USMLE USMLE Certifications USMLE-STEP-3 Questions & Answers

• Question 11:

  A 60-year-old male presents to the office with a growth on the inside of his lower lip. It has been present for several months and is slowly growing. He is a nonsmoker but has a long history of chewing tobacco. Which of the following is the most likely to be found on biopsy of the lesion?

  A. adenocarcinoma

  B. lymphoma

  C. basal cell carcinoma

  D. carcinoid tumor

  E. squamous cell carcinoma

  Correct Answer: E Section: (none)

  Explanation:

  Squamous cell carcinoma is the most common malignant tumor of the oral mucosa and may occur at any site. It most frequently involves the tongue, followed in descending order by the floor of the mouth, alveolar mucosa, palate, and buccal mucosa. The male to female ratio is 2:1 for the gum, but 10:1 for the lip. There are substantial variations in the geographical distribution of the oral cancer. For example, it is the single most common cancer of men in India.

• Question 12:

  A 53-year-old White female, with a history of systemic lupus erythematosus (SLE), hypertension, and peripheral vascular disease, is admitted to the hospital for chest pain and dyspnea. Her cardiac enzymes were positive for acute MI. She subsequently undergoes a cardiac catheterization and stenting of the right coronary artery. Her postcardiac catheterization course is unremarkable, and she is discharged home 3 days later with adequate blood pressure control. Five days later, she is brought to the ER by her husband for abdominal pain and nausea. Her medications consist of aspirin, metoprolol, and prednisone. On physical examination, her blood pressure is 190/95 and her heart rate is 85 bpm. In general, she appears nauseated but is in no acute distress. Her cardiac examination reveals a regular rate and rhythm without murmur or rub. Her lung fields are clear bilaterally. The abdominal examination is positive for diffuse discomfort, without guarding or rebound, and normoactive bowel sounds; her stool is positive for occult blood. Her lower extremities have trace edema bilaterally with 2+ distal pulses; moreover, she has a reddish-blue discoloration on both her lower extremities. You retrieve her records from prior hospitalization. The patient's laboratory results are as follows:

  Which of the following laboratory findings would be most suggestive of active lupus nephritis?

  

  A. urinary RBC casts

  B. urinary WBC casts

  C. >3.5 g of proteinuria on 24-hour urine sample

  D. normal serum complement levels

  E. urinary eosinophils by Hansel stain

  Correct Answer: A Section: (none)

  Explanation:

  This patient has atheroembolic disease, most likely from the dislodging of arterial plaque during or after the cardiac catheterization, with subsequent kidney embolization. The findings in her history and physical examination that would suggest this are the presence of significant hypertension, abdominal pain, the redblue rash on her extremities (livedo reticularis), and eosinophilia with urinary eosinophils. Furthermore, the time course of the development of acute renal failure is suggestive of atheroembolic disease. The typical time course for contrast nephropathy is of an immediate onset, usually with subsequent recovery. However, in patients with atheroembolic disease, the kidney failure can occur much later after the procedure. Contrast nephropathy is not associated with the laboratory abnormalities and physical examination findings seen in this case. Interstitial nephritis is unlikely, as is a lupus nephritis flare, given her classic presentation for emboli. Calculation of the fractional excretion of sodium (FeNa) is helpful in differentiating between "prerenal" causes (FeNa <1%) of acute renal failure versus intrinsic causes (FeNa >1%). A kidney ultrasound is helpful in determining the presence of urinary tract obstruction. Neither the anion gap nor calculation of glomerular filtration rate is helpful in determining if volume depletion is a possible etiology of acute renal failure. Examination of urine sediment would be helpful in determining the presence of a glomerular etiology of acute renal failure, not a prerenal etiology. Demerol and metabolites can accumulate in patients with depressed kidney function, leading to increased levels and, potentially, convulsions. NSAIDs should be avoided in patients with acute kidney failure, as these drugs are potential nephrotoxins and could prevent a recovery of kidney function. Ketorolac, indomethacin, and ibuprofen are all NSAIDs. Therefore, morphine is the best option of those given.WBC casts are suggestive of pyelonephritis. High levels of proteinuria are significant for the diagnosis of nephrotic syndrome, but not lupus nephritis specifically. Urine eosinophils are usually seen in patients with acute interstitial nephritis or atheroembolic disease. Lupus nephritis is usually associated with depressed serum complement levels. Of these tests, RBC casts are the most suggestive of glomerulonephritis.

