Case-based MCQ

🇨🇦 MCCQE1,2 | #Case_143 | #answer 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 ✅ D 🔎 Explanation Penicillin is the treatment of choice for treating syphilis. For treatment of syphilis during pregnancy, no proven alternatives to penicillin exist. Treatment guidelines recommend desensitization in penicillin-allergic pregnant women (choice D), followed by treatment with penicillin. Syphilis in pregnancy is associated with mental retardation, stillbirth and sudden infant death syndrome; therefore it should be treated promptly. ⚠ Data are insufficient to recommend ceftriaxone (choice A) for treatment of maternal infection and prevention of congenital syphilis. ⚠ Erythromycin (choice C) and azithromycin should not be used, because neither reliably cures maternal infection or treats an infected fetus. ⚠ Tetracyclin (choice E) and doxycycline (choice B) are contraindicated in pregnancy and ceftriaxone is much less effective than penicillin

🇨🇦 MCCQE1,2 | #Case_144 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 An 18-year-old pregnant woman presents to the clinic for a routine checkup. She is at the 5th week of gestation. Except for morning nausea, she denies any problems with her pregnancy so far. The patient is allergic to penicillin. Physical exam is unremarkable and appropriate for gestational age. Routine screening lab tests were ordered. VDRL screening returned positive and was confirmed by the FTA-ABS test.

🇨🇦 MCCQE1,2 | #Case_143 | #answer 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 ✅ D 🔎 Explanation Meckel’s diverticulum is the most common congenital abnormality of the small intestine. It is prone to bleeding because it may contain heterotopic gastric mucosa. Abdominal pain, distention, and vomiting may develop if obstruction has occurred, and the presentation may mimic appendicitis ⚠ Children with appendicitis (choice A) have right lower quadrant pain, abdominal tenderness, guarding, and vomiting, but not rectal bleeding. ⚠ With acute viral gastroenteritis (choice B), vomiting usually precedes diarrhea (usually without blood) by several hours, and abdominal pain is typically mild and nonfocal with no localized tenderness. ⚠ The incidence of midgut volvulus (choice C) peaks during the first month of life, but it can present anytime in childhood. Volvulus may present in one of three ways: as a sudden onset of bilious vomiting and abdominal pain in the neonate; as a history of “feeding problems” with bilious vomiting that now appears to be due to bowel obstruction; or, less commonly, as a failure to thrive with severe feeding intolerance. ⚠ Necrotizing enterocolitis (choice E) is typically seen in the neonatal intensive-care unit, occurring in premature infants in their first few weeks of life. The infants are ill, and signs and symptoms include lethargy, irritability, decreased oral intake, abdominal distention, and bloody stools. A plain abdominal film showing pneumatosis intestinalis, caused by gas in the intestinal wall, is diagnostic of this disease

🇨🇦 MCCQE1,2 | #Case_143 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 A previously healthy 2-year-old male is brought to your office with a 4-hour history of abdominal pain followed by vomiting. Just after arriving at your office he passes bloody stool. A physical examination reveals normal vital signs, and guarding and tenderness in the right lower quadrant. A rectal examination shows blood on the examining finger.

🇨🇦 MCCQE1,2 | #Case_142 | #answer 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 ✅ B 🔎 Explanation Acute interstitial nephritis (AIN) is often drug-induced. Discontinuation of medications that are likely to cause AIN is the most important first step in management. If these medications are withdrawn early, most patients can be expected to recover normal renal function. Of the medications listed, ibuprofen is the most likely offending agent, because all NSAIDs are known to be associated with AIN. Development of AIN usually becomes evident approximately 2 weeks after starting a medication and is not dose-related. Other medications strongly associated with AIN include various antibiotics (particularly cephalosporins, penicillins, sulfonamides, aminoglycosides, and rifampin), diuretics, and miscellaneous medications such as allopurinol.

