Case-based MCQ

🇨🇦 MCCQE1,2 | #Case_264 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 A 22-year-old male presents to the emergency department several hours after a rugby match in which he was struck in the face. His nose is bleeding. On examination the patient has a depression in his nose on the side of impact and an outward displacement on the opposite side. Internal inspection reveals a purple area of swelling and fluctuance on the left side of the nasal septum. The remainder of the examination demonstrates no findings to suggest other facial or periorbital trauma. Which one of the following would be most appropriate at this time? a) Immediate closed reduction of the nasal fracture b) Immediate plain radiographs of the nose and orbits c) Immediate CT imaging to assess for facial and mandibular fracture d) Incision and drainage of the swollen, fluctuant area e) Discharge with pain medication, ice packs, and head elevation, with referral to a specialist in 1 week

🇨🇦 MCCQE1,2 | #Case_263 | #answer 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 ✅ C 🔎 Explanation A thoracic duct injury, in which chyle leaks into the chest cavity, is a relatively common complication after neonatal repair of congenital cardiac disease. ⚠ A. A hemothorax would not have milky fluid on thoracentesis. ⚠ B. Parenteral nutrition is delivered via venous access, usually in a large vein (subclavian, femoral). If there were venous rupture in the thorax, the fluid obtained would be bloody. ⚠ D. A post-op pneumonia causing a parapneumonic effusion would tend to be clear to slightly blood tinged. ⚠ E. A hydrothorax would not have milky fluid and generally is associated with edema or fluid in other parts of the body. Causes include hepatic, cardiac, or renal failure.

🇨🇦 MCCQE1,2 | #Case_263 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 You are called to the bedside of a 1-month-old infant who is status post repair of coarctation of the aorta. He has been doing well and his feedings have been restarted. Since this morning, he has become more tachypneic. On exam, the patient has diminished breath sounds on the left with dullness to percussion. CXR shows a large effusion, so you urgently perform a diagnostic thoracentesis. The fluid returned is milky, and the patient continues to deteriorate. What is the most likely diagnosis? a) Hemothorax from cardiac surgery b) Parenteral nutrition leaking into the thoracic cavity c) Chylothorax from thoracic duct injury during surgery d) Parapneumonic effusion from a post-op pneumonia e) Hydrothorax

🇨🇦 MCCQE1,2 | #Case_262 | #answer 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 ✅ C 🔎 Explanation This scenario is a classic presentation for nephrotic syndrome. The most common histologic type in this age group is minimal change disease. ⚠ Acute glomerulonephritis would likely present with hypertension and red cell casts in the urine. ⚠ The normal BUN and creatinine rule out acute renal failure. ⚠ Orthostatic proteinuria, while much more common, is not associated with edema or the markedly elevated total cholesterol of 8 mmol/L. ⚠ Congenital renal artery stenosis is an uncommon cause of problems in childhood and typically presents with hypertension in adults.

🇨🇦 MCCQE1,2 | #Case_262 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 A 10-year-old female is brought in for a scheduled physical examination. The mother notes that her daughter’s allergies “seem to be getting worse”, and that her “eyes are puffy in the morning”. The patient has been healthy on previous examinations. Examination today reveals no other allergic stigmata. You note a trace of ankle edema and 3+ proteinuria on urinalysis. The remainder of the examination is normal. The patient returns the following morning for further studies. She is fasting. Laboratory findings show the following: Hematocrit: 42% WBCs: 6.2 x 10^9/L with normal differential Creatinine: 71 µmol/L BUN: 6.4 mmol/L Albumin: 23 g/L Calcium: 1.84 mmol/L Sodium: 128 mmol/L Potassium: 3.7 mmol/L Total cholesterol: 8 mmol/L Antinuclear antibody: negative Antistreptolysin: negative Urinalysis: 3 + protein, no WBCs, RBCs, or casts The most likely diagnosis is: a) Acute glomerulonephritis b) Acute renal failure c) Nephrotic syndrome d) Orthostatic proteinuria e) Congenital renal artery stenosis