• Question 13:

  A 53-year-old Black male, with a history of hypertension, hepatitis C, and newly diagnosed nonsmall cell lung cancer, undergoes his first round of chemotherapy, which includes cisplatin. You are called to see this patient 5 days into his hospitalization for oliguria and laboratory abnormalities. Other than the chemotherapy, he is receiving lansoprazole, acetaminophen, and an infusion of D5--0.9% normal saline at 50 mL/h. On examination, his BP is 98/60 and heart rate is irregular, between 40 and 50 bpm. His physical examination shows a middle-aged male in no acute distress. His cardiac examination is unremarkable, his lungs show bibasilar crackles, and the abdominal examination is positive for a palpable spleen tip without any hepatomegaly or abdominal tenderness. He has trace bilateral ankle edema. His distal pulses are irregular. The neurologic examination was unremarkable. His laboratory (serum sample) results are as follows What is the mechanism that best explains this patient's hyperkalemia?

  

  A. DKA

  B. acute kidney failure leading to an inability to excrete potassium in the urine

  C. release of potassium from the destruction of neoplastic cells

  D. chemotherapy-induced hyperkalemia

  E. type 4 renal tubular acidosis

  Correct Answer: C Section: (none)

  Explanation:

  The patient has tumor lysis syndrome. The destruction of malignant cells by chemotherapeutic agents will lead to the release of intracellular contents, including potassium, phosphorus, and uric acid (from nucleic acids). This can result in hyperkalemia, hyperuricemia, and hyperphosphatemia. Hyperkalemia will produce significant ECG abnormalities, including peaked T waves and widened QRS complexes. The presence of bradycardia and irregular heart rate on physical examination are suggestive of the cardiac effects of hyperkalemia, which can lead to lifethreatening arrhythmias if not addressed. Patients with tumor lysis syndrome can develop a severe hyperuricemia. The kidneys are responsible for the excretion of uric acid. In acidic urine, the uric acid can crystallize in collecting tubules, resulting in intratubular obstruction and acute kidney failure. Calcium oxalate stones are not a part of this entity. Cisplatin can cause renal potassium and magnesium losses, which is not the case in this patient. The laboratory data suggest the release of intracellular contents (high LDH, uric acid, potassium, and phosphate) and the diagnosis of urate nephropathy as the cause of his acute kidney failure. As mentioned before, hyperkalemia will produce significant ECG abnormalities, including peaked T waves and widened QRS complexes. Prominent U waves are found in hypokalemia, not hyperkalemia. Atrial fibrillation is not typically seen in hyperkalemia

• Question 14:

  A 68-year-old White male, with a history of hypertension, an 80 pack-year history of tobacco use and emphysema, is brought into the ER because of 4 days of progressive confusion and lethargy. His wife notes that he takes amlodipine for his hypertension. He does not use over-the-counter (OTC) medications, alcohol, or drugs. Furthermore, she indicates that he has unintentionally lost approximately 30 lbs in the last 6 months. His physical examination shows that he is afebrile with a blood pressure of 142/85, heart rate of 92 (no orthostatic changes), and a room-air O2 saturation of 91%. He is 70 kg. The patient appears cachectic. He is arousable but lethargic and unable to follow any commands. His mucous membranes are moist, heart rate regular without murmurs or a S3/S4 gallop, and extremities without any edema. His pulmonary examination shows mildly diminished breath sounds in the right lower lobe with wheezing bilaterally. The patient is unable to follow commands during neurologic examination but moves all his extremities spontaneously. Laboratory results are as follows:

  Blood Sodium: 109 Potassium: 3.8 Chloride: 103 CO2: 33 BUN: 17 Creatinine: 1.1 Glucose: 95 Urine osmolality: 600 Plasma osmolality: 229 White blood cell (WBC): 8000 Hgb: 15.8 Hematocrit (HCT): 45.3 Platelets: 410 Arterial blood gas: pH 7.36/pCO2 60/pO2 285 A chest x-ray (CXR) reveals a large right hilar mass.