🇨🇦 MCCQE1,2 | #Case_142 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 A 62-year-old male is admitted to the hospital with acute renal failure. A renal biopsy confirms the diagnosis of acute interstitial nephritis (AIN). Infection and immune-associated causes are ruled out, and you consider medications as a potential cause. Which one of the following would be most likely to cause AIN? a) Chronic daily use of metoprolol (Lopressor) b) Twice-daily use of ibuprofen for 2 weeks c) Initiation of lisinopril (Prinivil, Zestril) therapy 1 week ago d) A 5-day course of azithromycin (Zithromax) 6 months ago e) Intermittent use of acetaminophen, up to 4 g/day

🇨🇦 MCCQE1,2 | #Case_141 | #answer 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 ✅ B 🔎 Explanation People who are very old or alcoholic have smaller brains in a skull that has not changed in size; thus, very minimal trauma can make the brain "rattle around" and tear a venous sinus, from which a subdural hematoma very slowly forms. Senility does not occur in a 3 week period. Such marked changes in someone with recent trauma should trigger a search for chronic subdural hematoma

🇨🇦 MCCQE1,2 | #Case_141 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 An 77-year-old man becomes "senile" over a period of 3 or 4 weeks. He used to be active and managed all of his financial affairs. Now, he stares at the wall, barely talks, and sleeps most of the day. His daughter recalls that he fell off his rocking chair about a week before the mental changes began. Which of the following would a CT scan of his head most likely show? a) Chronic epidural hematoma b) Chronic subdural hematoma c) Diffuse intracerebral bleeding d) Frontal lobe infarction e) Generalized, severe brain atrophy

🇨🇦 MCCQE1,2 | #Case_140 | #answer 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 ✅ A 🔎 Explanation The clinical history and laboratory findings presented are consistent with a diagnosis of narcolepsy. Methylphenidate and other stimulant drugs remain the pharmacologic agents of choice in managing this disorder. Since there is no evidence of obstructive sleep apnea, weight reduction would not be expected to address his sleep problem. In general, sedatives, hypnotics, and alcohol should be avoidep. Periodic daytime naps may help to reduce symptoms

🇨🇦 MCCQE1,2 | #Case_140 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 A 40-year-old obese black male presents with a history of excessive daytime drowsiness. He readily falls asleep when reading or watching television. He admits to nearly crashing his car twice in the past month because he briefly fell sleep behind the wheel. Most frightening to the patient have been episodes characterized by sudden loss of muscle tone, lasting about 1 minute, associated with laughing. An overnight sleep study shows decreased sleep latency and no evidence of obstructive sleep apnea. Appropriate treatment includes which one of the following? a) Methylphenidate (Ritalin) b) Zolpidem (Ambien) at bedtime c) Carbidopa/levodopa (Sinemet) d) Weight reduction e) Avoidance of daytime napping

🇨🇦 MCCQE1,2 | #Case_139 | #answer 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 ✅ B 🔎 Explanation A painless ulcer on the genitalia is primary syphilis (Chancre) until proven otherwise. Patients with primary syphilis are best diagnosed with dark field microscopy of the lesion scraping that shows the spirochetes with its characteristic cork screw appearance. VDRL, RPR and FTA-Abs are tests looking for antibodies against syphilis. These are not helpful in primary syphilis; it takes a few weeks for these antibodies to appear in the serum. They are the diagnostic modalities of choice in secondary and tertiary syphilis. Blood culture is never helpful for syphilis as spirochetes can not be cultured. ⚠ Although the incidence of syphilis has decreased nowadays, it is frequently tested. Know its diagnostic tests and its treatment and do not forget the false positive VDRL in an SLE patient

🇨🇦 MCCQE1,2 | #Case_139 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 A 30-year-old male patient presents to your clinic with an ulcer on his penis. The ulcer (1x1cm) is non-tender, has a raised border and indurated base. Painless inguinal lympadenopathy is detected on physical exam. The rest of the examination is unremarkable and the review of systems is normal. What is the best diagnostic test to order for this patient? a) Blood culture b) Dark field microscopy c) FTA-Abs d) RPR e) VDRL

🇨🇦 MCCQE1,2 | #Case_138 | #answer 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 ✅ B 🔎 Explanation This patient has a clinical presentation consistent with acute sinusitis. Failure to respond to adequate antibiotic therapy suggests either a complication, progression to chronic sinusitis, or a different, confounding diagnosis. The diagnostic procedure of choice in this situation is coronal CT of the sinuses, due to its increased sensitivity and competitive cost when compared with standard radiographs. Cultures of the nasal discharge give unreliable results because of bacterial contamination from the resident flora of the nose. The other options listed do not contribute to the diagnosis and treatment of sinusitis

