Case-based MCQ

🇨🇦 MCCQE1,2 | #Case_90 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 A family physician has a short break between seeing patients in her busy clinic. Looking over her survey, she wants to identify which patients need to be referred for screening colonoscopy. Which of the following patients should be screened for colon cancer? a) A 47-year-old hypertensive female with no personal or family history of colon cancer b) A 30-year-old diabetic male with a family history of colon cancer in his father at the age of 45 c) A 40-year-old male with Peutz-Jeghers syndrome with negative family history of cancer and negative colonoscopy 1 year ago d) A 25-year-old male with a personal and family hereditary non-polyposis colorectal cancer e) A 60-year-old male with a history of colon cancer resection 2 years ago and a colonoscopy 1 year ago

🇨🇦 MCCQE1,2 | #Case_89 | #answer 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 ✅ C 🔎 Explanation The patient is suffering an inferior wall myocardial infarction, which is characterized by elevation of the ST segment of the leads II, III and aVF. The differential regarding the arteries that can be involved in such event is between the Right Coronary Artery, and the Left Circumflex Artery. The definite differential is, of course, defined when a coronary angiography is performed. However, the ECG can also be used to estimate which artery is involved in an inferior wall Myocardial Infarction. When the ST segment elevation in lead II is equal to the one present in lead III, combined with ST segment depression in leads V1 to V3 or ST elevation in leads I and aVL, it is most likely that the left circumflex coronary artery is occluded. This finding (ST segment depression in precordial leads) is highly sensitive, but not specific of left circumflex coronary artery occlusion; however, the absence of ST depression in precordial leads is of high negative predictive value for excluding the left circumflex artery as the affected artery. ⚠ When the findings in the ECG are ST segment elevation in lead III that exceeds the ST elevation in lead II, as well as depression in ST in I and aVL, the most likely artery to be occluded is the right coronary artery (70% sensitivity and 72% specificity) (choice A and B). When a patient has an inferior MI with right-sided ST elevation in leads V1 and V4R, that is indicative of a right ventricle infarction, in which case, the most likely affected artery is the right coronary artery. ⚠ An occlusion of the Left Anterior Descendant Coronary Artery (choice D) (causing an anterior infarction), ST elevation or Q waves in one or more of the precordial leads (V1-V6) and leads I and aVL is most likely to be the ECG finding. ⚠ ST elevation of aVR equal or greater to that of V1 in an anterior wall is helpful to distinguish between Left Main Coronary Artery (choice E) occlusion and Left Anterior Descendant Coronary Artery Occlusion. 🔖 Key point: It is important to consider the whole picture when evaluating an ECG of a patient with a suspected Myocardial Infarction. ST segment changes (depression) in the precordial leads helps to differentiate which artery is affected, pointing towards occlusion of the left circumflex artery. When such changes are absent it is most likely that the affected artery is the right coronary artery, rather than the left circumflex artery.

🇨🇦 MCCQE1,2 | #Case_89 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 A 68-year-old man is brought to the Emergency Department due to intense chest pain, accompanied with diaphoresis and vomiting, that started 30 minutes ago. He has a history of well controlled diabetes mellitus type 2 with metformin, and hypertension of difficult control for the last 10 years, as well as a history of heavy smoking.He is conscious, and in severe distress. His vital signs reveal a pulse of 80/min, BP 90/60 mmHg and his respiration of 21/min. An ECG is performed revealing ST segment elevations in II, III and aVF, noting that the ST segment elevation in III equal to the one in II, as well as ST depression in V1-V3. Troponin is increased. You give the diagnosis of inferior myocardial infarction. Considering this information, where would the occlusion most likely be found? a) Proximal right coronary artery b) Distal right coronary artery c) Left circumflex artery d) Left anterior descendant artery e) Left main coronary artery

🇨🇦 MCCQE1,2 | #Case_88 | #answer 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 ✅ D 🔎 Explanation Key features include the central location, history of smoking (small cell carcinomas are closely associated with a history of smoking), and the presence of a paraneoplastic syndrome, in this case Cushing’s syndrome from tumor elaboration of ACTH outside hypothalamic-pituitary-adrenal axis regulation. The syndrome of inappropriate ADH secretion and Eaton-Lambert syndrome are other paraneoplastic syndromes associated with small cell lung carcinoma. Metastases are commonly present at the time of diagnosis. Favored sites are brain, liver, and bone. ⚠Adenocarcinoma is incorrect because it typically presents peripherally and is not associated with Cushing’s syndrome.(choice A) ⚠Cancer metastatic to the lung is incorrect. In this instance, there is a single lesion in the lung and multiple lesions in the liver. The site of multiple solid masses is more likely the destination of the metastasis, while the solitary nodule in the lung is likely to be the primary.(choice B) ⚠Large cell carcinoma is incorrect because they typically present on the periphery, are not associated with Cushing’s syndrome, and are the least frequent type of lung cancer.(choice C) ⚠Squamous cell carcinoma is incorrect. Although squamous cell lung carcinoma presents centrally and is clearly linked to smoking, a paraneoplastic syndrome marked by excess ACTH would not be expected. Excess parathyroid hormone and resultant hypercalcemia, however, is associated with squamous cell cancers.(choice E)

