TL;DR
The Step 2 CK “Free 120” is the official set of 120 sample items published by the USMLE, available as a PDF (the current booklet is marked “updated July 2023”) and in the interactive testing experience that reproduces the real exam interface, including the sequential item sets and the abstract-based questions. It is the only Step 2 CK practice material written by the exam’s own authors, and the PDF gives you the answer letters but no explanations. Below is an item-by-item key with the reasoning behind each answer and the trap in each major distractor. We do not reproduce the question stems (they are NBME copyright); each entry carries a short descriptor so you can match it to the item in front of you. Take the set timed first, then work through this page with your incorrects and your lucky guesses.
How to use the Step 2 CK Free 120 (and this key)
The Free 120 is a calibration tool, not a content review. It is a small sample and it runs a little easier than a live form, so do not read too much into the percentage; what it shows you reliably is the interface, the pacing of the newer format (since May 7, 2026, Step 2 CK runs sixteen 30-minute blocks of up to 20 items), and the item styles that question banks imitate imperfectly: the two- and three-question sequential sets, the research-abstract set with its own data table, and the ethics and systems-based-practice items that make up a larger share of Step 2 CK than most students expect. Take it in the interactive testing experience during the last week before your exam, in 20-item timed blocks. Then use this key to review every item you missed or were unsure about. The explanations are written to teach the decision rule behind each item (why this test next, why this drug first, who decides) rather than just to defend the letter, because the same rules recur on the real exam in different patients. When one domain keeps showing up in your misses, that is the signal to drill it with more questions rather than to re-read.
Note on versions: USMLE revises the sample set periodically. This key matches the booklet marked “updated July 2023” (120 items in three blocks of 40). If your copy has a different date on the first page, item numbers may not line up.
Block 1: Items 1–40
1. 21-year-old man with six months of recurrent panic attacks who now avoids public places and dating. Answer: A, agoraphobia. Recurrent, unexpected panic attacks followed by avoidance of situations where escape might be difficult is agoraphobia (which can coexist with panic disorder, and panic disorder is not among the choices). Social anxiety disorder centers on fear of scrutiny rather than fear of having an attack; generalized anxiety is chronic worry without discrete attacks; illness anxiety and somatic symptom disorder focus on disease fears.
2. 35-year-old man with an acute left MCA stroke while weight-lifting, a swollen tender calf, and a normal carotid ultrasound. Answer: E, echocardiography with bubble study. A young stroke patient with signs of a deep venous thrombosis and no carotid disease needs evaluation for a paradoxical embolus across a patent foramen ovale, and a transthoracic echo with agitated-saline contrast is the test that shows right-to-left shunting (the Valsalva of lifting weights is the classic trigger). Stress testing and catheterization look for ischemia, not shunts; CT angiography of the head would not explain the mechanism.
3. 65-year-old man on amiodarone, warfarin, lisinopril, tiotropium and propranolol with two years of exertional dyspnea, dry cough and fine bibasilar crackles. Answer: A, amiodarone. Slowly progressive dyspnea, nonproductive cough and fine crackles in a patient on long-term amiodarone is amiodarone pulmonary toxicity (interstitial pneumonitis or fibrosis), the drug’s most serious adverse effect. Lisinopril causes a dry cough without crackles or dyspnea; propranolol can worsen bronchospasm; tiotropium and warfarin do not cause interstitial lung disease.
4. 18-month-old boy with recurrent fractures, blue sclerae and a mother with childhood fractures. Answer: A, audiography. This is osteogenesis imperfecta (type I collagen defect, autosomal dominant), and conductive and sensorineural hearing loss develops in a large share of patients, so regular hearing assessment is the recommended screening. DEXA is not standardized in toddlers, cardiac and retinal screening belong to Marfan syndrome, and calcium and vitamin D levels are normal in OI.
5. 70-year-old woman with dementia and lung cancer who lacks capacity and has no health care agent; a boyfriend of 20 years who is her caregiver, an adult son out of state, and a neighbor who helps. Answer: E, son. This is a surrogate-hierarchy item, and the exam applies the default statutory order used by most states when no health care agent has been appointed: spouse, then adult children, then parents, then siblings, and only then other relatives or close friends. An unmarried partner, however devoted, is not a legal spouse and in most jurisdictions has no standing above an adult child, so the son is the legal decision-maker. In practice the physician should involve the boyfriend heavily, because he knows her wishes best, and the son should decide by substituted judgment using that information. The neighbor is a helper, not a surrogate; the patient lacks capacity; the physician does not become the surrogate when family exists. The lesson: on the exam, legal hierarchy beats emotional closeness unless the patient has appointed someone.
6. 4-month-old girl five days after VSD repair: fever, cool clammy extremities, delayed capillary refill, minimal urine output; rhythm strip and arterial tracing shown. Answer: C, echocardiography. The rhythm strip shows a regular rhythm, so an arrhythmia is not the explanation, while the arterial pressure tracing shows beat-to-beat variation in pulse pressure, the respiratory swing of pulsus paradoxus. Fever, low cardiac output and a paradoxical pulse in the first postoperative week after cardiac surgery is pericardial effusion with tamponade (postpericardiotomy syndrome), and bedside echocardiography both confirms the effusion and guides drainage. Catheterization, CT, MRI and an electrophysiology study are slower, more invasive, and do not address the most likely and most dangerous diagnosis.
7. 6-year-old girl with periorbital then dependent edema after a cold; urine with large protein, no blood. Answer: B, serum albumin concentration. Nephrotic syndrome in a young child, almost always minimal change disease, produces heavy proteinuria and hypoalbuminemia, which drives the edema. Triglycerides and cholesterol rise, not fall; complement levels are normal in minimal change disease (they fall in post-infectious glomerulonephritis and lupus); hemoglobin is not characteristically low; urea nitrogen is normal or elevated from intravascular depletion.
8. 9-year-old girl with asthma, nocturnal cough about once a week, and avoidance of running; no albuterol use in four weeks. Answer: B, add fluticasone MDI with spacer. Nighttime symptoms more than twice a month and activity limitation mean her asthma is persistent rather than intermittent, and the first-line controller for persistent asthma in a child is a daily low-dose inhaled corticosteroid. A long-acting β-agonist is never added without an inhaled steroid; theophylline is a distant third-line option; oral prednisone is for exacerbations; and “no change” ignores the activity limitation.
9. 30-year-old man who smokes, BMI 29, father with an MI at 48. Answer: B, fasting serum lipid studies. A family history of premature coronary disease plus smoking and overweight justifies lipid screening in a 30-year-old; current guidelines support screening adults with risk factors from age 20 onward. A resting ECG has no screening value in an asymptomatic patient, and a chemistry profile is not a recommended screen in a healthy young man.
10. 82-year-old woman with foot numbness, absent ankle reflexes, severely reduced vibration and proprioception; decades of calcium carbonate and nightly wine. Answer: F, vitamin B12 (cyanocobalamin) supplementation. Loss of vibration and position sense (posterior column) with areflexia in an elderly patient is subacute combined degeneration from B12 deficiency, which is common in the elderly because of atrophic gastritis and is worsened by chronic antacid use that impairs acid-dependent B12 release from food. Alcohol causes a painful axonal neuropathy without dominant posterior-column signs; thiamine deficiency causes Wernicke encephalopathy and a different neuropathy; folate deficiency causes anemia without neuropathy.
11. 50-year-old chewing-tobacco user with a 1-cm white buccal lesion. Answer: B, surgical biopsy of the lesion. A persistent white oral patch in a tobacco user is leukoplakia until proven otherwise, and a proportion harbor dysplasia or squamous cell carcinoma; the standard of care is excisional or incisional biopsy. Cytology of a mucosal surface is unreliable for depth of invasion, nystatin treats candidiasis (which wipes off, unlike leukoplakia), and observation risks missing a cancer.
12. 48-year-old heavy drinker and smoker who collapsed: hypotension, S3, bilateral crackles, hepatomegaly and edema. Answer: B, dilated cardiomyopathy. Biventricular failure with an S3 and no murmur in a man drinking two dozen beers a week is alcoholic dilated cardiomyopathy. A large pericardial effusion would give muffled sounds and no S3 or pulmonary crackles; regional wall motion abnormalities suggest ischemic disease, which is possible but less specific to the history; LVH alone does not explain the low output; paradoxical septal motion points to constriction or right ventricular overload.