  Which of the following provides the best explanation for this patient's hyponatremia?

  A. inappropriate high level of antidiuretic hormone

  B. increased water intake (psychogenic polydipsia)

  C. volume depletion due to decreased oral intake over the last week

  D. the use of a thiazide for the treatment of hypertension E. decreased expression of renal collecting duct "water channels"

  Correct Answer: A Section: (none)

  Explanation:

  The patient has hypotonic hyponatremia, which can lead to increased water shifting into the brain, resulting in cerebral edema. This patient has nothing in history or physical examination to suggest a stroke or the presence of sepsis as the etiology of his altered mental status. Central pontine myelinolysis is a potentially devastating neurologic complication that can result from the treatment of hyponatremia, not hyponatremia itself. While respiratory acidosis could potentially contribute to this patient's change in mental status, cerebral edema due to hypotonicity is the most likely etiology. The patient's laboratory studies indicate a low plasma osmolality with an inappropriately increased urine osmolality. With this degree of hypotonicity, the urine should be maximally dilute (osmolality of <100 mOsmol/kg H2O). The high urine osmolality suggests the presence of antidiuretic hormone. In psychogenic polydipsia, the urine would be maximally dilute. Choice C is unlikely since his physical examination does not suggest volume depletion; furthermore, the patient is taking a calcium channel blocker, not a diuretic, for the treatment of his hypertension. Decreased expression of renal collecting duct water channels would lead to water wasting and, thus, the development of diabetes insipidus and hypernatremia. The patient has symptomatic hypotonic hyponatremia with signs of cerebral edema.

  This requires immediate attention. Choices A, C, and E are essentially hypotonic solutions which should be withheld in patients with hyponatremia. The serum sodium in this case should be increased by at least 5% for the treatment of cerebral edema. The use of 0.9% saline would require nearly 5 L of infusate to address this cerebral edema. This could lead to pulmonary edema and volume overload. The use of hypertonic saline (3% saline) is the ideal solution to use in this scenario, as the infusion of 3% saline will correct the symptoms while avoiding volume overload. As in all cases of hyponatremia management, frequent serum sodium assays are necessary in order to avoid too rapid of a correction, which could result in neurologic injury--pontine myelinolysis.

• Question 15:

  A 72-year-old man comes to your clinic for the first time, accompanied by his wife. His wife states that she is concerned because he has been growing increasingly forgetful over the past year. Within the past month, he has forgotten to turn off the stove and has got lost while walking to the post office one block away from their home. His past medical history is significant for well-controlled diabetes and chronic lower back pain. He has no history of falls or traumatic injury to the head. Examination of the patient is significant for a score of 18 on a Mini Mental Status Examination (MMSE). During the administration of the MMSE, the patient blurts out that his wife brought him to the doctor because she is having an extramarital relationship. Despite appropriate treatment, the patient experiences a gradual decline in mental function. He develops erratic sleep habits, frequently awakening at night and wandering throughout his home. His wife states that she once found him sitting on the ground in their yard, unable to recall how he arrived there. During your latest examination of the patient, you note that he has lost the ability to sign his name, holding the pen as if he is unsure of what to do with it. Exasperated, his wife states that he is now dependent on her for performance of his activities of daily living. Which of the following is indicated in the treatment of the patient's condition at its current severity?

  A. tacrine (Cognex)

  B. gingko biloba

  C. rivastigmine (Exelon)

  D. memantine (Namenda)

  E. galantamine (Reminyl)

  Correct Answer: D Section: (none)

  Explanation: This patient's symptoms are most consistent with Alzheimer disease. Alzheimer disease is a prominent condition in developed nations, ranking as the third most common terminal illness behind heart disease and cancer. It is the most common form of dementia, with over 4 million Americans having the condition in the United States alone. There is a direct correlation between advanced age and increasing prevalence of Alzheimer disease. While there is an early-onset form of familial Alzheimer disease that may appear as early as the third decade of life, this accounts for only a small percentage of total Alzheimer cases. There does appear to be a genetic component to the development of Alzheimer disease, as it has been demonstrated that first-degree relatives of Alzheimer patients possess an increased risk for development of the condition. Genes on chromosomes 1, 14, and 21 have been implicated in this association. While age and family history are important risk factors, there is no evidence proving that environmental factors lead to an increased chance for development of the disease. Progression of Alzheimer dementia is typically insidious, spanning as many as several years.