🇨🇦 MCCQE1,2 | #Case_261 | #answer 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 ✅ B 🔎 Explanation Screening for asymptomatic bacteriuria is done for patients taking immunosuppressive drugs (choice B), immunosuppression secondary to pathology, pregnant patients, and renal transplant patients. The general population does not receive screening for asymptomatic bacteriuria. The decision to screen for asymptomatic bacteriuria is based on whether or not treatment leads to improved outcomes. The reason these populations of patients receive screening, is because there is a high risk of complications. For example, immunocompromised patients have a greater risk of developing pyelonephritis, so treating asymptomatic bacteriuria leads to decreased incidence of pyelonephritis. ⚠ History of diabetes mellitus (choice A) is incorrect. While there is an increased incidence of asymptomatic bacteriuria, a study in diabetic women found that treating it did not lead to a decrease in complications, so screening is not recommended. ⚠ Spinal cord injury (choice C) is incorrect. When the bladder is affected in these injuries, there is a greater incidence of asymptomatic bacteriuria, but treating it does not decrease mortality, and in those who are treated, there is early recurrence of bacteria. Intermittent catheterization is a method used to decrease the mortality and incidence of complications in these patients. ⚠ Self catheterization (choice D) is incorrect, as this is the method used to decrease morbidity and mortality from asymptomatic bacteriuria in patients with spinal cord injury. Even in patients with indwelling catheters, screening for asymptomatic bacteriuria is not screened for unless they have other risk factors for urinary tract infections. ⚠ Age > 65 (choice E) alone is not an indication for screening for asymptomatic bacteriuria. As mentioned before, routine screening of the general population is not recommended. 🔖 Key point: Routine screening for asymptomatic bacteriuria is not performed. Screening for asymptomatic bacteriuria is done in pregnancy, renal transplant patients, and immunosuppressed patients (whether by disease or medication).

🇨🇦 MCCQE1,2 | #Case_261 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 A 66-year-old female is on the ward on her 5th post-operative day, recovering after receiving a renal transplant. The patient has no complaints and is eager to leave the hospital. She has a 30-year-history of diabetes mellitus, and she has a spinal cord injury from a motor vehicle accident 5 years ago that requires intermittent catheterization to allow her to urinate. Physical exam reveals a non-erythematous, mildly tender surgical site. She is ready to be released home, and will be taking mycophenolic acid, cyclosporine, and prednisone as preventive measures against graft rejection. The patient is instructed that she will need regular screening for asymptomatic bacteriuria. For which of the following reasons will screening for asymptomatic bacteriuria give the greatest benefit? a) History of diabetes mellitus b) Receiving immunosuppressive drugs c) Spinal cord injury d) Self catheterization e) Age > 65

🇨🇦 MCCQE1,2 | #Case_260 | #answer 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 ✅ E 🔎 Explanation Serum TSH (choice E) is the investigation expected to have the greatest diagnostic yield. High cardiac output heart failure due to thyrotoxicosis is a highly likely diagnosis in this patient. Dyspnea on exertion and low urine flow rate point towards the diagnosis of heart failure. The high LVEDV and high ejection fraction suggests the diagnosis of high cardiac output heart failure. Causes of high cardiac output heart failure include arteriovenous (AV) shunts, anemia and thyrotoxicosis. The patient has no signs suggestive of AV shunts and the normal CBC excludes anemia as a cause of high cardiac output heart failure. High systolic blood pressure, wide pulse pressure, sinus tachycardia, and short PR interval are known consequences of hyperthyroidism. Thus, hyperthyroidism is a highly likely cause of heart failure in this patient. Therefore, measurement of serum TSH is expected to have the greatest yield. ⚠ Renal function tests (choice A) are not expected to have the greatest diagnostic yield in this patient. In high cardiac output heart failure, blood is directed away from the kidney resulting in reduced perfusion pressure, glomerular filtration rate, and urine flow. Abnormal renal function tests would suggest renal impairment but may not be helpful in differentiation between different causes of high cardiac output heart failure. ⚠ Ambulatory ECG monitoring (choice B) is not the correct choice. Ambulatory ECG monitoring is used in surveillance of non-sustained or episodic arrhythmias. Palpitations in our patient most probably are due to the tachycardia ascertained by physical examination and ECG. Thus, the continuous symptoms and signs of our patient do not seem to be caused by an episodic arrhythmia. Also, arrhythmias usually cause low cardiac output rather than high cardiac output failure. Ambulatory ECG thus, is not expected to have a great diagnostic yield. ⚠ Cardiac enzymes (choice C) are not expected to be of high diagnostic yield. The patient's symptoms and signs were ongoing for at least two weeks and are thus unlikely to be due to myocardial infarction. Also, absence of chest pain, normal ECG (other than tachycardia) and high ejection fraction make infarction rather unlikely. Measurement of cardiac enzymes will only exclude the diagnosis of the already unlikely myocardial infarction. ⚠ Cardiac catheterization and angiography (choice D) is not the correct choice. Our patient does not have any of the indications of coronary angiography like disabling chronic unstable angina, high risk criteria, uncertain diagnosis or inability to undergo non-invasive testing. Thus, cardiac catheterization and angiography are not even indicated in this patient. 🔖 Key point: In patients with high cardiac output heart failure, thyrotoxicosis should be excluded by measurement of serum TSH