13. 68-year-old man with Parkinson disease, frequent backward falls and a wrist fracture; positive pull test. Answer: B, physical therapy. Postural instability in Parkinson disease responds poorly to dopaminergic drugs, and adding a dopamine agonist (pramipexole, ropinirole, rotigotine) would increase his orthostatic hypotension and fall risk. Gait and balance training with a physical therapist, with assistive devices, is the intervention shown to reduce falls. Biofeedback has no role here.
14. 6-year-old boy adopted from an orphanage who cannot read in any language despite average receptive language and age-appropriate daily living skills. Answer: D, learning disorder. Normal intelligence and adaptive function with a specific deficit in reading is a specific learning disorder (dyslexia). Intellectual disability requires deficits in both intellectual and adaptive function; autism requires social-communication deficits and restricted behaviors; reactive attachment disorder requires disturbed attachment behavior, and he is warm toward siblings and new parents; nothing in the vignette supports fetal alcohol syndrome or PTSD.
15. 17-year-old boy with urticaria, dyspnea and hypotension 36 hours into amoxicillin. Answer: C, epinephrine. Urticaria plus respiratory compromise plus hypotension is anaphylaxis, and intramuscular epinephrine is the first and only life-saving step; antihistamines and albuterol are adjuncts that do not treat the hypotension. Observation or laboratory testing while a patient is in anaphylaxis is a dangerous delay.
16. 47-year-old woman with recent Clostridioides difficile colitis and ongoing loose stools, in clinic for staple removal. Answer: B, hand wash with soap and water. C. difficile spores are not killed by alcohol-based hand rubs; the mechanical removal of soap-and-water washing is required, together with gloves and gown (contact precautions). Masks are not indicated for an enteric pathogen; sterile technique is for the procedure, not infection control.
17. Abstract set: 38-year-old woman on methadone considering buprenorphine; medium- and high-dose comparison. Answer: E, the efficacy difference at these doses is unclear. The abstract’s own numbers show no statistically significant difference in retention between buprenorphine and methadone at medium or high doses; the significant advantage for methadone appears only at flexible and low doses. Option A quotes the point estimates as if they were significant; C generalizes a subgroup finding; D contradicts the placebo comparison; B is not addressed by the data.
18. Abstract set: which aspect most limits confidence in the review’s conclusions. Answer: E, inclusion of trials with 2-week duration. Retention in maintenance treatment is a long-horizon outcome, and pooling two-week trials with year-long ones makes the summary estimate hard to interpret. Including only randomized trials and excluding detoxification studies and pregnant patients are reasonable design choices that narrow applicability rather than undermine validity; urinalysis is not how retention was measured.
19. Abstract set: which factor is most likely to bias the review’s results. Answer: C, likelihood that positive trials are more likely published. Systematic reviews and meta-analyses are vulnerable to publication bias, because studies with null results are less likely to appear in the literature from which the review draws. Variation in sample size is handled by weighting; funding source and exclusion criteria can introduce bias but are not the characteristic threat to a pooled estimate.
20. 57-year-old man with a ruptured aneurysm, GCS 3, absent brainstem reflexes; wife says he wanted to donate organs but there is no advance directive. Answer: B, contact the organ bank for potential donation. He meets clinical criteria for brain death, and the organ procurement organization should be notified early; an advance directive is not required because the next of kin can authorize donation, and hypertension does not exclude donation. An ethics consult is unnecessary when the family and the patient’s stated wishes agree, and the treating team should never match donors to recipients in-house.
21. 36-year-old woman in active labor progressing from 6 cm to 9 cm in 30 minutes; fetal heart tracing shown. Answer: C, expectant management. The tracing shows a normal baseline with moderate variability and two decelerations that mirror the contractions, beginning and ending with them with the nadir at the peak: early decelerations, which reflect fetal head compression during descent and are benign. Rapid cervical progress plus a reassuring tracing means nothing needs to be done. Pushing is not advised before complete dilation; amnioinfusion treats variable decelerations from cord compression; operative delivery requires a nonreassuring tracing or arrest of labor, neither of which is present.
22. 27-year-old woman with recurrent sinusitis, two pneumonias, and low IgA, IgG and IgM. Answer: E, monthly immune globulin replacement. Recurrent sinopulmonary infections with panhypogammaglobulinemia in a young adult is common variable immunodeficiency, and the treatment that prevents infections is replacement immune globulin (intravenous or subcutaneous). Prophylactic antibiotics are second-line; inhaled tobramycin is for cystic fibrosis; live intranasal influenza vaccine is contraindicated in immunodeficiency.
23. 37-year-old man from China with fatigue, mildly elevated transaminases, HBsAg positive and IgG anti-HBc positive. Answer: C, hepatocellular carcinoma. Surface antigen with IgG core antibody for more than six months is chronic hepatitis B, and the feared complication of untreated chronic HBV is hepatocellular carcinoma, which can occur even without cirrhosis; he needs antiviral therapy and surveillance ultrasound. Polyarteritis nodosa and membranoproliferative glomerulonephritis are associated with HBV but are far less common; cryoglobulinemia is a hepatitis C complication.
24. 10-year-old boy with hemophilia A and an acute hemarthrosis of the knee. Answer: B, factor VIII concentrate. Acute joint bleeding in hemophilia A is treated with factor VIII replacement to prevent hemophilic arthropathy; factor IX is for hemophilia B, fresh frozen plasma is a dilute and inferior source, desmopressin (not vasopressin) is useful only in mild hemophilia A and von Willebrand disease, and iron treats the consequence rather than the bleed.
25. 72-year-old man with three weeks of wavy, distorted vision in the right eye; clear lenses, normal red reflex. Answer: D, macular degeneration. Metamorphopsia (straight lines appearing curved) with central acuity loss in an older adult is macular degeneration, with the acute distortion suggesting neovascular (wet) disease. Cataracts are excluded by clear lenses; retinal artery occlusion is sudden and painless with a cherry-red spot; angle-closure glaucoma is painful with a fixed mid-dilated pupil; temporal arteritis causes abrupt monocular loss with headache and jaw claudication.
26. 28-year-old man with a very painful red forearm lesion two days after a spider bite in the southeastern mountains. Answer: A, eschar at wound center. A painful, erythematous bite that progresses over days is the picture of a brown recluse (Loxosceles) envenomation, whose hallmark is central necrosis forming a dark eschar surrounded by ischemic pallor and erythema. Lymphangitic streaking and rapidly spreading cellulitis suggest bacterial infection, disseminated purpura suggests meningococcemia or vasculitis, and distal gangrene is not a feature.
27. 37-year-old man with BMI 33 and blood pressure 138/87 on two occasions. Answer: C, DASH diet. Elevated blood pressure in the stage 1 range without diabetes, kidney disease or established cardiovascular disease (10-year risk well under 10% at his age) is managed with lifestyle change: weight loss, the DASH dietary pattern, sodium restriction, exercise and alcohol moderation. Drug therapy (ACE inhibitor, thiazide) is reserved for higher risk or stage 2 hypertension; fish oil and calcium supplements have no proven benefit for blood pressure.
28. 39-year-old thin man with six weeks of polyuria, 6.8-kg weight loss, glucose 578 and A1c 10.7%. Answer: B, insulin. A lean adult with marked symptomatic hyperglycemia, catabolic weight loss and an A1c above 10% needs insulin regardless of the eventual type label (this presentation is suggestive of type 1 or latent autoimmune diabetes). Oral agents alone are inadequate at this degree of hyperglycemia and can be dangerous if the patient is insulin-deficient.
29. 8-year-old girl hospitalized after head injury, now seizing with sodium 122. Answer: A, bolus of 3% saline IV. Symptomatic hyponatremia (seizure, altered mental status) is treated with hypertonic saline to raise sodium by a few mEq/L quickly, enough to stop the seizure. Isotonic saline would be too slow, vasopressin would worsen the water retention (she likely has SIADH from the head injury), and anticonvulsants, EEG and MRI do not address the metabolic cause.
30. 43-year-old man who lives with cats and dogs, with a tender 4-cm axillary node and an epitrochlear node. Answer: B, cat-scratch disease. Regional tender lymphadenopathy proximal to a scratch, in a cat owner, is Bartonella henselae infection; the epitrochlear node is a classic location. Hidradenitis causes recurrent axillary abscesses rather than a solitary node; Castleman disease and lymphoma produce nontender adenopathy; tuberculous adenitis is usually cervical and chronic.
