Case-based MCQ

🇨🇦 MCCQE1,2 | #Case_183 | #answer 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 ✅ E 🔎 Explanation Significant impact (eg, motor vehicle collision) can rupture a normal spleen. Rupture of the splenic capsule produces marked hemorrhage into the peritoneal cavity. The manifestations, including hemorrhagic shock, abdominal pain, and distention, are usually clinically obvious. However, splenic trauma can also produce a subcapsular hematoma, which may not rupture until hours or even months after the injury. Rupture is generally preceded by left upper quadrant abdominal pain. Splenic rupture should be suspected in patients with blunt abdominal trauma and hemorrhagic shock or left upper quadrant pain (which sometimes radiates to the shoulder); patients with unexplained left upper quadrant pain, particularly if there is evidence of hypovolemia or shock, should be asked about recent trauma. The diagnosis is confirmed by CT scan (in the stable patient), ultrasound, or peritoneal lavage (in the unstable patient). Treatment has traditionally been splenectomy. However, splenectomy should be avoided if possible, particularly in children, to avoid the resulting permanent susceptibility to bacterial infections

🇨🇦 MCCQE1,2 | #Case_183 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 Following a car accident a 33-year-old man is admitted to the hospital with a fracture of the tenth rib on the left side. He is noted to be pale,restless, and sweating, and his blood pressure is low. On examination there is pronounced guarding in the left upper quadrant of the abdomen. Which one of the following viscera is most likely damaged? a) Left lung b) Pericardium c) Left diaphragm d) Left kidney e) Spleen

🇨🇦 MCCQE1,2 | #Case_182 | #answer 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 ✅ B 🔎 Explanation Staphylococcal scalded skin syndrome (choice B) is an acute epidermolysis caused by a staphylococcal toxin. Newborns and children are most susceptible. Symptoms are widespread bullae with epidermal sloughing. The initial lesion is usually superficial and crusted. Within 24 h, the surrounding skin becomes painful and scarlet, changes that quickly spread to other areas. The skin may be exquisitely tender and have a wrinkled tissue paper-like consistency. Large, flaccid blisters arise on the erythematous skin and quickly break to produce erosions. Intact blisters extend laterally with gentle pressure (Nikolsky's sign). The epidermis may peel easily, often in large sheets. Widespread desquamation occurs within 36 to 72 h, and patients become very ill with systemic manifestations (eg, malaise, chills, fever). Desquamated areas appear scalded. Loss of the protective skin barrier can lead to sepsis and to fluid and electrolyte imbalance. Diagnosis is by examination and sometimes biopsy. Treatment is antistaphylococcal antibiotics and local care. Prognosis is excellent with timely treatment. ⚠ Kawasaki disease (choice A) is characterized with polymorphous rash, usually generalized but may be limited to the groin or lower extremities. Oropharyngeal changes include erythema, fissuring, and crusting of the lips; strawberry tongue; diffuse mucosal injection of the oropharynx (mucous membrane changes, which occur in more than 90% of patients) ⚠ Typically, Stevens-Johnson syndrome’s rash (choice C) begins as macules that develop into papules, vesicles, bullae, urticarial plaques, or confluent erythema. The center of these lesions may be vesicular, purpuric, or necrotic. The typical lesion has the appearance of a target; this is considered pathognomonic. Involvement of oral and/or mucous membranes may be very severe. ⚠ In toxic epidermal necrolysis (choice D), the cutaneous eruption begins as a poorly defined, erythematous macular rash with purpuric centers, which later coalesces to form flaccid blisters and sheetlike epidermal detachment. The lesions predominate on the torso and face, sparing the scalp. Mucous membrane is not spared. ⚠ Toxic shock syndrome (choice E) also includes mucosal involvement and is characterized by high fever, rash, hypotension, multiorgan failure, and desquamation, typically of the palms and soles.