🇨🇦 MCCQE1,2 | #Case_260 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 A 60-year-old man presented with palpitations and dyspnea on exertion for the last 2 weeks. He also believed that he has been passing less and less urine in the last 10 days. His heart rate was 108 per minute, pulse was regular and bounding, respiratory rate 23 breaths per minute, blood pressure 142/68mmHg, and body temperature was 37.3°C. Pericardium was hyperactive and the point of maximum impulse is in the fifth intercostal space at midclavicular line. Both first and second heart sounds were louder than normal and an ejection systolic murmur was best heard in the second intercostal space on the left. Rest of physical examination was normal. ECG shows a heart rate of 105 per minute, sinus rhythm and short PR interval; no ST segment changes or significant Q waves. Echocardiography shows raised left ventricular end-diastolic volume (LVEDV) and high ejection fraction. Complete blood count was normal. Which of the following lab investigations is expected to have the greatest diagnostic yield? a) Renal function tests b) Ambulatory ECG monitoring c) Cardiac enzymes d) Cardiac catheterization and angiography e) Serum TSH

🇨🇦 MCCQE1,2 | #Case_259 | #answer 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 ✅ E 🔎 Explanation Sjogren's syndrome (SS) is an autoimmune disorder that commonly affects labial and lacrimal glands leading to dry eyes and mouth. SS is associated with other autoimmune disorders and more seriously salivary gland tumors and B cell lymphomas. Diagnostic criteria includes four of six total criteria that include: 1) ocular symptoms, 2) oral symptoms, 3) ocular signs, 4) focal sialadenitis (inflammation of salivary gland), 5) salivary gland involvement, and 6) anti-Ro/La antibodies in the absence of head and neck radiation treatment, hepatitis C, HIV, sarcoidosis, graft versus host disease or anticholinergic drugs. In primary SS patients, such as the one presented in this question, the best initial treatment consists of pilocarpine and cyclosporine (choice E). Topical 0.05% cyclosporine is used for xerophthalmia (dry eyes) and oral pilocarpine and cevimeline for xerostomia (dry mouth). ⚠ Azathioprine (choice A) is not correct. Studies have shown that azathioprine was not more effective than cyclosporine. It also has higher rate of adverse effects such as nausea, vomiting, anemia and acute pancreatitis. ⚠ Corticosteroid (choice B) is not correct. Studies have shown that corticosteroids have not shown to be efficacious in comparison to placebo in treating primary Sjogren's syndrome. ⚠ High dose rituximab (choice C) is not correct. Recent studies suggest efficacy in treating patients with extraglandular features (glomerulonephritis, neuropathy, interstitial lung disease, or myelitis) or systemic vasculitis. This patient does not present with extraglandular symptoms and given rituximab's safety profile, it should not be used. ⚠ Symptomatic Sjogren's syndrome it not a self-limiting condition (choice D) and should be treated. 🔖 Key point: Sjogren's syndrome is an autoimmune disorder that commonly presents with xerostomia (dry mouth) and xerophthalmia (dry eyes). Pilocarpine/cevimeline are used to treat xerostomia and topical cyclosporine is used to treat xerophthalmia