31. Parents of a 2-year-old ask when to tell her she is adopted. Answer: B, as early as possible, even if she cannot process it fully. Children integrate adoption best when it is part of the family story from the beginning, with the explanation growing in detail as they mature; delaying disclosure until a milestone or until the child notices risks a sense of betrayal.
32. Surgical ICU with rising central-line days and bloodstream infections; the team wants to reduce catheter days. Answer: A, ask clinicians what they believe are common reasons for nonremoval. Quality improvement starts with understanding the process and its barriers (root cause analysis) before choosing an intervention. Routine catheter replacement increases complications and is not recommended; stickers are an intervention chosen before the problem is understood; a randomized trial is premature when the cause is unknown.
33. 17-year-old girl with three months of daily postprandial epigastric pain and a normal examination. Answer: B, endoscopy. Persistent epigastric pain with a meal relationship is dyspepsia from peptic ulcer disease or gastritis, and upper endoscopy is the definitive diagnostic test, allowing visualization and biopsy for Helicobacter pylori. CT and barium studies are insensitive for mucosal disease; the self-limited diarrhea weeks ago does not make this a parasitic or bacterial enteric infection.
34. 23-year-old man with paroxysmal cough and diffuse wheezing after cleaning mold with acetic acid; saturation 94%. Answer: A, albuterol. Acute irritant-induced bronchospasm is treated with an inhaled short-acting β-agonist; he is oxygenating adequately with a normal PCO2, so intubation is not indicated, and steroids, bronchoscopy and CT are not first steps for reactive airway symptoms after a chemical exposure.
35. 87-year-old man with metastatic colon cancer and malignant small-bowel obstruction who requests a laparotomy after being told surgery is no longer an option. Answer: C, explain the futility of the operation. Physicians are not obligated to provide interventions that offer no reasonable prospect of benefit, and the right response to a request for one is a compassionate, clear explanation of why it would not help, alongside the palliative plan (venting gastrostomy). Simply acceding, transferring the patient, or offering radiation or chemotherapy changes do not address the request honestly.
36. 62-year-old woman with weight loss, anxiety, atrial fibrillation, diffuse goiter with a bruit, widened palpebral fissures and pretibial skin thickening. Answer: E, thyrotoxicosis. A diffusely enlarged thyroid with a bruit, eye signs and pretibial myxedema is Graves disease; the systemic picture (tremor, weight loss, atrial fibrillation, hyperdefecation) is thyrotoxicosis. Pheochromocytoma causes paroxysmal hypertension without goiter; carcinoid causes flushing and diarrhea; Cushing and Addison do not match.
37. 28-year-old smoker with hematochezia, iron deficiency, and colonoscopy showing ulcers with normal intervening mucosa involving the ileum. Answer: D, smoking cessation. Skip lesions extending into the terminal ileum are Crohn disease, and smoking is the strongest modifiable risk factor for Crohn flares, surgery and recurrence (in contrast to ulcerative colitis, where smoking is paradoxically protective). Prophylactic colectomy is not indicated; citalopram is unrelated; lymphoma screening is not a routine recommendation.
38. 19-year-old man stabbed medial to the left nipple, now hypotensive with distended neck veins. Answer: D, pericardiocentesis. Hypotension with jugular venous distension after a penetrating wound in the “cardiac box” is pericardial tamponade, which a FAST examination confirms by showing pericardial fluid. The immediate step is to decompress the pericardium; needle decompression treats tension pneumothorax (which gives absent breath sounds, not JVD with normal lungs), and laparotomy or lavage address abdominal injury.
39. 47-year-old woman about to have knee arthroscopy; the signed consent cannot be found, there are no site markings, and spinal anesthesia has already begun. Answer: C, do not proceed; remove the patient from the operating room. Valid informed consent must be documented before anesthesia starts; a patient who has already received spinal anesthesia (with the sedation that typically accompanies it) is not in a position to give or re-give consent free of pressure, and the surgeon’s recollection does not substitute for the document. The missing site marking is a second failure of the pre-procedure checklist. The correct action is to stop, bring her out of the OR, and reschedule after proper consent and site marking. Proceeding on memory (A, E) or on a spouse’s verbal consent for a competent adult (D) are both wrong, and this item is a reminder that the exam treats the consent process and the time-out as hard stops, not formalities.
40. 30-year-old man with oligospermia, low-normal testosterone and a normal examination. Answer: A, ask about alcohol, smoking and stress. The initial step in male-factor infertility is to identify reversible contributors: tobacco, alcohol, heat exposure, drugs and stress all lower sperm counts. Exogenous testosterone suppresses spermatogenesis and would worsen the problem; PDE inhibitors treat erectile dysfunction; IVF is premature before a workup.
Block 2: Items 41–80
41. 40-year-old man ten days back from Malaysia with fever, sore throat and myalgias; leukopenia with lymphopenia, mild anemia, normal platelets, negative Monospot. Answer: D, HIV RNA PCR. A mononucleosis-like illness (fever, pharyngitis, myalgias, cytopenias) with a negative heterophile test is acute HIV infection until proven otherwise, and during the first weeks after exposure the antibody test can still be negative, so the diagnostic test is a viral RNA (nucleic acid) assay. Dengue is the travel-triggered distractor, but it characteristically produces thrombocytopenia and often a rash, and his platelets are normal; the hemagglutination inhibition assay is also the wrong test when influenza has been excluded by vaccination. CMV and EBV serologies are reasonable later, but missing acute HIV has far greater consequences for the patient and his contacts.
42. 22-year-old man found down after opioid and cocaine use; cold cyanotic leg, CK 50,000, potassium 5.5, bicarbonate 18. Answer: A, acute kidney injury. Prolonged immobilization and limb ischemia have produced rhabdomyolysis, and the dominant threat is pigment nephropathy from myoglobin, compounded by volume depletion; aggressive isotonic fluids are the treatment. Hyperkalemia and hypocalcemia occur but are consequences to monitor; arrhythmia risk follows from the potassium, which is only mildly elevated here; hypophosphatemia is wrong (phosphate rises).
43. 62-year-old woman with bipolar disorder, three days of confusion after playing tennis in the heat, a seizure, dry mucous membranes and second-degree AV block. Answer: C, lithium. Dehydration raises lithium levels (lithium is handled like sodium by the kidney), and lithium toxicity presents with confusion, tremor, seizures and cardiac conduction abnormalities including AV block. None of the other listed drugs explains the combination of neurotoxicity and heart block after volume depletion.
44. 32-year-old woman with infertility and a congenitally absent left kidney; hysterosalpingogram shown. Answer: E, preterm labor. Unilateral renal agenesis is strongly associated with Müllerian duct anomalies (a unicornuate uterus with a rudimentary horn is the classic pairing, and the HSG shows a single small uterine cavity). A unicornuate uterus has reduced capacity and poor vascularity, so its main obstetric risks are preterm labor, malpresentation and second-trimester loss. Macrosomia, multiple gestation and preeclampsia are not consequences of uterine anomalies; oligohydramnios would follow fetal, not maternal, renal problems.
45. 14-year-old girl with near-syncope and an orthostatic drop ten days after starting clonidine for ADHD. Answer: B, clonidine. Clonidine is a central α2 agonist that lowers sympathetic outflow and commonly causes hypotension, orthostasis and bradycardia, especially early in treatment. Methylphenidate and albuterol raise heart rate and blood pressure; a short prednisone burst does not cause orthostasis; rifampin colors body fluids orange and induces liver enzymes but does not drop blood pressure.
46. 51-year-old former smoker with absent pedal pulses and a femoral bruit, no symptoms. Answer: C, serum lipid studies. She has asymptomatic peripheral arterial disease, which is a coronary-equivalent risk state; management is aggressive risk-factor control (statin, blood pressure, antiplatelet), which starts with a lipid panel. Revascularization is for lifestyle-limiting claudication or critical limb ischemia; pentoxifylline has marginal benefit for symptomatic claudication; warfarin has no role in stable PAD.
47. 47-year-old woman with a mechanical mitral valve on warfarin, three days into trimethoprim-sulfamethoxazole for cellulitis; INR 5.2. Answer: A, review potential drug-drug interaction. Trimethoprim-sulfamethoxazole inhibits CYP2C9 and displaces warfarin from albumin, reliably driving the INR up within days. This is a patient-safety item: the near miss would have been prevented by checking for interactions before prescribing the antibiotic. Dietary counseling, imaging and stopping allopurinol do not address the cause.