🇨🇦 MCCQE1,2 | #Case_88 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 A 74-year-old man presents to his primary care physician complaining of dyspnea and cough with blood-tinged sputum for the past several weeks. He has diabetes and elevated cholesterol. Medications include a sulfonylurea and a statin. The patient has a 50 pack-year smoking history and a family history of hypertension. On examination, vital signs are withinnormal limits; abdominal striae and moon facies are noted, along with a trucal fat distribution. X-ray of the chest reveals a single central nodule, and follow-up CT again demonstrates the nodule and multiple solid hepatic masses. Which of the following is the most likely diagnosis? a) Adenocarcinoma of the lung b) Carcinoma metastatic to the lung c) Large cell carcinoma of the lung d) Small cell carcinoma of the lung e) Squamous cell carcinoma of the lung

🇨🇦 MCCQE1,2 | #Case_87 | #answer 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 ✅ A 🔎 Explanation The child is presenting with symptoms of Reye syndrome, which is an acute encephalopathy associated with high ammonia levels. It most commonly occurs in young children after a viral illness. Administration of aspirin increases the risk of developing this disorder. The vomiting is characteristic.

🇨🇦 MCCQE1,2 | #Case_87 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 A 4-year-old boy develops a headache, cough, myalgia and a fever. He has been a healthy child with all immunizations up to date. He is given a decongestant and an aspirin for his symptoms with some relief. However, 3 days later, he is brought back by his parents because of persistent vomiting and irritability. On physical examination, he is found to be semicomatose, becoming combative on stimulation. Which of the following levels should be measured to aid in the diagnosis of this patient? a) Serum ammonia level b) Serum blood urea nitrogen level c) Serum calcium level d) Serum opiate level e) Serum sodium level

🇨🇦 MCCQE1,2 | #Case_86 | #answer 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 ✅ B 🔎 Explanation This patient most likely experienced a simple febrile seizure. Most febrile seizures last less than 10 minutes, are generalized and nonfocal, and do not recur within 24 hours. These simple febrile seizures do not require evaluation beyond determining and treating the source of the fever and educating parents. ⚠ There is no need for neuroimaging studies in a case of simple febrile seizure. ⚠ There is no need for an EEG in the case of a simple febrile seizure with a negative family history, normal neurologic exam, and normal development. ⚠ Although anticonvulsant medications are sometimes used for recurrent episodes of febrile seizures, the initial simple febrile seizure does not warrant treatment with anticonvulsant drugs. ⚠ A lumbar puncture is not indicated in this patient unless the physical exam revealed symptoms suggestive of meningitis or encephalitis. In this case, the examination is normal except for the otitis media, the source of the fever.

🇨🇦 MCCQE1,2 | #Case_86 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 A 2-year-old boy presents to the emergency department for evaluation following a witnessed seizure. The seizure was described as generalized, lasting less than 10 minutes with a short postictal period. The child has no history of seizures, no family history of seizures, and no history of head injury. His exam currently is normal, except for a red, bulging right tympanic membrane and a temperature of 39°C. What is the most appropriate management for this patient? a) He should be sent for an urgent CT scan of the head b) He should be given antibiotics and antipyretics and observed at home c) He should be admitted to the hospital and an EEG should be performed d) He should be started on phenobarbital and sent home e) A lumbar puncture and blood cultures should be obtained and anticonvulsants started in the hospital