🇨🇦 MCCQE1,2 | #Case_259 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 A 42-year-old Caucasian female comes to the clinic complaining of worsening dry, blurry eyes, and dry mouth along with painful left side of the mouth. Her serologic studies are negative for anti-nuclear antibody, but positive for anti-Ro, anti-La, and salivary gland protein 1. What is her best initial treatment for her symptoms? a) Azathioprine b) Corticosteroid c) High dose rituximab d) Reassurance that is a self-limiting condition e) Pilocarpine and cyclosporine

🇨🇦 MCCQE1,2 | #Case_258 | #answer 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 ✅ E 🔎 Explanation Detection of normal percent saturation of hemoglobin (choice E) is required for making the diagnosis of Polycythemia Rubra Vera (PRV) according to the world Health Organization criteria. In any patient presenting with abnormally high hemoglobin level, hematocrit or red cell count, the first question to be answered is whether erythrocytosis is relative (caused by shrinkage of plasma volume due to dehydration for example) or absolute (a true increase in red cell mass). This question is answered by measurement of red cell mass which is already done in our patient (26% above predicted value) and confirmed absolute erythrocytosis. If erythrocytosis is absolute, the second question to be answered is whether erythrocytosis is secondary or primary (PRV). Secondary erythrocytosis can be excluded if percent saturation of hemoglobin is normal (> 92%). In hypoxia the kidneys respond by secreting erythropoietin, which stimulates red cell production and increases red cell mass in an attempt to deliver sufficient amounts of oxygen to tissues. ⚠ Detection of bone marrow fibrosis (choice A) is not required for making the diagnosis of PRV. Bone marrow fibrosis may or may not be found in patients with PRV. In addition, bone marrow fibrosis may also be found in the other myeloproliferative disorders (chronic myeloid leukemia, idiopathic myelofibrosis, and essential thrombocytosis). Thus, absence of myelofibrosis does not exclude the diagnosis of PRV and its detection does not confirm this diagnosis. ⚠ Detection of Philadelphia chromosome in bone marrow cells (choice B) supports the diagnosis of chronic myeloid leukemia (CML) rather than PRV. ⚠ Detection of Janus kinase-2 gene (JAK2) mutation in myeloid lineage (choice C) is not required for making the diagnosis of PRV but it supports it. Mutations of this gene are found in 95% of patients of PRV. However, detection of this mutation does not confirm the diagnosis of PRV and its absence does not exclude the diagnosis. ⚠ Detection of extra medullary hematopoiesis in liver and spleen (choice D) is not required for making the diagnosis of PRV. Splenomegaly and hepatomegaly are detected in 70% and 40% of patients with PRV, respectively. In patients with high red cell mass and in whom secondary erythrocytosis is excluded, splenomegaly is a major criterion for the diagnosis of PRV. 🔖 Key point: In a patient with absolute erythrocytosis, secondary causes should be excluded by assessing hemoglobin percent saturation before proceeding with further evaluation.

🇨🇦 MCCQE1,2 | #Case_258 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 A 55-year-old man presented to his family physician because he believed that his face has been unusually red over the last few weeks. Physical examination showed: stable vital signs, ruddy complexion of the face and hepatosplenomegaly. The rest of his physical examination was normal. His complete blood count showed the following findings: Hemoglobin level: 194g/L Hematocrit: 58% Red cell count: 6.6 x 1012/L White cell count: 12.5 x 109/L Platelet count: 575 x 109/L Red cell mass was 26% above predicted value. Polycythemia Rubra Vera was strongly suspected. Which of the following lab results is required for making this diagnosis? a) Detection of bone marrow fibrosis b) Detection of Philadelphia chromosome in bone marrow cells c) Detection of Janus kinase-2 gene (JAK2) mutation in myeloid lineage d) Detection of extra medullary hematopoiesis in liver and spleen e) Detection of normal percent saturation of hemoglobin

🇨🇦 MCCQE1,2 | #Case_257 | #answer 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 ✅ B 🔎 Explanation Damage to the front part of the parietal lobe on one side causes numbness and impairs sensation on the opposite side of the body. Affected people have difficulty identifying a sensation's location and type (pain, heat, cold, or vibration). Damage to the back part of the parietal lobe causes right-left disorientation and problems with calculations and drawing. Damage to the right parietal lobe can cause apraxia, the inability to perform simple skilled tasks, such as brushing the hair or dressing. Sudden damage to the parietal lobe can cause people to ignore the serious nature of their disorder and even neglect or deny the existence of the side of the body opposite the injury. Such people may become confused or delirious and unable to dress themselves or to perform other ordinary tasks.