48. 58-year-old woman with type 2 diabetes whose glucose has climbed with a new plantar foot lesion. Answer: A, glucose increased; insulin increased; receptor responsiveness decreased. Type 2 diabetes is defined by insulin resistance with compensatory hyperinsulinemia; an intercurrent infection (the foot lesion in a neuropathic foot) raises counter-regulatory hormones and worsens the resistance. Normal insulin with high glucose would suggest β-cell failure (late type 2 or type 1), which her still-good A1c and recent control argue against.
49. 57-year-old woman on day six of trimethoprim-sulfamethoxazole with fever, sore throat and WBC 2,200 with 16% neutrophils. Answer: C, adverse effect of trimethoprim-sulfamethoxazole. Profound neutropenia (absolute count under 500) with fever and pharyngitis within a week of starting a sulfonamide is drug-induced agranulocytosis; the antibiotic is stopped immediately and the fever is managed as neutropenic fever. Mononucleosis causes lymphocytosis with atypical lymphocytes, acute leukemia would show blasts and usually other cytopenias, lisinopril does not cause neutropenia at this tempo, and myelofibrosis is a chronic process.
50. 39-year-old man after an awkward landing: stable knee with full motion and negative Lachman; ankle with distal fibular tenderness, swelling and limited motion. Answer: C, knee no testing; ankle x-ray. The Ottawa rules decide this one. The knee has none of the criteria for imaging (no isolated patellar or fibular-head tenderness, no inability to flex to 90 degrees or to bear weight). The ankle has bony tenderness at the posterior edge or tip of the lateral malleolus with limited motion, which meets the Ottawa ankle criteria, so it needs radiographs.
51. 13-year-old girl below the 3rd percentile for height since birth, no menarche, Tanner 1 breasts. Answer: C, x-rays of left hand and wrist. The first step in evaluating short stature with delayed puberty is a bone age, obtained from a radiograph of the nondominant hand and wrist; it separates constitutional delay (delayed bone age) from familial short stature (normal bone age) and flags pathologic causes for further testing (a karyotype for Turner syndrome would follow). Skull and long-bone films, cortisol and routine chemistries are not the initial discriminating study.
52. 20-year-old woman with a year-old lump on her ear that appeared two months after piercing. Answer: A, corticosteroid injection. A firm nodule that developed after piercing and grew beyond the wound is a keloid, and intralesional triamcinolone is first-line therapy. Excision alone recurs in most cases (and often larger); cryotherapy and laser are adjuncts; aspiration is for cysts.
53. 42-year-old restrained driver after a head-on collision: tachypnea, hypoxia on oxygen, decreased right breath sounds, midline trachea; chest x-ray shown. Answer: F, tube thoracostomy. The film shows dense opacification of the right hemithorax with the lung compressed medially, a large hemothorax in a patient with a seat-belt injury, a hemoglobin of 10 and hypoxia. A chest tube evacuates the blood, re-expands the lung, and tells you the rate of ongoing bleeding (the trigger for thoracotomy is a large initial output or continued brisk drainage, not the initial film). Thoracentesis is for diagnostic sampling of effusions, not trauma; intubation is not yet needed in an alert patient with a normal PCO2; an epidural treats rib-fracture pain but does not drain blood; bronchoscopy is for suspected airway injury.
54. 31-year-old woman with three months of nonbloody diarrhea and weight loss after drinking pond water; stool smear shown. Answer: E, Giardia lamblia. Prolonged, nonbloody, often greasy diarrhea with weight loss after drinking untreated surface water is giardiasis, and the smear shows the pear-shaped trophozoites or oval cysts. The bacterial causes listed produce acute, often bloody illness lasting days; Entamoeba causes bloody dysentery and liver abscess; C. difficile follows antibiotics.
55. SERM chemoprevention trial: 1 cancer per 1,000 woman-years with the drug versus 3.6 per 1,000 with placebo. Answer: B, 2.6. Absolute risk reduction is the difference between the two incidence rates: 3.6 minus 1.0 equals 2.6 fewer invasive cancers per 1,000 woman-years. Option A (0.28) is the relative risk (1/3.6), and the raw counts (7 and 13) are distractors because the arms have different sizes.
56. Sequential set: 57-year-old woman with hematemesis, a month of early satiety, tachycardia; after fluids and nasogastric lavage. Answer: E, esophagogastroduodenoscopy. Upper GI bleeding is evaluated and treated with urgent endoscopy once the patient is resuscitated; it both finds the source and allows therapy. Colonoscopy is for lower GI bleeding; angiography and tagged red-cell scans are for bleeding that endoscopy cannot localize; CT does not treat.
57. Sequential set: after EGD, the next step (endoscopic photograph shown). Answer: D, endoscopic hemostatic therapy. The photograph shows an ulcer with active bleeding from a visible vessel, the highest-risk endoscopic finding for rebleeding, and the standard of care is immediate endoscopic therapy (epinephrine injection plus a thermal or mechanical method such as clips) during the same procedure, followed by a high-dose proton pump inhibitor. Omeprazole alone is adjunctive, not a substitute for hemostasis; biopsy of an actively bleeding lesion waits until bleeding is controlled (and her month of early satiety does warrant biopsy at follow-up to exclude malignancy); octreotide is for variceal bleeding; tyrosine kinase inhibitors treat GIST after diagnosis, not acute hemorrhage.
58. 77-year-old bedbound nursing-home resident on warfarin with blood on the sheets and a 3-cm fleshy lesion on the labium majus. Answer: F, vulvar biopsy. Any new raised or bleeding vulvar lesion in an older woman is biopsied to exclude vulvar squamous cell carcinoma or melanoma; topical steroids or antifungals without a diagnosis delay cancer detection, cytology of keratinized vulvar skin is unreliable, and imaging or colonoscopy does not address a visible lesion.
59. 68-year-old man with back pain radiating to both legs on standing, relieved by sitting; normal ankle-brachial index. Answer: D, spinal stenosis. Neurogenic claudication is positional: it comes on with standing and walking (extension narrows the canal) and resolves with sitting or bending forward, and the normal ABI excludes vascular claudication, which is distance-dependent and relieved by standing still. Peripheral neuropathy gives a stocking distribution rather than postural leg pain; an aneurysm would be a pulsatile mass; osteoporosis is painless until fracture.
60. 50-year-old man with schizophrenia and emphysema, headache and confusion, sodium 116, euvolemic. Answer: D, urine and plasma osmolarity. Severe euvolemic hyponatremia in a smoker on an SSRI is presumptively SIADH (from the drug, or from an occult small cell lung cancer), and the diagnosis is confirmed by showing an inappropriately concentrated urine against a low plasma osmolality before treating or imaging. Cortisol and TSH come next to exclude mimics; a chest CT may follow once SIADH is confirmed.
61. 67-year-old man with end-stage pancreatic cancer and respiratory failure; wife reports he refused ventilation, daughter demands it, no written directive. Answer: D, palliative therapy only. A patient’s previously expressed wishes, conveyed by a credible surrogate, carry the weight of an advance directive even without paperwork (substituted judgment); the daughter’s preference does not override them. Intubating against his stated wishes and then convening an ethics committee gets the sequence backward; court involvement is for genuine, unresolvable disputes about who speaks for the patient.
62. 5-day-old boy with an FS pattern on newborn hemoglobin electrophoresis. Answer: E, penicillin prophylaxis. An FS pattern (fetal plus sickle hemoglobin, no adult hemoglobin A) is sickle cell disease. Functional asplenia develops in infancy, so daily penicillin from about two months of age, plus pneumococcal vaccination, is what prevents the overwhelming sepsis that used to kill these infants. Hydroxyurea is started later for symptomatic disease; transfusions and iron chelation are for specific complications; iron and B12 are not indicated.
63. 1-week-old girl with a newborn-screen TSH of 40 and now TSH 14 with a low free T4. Answer: B, levothyroxine. A persistently elevated TSH with a low free T4 confirms congenital hypothyroidism, and treatment must start immediately to protect neurodevelopment; waiting a month to recheck risks permanent intellectual disability. Imaging (ultrasound, uptake scan) can define the cause but must never delay therapy; hydrocortisone is for adrenal insufficiency.
