHg and his body mass index (BMI) is 26. Which of the following is the most effective step to successfully help the patient quit smoking?

  A. smoking cessation counseling sessions
  B. nicotine patches
  C. bupropion hydrochloride
  D. physician recommendation to stop smoking
  E. identifying social supports to help in his cessation attempts
  C. bupropion hydrochloride

  ---

  Explanation

  Whereas all of the interventions have a positive effect on smoking cessation, the bupropion hydrochloride has the greatest effect at 6-month follow-up.

• Question 276:

  Otitis media occurring during the first 8 weeks of life deserves special consideration, because the bacteria responsible for infections during this time may be different from those that affect older infants and children. Which of the following organisms is the most likely to cause otitis media in these infants?

  A. Chlamydia trachomatis
  C. Neisseria gonorrhoeae
  D. Treponema pallidum
  E. Toxoplasma gondii
  B

  ---

  Explanation

  C. trachomatis is considered an unusual cause of otitis media at any age.

  N. gonorrhoeae causes conjunctivitis in the newborn. Syphilis and toxoplasmosis cause congenital infections.

  E. coli is one of the neonatal pathogens that also cause otitis media in neonates. The symptoms of otitis media in newborns are often similar to those of sepsis; they are subtle and nonspecific and may include poor feeding, lethargy, vomiting, or diarrhea. Once the diagnosis is established, the initial therapy should be similar to

  that for neonatal sepsis, such as parenteral ampicillin and cefotaxime. Under ideal circumstances, the results of cultures obtained by tympanocentesis may then allow further treatment with a more specific antibiotic of low toxicity. Older infants may respond well to oral therapy but require frequent observation.

• Question 277:

  A 75-year-old man who developed diabetes within the last 6 months was found to be jaundiced. He has remained asymptomatic, except for weight loss of about 10 lbs in 6 months. On physical examination, he is found to have a nontender, globular, right upper quadrant mass that moves with respiration. A CT scan shows enlargement of the head of the pancreas, with no filling defects in the liver. What is the most likely cause of his painless jaundice?

  A. malignant biliary structure
  B. carcinoma of the head of the pancreas
  C. choledocholithiasis
  D. cirrhosis of the liver
  E. pancreatitis
  B. carcinoma of the head of the pancreas

  ---

  Explanation

  Adenocarcinoma of the pancreas arises from ductal epithelium. Because of fibrous tissue formation, the terminal bile duct occludes, causing jaundice. Typically, in the early stages, the patient is free of pain. With invasion of retroperitoneal structures, the patient may sometimes have severe and constant pain. Often, patients have a history of weight loss and present with unexplained diabetes. Because of gradual obstruction, the gallbladder distends, unless it has lost its distensibility because of previous scarring. Malignant biliary stricture, choledocholithiasis, and cirrhosis of the liver are ruled out by the appearance of the CT. Pancreatitis is rarely associated with jaundice and would be painful.

• Question 278:

  For each antihypertensive agent listed below, select the set of undesirable side effects with which it is most commonly associated with lisinopril

  A. cough, hyperkalemia, angioedema
  B. positive Coombs test, hemolytic anemia, hepatitis
  C. hypokalemia, hyperuricemia, hyperglycemia
  D. peripheral edema, flushing, and constipation
  E. increased angina, tachycardia, systemic lupus erythematosus (SLE)
  A. cough, hyperkalemia, angioedema

  ---

  Explanation

  All of the drugs used to treat hypertension can cause adverse reactions, ranging from trivial to life threatening. Thiazide diuretics are associated with hypokalemia, causing arrhythmias; hyperuricemia causing gout; and hyperglycemia due to insulin resistance. The vasodilator hydralazine can cause tachycardia with increased angina and a lupuslike syndrome. As many as 10% of patients on angiotensin- converting enzyme (ACE) inhibitors develop an annoying dry cough. Because they block aldosterone, they can lead to hyperkalemia. ACE inhibitors cause 1025% of all cases of angioedema. Peripheral edema is the most commonly reported side effect of calcium channel blockers, especially amlodipine and nifedipine. Constipation, flushing, and dizziness are also frequently reported. Coombs'-positive hemolytic anemia and hepatitis are idiosyncratic reactions to the central adrenergic-stimulant methyldopa.

• Question 279:

  A dentist asks you to evaluate a 42-year-old woman before tooth extraction. In patients who are not intravenous (IV) drug users and who do not have prosthetic valves, which of the following organisms is the most common cause of bacterial endocarditis?

  A. Enterococcus
  B. Streptococcus
  C. gram-negative bacilli
  D. Candida
  E. Pseudomonas
  B. Streptococcus

  ---

  Explanation

  Guidelines for antibiotic prophylaxis of infective endocarditis (IE) underwent a major revision in 2007. Prophylaxis is now only recommended for those patients at highest risk of IE including patients with a prosthetic valve, history of IE, cardiac transplant patients that develop valvulopathy, cyanotic congenital heart disease that remains unrepaired, cyanotic congenital heart disease that has been repaired with a prosthesis during the first 6 months after the procedure or if a defect remains at the site of the prosthesis after 6 months. Congestive heart failure, an S4 gallop, and diabetes do not increase risk. Recommended antibiotic coverage for high-risk patients before dental procedures is amoxicillin 2 g PO 1 hour before the procedures. Penicillin- allergic patients can receive clarithromycin, cephalexin, cefadroxil, or clindamycin as prophylaxis. Streptococci and S. aureus are responsible for the majority of community- acquired native valve endocarditis cases.

  In IV drug abusers, S. aureus is responsible for more than 50% of cases, and Candida and Pseudomonas for about 6% each. Patients with prior endocarditis are at high risk. Bacterial endocarditis carries a mortality rate of about 25%, and prevention is of paramount importance. In S. aureus endocarditis in injection drug users, mortality is only 1015%. As many as 40% of cases occur without underlying heart disease. VSD, patent ductus arteriosus, and tetralogy of Fallot are most commonly associated;

  whereas, ASD is rarely a predisposing factor.

• Question 280:

  For each antihypertensive agent listed below, select the set of undesirable side effects with which it is most commonly associated with amlodipine

  A. cough, hyperkalemia, angioedema
  B. positive Coombs test, hemolytic anemia, hepatitis
  C. hypokalemia, hyperuricemia, hyperglycemia
  D. peripheral edema, flushing, and constipation
  E. increased angina, tachycardia, systemic lupus erythematosus (SLE)
  D. peripheral edema, flushing, and constipation

  ---

  Explanation

  All of the drugs used to treat hypertension can cause adverse reactions, ranging from trivial to life threatening. Thiazide diuretics are associated with hypokalemia, causing arrhythmias; hyperuricemia causing gout; and hyperglycemia due to insulin resistance. The vasodilator hydralazine can cause tachycardia with increased angina and a lupuslike syndrome. As many as 10% of patients on angiotensin- converting enzyme (ACE) inhibitors develop an annoying dry cough. Because they block aldosterone, they can lead to hyperkalemia. ACE inhibitors cause 1025% of all cases of angioedema. Peripheral edema is the most commonly reported side effect of calcium channel blockers, especially amlodipine and nifedipine. Constipation, flushing, and dizziness are also frequently reported. Coombs'-positive hemolytic anemia and hepatitis are idiosyncratic reactions to the central adrenergic-stimulant methyldopa.