Case-based MCQ

🇨🇦 MCCQE1,2 | #Case_153 | #answer 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 ✅ D 🔎 Explanation Ulcerative colitis and Crohn's disease are the two major types of inflammatory bowel diseases. Non-caseating granulomas are pathognomonic of CD, and not seen in UC. However, it should be noted that they are present in most and not all patients with CD. ⚠ Crypt abscesses may be seen in both UC and CD. ⚠ Elevated ESR is a very non-specific marker of inflammation; it can be elevated in inflammatory, neoplastic and rheumatic diseases. ⚠ Hyperplastic polyps are inflammatory polyps that denote chronic inflammatory diseases; they are non specific lesions. ⚠ Pseudomembranes are the hallmarks of Clostridium difficile colitis.

🇨🇦 MCCQE1,2 | #Case_153 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 A 35-year-old man businessman presents to your clinic complaining of intermittent abdominal cramps and diarrhea of two months duration. The episodes of diarrhea have increased in frequency recently and have been associated with blood per stool in the last few days. After a detailed history and physical exam, you ordered several blood tests which were significant for a microcytic anemia and elevated ESR. Colonoscopy reveals extensive disease from terminal ileum to the rectum with multiple ulcerations. Biopsies of the lesions reveal the presence of non-caseating granulomas. Which of the following findings would suggest Crohn’s disease rather than ulcerative colitis? ❤Crypt abscess 💛Elevated ESR 💚Hyperplastic polyps 💙Non caseating granulomas 💜Pseudomembranes

🇨🇦 MCCQE1,2 | #Case_152 | #answer 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 ✅ C 🔎 Explanation Neuroblastoma is a cancer arising in the adrenal gland or less often from the extra-adrenal sympathetic chain, including the retroperitoneum, chest, and neck. Diagnosis is based on biopsy When sensitive assays are used, 90 to 95% of tumors produce sufficient catecholamines to increase urinary metabolites. This provides a great advantage in confirming the diagnosis of neuroblastoma, as well as in following disease activity in the care of patients with secreting tumors. The two enzymes primarily responsible for the catabolism of catecholamines are catechol-O-methyl transferase and monoamine oxidase. Dopa and dopamine are converted primarily to homovanillic acid, whereas norepinephrine and epinephrine are converted primarily to vanillylmandelic acid. Most laboratories involved in neuroblastoma diagnosis measure levels of both homovanillic acid and vanillylmandelic acid in the urine. Because of the varied clinical presentation, neuroblastoma can be confused with other neoplasms as well as nonneoplastic conditions. Diagnosis of the 5 to 10% of tumors that do not produce catecholamines is particularly difficult, as is that of the 1 % or so in which the primary tumor is not obvious. The conventional diagnostic imaging modalities include plain radiography, bone scintigraphy, CT, and MRI. The potential specificity and sensitivity of metaiodobenzylguanidine (MIBG) scintigraphy for evaluation of bone and soft-tissue involvement of neuroblastoma are attractive

🇨🇦 MCCQE1,2 | #Case_152 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 You suspect a neuroblastoma in a 4-year-old boy with headaches and hypertension. Which one of the following investigations provides a great advantage in confirming the diagnosis, as well as in following disease activity in the care of patients with secreting tumors? ❤Serum alpha-fetoprotein 💛Serum ferritin and lactate dehydrogenase 💚Levels of homovanillic acid and vanillylmandelic acid in the urine 💙Serum catecholamines 💜MRI or CT scan of the involved area of the body

🇨🇦 MCCQE1,2 | #Case_151 | #answer 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 ✅ B 🔎 Explanation Lower urinary tract obstruction in a newborn or young boy should be assumed to be caused by posterior urethral valves (choice B) until proven otherwise. These valves consist of folds of mucosa obstructing the urethra at the prostatic level. A lower abdominal mass may represent a markedly distended urinary bladder. The diagnosis can be confirmed by voiding cystourethography or by endoscopy of the urethra. The prognosis depend on the extent of renal damage at the time of diagnosis

🇨🇦 MCCQE1,2 | #Case_151 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 A week-old white male is brought to your office because of “irritability”. The physical examination is normal except for a suprapubic mass. When the mother is questioned, she tells you that the infant has a dribbling urinary stream. The most likely diagnosis is: ❤Wilms’ tumor 💛Posterior urethral valves 💚Urinary tract infection 💙Spina bifida occulta involving the sacral plexus 💜Horseshoe kidney

🇨🇦 MCCQE1,2 | #Case_150 | #answer 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 ✅ D 🔎 Explanation The radial nerve provides cutaneous innervation to the dorsum of the hand. As such, an injury to that nerve can cause deficient sensation on the dorsum (back of) the hand. Because she has intact sensation on the palmar surface of her hand, her median and ulnar nerves are not likely injured.

🇨🇦 MCCQE1,2 | #Case_150 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 A 45-year-old female presents with a history of a direct blow over the shaft of her left humerus. Her x-ray shows a spiral fracture of the distal third of the humerus. On examination of her hand, sensation is intact on the palmar side but absent on the dorsum of her hand. Which one of the following nerves is most likely injured? ❤Axillary nerve 💛Musculocutaneous nerve 💚Median nerve 💙Radial nerve 💜Ulnar nerve

🇨🇦 MCCQE1,2 | #Case_149 | #answer 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 ✅ B 🔎 Explanation The most common cause for a cystic enlargement of the ovary in a reproductive age woman is a functional cyst (follicular or corpus luteum). These are thin walled and usually resolve or rupture spontaneously. Any cystic mass 6 cm or less can be followed for two cycles. Some texts recommend using oral contraceptive pills to decrease the gonadotropin stimulation of the ovary during this time, but there is no literature that shows any improvement over simple observation. -If the mass persists, further evaluation and possible surgical intervention is indicated. Laparoscopic surgery is less invasive and just as successful as laparotomy. -As most cystic masses in the adnexa are functional cysts that resolve spontaneously, no other workup is indicated at this time