64. 18-year-old patient with periumbilical pain migrating to the right lower quadrant, low-grade fever and WBC 11,000. Answer: C, CT of the abdomen. In an adult (nonpregnant) patient with a classic appendicitis history, CT with contrast is the imaging test of choice; ultrasound is preferred in children and pregnancy because of radiation concerns. Contrast enemas and small-bowel studies are not used for acute appendicitis, and a nuclear scan is for occult GI bleeding. (The two months of intermittent diarrhea raise Crohn ileitis as an alternative, which CT also evaluates.)
65. 25-year-old woman at 36 weeks without prenatal care, heavy painless vaginal bleeding after intercourse, reassuring fetal heart rate. Answer: E, transabdominal ultrasonography. Painless third-trimester bleeding is placenta previa until excluded, and a digital examination can provoke catastrophic hemorrhage, so placental location must be established by ultrasound before anyone examines the cervix. The fetus is stable, so immediate cesarean is not required; oxytocin and magnesium have no role before the diagnosis.
66. 75-year-old man recovering from pneumonia who wants to go home; his son, who says he holds power of attorney, insists on a nursing facility. Answer: A, inform the son that the decision is the patient’s regardless of the team’s recommendation. A durable power of attorney for health care activates only when the patient lacks decision-making capacity. This patient is alert and able to weigh the risks, so he decides, even against medical advice. A competency evaluation or document review is unnecessary when capacity is evident, and a family meeting cannot override him.
67. 59-year-old hypertensive man with acute left hemiplegia and a hyperdense right putaminal lesion on CT. Answer: C, small vessel disease. Deep hemorrhages in the putamen, thalamus, pons and cerebellum are the signature of chronic hypertension, which produces lipohyalinosis and Charcot-Bouchard microaneurysms in the small penetrating arteries. Amyloid angiopathy causes lobar (cortical) hemorrhages in the elderly; embolism causes ischemic infarcts; venous thrombosis causes hemorrhagic infarcts in a venous distribution; vasculitis is rare and not suggested.
68. 24-year-old woman scheduled for suction curettage; homogeneous gray-white discharge with vaginal pH 5.5. Answer: D, type of vaginal discharge. A thin, homogeneous gray discharge with elevated pH is bacterial vaginosis, which is the best-established risk factor for post-abortal and post-procedural upper genital tract infection; treating it (or giving periprocedural prophylaxis) lowers the risk. HSV-2 without active lesions, a resolved URI, obesity and shaving are not meaningful predictors of endometritis.
69. 74-year-old woman with diabetes on a thiazide, two days of severe toe pain, uric acid 7.8; photograph of the great toe. Answer: B, gout. Acute monoarticular pain and erythema of the first metatarsophalangeal joint (podagra) in a patient on hydrochlorothiazide (which raises urate) with a borderline-high uric acid is gout; the level can be normal during an attack, so the clinical picture decides. Pseudogout favors the knee and wrist; cellulitis does not localize to a joint; osteoarthritis and rheumatoid arthritis are not acute monoarticular.
70. 47-year-old man with 25 years of type 1 diabetes and toe numbness whose exercise stress test shows 3-mm ST depression early, without pain. Answer: C, coronary artery disease. Early, deep ST depression on a stress test is ischemia regardless of symptoms, and a long-standing diabetic with peripheral neuropathy very likely has autonomic neuropathy as well, which is why the ischemia is silent. The soft, early-peaking flow murmur is innocent. Valvular disease would show a different murmur and no ST change; cardiomyopathy and congenital disease do not produce exercise-induced ST depression of this degree; a 3-mm depression is never a normal finding.
71. 22-year-old soldier back from deployment, smoking a pack a day and drinking six beers daily, with blood pressure in the 150s/90s on two readings. Answer: C, excessive alcohol use. Heavy daily drinking is a common, reversible cause of secondary hypertension in young adults, and his pressure was normal before the drinking began. Smoking raises pressure acutely but is not the usual cause of sustained hypertension; essential hypertension is a diagnosis of exclusion that should not be made in a 22-year-old with an obvious reversible cause; pheochromocytoma and renal artery stenosis would come with other clues (paroxysms, bruit) and are far rarer.
72. 32-year-old man with a painless violaceous plaque rash on both arms and recent weight loss; photograph shown. Answer: C, Kaposi sarcoma. Purple-red, nonblanching, painless plaques and nodules in a young man with unexplained weight loss are Kaposi sarcoma, the HHV-8-driven vascular tumor that signals advanced HIV infection; the next step is HIV testing. Dermatitis herpetiformis is intensely itchy and vesicular on extensor surfaces; lichen planus gives flat-topped pruritic violaceous papules with Wickham striae; actinic keratoses are rough scaly patches on sun-damaged skin of older adults; seborrheic dermatitis is greasy scale on the scalp and face.
73. 42-year-old smoker with six months of amenorrhea, hot flashes and palpitations after two years of lengthening cycles. Answer: A, measurement of serum follicle-stimulating hormone concentration. Vasomotor symptoms and amenorrhea after progressively irregular cycles in a woman in her early forties is early menopause (smoking brings it forward), and an elevated FSH confirms ovarian failure. LH is less reliable, testosterone is for hyperandrogenism, an ECG is not needed for symptomatic hot-flash palpitations in a patient with a normal examination, and ultrasound does not diagnose menopause.
74. A colleague notices that the physician running walk-in clinic appears groggy, slurs his speech and smells of alcohol, with four hours of patients still scheduled. Answer: E, report the physician to the clinic administrator and conduct the remainder of the clinic hours without him. Patient safety comes first: an apparently impaired physician must be removed from patient care immediately, through the institution’s chain of authority, and the patients still need to be seen. Waiting for a staff meeting (A) leaves patients at risk; cancelling clinic (B) abandons them; having the physician assistant quietly work around him (C) and a personal confrontation (D) bypass the institutional process; the state medical board is the escalation for a pattern of impairment or an institution that fails to act, not the first step for a single witnessed episode.
75. 68-year-old woman whose proteinuria during a urinary tract infection has resolved on repeat urinalysis. Answer: E, no additional testing is indicated. Transient proteinuria during fever, infection or exertion is common and benign; a normal repeat urinalysis after the infection has cleared closes the question. Albumin-to-creatinine ratios, 24-hour collections, sulfosalicylic acid testing and renal imaging are for persistent proteinuria.
76. 22-year-old man two days after a scratch in the woods: rapidly worsening leg pain, diffuse cellulitis, hemorrhagic bullae, tachycardia and hypotension. Answer: D, surgical debridement. Pain out of proportion, rapid progression, hemorrhagic bullae and systemic toxicity after a minor wound are necrotizing fasciitis, a surgical emergency; antibiotics and fluids are already running, and the only intervention that changes survival is immediate operative exploration and debridement. Imaging (MRI) delays surgery and must never be used to rule out the diagnosis in an unstable patient; aspiration of bullae and hyperbaric oxygen are adjuncts at best; observation is fatal.
77. 27-year-old woman at 12 weeks with two prior macrosomic infants, pre-pregnancy BMI 38 and two parents with type 2 diabetes. Answer: C, fasting glucose tolerance test. Prior macrosomia, obesity, a strong family history and high-risk ethnicity are all indications for early screening for pre-existing or early gestational diabetes at the first prenatal visit rather than waiting for the routine 24-to-28-week test. The sister’s stillbirth does not by itself justify antiphospholipid testing; thyroid testing, chest x-ray and alpha-fetoprotein are not indicated by this history.
78. 84-year-old woman with well-controlled diabetes six months ago, now unkempt, missing appointments, with a glucose of 380 and no ketones, since her unemployed son moved in. Answer: B, elder neglect. A previously well-managed, independent patient who becomes unkempt, dehydrated, uncontrolled and absent from care after a dependent adult child moves in is showing the pattern of elder neglect, in which medications are not being given and basic care is not being provided. Depression is a consideration (flat affect) but does not explain the missed insulin and poor hygiene as directly; dietary indiscretion does not produce this global decline; there is no evidence of infection or malignancy.
79. 15-year-old in New Jersey with two weeks of headache, photophobia and neck pain, now a peripheral right facial palsy; CSF with lymphocytic pleocytosis and normal glucose. Answer: B, measurement of serum Lyme antibody concentration. Facial nerve palsy with aseptic meningitis in a summer-exposed adolescent from an endemic state is early disseminated Lyme disease, and the diagnosis is made serologically (ELISA with confirmatory Western blot). Sarcoidosis (ACE), lupus (ANA), CMV and myeloma are not supported by the setting. Treatment is doxycycline or ceftriaxone depending on the degree of CNS involvement.