🇨🇦 MCCQE1,2 | #Case_85 | #answer 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 ✅ D 🔎 Explanation Tics are abnormal movements or vocalizations involving one or more muscles; resulting in blinking of eye, nose sniffing, coughing, neck twitching or jerking, abnormal phonation, and jerking of limbs. Unlike seizures, the tics are suppressible for some time with conscious effort. When both motor and phonic tics are present for more than a year, as in this patient, the condition is described as Tourette syndrome (TS).TS is a genetic neurological condition and is often associated with attention deficit hyperactivity disorder (ADHD) and obsessive-compulsive disorder (OCD). Over half of the patients with TS also have significant obsessive-compulsive symptoms, and approximately 30% meet the diagnostic criteria for OCD (choice D). The pattern of co-morbidity indicates that the TS gene may be responsible for a spectrum of disorders, including OCD and ADHD. ⚠ Autism (choice A) is a neuro-developmental disorder of impaired social interaction and communication, and of restricted and repetitive behavior. The movements in autism are purposeful and repetitive unlike in TS. ⚠ Bipolar disorder (choice B), also known as manic-depressive disorder, is a mood disorder characterized by changes in mood, energy and activity levels affecting ability to carry out daily tasks. It is not known to be present with TS. ⚠ Chorea (choice C) is a state of excessive, spontaneous movements, irregular, non-repetitive, randomly distributed and abrupt in character. TS does not have an association with chorea. ⚠ Schizophrenia (choice E) is a thought disorder characterized by abnormal social behavior due to failure to recognize what is real. Thought is not affected in TS and TS is not associated with schizophrenia. 🔖 Key point: In Tourette syndrome, trying to suppress the tics produce anxiety and tension that can only be relieved by allowing the tics to occur, whereas In OCD, the repetitive compulsive behaviors are performed to relieve anxiety caused by an obsession. Neuroimaging studies suggest that both disorders involve defect in the basal-ganglia thalamo-cortical pathways, explaining the co-morbidity.

🇨🇦 MCCQE1,2 | #Case_85 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 A 15-year-old boy is brought by his parents with a complaint of involuntary excessive blinking and twitching of hand muscles that has increased in frequency in the last 2 months and is interfering with preparation for his exams. Involuntary blinking (almost daily) and occasional repetitive vocalizations have been present since he was seven years old. He can suppress the movements sometimes if he tries hard. The episodes are not associated with loss of consciousness.Electroencephalography is normal.Which one of the following conditions is the most common comorbidity associated with the disorder? a) Autism b) Bipolar disorder c) Chorea d) Obsessive compulsive disorder e) Schizophrenia

🇨🇦 MCCQE1,2 | #Case_84 | #answer 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 ✅ D 🔎 Explanation The first rule of thumb in your clinical practice: DO NOT HARM! A solid mass arising from the testicle in a young adult is likely to be malignant! Surgical referral for high inguinal orchiectomy should be warranted. A biopsy of a suspicious mass of the testicle is contraindicated because it can result in spillage of cancer cells, which can spread through lymphatics and blood vessels.Reassurance or follow up in a case suspected to have cancer is never appropriate.Never take biopsy from a suspicious solid testicular mass!

🇨🇦 MCCQE1,2 | #Case_84 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 A 25 year old male patient presents to your clinic complaining of heaviness in his scrotum. His past medical history is unremarkable. He does not smoke or drink alcohol. His family history is noncontributory. Physical exam is normal except for a painless, hard mass in his right testicle.You order a testicular ultrasound which reveals a solid mass arising from the right testicle 2x2 cm. What should you do next? a) Fine needle aspiration b) Reassurance c) Repeat the ultrasound after 6 months d) Surgery e) Trans-scrotal biopsy

🇨🇦 MCCQE1,2 | #Case_83 | #answer 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 ✅ A 🔎 Explanation Guidelines have been established for the management of anticoagulation during invasive procedures. Patients with lone atrial fibrillation without previous thromboembolic events are at low risk (<1% annualized thrombotic risk) for a thrombotic event in the absence of anticoagulation. They can be safely managed with cessation of warfarin 3-4 days preoperatively, and resumption of warfarin postoperatively when the surgeon indicates it is safe to do so. If the operative procedure is associated with a high risk of thrombosis, then prophylactic, rather than therapeutic, doses of unfractionated or low-molecular-weight heparin can be used as a postoperative bridge to restarting warfarin. Patients at high risk for a thrombotic event in the absence of anticoagulation, such as those with prosthetic heart valves, should be managed by stopping warfarin 3-4 days preoperatively, beginning fully therapeutic doses of low-molecular weight heparin or intravenous unfractionated heparin when the INR decreases below the therapeutic range, stopping therapy briefly for surgery, and then resuming the heparin bridge postoperatively until warfarin is resumed. Dental procedures do not generally require interruption of anticoagulation therapy with warfarin.

🇨🇦 MCCQE1,2 | #Case_83 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 A 73-year-old black male being treated with warfarin (Coumadin) for chronic atrial fibrillation has been scheduled by his podiatrist for a bunionectomy. He has no history of a previous thromboembolic event, and his most recent INR was 2.5. The patient consults you regarding the preoperative and postoperative management of his anticoagulation.You plan to stop his regular daily warfarin dose 3-4 days prior to his scheduled operation and restart it the day after. Which one of the following would be most appropriate during the 4-5 days he is not taking his regular warfarin? a) No additional medication b) Aspirin, 81-325 mg/day orally c) Half of his usual daily warfarin dose d) Low-molecular-weight heparin injections once or twice a day e) Admission to the hospital for treatment with intravenous heparin