🇨🇦 MCCQE1,2 | #Case_257 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 A 74-year-old, right-handed man presents with a past medical history of hypertension and dyslipidemia for 30 years. He is a retired banker who recently has had trouble calculating his restaurant bill. He also notices that his writing has deteriorated. On physical exam, he has difficulty naming his fingers and is confused with distinguishing left from right. The lesion is most likely in which part of the brain? a) Occipital b) Parietal c) Temporal d) Frontal

🇨🇦 MCCQE1,2 | #Case_256 | #answer 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 ✅ E 🔎 Explanation A pituitary tumour can cause bitemporal hemianopsia. This is a condition where one cannot see out of the periphery. Damage to the medial aspect of the optic chiasm, as is often seen with a pituitary gland tumor, may compromise the decussating fibers from both nasal hemiretinas. The loss of peripheral vision in both eyes is called bitemporal hemianopia.Keep in mind MEN (Multiple endocrine neoplasia). In particular Multiple endocrine neoplasia, type I (MEN-I) is a hereditary syndrome characterized by tumors of the parathyroid glands, pancreatic islet cells, and pituitary gland.

🇨🇦 MCCQE1,2 | #Case_256 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 A 58-year-old man with a past history of a parathyroidectomy for primary hyperparathyroidism is now in your office complaining of headaches worse in the morning, made worse by a small motor vehicle accident he credits to a loss of peripheral vision. You plan to: a) Send to the Emergency Department for an immediate CT head b) Check his calcium to ensure there’s no remaining parathyroid tissue c) Check for a pheochromocytoma because you are concerned he has MEN I syndrome d) Check for a homonymous hemianopia because you are worried about a pituitary tumor e) Check for a bitemporal hemianopia because you are worried about a pituitary tumor

🇨🇦 MCCQE1,2 | #Case_255 | #answer 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 ✅ A 🔎 Explanation The serum-ascitic fluid albumin gradient > 1.1 indicates that this patient has ascites due to portal hypertension. The negative cytology and an ascitic fluid amylase level < 100 U/L make peritoneal carcinomatosis and ascites secondary to pancreatitis unlikely. An ascitic fluid WBC count > 500 x 10^9/L, with > 50% polymorphonuclear leukocytes, points to bacterial peritonitis. Secondary bacterial peritonitis is usually polymicrobial, with ascitic fluid total protein levels >10 g/L. With primary bacterial peritonitis a single organism is usually seen on a culture, with ascitic fluid total protein levels < 10 g/L.

🇨🇦 MCCQE1,2 | #Case_255 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 A 45-year-old female is hospitalized with fever and mild confusion. On examination she has ascites, and the liver edge is firm and irregular. Blood is drawn, and paracentesis is performed. Laboratory Findings: Serum albumin: 24 g/L (N 35-50) Total protein: 47 g/L (N 60-80) Ascitic fluid: cloudy yellow Cytology: negative for malignant cells Albumin: 6 g/L Protein: 9 g/L WBCs: 525 x 10^9/L with 75% polymorphonuclear leukocytes Amylase: 50 U/L Empiric therapy is started. The next day, gram-negative rods are noted in the ascitic fluid. Which one of the following is the most likely diagnosis? a) Spontaneous bacterial peritonitis b) Pancreatic ascites c) Peritoneal carcinomatosis d) Tuberculous peritonitis e) Bacterial peritonitis secondary to bowel rupture

🇨🇦 MCCQE1,2 | #Case_254 | #answer 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 ✅ B 🔎 Explanation The fact that this patient’s hair is breaking off rather than coming out by the roots strongly suggests that her hair loss is the result of improper use of hair cosmetics. Findings that lend additional support to this diagnosis include the lack of scarring, the absence of bald areas, and the normal KOH examination for fungal elements. Bleaching and permanent straightening products contain hydrogen peroxide, which can reconfigure and weaken hair fiber bonds. Eventually, light to moderate brushing will cause the hair to break off and fall out. Treatment is preventive.