80. 2-year-old with a barking cough, hoarse cry, retractions and inspiratory stridor at rest after a runny nose. Answer: D, nebulized epinephrine. Moderate-to-severe croup (stridor at rest with retractions) is treated with nebulized racemic epinephrine to shrink subglottic edema quickly, alongside a dose of dexamethasone (oral or intramuscular) for sustained benefit. The question asks for the initial pharmacotherapy that addresses the airway now, which is the epinephrine. Albuterol treats lower-airway bronchospasm, not laryngeal edema; prednisone and budesonide are weaker alternatives to dexamethasone; subcutaneous epinephrine is for anaphylaxis.
Block 3: Items 81–120
81. 28-year-old man three hours after nephrectomy and bowel repair, with pelvic fractures, whose bloody urine output has fallen from 40 mL/h to 5 mL in the last hour. Answer: D, ultrasonography of the bladder. Sudden anuria in a catheterized postoperative patient with hematuria is most often a catheter obstructed by clot, and a bedside bladder ultrasound (or bladder scan) that shows a full bladder makes the diagnosis in seconds and leads to irrigation or catheter exchange. Jumping to transfusion, CT or re-exploration assumes hemorrhage or a surgical complication before excluding the simplest mechanical cause; in a hemodynamically stable patient the simple test comes first.
82. 15-year-old with cerebral palsy and situs inversus examined in her wheelchair and diagnosed with gastroenteritis after four similar cases that day; returned hours later in shock with volvulus. Answer: D, premature closure. The physician settled on a diagnosis early (anchored by the day’s other cases and by the inconvenience of a full examination) and stopped considering alternatives despite a patient with anatomic risk factors and tachycardia out of proportion. That cognitive error is premature closure. A latent error is a hidden system flaw; a near miss causes no harm; a systems failure would implicate process rather than an individual’s reasoning; the error was clearly preventable.
83. 27-year-old man with a month of depressed mood, anhedonia, poor concentration and initial insomnia, whose epilepsy is controlled on levetiracetam. Answer: E, mirtazapine. He meets criteria for major depressive disorder and needs an antidepressant; mirtazapine is sedating and helps insomnia, and it does not lower the seizure threshold. Bupropion is contraindicated in epilepsy because it provokes seizures. Alprazolam and buspirone are anxiolytics, not antidepressants; aripiprazole is an augmenting agent, not first-line monotherapy.
84. 23-year-old woman with a year of infertility, prior ruptured appendicitis and pelvic inflammatory disease; hysterosalpingogram shown. Answer: A, female factor infertility. The HSG shows contrast filling the uterus but failing to spill freely from the tubes, the picture of tubal occlusion and hydrosalpinx from prior pelvic infection and peritonitis. Without treatment (IVF, or tubal surgery) she is unlikely to conceive; her cycles are ovulatory, so the problem is mechanical. Recurrent miscarriage and molar pregnancy are unrelated to tubal disease.
85. 50-year-old asymptomatic woman whose screening mammogram shows a 1-cm cluster of 20 pleomorphic microcalcifications. Answer: A, ductal carcinoma in situ. Clustered, pleomorphic (varying size and shape) microcalcifications without a mass are the classic mammographic signature of DCIS, which arises in ducts and calcifies the necrotic debris within them; stereotactic core biopsy is the next step. Fat necrosis produces coarse or eggshell calcifications after trauma or surgery; fibroadenomas calcify in a popcorn pattern; sclerosing adenosis gives diffuse, usually benign-appearing calcifications; mastitis is clinical.
86. Clinic where only 34% of asthma patients get the annual pulmonary function testing the community standard calls for. Answer: B, diagnosis-driven reminders in patient charts. Point-of-care reminders tied to the diagnosis (clinical decision support) are the intervention most consistently shown to raise adherence to guideline-based care, because they act at the moment the decision is made. Annual chart audit with feedback helps but is retrospective; waiting-room flyers rely on patients; testing everyone with respiratory symptoms or only after exacerbations misses the target population.
87. 27-year-old woman three weeks postpartum, breastfeeding with poor latch on the right, with fever 38.9°C and a wedge-shaped area of breast erythema and tenderness. Answer: B, dicloxacillin therapy. Lactational mastitis is a bacterial (usually Staphylococcus aureus) cellulitis of a poorly drained segment; treatment is an anti-staphylococcal antibiotic, continued breastfeeding or pumping to keep the breast empty, and analgesia. A binder worsens stasis; fluconazole treats candidal nipple infection, which causes burning without fever; aspiration is for a fluctuant abscess, which is not described.
88. 12-year-old girl with no breast development or pubic hair, normal growth and examination. Answer: E, no additional diagnostic steps are indicated. Delayed puberty in girls is defined as absence of breast development by age 13 (or no menarche by 15), so a 12-year-old with normal height velocity and a normal examination is still within the normal range and needs reassurance and follow-up. Gonadotropins, bone age and brain imaging are for true delay or for signs of a pathologic cause.
89. 42-year-old woman with recurrent hypoglycemic episodes relieved by eating and weight gain: glucose 41, insulin 80 (high), C-peptide 0.5 (low-normal). Answer: E, no abnormalities. Hypoglycemia with high insulin but suppressed C-peptide means the insulin did not come from her own pancreas (which releases C-peptide in equal amounts): she is injecting exogenous insulin, whether factitious disorder or surreptitious use. An insulinoma (D, the classic vascular pancreatic mass) would raise both insulin and C-peptide. So the abdominal CT will be normal; the next step is a careful, nonjudgmental conversation and a psychiatric evaluation.
90. ICU seeking to maintain a shared mental model across the care team under a designated leader. Answer: A, conduct weekly structured team briefings and daily huddles. Shared understanding is built by regular, structured, whole-team communication in which everyone hears the same plan and can speak up; that is what briefings and huddles are for. One-on-one conversations with the leader (C) fragment the model; protocols, consistent staffing and disease-specific units help in other ways but do not create a common real-time picture of each patient.
91. 12-month-old girl with a first febrile UTI (catheterized urine positive, E. coli sensitive to the antibiotic started). Answer: D, ultrasonography of the kidneys and bladder. Current guidelines call for a renal and bladder ultrasound after a first febrile UTI in a child aged 2 to 24 months to look for anatomic abnormalities; voiding cystourethrography is reserved for an abnormal ultrasound or a recurrent febrile UTI. Antibiotic prophylaxis is not started after a single infection, and CT urography exposes the child to unnecessary radiation.
92. 32-year-old man with two weeks of paroxysmal coughing, post-tussive vomiting and chest-wall pain after a week-long cold, afebrile with clear lungs. Answer: B, azithromycin. A catarrhal prodrome followed by weeks of paroxysmal cough with post-tussive emesis in an adult (whose childhood immunity has waned) is pertussis, and a macrolide is the treatment, mainly to reduce transmission since the cough itself is driven by established airway damage. Fluoroquinolones, bronchodilators, acid suppression and steroids do not treat Bordetella pertussis.
93. 18-year-old with cystic fibrosis in a pulmonary exacerbation (purulent sputum, fever, hypoxemia, basilar consolidations). Answer: D, sputum culture. CF exacerbations are treated with antibiotics chosen against the patient’s own colonizing organisms (Pseudomonas aeruginosa, Staphylococcus aureus, Burkholderia), so a sputum culture is obtained at presentation to guide and narrow therapy. CT angiography would be for suspected embolism, which the picture does not suggest; spirometry is for monitoring, not acute evaluation; immunoglobulins and lung biopsy have no role here.
94. 16-year-old skateboarder with an EXT1 mutation and stable, unchanged bony outgrowths at the proximal tibia on x-ray after a knee injury without effusion or instability. Answer: E, recommendation to bear weight as tolerated; no further workup needed. EXT1 mutations cause hereditary multiple osteochondromas, benign cartilage-capped exostoses that need attention only if they grow after skeletal maturity, cause mechanical symptoms or change in appearance (malignant transformation to chondrosarcoma is rare). Lesions that are unchanged over six months in a stable knee need neither biopsy nor MRI, and a contusion is treated with activity as tolerated.