🇨🇦 MCCQE1,2 | #Case_82 | #answer 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 ✅ E 🔎 Explanation Leukoplakia is a white keratotic lesion seen on mucous membranes. Irritation from various mechanical and chemical stimuli, including alcohol, favors development of the lesion. A definitive diagnosis of leukoplakia is made when any aetiological cause, e.g. tobacco, C. albicans, mechanical irritation, has been excluded and histopathologic examination (choice E) has not disclosed any other specific disorder. Leukoplakia can occur in any area of the mouth and usually exhibits benign hyperkeratosis on biopsy. ⚠ On long-term follow-up (choice A), 2%-6% of these lesions will have undergone malignant transformation into squamous cell carcinoma. ⚠ An idiosyncratic reaction to propranolol (choice B) is unlikely in this patient. ⚠ Oral nystatin (choice C) would not be appropriate treatment, as this lesion is not typical of oral candidiasis. Candidal lesions are usually multiple and spread quickly when left untreated. ⚠ A fluorescent antinuclear antibody test (choice D) is also not indicated, as the oral lesions of lupus erythematosus are typically irregular, erosive, and necrotic

🇨🇦 MCCQE1,2 | #Case_82 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 A 45-year-old white male consults you because of a painless, circular, 1-cm white spot inside his mouth, which he noticed 3 days ago. You are treating him with propranolol for hypertension, and you know him to be a heavy alcohol user. After a careful physical examination, your tentative diagnosis is leukoplakia of the buccal mucosa. You elect to observe the lesion at that time. On the patient’s return, the lesion is still present and unchanged in appearance. The best course of management at this time is to: a) reassure the patient and continue to observe b) discontinue propranolol c) treat with oral nystatin d) order a fluorescent antinuclear antibody test e) perform a biopsy of the lesion

🇨🇦 MCCQE1,2 | #Case_81 | #answer 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 ✅ E 🔎 Explanation Erysipelas, most commonly caused by group A beta-hemolytic Streptococci, is the most likely diagnosis of this patient. The characteristic finding of erysipelas is a sharply demarcated, erythematous, edematous tender skin lesion with raised borders. It is frequently seen in diabetics where a tinea pedis infection is the usual portal of entry of the infection.Staphylococcus aureus is a rare cause of erysipelas. Remember that staph aureus are coagulase positive organisms that secrete coagulase enzyme which limits the spread of the infection in the dermis. Dermatophytes are the cause of the toe web infection and not the erysipelas. Actinomyces israelii is the causative agent of cervicofacial infections characterized by the sinuses discharging sulphur granules.Clostridium perfringens is the causative agent of gas gangrene

🇨🇦 MCCQE1,2 | #Case_81 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 A 60-year-old diabetic male presents to the ED with fever and painful swelling of his right leg that began few hours ago. He is taking metformin and glyburide for his diabetes since he was diagnosed 5 years ago and admits to medication non-compliance. Vital signs are within normal limits except for a fever of 39°C. Examination of the leg shows raised borders of a well-demarcated area of erythema that is warm and extremely painful to touch. Cracks in the skin of the toe webs are noted on the examination of his feet. Which of the following is the most likely causative organism for the patient’s condition? a) Actinomyces israeili b) Clostridium perfringens c) Dermatophytes d) Staphylococcus aureus e) Streptococcus pyogenes (group A)

🇨🇦 MCCQE1,2 | #Case_80 | #answer 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 ✅ A 🔎 Explanation Aldosterone, a hormone produced and secreted by the adrenal glands, signals the kidneys to excrete less sodium and more potassium. Hyperaldosteronism can be caused by a tumor (usually a noncancerous adenoma) in the adrenal gland (a condition called Conn's syndrome), although sometimes both glands are involved and are overactive. Sometimes hyperaldosteronism is a response to certain diseases, such as very high blood pressure (hypertension) or narrowing of one of the arteries to the kidneys.The amount of salt in the diet and medications, such as over-the-counter pain relievers of the non-steroid class (such as Motrin and Advil), diuretics (water pills), beta blockers, steroids,angiotensin-converting enzyme (ACE) inhibitors, and oral contraceptives can affect the test results. You should ask your patient to stop taking some of his medicines for 2 weeks before the test. ✅ Screening test: Random plasma aldosterone/plasma renin activity (PRA) ratio - Because this ratio is fairly constant over many physiologic conditions, it can be used as a screening test. Normal values are less than 270 when aldosterone concentration is expressed in pmol/L, or are less than 10 when aldosterone concentration is expressed in ng/dL. ✅ Confirmatory test: The 24-hour urinary aldosterone (U-Aldo) excretion test is one of the most useful confirmatory diagnostic tools