🇨🇦 MCCQE1,2 | #Case_182 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 A 10-month-old child develops low-grade fever and sunburn-like erythema over much of the body, but most prominently in the intertriginous areas. Within 36 hours sheet-like desquamation is noted in the flexures and around the mouth. The mucous membranes are spared. Which of the following is the most likely diagnosis? a) Kawasaki disease b) Staphylococcal scalded skin syndrome c) Stevens-Johnson syndrome d) Toxic epidermal necrolysis e) Toxic shock syndrome

🇨🇦 MCCQE1,2 | #Case_181 | #answer 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 ✅ D 🔎 Explanation Cholestasis is a common cause of an isolated elevation of alkaline phosphatase in apparently healthy middle-aged women. Like alkaline phosphatase, serum 5’-nucleotidase (choice D) is also elevated in cholestasis. If serum 5’-nucleotidase is also elevated, cholestasis is the most likely cause and further investigations should be directed to elucidate the cause of cholestasis. If 5’-nucleotidase is normal, other causes of high alkaline phosphatase cholestasis should be sought. These might include bone diseases like Paget's disease of bone. ⚠ Radionuclide bone scan (choice A), osteocalcin (choice B) and serum calcium and phosphate (choice C) are not the correct choices. These investigations would be done if our patient were a male of older age (> 55 years) complaining of bone pain or deformities because Paget's disease may then be the most likely cause. ⚠ ERCP (choice E) is not the correct choice. Before performing such an invasive investigation, the diagnosis of cholestasis must first be established. Even if the diagnosis of cholestasis is established, investigations less invasive than ERCP might be enough for elucidating the cause of cholestasis. 🔖 Key point In apparently healthy people with an isolated elevation of alkaline phosphatase, measurement of serum 5’-nucleotidase is the best substantiated method for identification of the source of an elevated ALP.

🇨🇦 MCCQE1,2 | #Case_181 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 A 45-year-old woman with an unremarkable past medical history was found to have an elevated serum alkaline phosphatase (ALP) of four times the normal value. Serum bilirubin, aspartate and alanine transaminases, albumin and coagulation profile were within their normal limits. Which of the following investigations should be done next? a) Radionuclide bone scan b) Serum osteocalcin c) Serum calcium and phosphate d) Serum 5’-nucleotidase e) Endoscopic retrograde cholangiopancreatography (ERCP)

🇨🇦 MCCQE1,2 | #Case_180 | #answer 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 ✅ D 🔎 Explanation This patient’s refractory hypertension history and the imaging studies results clearly point to the diagnosis of renal artery stenosis. The best non-invasive study to diagnose this condition is duplex ultrasonographic scanning while the gold standard test remains digital subtraction angiography. In patients >50 years old the most common cause of renal artery stenosis is atherosclerosis. Renal artery stenosis results in kidney hypoperfusion, which leads to the release of abnormally high levels of renin. This will increase systemic angiotensin II and aldosterone levels, which will cause widespread vasoconstriction and significant Na+ and water retention by both normal and abnormal kidney. Both these actions result in increased blood pressure. Angiotension II has a preferential action on the efferent arterioles this allows it to maintain GFR despite reduced renal perfusion. Although vasoconstriction of the efferent arterioles further decreases renal blood flow, it also increases hydrostatic pressure of the glomerulus, which increases the net filtration pressure of the glomerulus and maintains the GFR. This makes choice D with increased renin, increased angiotensin, elevated aldosterone, decreased Na+ excretion (increased retention), maintained GFR, and decreased renal blood flow the best answer. ⚠ Renin [ I ]; Angiotensin II [ I ]; Aldosterone [ I ]; Na+ excretion [ I ]; GFR [ I ]; Renal blood flow [ I ] (choice A) is incorrect. Na+ excretion is reduced as salt retention increases and the renal blood flow is reduced. ⚠ Renin [ I ]; Angiotensin II [ I ]; Aldosterone [ D ]; Na+ excretion [ D ]; GFR [ D ]; Renal blood flow [ I ] (choice B) is incorrect because aldosterone increases and renal blood flow decreases. ⚠ Renin [ I ]; Angiotensin II [ I ]; Aldosterone [ I ]; Na+ excretion [ D ]; GFR maintained; Renal blood flow [ I ] (choice C) is incorrect because renal blood flow is decreased in renal artery stenosis, not increased. ⚠ Renin [ I ]; Angiotensin II [ I ]; Aldosterone [ I ]; Na+ excretion maintained; GFR [ D ]; Renal blood flow [ I ](choice E) is incorrect because Na+ retention is increased while Na+ excretion is decreased. 🔖Key point: In renal artery stenosis renal hypoperfusion leads to the release of high levels of renin, which results in high levels of angiotensin II and aldosterone. This subsequently increases Na+ and water retention. GFR is maintained in the early phase of this disease