95. 70-year-old woman with three episodes of painless, sudden bright-red rectal bleeding, normal colonoscopy eight years ago, hemodynamically stable. Answer: C, diverticulosis. Painless, brisk hematochezia in an older adult is most often diverticular bleeding, which arises from a vasa recta eroded at the dome of a diverticulum, and usually stops on its own. Anal fissures cause pain with defecation and streaks on the stool; polyps cause occult or minor bleeding; ulcerative colitis causes bloody diarrhea with urgency and cramping; upper GI sources (duodenal ulcer, gastritis) produce melena unless bleeding is massive, and she is stable with normal orthostatics.
96. 14-year-old boy, formerly close with his parents, now absorbed in a new peer group, arguing about curfew and caught trespassing with friends; negative toxicology. Answer: E, normal development. Shifting allegiance from parents to peers, secrecy, irritability at home and testing of limits are the normal work of early adolescence; a single episode of trespassing with friends does not meet criteria for conduct disorder (a persistent pattern violating the rights of others) or oppositional defiant disorder (a pattern of angry, defiant behavior toward authority over six months in multiple settings). There is no identifiable stressor for an adjustment disorder and no inattention or hyperactivity.
97. 6-year-old boy with acute severe right flank pain, vomiting, hematuria, and ultrasound showing hydronephrosis with hydroureter down to the bladder. Answer: B, CT scan of the abdomen and pelvis. Renal colic with gross hematuria and a dilated collecting system all the way to the bladder means an obstructing stone at or near the ureterovesical junction, and a noncontrast CT is the study that locates and sizes it (low-dose protocols are used in children). Nuclear scans, cystography and retrograde pyelography assess reflux, drainage or anatomy, not an acute obstructing calculus; captopril renography is for renovascular hypertension.
98. 20-year-old summer lumber-mill worker with two months of malaise, cough, weight loss, bilateral crackles, an upper-lobe reticulonodular pattern and mixed obstructive-restrictive physiology. Answer: C, hypersensitivity pneumonitis. Subacute constitutional symptoms with diffuse crackles and an upper-zone reticulonodular infiltrate beginning after an organic-dust exposure (wood dust and the molds that grow on it) is hypersensitivity pneumonitis, and the mixed PFT pattern fits its bronchiolar involvement. Silicosis takes years of silica exposure; sarcoidosis would show hilar adenopathy and is not exposure-related; asthma does not produce weight loss, crackles or a nodular infiltrate; aspergillosis in a healthy host would be allergic bronchopulmonary disease with asthma-like symptoms and eosinophilia.
99. 32-year-old woman with two years of “seizures” (eyes closed, side-to-side head movement, crying, intermittent responsiveness, 15 to 20 minutes) and no EEG correlate on video monitoring. Answer: A, cognitive behavioral therapy. Prolonged episodes with closed eyes, asynchronous movements and preserved responsiveness that occur without EEG change are psychogenic nonepileptic seizures, a functional neurologic (conversion) disorder, often with a trauma history. Evidence-based treatment is psychotherapy, with CBT having the best support, plus tapering the ineffective anticonvulsants. Increasing pregabalin and epilepsy surgery treat a disease she does not have; hypnosis and psychoanalysis lack comparable evidence.
100. 2-year-old adoptee with cleft palate, an unrepaired VSD, recurrent otitis and pneumonia; chest x-ray shown. Answer: C, lymphopenia. The film shows no thymic shadow in a toddler, and palatal cleft plus conotruncal heart defect plus recurrent infections is DiGeorge syndrome (22q11.2 deletion): thymic hypoplasia means T-cell deficiency, which appears on the CBC as lymphopenia. Neutrophil counts are normal, eosinophilia suggests allergy or parasites, and lymphocytosis would argue against a T-cell defect.
101. 25-year-old Rh-negative primigravida at 28 weeks who received Rh immune globulin at 18 weeks; antibody screen now positive with an anti-D titer too weak to measure. Answer: C, administration of Rho(D) immune globulin. A barely detectable anti-D antibody ten weeks after a dose of Rh immune globulin is the passively administered antibody, not sensitization, and it should not change management: she receives the routine 28-week prophylactic dose. True alloimmunization produces a measurable and rising titer, at which point serial titers, middle cerebral artery Doppler and possibly amniocentesis come into play. Induction is not indicated.
102. 5-year-old boy in July with an itchy rash of red papules and linear vesicles on the forearm, cheek and ankle three days after a park picnic. Answer: B, flora. Linear streaks of vesicles on exposed skin a few days after outdoor play are allergic contact dermatitis from poison ivy or poison oak (urushiol), and avoiding the plants is the prevention. The soap change is a distractor (irritant dermatitis would be diffuse and in the areas washed, not linear and asymmetric); the pets, peanut butter and sun do not produce linear vesicles.
103. 56-year-old woman with fatigue, early satiety, splenic dullness, and a WBC of 67,000 with 83% neutrophils, left shift (myelocytes, metamyelocytes), basophilia and eosinophilia. Answer: D, chronic myeloid leukemia. A very high granulocyte count with the full spectrum of maturing myeloid forms, basophilia and splenomegaly (the early satiety and the dullness in the left upper quadrant) is CML, confirmed by the BCR-ABL fusion. Acute leukemias show blasts and cytopenias; CLL shows mature lymphocytosis; MGUS is a plasma-cell disorder with a normal white count.
104. 65-year-old woman with 50 pack-years, a year of cough and progressive dyspnea, prolonged expiration, end-expiratory wheezes and distant heart sounds. Answer: E, pulmonary function testing. The history and examination point to COPD, and the diagnosis requires spirometry demonstrating a post-bronchodilator FEV1/FVC below 0.70. Echocardiography is for suspected heart failure (no orthopnea or JVD here); CT is for nodules or complications; stress testing is for ischemia; tuberculosis testing is not suggested.
105. 45-year-old man with six months of worry, tension, poor sleep and fatigue after losing his job, in recovery from alcohol use disorder. Answer: A, buspirone. Persistent anxiety with insomnia, muscle tension and fatigue is generalized anxiety disorder, and in a patient with a substance use history the nonsedating, non-habit-forming option is buspirone (an SSRI would also be appropriate but is not listed). Benzodiazepines (clonazepam, temazepam) carry dependence risk and cross-addiction; diphenhydramine and quetiapine are not treatments for GAD; imipramine has a worse side-effect profile.
106. 56-year-old man whose wife reports he punches, kicks and shouts in his sleep, acting out dreams; also has constipation. Answer: E, Parkinson disease. REM sleep behavior disorder (loss of normal REM atonia, with dream enactment) is a prodromal marker of the α-synucleinopathies, and in combination with constipation (another early autonomic sign) it strongly predicts Parkinson disease or dementia with Lewy bodies over the following decade. It is not a risk factor for Alzheimer disease, ALS, stroke or narcolepsy.
107. 77-year-old nonverbal woman with advanced dementia, unkempt, with bruises on both forearms and an unexplained distal radius fracture; her son is her sole caregiver. Answer: C, contact adult protective services. An unexplained fracture plus bilateral forearm bruising (defensive or grab injuries) plus poor hygiene in a dependent elder is elder abuse until proven otherwise, and physicians are mandated reporters: the required step is a report to adult protective services, which investigates and arranges safety. Hospital admission may be part of ensuring safety but is not the mandated action; nursing-home placement, phone numbers and a geriatric referral leave her in the caregiver’s hands.
108. 27-year-old man with four weeks of heart failure (orthopnea, edema, S3, crackles), six months of exertional chest pain, hypertension, tachycardia and severe gingivitis. Answer: D, methamphetamine. New dilated cardiomyopathy with hypertension and tachycardia in a young adult, plus severe dental and gum disease (“meth mouth”), is methamphetamine cardiotoxicity. Cocaine causes ischemia and hypertension but is less associated with the dental findings and chronic cardiomyopathy at this age; opioids (heroin, methadone) cause respiratory depression and bradycardia; toluene causes renal tubular acidosis and neurologic effects.
109. 39-year-old man with episodic headaches, palpitations and sweating, resistant hypertension and a 4-cm adrenal mass on CT. Answer: D, measurement of plasma and urine catecholamine and metabolite concentrations. The triad plus an adrenal mass means pheochromocytoma, but the diagnosis must be confirmed biochemically (plasma free metanephrines or 24-hour urine metanephrines and catecholamines) before any surgery, because the patient needs alpha blockade first and because an incidentaloma could be something else. Option A pairs VMA with 5-HIAA, a carcinoid test, which is wrong; adrenal venous sampling is for aldosteronoma lateralization; operating without confirmation or alpha blockade risks a hypertensive crisis.
