A 24-year-old man comes to clinic for a follow-up visit.  The patient was diagnosed with Hodgkin lymphoma 4 months ago and received combination chemotherapy.  He has had a nonproductive cough and shortness of breath with exertion over the past 2 weeks.  On examination, there is no jugular venous distension or pedal edema.  Heart sounds are normal with no murmurs.  Lung auscultation reveals bilateral fine inspiratory crackles.  Chest radiograph shows bilateral reticular interstitial opacities.  Pulmonary function testing shows a restrictive pattern with decreased diffusing capacity for carbon monoxide.  Chest x-ray and pulmonary function testing prior to the initiation of chemotherapy were normal.  Which of the following is the most likely mechanism of action of the medication causing this patient’s current symptoms?

A 2-year-old boy is brought to the clinic for evaluation of behavior concerns and developmental delay.  The child was born at term and was healthy during early infancy.  However, he has not started walking or talking, and the parents are concerned because he recently began biting his lips and fingers.  Examination shows small open wounds on the bottom lip and bleeding along the tips of the fingers.  The patient also has occasional involuntary twisting movements of the extremities.  He is otherwise healthy.  This patient most likely has a deficiency in an enzyme utilized in which of the following steps?

A 55-year-old woman comes to the office due to fatigue, abdominal pain, and a 15-lb weight loss over the last 3 months.  She has no prior medical conditions and takes no medications.  Temperature is 37 C (98.6 F), blood pressure is 90/70 mm Hg, pulse is 80/min, and respirations are 16/min.  BMI is 21 kg/m².  Laboratory results are as follows:

Which of the following glandular pathologies is the most likely etiology of this patient’s condition?

The distribution of a certain biomarker in patients with myocardial infarction (MI) is approximately normal with a mean of 115 IU/L.  If 95% of the values for the biomarker in patients with MI lie between 55 and 175 IU/L, which of the following is the approximate value for the standard deviation of the biomarker?

A 48-year-old woman is being evaluated in the emergency department for fever and chills.  Two weeks ago, she began treatment with combination cytotoxic chemotherapy after being diagnosed with infiltrating ductal carcinoma that is negative for estrogen, progesterone, and HER2 receptors.  Today the woman reports no cough, abdominal pain, diarrhea, or urinary symptoms.  Temperature is 39 C (102.2 F).  Physical examination shows oral mucositis.  Laboratory evaluation reveals her absolute neutrophil count is 200/mm³ (normal: >1,500/mm³).  Blood, sputum, and urine cultures are obtained, and empiric broad-spectrum antibiotics are begun.  In addition to neutropenia, which of the following effects of chemotherapy most likely predisposed this patient to her current condition?

A 32-year-old man comes to the office due to persistent fatigue.  His exercise tolerance has decreased dramatically over the past 3 weeks.  The patient has no significant past medical history.  Blood pressure is 126/72 mm Hg, and pulse is 88/min.  Physical examination shows prominent conjunctival pallor with no icterus.  Fundoscopy demonstrates small areas of retinal hemorrhages and cotton wool spots bilaterally.  White patches with an erythematous base are present on the gingival and buccal mucosa.  Lungs are clear on auscultation and heart sounds are normal.  The abdomen is soft and nontender with no hepatosplenomegaly.  Skin examination reveals scattered petechiae and ecchymoses.  No lymphadenopathy is present.

Item 1 of 2

Which of the following peripheral blood smear findings is most specific for this patient’s condition?

Item 2 of 2

The patient is diagnosed with a hematologic malignancy and started on chemotherapy.  Four weeks later, he develops cough, dyspnea, and pleuritic chest pain.  Temperature is 38.8 C (102 F), blood pressure is 105/60 mm Hg, and pulse is 114/min.  Pulse oxymetry shows 91% on room air.  Physical examination reveals right lung crackles.  Chest x-ray demonstrates a nodular infiltrate in the right upper lung lobe with a small area of cavitation.  A bronchoscopy is performed and bronchoalveolar lavage findings are shown in the image below.

The organism responsible for this patient’s current infection is most likely to exhibit which of the following features?