🇨🇦 MCCQE1,2 | #Case_180 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 A 71-year-old male presents to your department for hypertension management follow-up. He denies any symptoms. He is known to have refractory hypertension and his current antihypertensive drugs include furosemide, ramipril, metoprol, and doxazosin. He smoked 40 packs of cigarettes a year for 30 years but quit smoking 10 years ago. Physical examination reveals temperature 37.3°C, BP 170/100 mmHg, pulse is 90 bpm, respirations 14/min. An abdominal bruit is heard on auscultation. Dupplex ultrasonographic scanning suggests renal artery stenosis while digital subtraction angiography reveals a 90% occlusion of the left renal artery. The patient is scheduled to undergo surgical revascularization. Which of the following options best states the pathophysiology of this patient’s disease in its early phase? [I-increased, D-decreased] a) Renin [ I ]; Angiotensin II [ I ]; Aldosterone [ I ]; Na+ excretion [ I ]; GFR [ I ]; Renal blood flow [ I ] b) Renin [ I ]; Angiotensin II [ I ]; Aldosterone [ D ]; Na+ excretion [ D ]; GFR [ D ]; Renal blood flow [ I ] c) Renin [ I ]; Angiotensin II [ I ]; Aldosterone [ I ]; Na+ excretion [ D ]; GFR maintained; Renal blood flow [ I ] d) Renin [ I ]; Angiotensin II [ I ]; Aldosterone [ I ]; Na+ excretion [ D ]; GFR maintained; Renal blood flow [ D ] e) Renin [ I ]; Angiotensin II [ I ]; Aldosterone [ I ]; Na+ excretion maintained; GFR [ D ]; Renal blood flow [ I ];

🇨🇦 MCCQE1,2 | #Case_179 | #answer 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 ✅ A 🔎 Explanation The first line therapy in a patient with hiccups when no cause can be identified is physical maneuvers. Asides from being easy to perform, they are safe and in many cases effective to stop the bout. Examples of physical maneuvers for the treatment of hiccups are: 🔹 Interrupting the respiratory cycle (breath holding) 🔹 Valsalva maneuver 🔹 Catheter or cotton swab stimulation of nasooropharynx 🔹 Vagal maneuvers (choice A) - Pressing on the eyeballs, putting an ice bag on the forehead. 🔹 Counteract irritation of the diaphragm - knees to chest or leaning forward to compress the chest Pharmacological therapy is reserved for hiccups when physical therapy has failed. This is because the medications that have proven to be effective can have serious adverse effects. The pharmacological therapy includes the following medications: ⚠ Chlorpromazine (choice B) - the most widely used medication used to treat hiccups, regarded as the most effective. It can cause dystonic reactions and drowsiness on short term use, and tardive dyskinesia. ⚠ Metoclopramide (choice C) - has also proven to be effective in large case series. It is associated with tardive dyskinesia, especially in long term use and high doses. ⚠ Baclofen (choice D) - is a muscle relaxant. It is effective in the treatment of hiccups, although it causes drowsiness and its effectiveness has only been proven in a few small case series. ⚠ When physical therapy and pharmacological therapy fail, the use of complementary medicine is available for the treatment of hiccups. Acupuncture (choice E) has been reported to be effective to treat hiccups in a small study. 🔖 Key point: Physical therapy in the management of a bout of hiccups without an identified cause is the first line therapy of treatment. This is important to know as the medications used to treat hiccups carry adverse effects that can be avoided if physical therapy is effective

