Case-based MCQ

🇨🇦 MCCQE1,2 | #Case_118 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 A 27-year-old man with advanced HIV is sent for evaluation of his nephrotic syndrome. His blood pressure is 142/84 mm Hg. He has 3+ edema in both legs. His risk factor for AIDS is his IV heroin use. His creatinine is 2.1 mg/dL, and his urine reveals +3 protein, no blood. A kidney biopsy would most likely reveal which of the following? a) Diabetic nephropathy b) Focal glomerular sclerosis c) IgA nephropathy d) Membranous nephropathy e) Minimal change disease

🇨🇦 MCCQE1,2 | #Case_117 | #answer 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 ✅ C 🔎 Explanation This girl has primary amenorrhea, a webbed neck, and a significant difference between the blood pressure in the upper and lower extremities (suggesting possible coarctation of the aorta). These findings suggest Turner syndrome as the most likely diagnosis. The best way to confirm this diagnosis is a standard 30 cell Karyotype, which in Turner syndrome would reveal 45, XO cell line or a cell line with deletion of the short arm of the X chromosome. ⚠ An echocardiography (choice A) is useful in evaluating cardiovascular abnormalities of Turner syndrome such as the coarctation of the aorta; while this is an important characteristic of Turner syndrome, it is not the best way to confirm it. ⚠ FSH, LH, and Estrogen (choice B) are likely to be abnormal in this patient. With estrogen being low while FSH and LH are elevated; this, however, is not the best way to confirm Turner syndrome. ⚠ Brain MRI (choice D) would be useful in cases of amenorrhea caused by pituitary pathology such as craniopharyngioma, it is not the best way to confirm Turner syndrome. ⚠ Bone age assessment (choice E) will be useful in the management of this patient as hormone therapy is being considered; however, this is not the best way to confirm Turner syndrome. 🔖 Key point: When Turner syndrome is suspected, Karyotype is the best way to confirm it.

🇨🇦 MCCQE1,2 | #Case_117 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 A 15-year-old female is brought to the hospital by her mother because she has never had menstrual periods and the mother is concerned. On physical examination the girl appears short, has a webbed neck. Four-limb blood pressures were also evaluated: higher blood pressures were noted in the arms while the ones of the lower extremities were normal. Which of the following is the best way to confirm this girl’s diagnosis? a) Echocardiography b) FSH, LH, and Estrogen levels c) Karyotype d) Brain MRI e) Bone age assessment

🇨🇦 MCCQE1,2 | #Case_116 | #answer 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 ✅ C 🔎 Explanation Otosclerosis typically presents between the third and fifth decades, and is more common in women. The chief feature of otosclerosis is a progressive conductive hearing loss. Occasionally, when lesions impinge on the stapes footplate, a sensorineural loss may occur. All of the other choices are exclusively sensorineural in character. Meniere’s disease also causes fluctuating hearing loss. Noise-induced hearing loss frequently and characteristically is accompanied by tinnitus. Perilymphatic fistula is associated with sudden unilateral hearing loss with tinnitus and vertigo. Acoustic neuroma is associated with tinnitus and gradual hearing impairment

🇨🇦 MCCQE1,2 | #Case_116 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 A 47-year-old female presents with progressive difficulty hearing. She is employed as an office worker, has no significant past medical history, and takes no medications. Physical examination shows no gross abnormalities of her outer ears. The external ear canals are free of cerumen, and the tympanic membranes move well to insufflation. Weber’s test and the Rinne test have results that are compatible with a conductive hearing loss. Which one of the following is the most likely cause of this patient’s hearing loss? a) Noise-induced hearing loss b) Meniere’s disease c) Otosclerosis d) Acoustic neuroma e) Perilymphatic fistula