110. 41-year-old woman with alcohol use disorder, a fourth admission for pancreatitis, and insecure housing. Answer: A, abstinence from alcoholic beverages. Her pancreatitis is alcoholic, and the single intervention that most reduces recurrent episodes and readmission is stopping drinking, so counseling and referral for alcohol use disorder treatment is the priority at discharge. Shelter placement, insurance and nutrition matter for her overall care but do not address the cause of the admissions.
111. 8-year-old boy with three days of tiny clear, fragile, water-droplet vesicles on his back without erythema during a Florida heat wave. Answer: B, heat avoidance. Superficial, easily ruptured, asymptomatic-to-mildly-itchy clear vesicles without inflammation during hot weather are miliaria crystallina, caused by obstruction of sweat ducts at the surface; it resolves with cooling and clears on its own. Antibiotics, antivirals, antifungals, retinoids and phototherapy are all wrong because this is not an infection or a keratinization disorder.
112. 55-year-old woman three months after an MI with four weeks of depressed mood, anhedonia, anorexia and insomnia, now skipping cardiac rehabilitation. Answer: B, it is likely to double her risk for death during the next three months. Major depression after myocardial infarction is an independent predictor of mortality, roughly doubling the risk of death in the months after the event, through both biological effects (autonomic imbalance, platelet activation, inflammation) and behavioral ones (nonadherence to medication and rehabilitation, which she is already showing). Screening and treating post-MI depression is therefore part of cardiac care, not an optional extra.
113. 78-year-old man with five years of intermittent dysphagia and regurgitation of undigested food, now with aspiration pneumonia. Answer: D, Zenker diverticulum. Regurgitation of undigested food hours after eating, in an elderly patient, with halitosis and aspiration, is the picture of a pharyngoesophageal (Zenker) diverticulum, a pulsion outpouching through the cricopharyngeus that traps food. Achalasia causes dysphagia to both solids and liquids with regurgitation but typically in younger patients and without the characteristic undigested-food history; esophageal cancer causes progressive solid-food dysphagia and weight loss; a hiatal hernia causes reflux symptoms.
114. 27-year-old woman with three days of mild left lower quadrant pain, a 3 × 4 cm left adnexal cyst and a small amount of pelvic free fluid, negative pregnancy test, stable vital signs. Answer: E, observation only. A small simple adnexal cyst with a little free fluid in a hemodynamically stable, nonpregnant woman mid-cycle is a functional (likely corpus luteum) cyst with minor leakage; it is managed with analgesia and a repeat ultrasound in six to eight weeks, by which time most have resolved. Laparoscopy is for suspected torsion, rupture with hemoperitoneum or instability; antibiotics are for PID, which needs cervical motion tenderness and fever; appendicitis is on the wrong side; aspiration of cysts is not standard.
115. 60-year-old asymptomatic woman whose ear canals are full of cerumen; she hears well. Answer: E, no further management is indicated at this time. Cerumen is removed only when it causes symptoms (hearing loss, fullness, itching) or when the tympanic membrane needs to be seen for a clinical reason; asymptomatic impaction in a patient who hears normally needs nothing. Cotton swabs push wax deeper and are never recommended; irrigation, ceruminolytics and specialist removal are for symptomatic impaction.
116. 37-year-old woman four days after surgery for ovarian cancer, on prophylactic heparin, with pleuritic chest pain, blood-streaked sputum, a pleural rub, and a wedge-shaped pleural-based density; no emboli in the major pulmonary branches and no DVT on duplex. Answer: H, pulmonary infarction. A peripheral wedge-shaped (Hampton hump) opacity with pleuritic pain, hemoptysis and a rub in a postoperative cancer patient is pulmonary infarction from a small peripheral embolus; CT angiography is less sensitive for subsegmental clots, and a negative leg duplex does not exclude embolism because the clot has already left the leg. Pneumonia would bring fever and purulent sputum; pulmonary hemorrhage is diffuse and bilateral; empyema and hemothorax are effusions, not parenchymal wedges; pericarditis gives a positional pain and a different rub.
117. 77-year-old heavy smoker with sudden severe abdominal pain, hypotension and tachycardia, diminished groin pulses, and an abdominal x-ray showing a curvilinear calcified outline beside the spine. Answer: D, ruptured abdominal aortic aneurysm. The plain film shows the calcified wall of a large aneurysm, and sudden pain with shock in a 77-year-old smoker is rupture until proven otherwise; a stable patient gets CT, an unstable one goes directly to the operating room or endovascular suite. Normal amylase argues against pancreatitis; mesenteric ischemia presents with pain out of proportion but not with an aneurysmal silhouette and shock this abrupt; perforated ulcer gives free air and a rigid abdomen; obstruction gives dilated loops and vomiting.
118. 1-week-old boy after myelomeningocele repair, with no lower-extremity movement and mildly enlarged ventricles. Answer: D, neurogenic bladder. Nearly all children with myelomeningocele have neurogenic bladder and bowel dysfunction from the spinal cord defect, and lifelong urologic management (clean intermittent catheterization, surveillance for reflux and renal damage) is part of care. Hydrocephalus from the associated Chiari II malformation is common and usually shunted, and with treatment most children do not have severe cognitive impairment. The folate connection is a risk factor for the mother, not a finding in the child; cardiac malformations and cryptorchidism are not characteristic associations.
119. Randomized trial of an antiarrhythmic that reduced recurrent ventricular tachycardia (p < 0.05); the authors conclude it decreases mortality. Answer: A, extrapolation of findings beyond data. The trial measured recurrence of arrhythmia, a surrogate endpoint, and never measured death; concluding a mortality benefit goes beyond the data (and antiarrhythmic history, from the CAST trial onward, shows that suppressing arrhythmias can increase mortality). The result was statistically significant, so power is not the issue for the finding reported; randomization addresses selection bias; the absence of a confidence interval is a reporting flaw, not what invalidates the conclusion.
120. 42-year-old woman with two weeks of sore throat and a tender, full anterior neck, low-grade fever, tachycardia and anxiety, clear oropharynx and normal CBC. Answer: D, subacute thyroiditis. A painful, tender thyroid with mild fever and signs of thyrotoxicosis (tachycardia, anxiety) after a viral illness is subacute granulomatous (de Quervain) thyroiditis; the ESR is high, radioiodine uptake is low, and treatment is NSAIDs or steroids with beta blockade for symptoms. Mononucleosis would show pharyngitis, lymphadenopathy and atypical lymphocytes; laryngitis and tracheitis cause hoarseness or cough without thyroid tenderness; reflux does not cause a tender neck.
What to do with your misses
Step 2 CK misses tend to fall into three piles. Knowledge gaps (you did not know that rifampin induces warfarin metabolism) are fixed with a card. Decision-rule errors (you knew the diagnosis but picked the test before the resuscitation, or the imaging before the exam) are fixed by more vignettes on the same decision under time, because the rule has to become reflexive at 90 seconds a question. Ethics and systems items are their own pile: the pattern on this exam is consistent (the competent patient decides, the surrogate speaks for the patient’s known wishes, the physician discloses honestly, the system fix starts with understanding the process), and the fastest way to internalize it is to read the explanations for every ethics item you saw, right or wrong. When one clinical topic appears twice in the second pile, that is the cue for ten more questions, not another read-through. If your bank is spent on that topic, Neural Consult’s Question Generator builds board-style vignettes by topic and difficulty with explanations (it scored a perfect score on this exact Step 2 CK sample set, as well as the Step 1 and Step 3 sets), the Flashcard Hub turns the first pile into spaced-repetition cards with Anki export, and the Case Simulator lets you practice committing to a workup and plan out loud, which is the generation skill behind the “next best step” items. For a rotation-by-rotation plan that ends in a short dedicated, see How to Study for Step 2 CK with AI.
The bottom line
The Step 2 CK Free 120 is the only practice material written by the people who write the exam, and the official key tells you what without telling you why. Use this page for the why, sort your misses honestly, and spend the final days on timed mixed blocks rather than new material. If you want more practice on the decisions this set exposed, try Neural Consult. Good luck on test day.
This key reflects our reading of the current official sample items and is provided for study purposes. The questions and the official answer key are the property of the Federation of State Medical Boards and the National Board of Medical Examiners; download them directly from usmle.org.