🇨🇦 MCCQE1,2 | #Case_179 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 A 26-year-old male comes to your office complaining of hiccups. He refers to you that the bout began 2 hours ago, and has not stopped since. He does not report any remarkable medical history, does not drink alcohol or smoke, carries a healthy lifestyle and does not have any other symptoms, other than the hiccups. Physical examination is unremarkable other than obvious hiccups. Vital signs are within normal limits. Which of the following would be considered the first line therapy for this particular patient? a) Initiate vagal maneuvers b) Chlorpromazine c) Metoclopramide d) Baclofen e) Acupuncture

🇨🇦 MCCQE1,2 | #Case_178 | #answer 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 ✅ B 🔎 Explanation The two major controllers of aldosterone secretion are the renin-angiotensin-system and plasma potassium level. The kidneys produce the enzyme renin in response to reduction in effective renal blood flow (caused, for example, by hemorrhage or heart failure). Renin in turn splits a plasma protein called angiotesniongen to produce angiotensin which stimulates the adrenal cortex to produce aldosterone. High plasma potassium directly stimulates and low potassium inhibits release of aldosterone by the adrenal cortex. Thus, plasma aldosterone level is a function of plasma potassium level. To avoid false negative results in patients suspected of having hyperaldosteronism, plasma potassium should thus, be normalized first (choice B) before measurement of plasma aldosterone and renin activity. ⚠ Adrenal CT scan (choice A) is used to find whether primary hyperaldosteronism is caused by adrenal adenoma or bilateral idiopathic hyperplasia. This is a later step in the diagnosis and should be done only when the diagnosis of primary hyperaldosteronism is confirmed. ⚠ Control of blood pressure (choice C) is not required. Indeed, drugs commonly used in treatment of hypertension like diuretics, angiotensin converting enzyme inhibitors and beta-blockers can interfere with measurement of aldosterone and plasma renin activity. However, the blood pressure should be controlled because it is high but not necessarily before performing the test. ⚠ Loading this patient with sodium orally (choice D) or intravenously (choice E) is contraindicated in this patient because he has severe hypertension and a hypertensive emergency can be precipitated by this. 🔖Key point: Plasma potassium levels should be normalized prior to investigation of hyperaldosteronism (to avoid false negative results)

🇨🇦 MCCQE1,2 | #Case_178 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 A 45-year-old woman presented to hospital with fatigue and muscle pain. She was feeling fatigue for the last 10 to 12 months. Seven months ago she was prescribed iron because she had mild iron deficiency anemia. No other symptoms could be elicited. The patient is not a known diabetic or hypertensive and was not on any medication. The patient looked well, not pale, jaundiced or cyanosed. Her body mass index was 36. Body temperature was normal, heart rate 83 per minute and blood pressure 151/116 mm Hg. Cardiac and chest examination were normal and her muscles were not tender. No edema could be demonstrated in the lower limbs or sacrum. Lab investigation results were as follows: Complete blood count and ESR were normal Sodium 144 mmol/L Potassium 2.9 mmol/L Creatinine 63 µmol/L Blood urea nitrogen (BUN) 3.6 mmol/L Diagnosis of hyperaldosteronism is strongly suspected and measurement of plasma aldosterone and plasma renin activity was contemplated. Before doing this test you should: a) Perform adrenal CT scan b) Normalize plasma potassium level c) Control the blood pressure d) Load patient with sodium orally e) Load patient with sodium intravenously