🇨🇦 MCCQE1,2 | #Case_115 | #answer 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 ✅ B 🔎 Explanation The superior division of the right middle cerebral artery (MCA) (choice B) is the most likely site of blockage in this patient. Patients with blockage of this division of MCA usually present with contralateral weakness and sensory loss on the arm and face. This division of the right MCA supplies the lateral surface of the right cerebral hemisphere above the lateral fissure but short of the superolateral portions, which are supplied by the anterior cerebral artery (ACA). Thus, motor, sensory and sensory association areas for the left upper part of the body (arm and face) are supplied by this division of MCA and weakness and sensory impairment are expected to affect these parts of the body. The lower limb is spared because its motor and sensory representation is located in the superolateral of frontal and parietal lobes which are supplied by the ACA. Because the right or non-dominant hemisphere is affected, our patient does not have any form of aphasia. ⚠ Patients with MCA blockage (choice A) usually present with symptoms and signs of blockage of its superior division (choice B), inferior division (choice C) and lenticulostriate division (choice D). Thus, these patients are expected to present with left sided weakness and hemianesthesia affecting the face, arm, and leg. Because the non-dominant right hemisphere is affect, hemi-neglect, astereognosis and anosognosia, hemianopsia rather than aphasia are also present. ⚠ Patients with inferior division of right middle cerebral artery (MCA)blockage (choice C) usually present with left sided homonymous hemianopsia because this artery supplies the parts of optic pathway that pass through the temporal lobe. Because the non-dominant hemisphere is affected, hemi-neglect, astereognosis, and anosognosia rather than aphasia accompanies the hemianopsia. ⚠ Patients with blockage of lenticulostriate branches of the right MCA(choice D) usually present with left sided hemianesthesia and hemiparesis of the leg, arm, and face. The lenticulostriate branches of the right MCA together with anterior choroidal artery supply the posterior limb of the internal capsule on the right where the motor and sensory fibers pass between the cortex and brain stem. Because motor and sensory fibers for both upper and lower parts of the body come close to each other, both of these parts of the body are affected. ⚠ Patients with right anterior cerebral artery (ACA) blockage (choice E) usually present with left sided hemianesthesia and hemiparesis of the leg. The right ACA supplies the superolateral portions of the right frontal and parietal lobes, which due homunculus topography, contains the motor and sensory areas of the lower part of the body (leg). The arms and the face are usually not affected by blockage of the ACA because cortical areas representing these parts of the body are located along the lateral surface of the cerebral hemisphere and are supplied by superior division of MCA. 🔖Key point: Weakness and anesthesia of the left arm and left half of the face and sparing of the lower leg is most likely caused by blockage in the territory of the middle cerebral artery (MCA) other than the lenticulostriate division. Absence of hemi-neglect and hemianopsia exclude blockage of the inferior division and favours blockage of the superior division of the right MCA

🇨🇦 MCCQE1,2 | #Case_115 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 A 50-year-old known hypertensive man was brought to the emergency department after a sudden feeling of numbness and weakness of his left arm and left half of the face. No other symptoms could be elicited and the patient could engage in dialogue, normally. Vital signs including blood pressure were stable. Left shoulder, upper arm, forearm and hand muscles have power of 2. Pain and temperature sensations are impaired on the left arm and left side of the face. No motor or sensory impairment could be detected on the right side or left lower side of the body. Visual fields were normal. The rest of physical examination was normal. Ischemic stroke was suspected. Which of the following arteries is the most likely site of blockage? a) Right middle cerebral artery b) Superior division of right middle cerebral artery c) Inferior division of right middle cerebral artery d) Lenticulostriate branches of the right middle cerebral artery e) Right anterior cerebral artery

🇨🇦 MCCQE1,2 | #Case_114 | #answer 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 ✅ C 🔎 Explanation The majority of patients presenting with spontaneous pneumothorax are tall, thin individuals under 40 years of age. Most do not have clinically apparent lung disease, and the chest pain is sometimes minimal at onset and may resolve within 24 hours even if untreated. Patients with small pneumothorax involving less than 15% of the hemithorax may have a normal physical examination, although tachycardia is occasionally noted. The diagnosis is confirmed by chest radiographs. Studies of recurrence have found that an average of 30% of patients will have a recurrence within 6 months to 2 years. The treatment of an initial pneumothorax of less than 20% may be monitored if a patient has few symptoms. Follow-up should include a chest radiograph to assess stability at 24-48 hours. Indications for treatment include progression, delayed expansion, or the development of symptoms. The majority of patients with spontaneous pneumothoraces, and perhaps almost all of them, will have subpleural bullae on a CT scan.

