USMLE USMLE Certifications USMLE Questions & Answers

• Question 511:

  A previously healthy 40-year-old woman is brought to the emergency department by her husband because of a 2-day history of fever, lethargy, and confusion. Her temperature is 38°C (100.4°F), pulse is 80/min, respirations are 18/min, and blood pressure is 140/90 mmHg. Physical examination shows scattered petechiae and ecchymoses over the lower extremities. Neurologic examination shows moderate generalized motor weakness. She is oriented to person but not to place or time. Laboratory studies show:

  

  A peripheral blood smear shows 3+ polychromasia and 3+ schistocytes. Urine and blood cultures grow no organisms. A chest x-ray shows no abnormalities. Which of the following is the most likely diagnosis?

  A. Acute myeloid leukemia

  B. Autoimmune hemolytic anemia

  C. Thrombotic thrombocytopenic purpura

  D. Toxic shock syndrome

  E. von Willebrand disease

  Correct Answer: C

• Question 512:

  A 17-year-old girl has never had a menstrual period. Physical examination shows a normal female body habitus, normal breast development, and normal appearing external genitalia. She has no axillary or pubic hair. The patient refuses to have a pelvic or rectal examination. Which of the following is the most likely explanation for the clinical presentation?

  A. Androgen insensitivity

  B. Congenital adrenal hyperplasia

  C. Ectodermal dysplasia

  D. A psychiatric disorder

  E. A sex chromosome mosaicism

  Correct Answer: A

• Question 513:

  

  An otherwise healthy 45-year-old man comes to the physician because of a 3-week history of progressive epigastric heartburn and a 4.5-kg (10-lb) weight loss. The pain tends to be more severe at night and occurs 1 to 3 hours after meals during the day. He has had similar episodes with lesser intensity during the past year. Abdominal examination shows tenderness to deep palpation. Test of the stool for occult blood is positive. Endoscopy shows a bleeding 3-cm ulcer in the antrum of the stomach. A photomicrograph of Steiner silver-stained tissue (400x) from a biopsy of the gastric mucosa adjacent to the ulcer is shown. Which of the following processes is most likely to be involved?

  A. Elaboration of proteases and urease with local tissue destruction

  B. Hyperacidity and gastric ulcer development

  C. Ingestion of preformed toxins in contaminated well water

  D. Spirochete invasion of gastric cells

  Correct Answer: A

• Question 514:

  A 3-year-old boy with chronic granulomatous disease is brought to the physician because of a 3-week history of fever and warm, red lumps under both arms. His temperature is 38°C (100.4°F). Physical examination shows enlarged, 3-cm, erythematous axillary lymph nodes bilaterally. On palpation, the nodes are tender, fluctuant, and movable. Examination of a fine-needle aspirate from one of the nodes shows gram-positive cocci in clusters. Cultures of the aspirate grow yellow, β-hemolytic colonies that are catalase and coagulase positive. A polymerase chain reaction test shows mecA-positive organisms. Which of the following is the most appropriate pharmacotherapy for this patient?

  A. Cefazolin

  B. Ciprofloxacin

  C. Penicillin G

  D. Rifampin

  E. Vancomycin

  Correct Answer: E

• Question 515:

  A 24-year-old man is brought to the emergency department 40 minutes after he was involved in a motor vehicle collision. He was the unrestrained driver. He is conscious. Physical examination shows numerous lacerations and ecchymoses over the face. His vision is normal. Ocular, facial, and lingual movements are intact. The gag reflex is present. Sensation to pinprick is absent over the right side of the face anterior to the right ear, extending down along the full extent of the mandible to the chin. Sensation also is absent over the right side of the tongue. X-rays of the skull show fractures of the orbit, zygomatic arch, and infratemporal fossa. The most likely cause of these findings is a fracture affecting which of the following locations?

  A. Foramen lacerum

  B. Foramen ovale

  C. Foramen rotundum

  D. Foramen spinosum

  E. Jugular foramen

  Correct Answer: B

• Question 516:

  A 55-year-old man who is a business executive is admitted to the hospital for evaluation of abdominal pain. He is polite to the physician but berates the nurses and other staff. The patient's wife and two of his three adult children arrive for a visit. The patient says with disgust that the missing child is and always has been worthless. Which of the following is the most likely explanation for this patient's behavior?

  A. Countertransference

  B. Projection

  C. Projective identification

  D. Reaction formation

  E. Splitting

  Correct Answer: E

• Question 517:

  A 42-year-old man comes to the physician for a follow-up examination 1 week after he passed a renal calculus. X-ray crystallographic analysis of the calculus showed calcium as the primary cation. Physical examination today shows no abnormalities. A 24-hour collection of urine shows increased calcium excretion. Which of the following is the most appropriate pharmacotherapy?

  A. Carbonic anhydrase inhibitor

  B. Na+ - Cl-symport inhibitor

  C. Na+ - K+ - 2Cl-symport inhibitor

  D. Osmotic diuretic

  E. Renal epithelial sodium channel inhibitor

  Correct Answer: B

• Question 518:

  A 55-year-old man comes to the physician because of a 2-week history of recurrent, widespread blister formation. Physical examination shows lesions that are most numerous in the flexural areas including the axillae and groin. The blisters do not break easily, and there are no oral lesions. These blisters are most likely the result of adhesion failure involving which of the following?

  A. Basement membrane

  B. Dermal papillae

  C. Langerhans cells

  D. Melanocytes

  E. Merkel cells

  Correct Answer: A

• Question 519:

  A 45-year-old man comes to the physician because of right shoulder pain that began after he chopped wood 2 days ago. Examination of the right upper extremity shows no obvious bone deformities or point tenderness. The pain is reproduced when the patient is asked to externally rotate the shoulder against resistance; there is no weakness. In addition to the teres minor, inflammation of which of the following tendons is most likely in this patient?

  A. Infraspinatus

  B. Pectoralis

  C. Subscapularis

  D. Supraspinatus

  E. Trapezius

  Correct Answer: A

• Question 520:

  A 54-year-old man comes to the physician for a follow-up examination 10 days after undergoing a stereotactic brain operation to remove a small tumor. The operation was successful. During the procedure, he was under conscious sedation. The patient recalls that at one point during the operation he experienced a sudden, intense feeling of overwhelming fear. Which of the following areas of the brain was most likely stimulated at that time?

  A. Amygdala

  B. Hippocampus

  C. Mammillary body

  D. Prefrontal cortex

  E. Thalamus

  Correct Answer: A