  Anticholinergic agents and any other medication with anticholinergic effects are contraindicated in the setting of Alzheimer dementia. Their use may lead to worsening of cognition and may contribute to decreased efficacy of medications used in the treatment of Alzheimer dementia. Tricyclic antidepressants such as amitriptyline should be avoided for this reason. Risperidone, olanzapine, and quetiapine are atypical antipsychotic medications which are useful in the treatment of emotional withdrawal and delusions which may arise in Alzheimer patients. Trazodone, carbamazepine, and divalproex are moodstabilizing medications which are useful in patients who display marked agitation. While trazodone does display some anticholinergic side effects, they are far less pronounced than those seen with amitriptyline.

• Question 16:

  A 52-year-old man presents to the ED with a complaint of rectal bleeding and hematuria. He has a medical history significant for atrial fibrillation diagnosed 10 years ago and states that he takes metoprolol as well as warfarin for this condition. Upon examination, you find that his blood pressure is 122/78, his pulse is 84, his respiratory rate is 18, and his O2 saturation is 98% on room air. He has an irregularly irregular heart rhythm, gingival bleeding, and some bruises on his extremities. He has a positive fecal occult blood test, and laboratory studies return showing an international normalized ratio (INR) of 16.5.

  Reviewing the patient's medication list, you note that he mentions a "medication for depression" but does not recall the name. Which of the following is most concerning given the patient's current condition?

  A. amitriptyline

  B. trazodone

  C. fluoxetine

  D. venlafaxine

  E. imipramine

  Correct Answer: C Section: (none)

  Explanation:

  This patient has a markedly supratherapeutic INR and clinical evidence of bleeding. Discontinuation or dosage reduction of warfarin is an appropriate intervention by itself in patients with an INR less than 5.0 or in patients without signs of bleeding. In patients with bleeding or with an INR greater than 5.0, however, further interventions are indicated. Vitamin K1 administration provides a more rapid reversal of the anticoagulation caused by warfarin, but it takes 68 hours to begin having an effect and up to 24 hours to achieve its maximal effect. Immediate reversal may be obtained by the administration of fresh frozen plasma intravenously in addition to vitamin K1

• Question 17:

  A54-year-old Asian female with no significant medical history presents with frontal headache, eye pain, nausea, and vomiting. Her abdominal examination shows mild diffuse tenderness but no rebound or guarding. Her mucous membranes are dry. Her vision is blurry in both eyes, her eyes are injected but her extraocular muscles are intact. Her pupils are mid-dilated and fixed Which of the following is appropriate initial management of this patient?

  A. urgent consultation of a general surgeon

  B. urgent consultation of an ophthalmologist

  C. prescription of an antiemetic with follow-up the next day in the office

  D. bed rest with head of bed elevated to45 degrees

  E. performance of a dilated eye examination prior with referral if abnormalities seen

  Correct Answer: B Section: (none)

  Explanation:

  The presence of headache, eye pain, nausea, and vomiting should prompt the consideration of the diagnosis of acute angle closure glaucoma. This is a rare but serious condition in which the aqueous outflow is obstructed, and the intraocular pressure abruptly rises. Susceptible eyes have a narrow anterior chamber and when the pupil becomes dilated, the peripheral iris blocks the outflow via the anterior chamber angle. Edema of the cornea occurs, resulting in cloudiness on examination. Diagnosis is made by measuring the intraocular pressure during an acute attack. Treatment includes medications to induce miosis in an effort to relieve the blockage or, if that fails, surgical intervention. In some patients, the headache or GI symptoms can overshadow the ocular symptoms, resulting in a delay in diagnosis and unnecessary workup for other conditions. In this case, the lack of findings on abdominal examination makes appendicitis or perforated bowel unlikely. DKA can present with primary GI symptoms, but would not explain the ocular symptoms. Similarly, cerebellar or other brain tumors may cause headache, nausea, and vomiting, but would not be causes of a painful, red eye.