🇨🇦 MCCQE1,2 | #Case_114 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 A 35-year-old male consults you about a vague chest pain he developed while sitting at his desk earlier in the day. The pain is right-sided and was sharp for a brief time when it began, but it rapidly subsided. There was no hemoptysis and the pain does not seem pleuritic. His physical examination, EKG, and oxygen saturation are unremarkable. A chest film shows a 10% right pneumothorax. Which one of the following is true in this situation? a) He is likely to be an overweight smoker with a chronic cough b) Rupture of subpleural bullae would be an unlikely cause of his problem c) Outpatient observation with a repeat chest radiograph in 24 hours is indicated d) A chest tube should be placed expeditiously e) After treatment his probability of recurrence is less than 15%

🇨🇦 MCCQE1,2 | #Case_113 | #answer 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 ✅ A 🔎 Explanation Diabetic ulcers typically develop at pressure points, and the heel is a favorite location. The patient has evidence of neuropathy, and the correlation with the trauma inflicted by the new shoes is classic. Diabetic ulcers tend to occur in the following areas: -Areas most subjected to weight bearing, such as the heel, plantar metatarsal head areas, the tips of the most prominent toes (usually the first or second), and the tips of hammer toes (Ulcers also occur over the malleoli because these areas commonly are subjected to trauma.) -Areas most subjected to stress, such as the dorsal portion of hammer toes Ischemic ulcers, whether due to arteriosclerosis or embolization are typically seen at the tip of the toes, as far away from the heart as one can get.

🇨🇦 MCCQE1,2 | #Case_113 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 A 70 year old man has had an indolent, unhealing ulcer at the heel of the right foot for several weeks, since he started wearing his new shoes. He indicates that neither the blister nor the ulcer ever gave him any pain. The ulcer is 3.5 cm in diameter, the ulcer base looks dirty, and there is hardly any granulation tissue. The skin around the ulcer looks normal. The patient has no sensation to pin prick anywhere in that foot. Peripheral pulses are weak but palpable. He is obese and has varicose veins, high cholesterol, and poorly controlled type 2 diabetes mellitus. Which of the following most accurately characterizes the ulcer? a) Diabetic ulcer due to trauma, neuropathy, and microvascular disease b) Ischemic ulcer due to arteriosclerosis c) Ischemic ulcer due to embolization d) Neoplastic in nature, probably squamous cell carcinoma e) Stasis ulcer due to venous insufficiency

🇨🇦 MCCQE1,2 | #Case_112 | #answer 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 ✅ B 🔎 Explanation When straw-colored or gray-green fluid is obtained by fine-needle aspiration of a breast nodule and the lesion completely disappears, the diagnosis is simple cyst. The fluid should not be sent for analysis because the risk for cancer is exceedingly small. If the fluid is bloody or otherwise unusual, it should be sent for cytologic examination because about 7% of bloodstained aspirates are associated with cancer

🇨🇦 MCCQE1,2 | #Case_112 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 A 38 year old white female presents to your office with a 4-cm palpable nodule in her right breast. Fine-needle aspiration yields 4 cc of bloody fluid. Following the aspiration, the breast nodule is no longer palpable. Which one of the following would be most appropriate at this point? a) No further workup b) Cytologic examination of the fluid c) Surgical referral for core needle biopsy d) Surgical referral for excisional biopsy e) Ultrasonography of the breast