A 64-year-old woman is brought to the emergency department due to several episodes in which she was found unresponsive, staring into space, and smacking her lips.  In addition, her family reports that, over the past 2 weeks, the patient has had increasing confusion and anxiety.  Earlier this evening, she forgot that she had just had dinner with her son and accused him of being a spy.  The patient has no history of seizure or other neurologic disorders.  She was recently found to have a central lung mass, and bronchoscopic biopsy was planned.  Laboratory evaluation reveals positive antineuronal nuclear antibodies, and paraneoplastic encephalitis is suspected.  Gadolinium-enhanced MRI is most likely to reveal abnormalities in which of the following brain regions?

A 25-year-old man comes to the office due to bilateral hip pain for the last 6 months.  The pain started insidiously and has progressively worsened to the point where he has difficulty walking.  The patient has no history of trauma.  Medical history is significant for a seizure disorder, for which he has taken phenytoin for the past 5 years.  The patient does not use tobacco or alcohol.  X-ray of the hip joint shows bilateral, symmetric, narrow radiolucent lines of 2-3 mm in width with sclerotic borders as well as diffuse cortical thinning.  Which of the following is the most likely cause of this patient’s current condition?

A 4-week-old, previously healthy newborn is brought to the office by her mother due to progressively increasing jaundice and pale stools for the past 5 days.  The patient was born at term after an uncomplicated pregnancy and vaginal delivery.  She is exclusively formula-fed.  Vital signs are within normal limits.  Examination shows jaundice.  There are no dysmorphic features.  Laboratory evaluation shows a total serum bilirubin concentration of 10.0 mg/dL and a direct bilirubin of 7.0 mg/dL.  Serum alanine aminotransferase (SGPT) and aspartate aminotransferase (SGOT) are elevated.  Right upper quadrant ultrasound reveals an absent gallbladder.  Liver biopsy is performed.  Which of the following findings are most likely to be present?

A 10-year-old boy who recently immigrated from overseas with his family is brought to the office due to exertional dyspnea and fatigability.  The boy tires easily when walking and cannot keep up with his peers at the playground.  According to his parents, he was diagnosed with congenital heart disease in infancy, but corrective treatment was unavailable.  They cannot recall the details of his diagnosis.  He takes a daily multivitamin and no medications.  Pulse oximetry shows 98% in the right hand and 84% in the right foot.  Physical examination reveals no murmurs.  There is bilateral cyanosis and clubbing of the toes.  The hands and fingers appear normal.  All extremity pulses are full and equal.  Which of the following is the most likely diagnosis?

A 75-year-old man is brought to the emergency department by paramedics following a high-speed motor vehicle collision.  Several attempts are made to resuscitate him but they are unsuccessful.  Autopsy findings include heavy calcifications of the aortic valve.  The patient’s medical records indicate that he had no significant medical history and took no medications.  He is described as being in good health and tolerant of moderate levels of physical activity.  ECG from his last office visit shows no abnormalities.  Which of the following most likely preceded the aortic valve changes observed in this patient?

A prospective observational study is performed to determine factors affecting bone mass and fracture risk.  Detailed demographic data and clinical information are obtained from a large number of volunteers, and bone mass is monitored over time.  The data obtained from 2 specific groups of women are shown below.

The prevalence of which of the following factors is most likely to be higher in Group A than in Group B?

A 32-year-old man is brought to the emergency department with a several-day history of high-grade fever, dyspnea, and fatigue.  The patient’s temperature is 39.4 C (102.9 F), blood pressure is 122/70 mm Hg, and pulse is 102/min and regular.  Physical examination reveals a new holosystolic murmur with a blowing quality that is best heard over the cardiac apex.  Skin examination shows nontender lesions on the palms.  A representative lesion is shown in the image below:

Which of the following do this patient’s skin lesions most likely represent?

A 39-year-old, previously healthy man comes to the emergency department due to a 12-hour history of severe, colicky, left flank pain that radiates to the groin.  Temperature is 37 C (98.6 F), blood pressure is 132/84 mm Hg, and pulse is 94/min.  On physical examination, the patient appears distressed, restless, and in pain.  There is left costovertebral angle tenderness, but the remaining genitourinary examination shows no abnormalities.  Urinalysis reveals numerous red blood cells.  CT scan of the abdomen and pelvis reveals a 6-mm stone in the distal left ureter without hydronephrosis.  Adequate analgesics are provided.  Administration of which of the following pharmacological agents would be most helpful to facilitate passage of the stone?