• Question 18:

  A 42-year-old man presents to your clinic with a 1-week history of pain and inflammation involving his right first metatarsophalangeal (MTP) joint. He describes the pain as sudden in onset and worse at night. He denies experiencing any fever or traumatic injury to the joint and states that he has never had this type of pain before. He denies any chronic medical conditions, any prior surgery, and any current medication use. Besides an erythematous and exquisitely tender right first MTP joint, the remainder of his physical examination is unremarkable. Aspiration of the patient's right first MTP joint space is likely to reveal which of the following?

  A. negatively birefringent crystals

  B. positively birefringent crystals

  C. nonbirefringent crystals

  D. acellular synovial fluid

  E. gram-positive cocci in clusters

  Correct Answer: A Section: (none)

  Explanation:

  This patient's presentation is consistent with gout. Aspiration of his first MTP joint is likely to reveal the presence of needle-shaped, negatively birefringent crystals. Rhomboid-shaped, positively birefringent crystals are characteristic of calcium pyrophosphate deposition disease, or pseudogout, with the knee being the joint most commonly affected. Nonbirefringent crystals are found in hydroxyapatite crystal deposition disease. The synovial fluid from joints affected by gout typically show evidence of inflammation in the form of leukocytosis with a predominance of polymorphonuclear neutrophils. The presence of bacteria in synovial fluid is characteristic of infection rather than gout, although gout and infectious arthritis may coexist. (Cecil Textbook of Medicine, pp. 17031708) Acute gouty arthritis usually presents in a monoarticular or oligoarticular distribution, with the first MTP joint most commonly affected. The diagnostic gold standard is detection of urate crystals within the synovial fluid of affected joints. It most commonly affects adult men with a peak incidence in the fifth decade of life. While patients with gout typically also have hyperuricemia, only a small fraction of the people with hyperuricemia actually have or will develop gout.

  Tophi are primarily seen in patients with long-standing hyperuricemia and is considered a finding of chronic gouty arthritis. As the disease progresses, acute attacks become more frequent and last longer if left untreated. Indomethacin inhibits the prostaglandin synthesis that facilitates the inflammation of acute gout and inhibits the phagocytosis of urate crystals by leukocytes. This inhibits the cell lysis and release of cytotoxic factors that initiate the inflammatory cascade. Allopurinol (an inhibitor of urate synthesis) and probenecid and sulfinpyrazone (promoters of urate excretion) are useful for preventing gout but are not effective during an acute gout attack. Aspirin is inappropriate in the treatment of gout since it can inhibit urate elimination and, therefore, increase hyperuricemia.

• Question 19:

  A 65-year-old man presents to your office for evaluation of abdominal pain. The patient states that he has epigastric pain that radiates to his back. The pain is worse with eating and improves with fasting. The pain has been present for 6 months and is gradually worsening. The patient has lost 15 lbs but feels his oral intake has been adequate. He complains of greasy stools and frequent thirst and urination. Examination reveals a thin male with temporal wasting and oderate abdominal pain with palpation. The patient consumes approximately 1015 beers per day and smokes a pack of cigarettes per day for the past 20 years. The patient's weight loss would be best treated by which of the following regimens?

  A. pancreatic enzyme replacement therapy

  B. liquid caloric supplementation by mouth

  C. liquid caloric supplementation via gastrostomy tube

  D. total parenteral nutrition (TPN)

  E. partial parenteral nutrition (PPN)

  Correct Answer: A Section: (none)

  Explanation:

  The patient's history and examination are worrisome for pancreatic disease, and he has strong signs of pancreatic insufficiency. His long history of alcohol use suggests the possibility of chronic pancreatitis or pancreatic cancer. Fecal fat studies would only confirm or quantify his steatorrhea. ACT scan would image the pancreas for changes consistent with chronic pancreatitis (duct dilation, calcifications, pseudocysts) and could look for a neoplasm of the pancreas as well. ERCP is not indicated as a first-line test in patients with abdominal pain given its risk of causing acute pancreatitis. Upper endoscopy would be helpful to rule out peptic ulcer disease and other gastric complaints, but would not provide more global information about the abdomen. The patient has greasy stools and weight loss, findings seen in patients with steatorrhea due to chronic pancreatitis.