🇨🇦 MCCQE1,2 | #Case_177 | #answer 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 ✅ E 🔎 Explanation Perinephric abscess is an elusive diagnostic problem that is defined as a collection of pus in the tissue surrounding the kidney, generally in the space enclosed by Gerota’s fascia. Mortality rates as high as 50% have been reported, usually from failure to diagnose the problem in a timely fashion. The difficulty in making the diagnosis can be attributed to the variable constellation of symptoms and the sometimes indolent course of this disease. The diagnosis should be considered when a patient has fever and persistence of flank pain. Most perinephric infections occur as an extension of an ascending urinary tract infection, commonly in association with renal calculi or urinary tract obstruction. Patients with anatomic urinary tract abnormalities or diabetes mellitus have an increased risk. Clinical features may be quite variable, and the most useful predictive factor in distinguishing uncomplicated pyelonephritis from perinephric abscess is persistence of fever for more than 4 days after initiation of antibiotic therapy. The radiologic study of choice is CT. This can detect perirenal fluid, enlargement of the psoas muscle (both are highly suggestive of the diagnosis), and perirenal gas (which is diagnostic). The sensitivity and specificity of CT is significantly greater than that of either ultrasonography or intravenous pyelography. Drainage, either percutaneously or surgically, along with appropriate antibiotic coverage reduces both morbidity and mortality from this condition

🇨🇦 MCCQE1,2 | #Case_177 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 A 48-year-old female with type 2 diabetes has been hospitalized for 4 days with persistent fever. Her diabetes has been controlled with diet and glyburide. You saw her 2 weeks ago in the office with urinary frequency, urgency, and dysuria. At that time a urinalysis showed 25 WBCs/hpf, and a urine culture subsequently grew Escherichia coli sensitive to all antibiotics. She was placed on trimethoprim/ sulfamethoxazole empirically, and this was continued after the culture results were reported. She improved over the next week, but then developed flank pain, fever to 39.5°C (103.1°F), and nausea and vomiting. She was hospitalized and intravenous cefazolin and gentamicin were started while blood and urine cultures were performed. This urine culture also grew E. coli sensitive to the current antibiotics. Her temperature has continued to spike to 39.5°C since admission, without any change in her symptoms. Which one of the following would be most appropriate at this time? ❤Add vancomycin to the regimen 💛Order a radionuclide renal scan 💚Order intravenous pyelography 💙Order a urine culture for tuberculosis 💜Order CT of the abdomen

🇨🇦 MCCQE1,2 | #Case_176 | #answer 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 ✅ A 🔎 Explanation Graves disease is an autoimmune disease characterized by hyperthyroidism due to circulating autoantibodies. Mild hyperthyroidism (slightly elevated thyroid hormone levels, minimal symptoms) often is monitored closely without therapy as long as both the mother and the baby are doing well. When hyperthyroidism is severe enough to require therapy, anti-thyroid medications are the treatment of choice, with propylthiouracil (PTU) being the drug of choice. PTU is usually prescribed in the first trimester (up to week 14), and Methimazole (MMI) for the rest of the pregnancy. Thyroid surgery is rarely an option for pregnant women. ⚠ The combination of propylthiouracil and levothyroxine is frequently used for hyperthyroidism in nonpregnant patients, but transplacental passage of the levothyroxine would be harmful to the developing fetus. ⚠ Methimazole (MMI) crosses the placenta more readily than propylthiouracil and is associated with aplasia cutis. In areas where PTU is not available, or when a woman is allergic to PTU, methimazole and carbimazole are used during pregnancy, ⚠ Radioactive iodine therapy is contraindicated in pregnancy, and immediate surgery might present hazards to both the mother and the fetus. ⚠ Propranolol would control the patient’s heart rate, but would do nothing about the underlying hyperthyroidism

🇨🇦 MCCQE1,2 | #Case_176 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 At a prenatal visit at 12 weeks gestation a 38-year-old gravida 3 para 2 has a pulse rate of 110 beats/min and has lost 2 kg (4 lb) since her previous visit. At age 26, she was treated for Graves’ disease with radioactive iodine and has been euthyroid on no medication for over 10 years. A CBC shows a mild anemia. Her hematocrit is 34% (N 35-45) and her TSH level is 0.00 U/mL (N 0.5-5.0). Which one of the following would be most appropriate at this time? ❤Propylthiouracil 💛Propylthiouracil plus levothyroxine 💚Methimazole 💙Radioactive iodine therapy 💜Propranolol