A 55-year-old man develops difficulty walking and tremor while receiving medication for paranoid behavior.  Vital signs are normal.  Physical examination shows an expressionless face and diffuse muscle rigidity.  The patient is slow in initiating movement and walks with a shuffling, short-stride gait.  Resting tremor is noted.  All home medications are discontinued.  Two months later, the patient continues to have symptoms.  Further evaluation is performed using an injection of radioactive ioflupane, which binds to presynaptic dopamine transporters.  The scan results show normal uptake of the radiotracer within the striatum, consistent with a normal number of presynaptic dopamine transporters.  Which of the following is the most likely cause of this patient’s symptoms?

A 19-year-old woman with cystic fibrosis comes to the clinic due to episodes of nausea, lightheadedness, and diaphoresis.  The episodes started 3 months ago.  She feels better after eating a candy bar.  The patient has also experienced polyuria and a 4.5-kg (10-lb) weight loss.  Current medications include pancreatic enzyme supplements and nebulized respiratory treatments.  BMI is 19.5 kg/m².  Physical examination is unremarkable.  Glucose level measured by random fingerstick check is elevated at 201 mg/dL, and hemoglobin A1c is 6.8%.  The patient is asked to measure and record her blood glucose level prior to each meal.  The results over 4 days are shown below.

Which of the following is most likely responsible for this patient’s low blood glucose levels?a

A 55-year-old woman, gravida 3 para 3, comes to the office due to constipation.  For the past 6 months, the patient has had increasing constipation associated with mild, crampy abdominal pain and fatigue.  She has only 1 or 2 bowel movements every week.  Medical history is notable for nephrolithiasis, for which the patient was briefly hospitalized a year ago.  She has not undergone colonoscopy.  Vital signs are normal.  The abdomen is soft.  Rectal tone is normal.  Deep tendon reflexes are 2+.  The remainder of the examination shows no abnormalities.  Laboratory results are as follows:

Which of the following is the most likely underlying cause of constipation in this patient?

A 2-year-old girl is brought to the clinic by her mother for evaluation of ambiguous genitalia.  She was born with clitoral enlargement and partial fusion of the labioscrotal folds.  The patient has also had high blood pressure recorded on 3 consecutive office visits.  She has been tracking at the 50th percentile for height and weight, and has not had any other medical problems.  Family history is noncontributory.  Laboratory studies are significant for moderate hypokalemia.  Cytogenetic studies show a 46,XX karyotype.  Which of the following enzymes is most likely deficient in this patient?

A 64-year-old man comes to the emergency department due to severe abdominal pain, nausea, and vomiting.  Medical history is significant for hypertension, myocardial infarction, and heart failure with reduced ejection fraction.  The patient does not use alcohol but smokes a half-pack of cigarettes daily.  Temperature is 37.6 C (99.7 F), blood pressure is 100/60 mm Hg, pulse is 116/min and irregular, and respirations are 24/min.  The abdomen is soft, mildly distended, and mildly tender without rebound or guarding.  Laboratory results are as follows:

CT angiography of the abdomen reveals an occlusion within the proximal superior mesenteric artery.  Decreased activity of which of the following enzymes best explains this patient’s acid-base disorder?

A 55-year-old, right-handed man comes to the emergency department due to persistent right arm tingling and numbness for the past several hours.  The patient has no headache, muscle weakness, slurred speech, or difficulty ambulating.  Medical history includes hypertension, paroxysmal atrial fibrillation, and prior ischemic stroke without residual symptoms.  Anticoagulation was discontinued 2 months ago after he developed a gastrointestinal hemorrhage.  Blood pressure is 150/90 mm Hg, and pulse is 92/min and regular.  During the evaluation, the right arm paresthesia spreads to the entire right side of the body, and the patient develops right-sided convulsions, followed by a bilateral tonic-clonic seizure.  The patient’s seizure most likely originated from which of the following structures in the left cerebral hemisphere?