  Patients with steatorrhea malabsorb fat-soluble vitamins (vitamins A, D, E, and K). "Night blindness" (poor night vision) due to vitamin Adeficiency is common among patients with advanced chronic pancreatitis and likely led to this patient's motor vehicle accident. The patient has DM as a consequence of pancreatic endocrine insufficiency, another feature of chronic pancreatitis. Diabetes develops when greater than 8090% of the gland has been destroyed. Patients with chronic pancreatitis have a coexisting loss of glucagon from islet cells and, thus, often become brittle diabetics, with hypoglycemia seen after insulin administration. Vitamin K and B12 deficiency, which the patient may have, do not cause hypoglycemia. The patient was previously noted to eat well, so inadequate oral intake is unlikely. Diabetic education should decrease the rate of chronic insulin overdosage.

  The patient has pancreatic exocrine insufficiency and thus cannot produce enough pancreatic enzymes to digest his food. Pancreatic enzyme replacement therapy in tablet form is a mainstay of therapy for chronic pancreatitis. It can rapidly reverse this problem by providing exogenously produced pancreatic enzymes to break down fats, carbohydrates, and proteins for absorption in the small bowel. The patient would not benefit from additional oral feedings without enzyme supplementation and would only worsen his steatorrhea by doing so. He can take food orally, so feeding via gastrostomy, TPN, or PPN are not indicated. The patient's worsening pain and weight loss despite therapy is worrisome for the development of pancreatic cancer. CA-19-9 is frequently (but not universally) elevated in pancreatic cancers, although it can be elevated in cholangiocarcinoma as well. PSA is associated with prostate cancer. CEA is associated with colon cancer. CA-125 is associated with ovarian cancer. AFP is associated with hepatocellular carcinoma.

• Question 20:

  A61-year-old man comes to your office for a checkup. He currently feels well and has no focal complaints. He has a past medical history significant for wellcontrolled hypertension, and his gallbladder was removed 3 years ago in the setting of acute cholecystitis. He does not smoke and drinks one to two alcoholic beverages per day. Family history is remarkable for colon cancer in his mother at age 45 and a brother at age 49. He has a sister who developed endometrial cancer at age 53. He has never undergone colon cancer screening and is interested in pursuing this. Which colorectal cancer screening test would be best for this patient?

  A. virtual colonoscopy (aka CT colography)

  B. barium enema alone

  C. barium enema with flexible sigmoidoscopy

  D. fecal occult blood testing three times

  E. colonoscopy

  Correct Answer: E Section: (none)

  Explanation:

  The patient should undergo screening colonoscopy, especially with his strongly positive family history of first-degree relatives developing colon cancer before age 50. Colonoscopy is the only test that can directly evaluate the entire colon and rectum. Most polyps can be removed completely at colonoscopy, and large lesions or masses can be directly biopsied. Virtual colonoscopy and barium enema combined with flexible sigmoidoscopy are good tests, but any positive findings on either of these tests would warrant further examination with colonoscopy. Barium enema alone is insufficient for screening. Fecal occult blood testing is helpful as a screening tool, but would be inadequate alone in this patient given his family history. The patient satisfies criteria for HNPCC, a syndrome seen in patients with germline mutations in DNA mismatch repair (MMR) genes. He has three first-degree relatives with cancer of the colorectum, endometrium, small bowel, ureter, or renal pelvis (all of whom are first-degree relatives of each other). The colorectal cancers involve at least two generations and at least one case was diagnosed before age

  50. FAP involves a mutation of the APC gene and results in dense colonic polyposis, mandibular osteomas, and universal colon cancer at a young age unless colectomy is performed. Peutz Jeghers syndrome results in hamartomatous polyps of the gut as well as mucocutaneous pigmentation changes. Cronkhite-Canada syndrome manifests as GI polyposis, alopecia, cutaneous hyperpigmentation, malnutrition, and dystrophic fingernails. Turcot syndrome is a variant of FAP in which patients can also develop medulloblastoma, glioblastoma multiforme, and hypertrophy of retinal pigmented epithelium.