🇨🇦 MCCQE1,2 | #Case_111 | #answer 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 ✅ B 🔎 Explanation Since this patient’s wound is dirty, it would be inappropriate to fail taking prophylactic measures against tetanus, therefore choices D and E that do not include tetanus prophylaxis are incorrect. If the patient has already received tetanus booster in the last 5 years, usually the vaccine is not needed. Since this patient was last administered the tetanus toxoid 7 years ago, he should receive a shot of tetanus toxoid today (choice B). ⚠ Tetanus immune globulin (TIG) alone would not be enough prophylaxis in this patient. ⚠ Tetanus immune globulin and tetanus toxoid (choice C) would be appropriate in a patient who has not received a booster in the last 10 years. 🔖 Key point: For dirty wounds, tetanus prophylaxis should be considered as follows: If the patient has not received the tetanus booster in the last 10 years, both tetanus toxoid and tetanus immunoglobulin (TIG) are given, if the patient has received the booster in the last 10 years but not within the last 5 years, then the tetanus toxoid is given, if a patient has received the tetanus vaccine booster within the last 5 years, neither the vaccine nor the immunoglobulin are necessary

🇨🇦 MCCQE1,2 | #Case_111 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 A 35-year-old who was injured at his work site presents to your department with a minor wound that got dirty. The patient has no symptoms other than the bleeding he had after the injury and the pain he feels at the site of injury. He was previously healthy and has had regular check-ups and appropriate immunizations. His last tetanus booster was 7 years ago. Which of the following is the most appropriate course of action? a) Give tetanus immune globulin (TIG) b) Give tetanus toxoid alone c) Give both TIG and tetanus toxoid d) Clean the wound and give amoxicillin e) Clean wound and monitor for symptoms

🇨🇦 MCCQE1,2 | #Case_110 | #answer 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 ✅ A 🔎 Explanation Cryptosporidium parvum is the most common cause of chronic diarrhea in HIV-positive patients with a CD4+ count less than 200 cells/mm³. An acid fast staining of the stool (choice A) showing oocysts is very suggestive of cryptosporidiosis. ⚠ Stool gram stain (choice E), culture an sensitivity (choice D) is very helpful for bacterial diarrheal diseases. ⚠ Colonoscopy would be warranted when inflammatory bowel diseases are suspected. ⚠ Clostridium difficile toxin assay (choice B) is the diagnostic modality of choice of pseudomembrenous colitis.

🇨🇦 MCCQE1,2 | #Case_110 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 A 35-year-old female presents to your office with a chronic diarrhea of 8 weeks duration. The diarrhea is associated with abdominal cramps and anorexia. She denies any blood per stool. Her past medical history is significant for HIV, diagnosed 10 years ago. Her last CD4 count, 2 months ago, was 140 cells /mm³. Which of the following tests would be the most helpful to diagnose the patient’s condition? a) Acid fast stain of the stool b) Clostridium difficile toxin assay c) Colonoscopy d) Stool culture and sensitivity e) Stool gram stain

🇨🇦 MCCQE1,2 | #Case_109 | #answer 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 ✅ A 🔎 Explanation There is not a linear correlation between bone mineral density and fracture risk. Bone architecture may be changed by bisphosphonate therapy, which may result in a decreased fracture risk. This patient has not had a fracture and is on adequate medical therapy that should be continued

🇨🇦 MCCQE1,2 | #Case_109 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 A 70-year-old female consults you about osteoporosis treatment. Two years ago her T score was -2.6, and she began taking risedronate (Actonel), 35 mg/week. Her BMI is 24 kg/m², she takes appropriate doses of calcium and vitamin D, and she walks for at least 30 mins almost every day. Her current T score is -2.5, and she is concerned about the minimal change in spite of therapy. She has never had a fracture, but asks if more could be done to reduce her fracture risk. Which one of the following would be the most appropriate recommendation? a) Continue current treatment b) Stop risedronate and start alendronate c) Stop risedronate and start teriparatide d) Add raloxifene e) Order a bone biopsy to evaluate bone architecture

🇨🇦 MCCQE1,2 | #Case_108 | #answer 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 ✅ E 🔎 Explanation The best initial therapy for Acute cardiogenic pulmonary edema includes Loop diuretics, Morphine, Nitrates and Oxygen “LMNO”. Morphine promotes venodilation thus decreases the preload; moreover, morphine alleviates the severe anxiety of acute pulmonary edema patients.