🇨🇦 MCCQE1,2 | #Case_138 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 A 30-year-old white male complains of several weeks of nasal stuffiness, purulent nasal discharge, and facial pain. He does not respond to a 3-day course of trimethoprim/ sulfamethoxazole (Bactrim, Septra). Follow-up treatment with 2 weeks of amoxicillin/clavulanate (Augmentin) is similarly ineffective. Of the following diagnostic options, which one is most appropriate at this time? a) Pulmonary function testing b) Coronal CT of the sinuses c) Culture and sensitivity testing of the discharge d) Erythrocyte sedimentation rate e) Complete Blood Count

🇨🇦 MCCQE1,2 | #Case_137 | #answer 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 ✅ A 🔎 Explanation In the absence of risk factors for cancer, a patient with a normal TSH level who is found to have a thyroid nodule on physical examination should have a fine-needle aspiration biopsy. Independent of morphology, fine-needle aspiration provides the most direct and specific information about a thyroid nodule

🇨🇦 MCCQE1,2 | #Case_137 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 A 56-year-old female presents for a routine visit. An otherwise normal physical examination reveals a 2-cm right-sided thyroid nodule. Her TSH levels are normal. She has no history of neck irradiation, and there is no family history of thyroid cancer. You recommend: a) A fine-needle aspiration biopsy b) Suppression of the nodule with levothhyroxine (Synthroid) c) Removal of the nodule d) A serum calcitonin level e) A radioactive iodine uptake test and a thyroid scan

🇨🇦 MCCQE1,2 | #Case_136 | #answer 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 ✅ C 🔎 Explanation Gilbert’s syndrome (choice C), which is more common in males in their early adult life, is usually discovered incidentally when liver function tests are done for purposes other than suspected liver disease. Typically, hyperbilirubinemia is mild (< 51µmol/L) and more than 95% of bilirubin is of the unconjugated type in Gilbert’s syndrome. Hyperbilirubinemia in patients with Gilbert’s syndrome is due to deficiency of uridine diphosphate-glucouronosyl transferase that is responsible for conjugation of bilirubin in the liver. Other than the raised serum bilirubin, liver function tests and complete blood count are usually normal in this syndrome. Our patient had most of these features and Gilbert’s syndrome is thus, the most likely diagnosis. The high prevalence of Gilbert’s syndrome (about 8%) also puts this syndrome on the top of the list of causes of isolated hyperbilirubinemia. ⚠ Hereditary spherocytosis (choice A), autoimmune hemolytic anemia (choice B) and G6PD (choice E) are incorrect choices. In these disorders, unconjugated hyperbilirubinemia is caused by hemolysis (hemolytic jaundice) and complete blood count would show high reticulocyte count and low hemoglobin concentration. In our patient CBC was normal. ⚠ Alcoholic hepatitis (choice D) is not the correct choice. Although hyperbilirubinemia is usually mild in alcoholic hepatitis, levels of serum transaminases are moderately elevated. In our patient serum level of these enzymes are normal and alcoholic hepatitis is an unlikely cause of his hyperbilirubinemia. The fact that our patient drinks alcohol is not enough to establish a causal relation between alcohol consumption and liver disease. In addition, for alcohol consumption to cause liver disease, consumption of more than three drinks per day for ten years is usually required. 🔖Key point: The cause of isolated hyperbilirubinemia in an apparently healthy young man is Gilbert’s syndrome until proven otherwise.

🇨🇦 MCCQE1,2 | #Case_136 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 A 20-year-old man was found to have an isolated elevation of serum bilirubin of 50µmol/L when baseline liver function tests were ordered prior to prescribing phenytoin for treatment of epilepsy. More than 97% of bilirubin was of the unconjugated type. Complete blood count was normal. Apart from daily consumption of one to two drinks of alcohol for the last three years, and the recently diagnosed epilepsy, his medical history was otherwise unremarkable. Physical examination was normal. Which of the following disorders is most likely to be the cause of jaundice in this patient? a) Hereditary spherocytosis b) Autoimmune hemolytic anemia c) Gilbert’s syndrome d) Alcoholic hepatitis e) Glucose 6-phosphate dehydrogenase deficiency (G6PD)