🇨🇦 MCCQE1,2 | #Case_175 | #answer 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 ✅ E 🔎 Explanation Prophylaxis is indicated with total knee or hip replacements. The two regimens recommended are low-molecular-weight heparin and adjusted-dose warfarin. These may be augmented by intermittent pneumatic compression

🇨🇦 MCCQE1,2 | #Case_175 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 A 72-year-old white female is scheduled to undergo a total knee replacement for symptomatic osteoarthritis. She is otherwise healthy, with no history of vascular disease or deep vein thrombosis. She takes no routine medications. Which one of the following is most appropriate for prophylaxis against deep vein thrombosis? ❤No prophylaxis if there are no surgical complications 💛Aspirin, 325 mg daily 💚Unfractioned heparin, 5000 U subcutaneously every 12 hours 💙Thigh-high compression stockings 💜Enoxaparin (Lovenox), 30 mg subcutaneously every 12 hours

🇨🇦 MCCQE1,2 | #Case_174 | #answer 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 ✅ B 🔎 Explanation This patient presents with hemoptysis and hematuria, which suggest pulmonary and renal disease. Given the patient’s history of recurrent rhinitis and sinusitis and the positive cytoplasmic antineutrophil cytoplasmic antibodies, the most likely diagnosis is granulomatosis with polyangiitis (choice B) formerly known as Wegener’s granulomatosis. It is a multisystem autoimmune disease of unknown etiology characterized by necrotizing granulomatous inflammation and pauci-immune vasculitis in small- and medium-sized blood vessels. Diagnosis is generally confirmed with tissue biopsy from a site of active disease; renal and lung biopsies are most specific for granulomatosis with polyangiitis. ⚠ Churg-Strauss syndrome (choice A) is an allergic granulomatous angiitis that presents with asthma, paranasal sinusitis, and rapidly progressive glomerulonephritis. Eosinophilia is a common finding and perinuclear-ANCA (antimyeloperoxidase antibodies) are better diagnostic markers than c-ANCA. ⚠ Goodpasture’s syndrome (choice C) causes acute glomerulonephritis and pulmonary hemorrhage due to the presence of circulating anti-glomerular basement membrane antibodies. ⚠ Sarcoidosis (choice D) a multisystem inflammatory disease of unknown etiology that manifests as noncaseating granulomas, predominantly in the lungs and intra-thoracic lymph nodes. Black people have increased risk of developing this disease. It is not associated with cytoplasmic anti-neutrophil cytoplasmic antibodies. ⚠ Cryoglobulinemia (choice E) is characterized by the presence of cryoglobulins in the serum. Cryoglobulins are single or mixed immunoglobulins that undergo reversible precipitation at low temperatures. Studies have shown close association of this condition with Hepatitis C. 🔖Key point: Granulomatosis with polyangiitis is a multisystem necrotizing granulomatous inflammation that often presents with respiratory and renal involvement with symptoms such as hemoptysis and hematuria. Cytoplasmic anti-neutrophil cytoplasmic antibodies are commonly present and biopsy is diagnostic of this condition

🇨🇦 MCCQE1,2 | #Case_174 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 A 27-year-old male presents to your department because he has been coughing up bloody sputum for the past 5 days. His past medical history is significant for recurrent rhinitis and sinusitis for many years, but according to the patient, they have been more frequent in the past 2 years. On physical examination saddle nose deformity is noted. Hematuria is observed on urinalysis. Further work-up reveals positive cytoplasmic anti-neutrophil cytoplasmic antibodies. What is the most likely diagnosis? ❤Churg-Strauss syndrome 💛Granulomatosis with polyangiitis 💚Goodpasture’s syndrome 💙Sarcoidosis 💜Cryoglobulinemia