🇨🇦 MCCQE1,2 | #Case_149 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 A 19-year-old nulligravid healthy woman comes to see you for her annual Pap smear and routine health care maintenance. During your routine pelvic exam, you note that she has a 5-cm cystic, nontender, mobile mass in her left adnexa. Rectovaginal exam confirms this and does not note any abnormalities in the cul-de-sac. Transvaginal ultrasonography results are consistent with pelvic exam findings. Which of the following is the most appropriate next step? ❤Laparotomy with ovarian cystectomy 💛Repeat ultrasound in 2 months 💚MRI scan of the pelvis 💙Serum CA-125 💜Laparoscopy with ovarian cystectomy

🇨🇦 MCCQE1,2 | #Case_148 | #answer 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 ✅ A 🔎 Explanation A history of kitten scratch (choice A) in this patient would suggest diagnosis of cat scratch disease. Patients with cat scratch disease typically present with tender lymphadenopathy usually of a single lymph node that is tender, red, and warm. Most of these patients usually develop a few red-brown papules at the site of cat scratch days before development of lymphadenopathy. Some patients may also have hepatosplenomegaly. Our patient showed most of these symptoms and signs, and a history of kitten scratch supports the diagnosis of cat scratch disease. This disease is caused Bartonella henselae, which is transmitted from cat to humans. ⚠ Working in the forest (choice B) is less likely to support a specific diagnosis in this patient. Working in the forest would support the diagnosis of Lyme disease. However, the symptoms and signs of this patient are not suggestive of such a diagnosis. Most patients with Lyme disease present with erythema migrans, which classically starts with a single maculae or papulae at the site of tick bite. The eruption then expands over days to weeks rather than disappearing within days as in our patient. Patients with this disease usually report flu-like symptoms within a week after infection with Borrelia burgdorferi, inoculated by the tick. Lyme disease is not usually associated with lymphadenopathy but may be accompanied by lymphocytomas, which are almost always located in the ear lobe or breast nipple. Also, Lyme disease is usually not associated with hepatosplenomegaly. For all these reasons Lyme disease is an unlikely diagnosis and working in the forest is not likely to support specific diagnosis in this patient. ⚠ Residence in Rocky mountain region (choice C) would support the diagnosis of Rocky Mountain spotted fever. However, the symptoms and sings of this patient are not suggestive of this disease. Rocky Mountain spotted fever, a disease caused by Rickettsia rickettsia and transmitted by Dermacentor ticks, typically presents with rash that begins on the wrist and ankles and then spreads to arms legs and trunk. The rash also involves the palms and soles. ⚠ Having a sibling with Hodgkin’s lymphoma (choice D) is not likely to support a specific diagnosis in this patient. Hodgkin’s lymphoma presents with painless, non-tender enlargement of lymph nodes usually in the cervical region. Siblings of patients with Hodgkin’s lymphoma have a 3 to 7 time increase in the risk of developing this disease. However, this diagnosis is not supported by symptoms and signs of this patient. ⚠ History of flu-like symptoms in the past two months (choice E) is not likely to support a specific diagnosis in this patient. This symptom typically occurs in patients with Lyme disease and Rocky Mountain spotted fever. Both of these diseases are unlikely in this patient (see explanation above). 🔖 Key point: With tender lymphadenopathy and hepatosplenomegaly preceded by localized rash, cat scratch disease should be strongly suspected and history of exposure to cats or kittens sought.

🇨🇦 MCCQE1,2 | #Case_148 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 A 21-year-old man presented to his family physician with a swelling in his left axilla. He recalls that about two weeks ago he observed red papules on the back of his left hand, which were not tender or painful disappeared in about two days. Physical examination: heart rate 91 beat per minute, respiratory rate 16 per minute, blood pressure 124/76 mmHg and body temperature 37.2°C. An enlarged tender, erythematous, warm single lymph node could be palpated in his left axilla. Both liver and spleen were slightly enlarged. The rest of his physical examination was normal. Which of the following pieces of history is most likely to support your presumptive diagnosis in this patient? ❤Kitten scratch 💛Working in the forest 💚Residence in Rocky mountain region 💙Having a sibling with Hodgkin’s lymphoma 💜History of flu-like symptoms in the past two months

🇨🇦 MCCQE1,2 | #Case_147 | #answer 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 ✅ D 🔎 Explanation Infectious keratitis must be considered in the differential diagnosis for anyone presenting with pain, redness, and tearing of the eyes. Contact lens users are more prone to infectious keratitis and the causative organism is usually bacterial but can be viral, fungal or protozoan. Urgent ophthalmology referral is needed to exclude or confirm the diagnosis of infectious keratitis and to determine the causative organism (choice D). ⚠ Regular use of topical anesthetic is not a form of therapy for a patient with infectious keratitis (choice A). ⚠ Use of topical steroids (choice B and C) prior to determining the microbial origin and appropriate antimicrobial therapy can worsen the condition. Indiscriminate use of topical steroids for infectious keratitis can lead to blindness. ⚠ Topical antibiotic treatment alone (choice E) may not only be ineffective but also delay appropriate treatment if the causative organism is viral, fungal or protozoan; and should be considered only if urgent ophthalmology opinion is not possible. 🔖 Key point: A diagnosis of infectious keratitis should be considered in a patient presenting with painful red eye and urgent ophthalmology opinion should be sought. If the patient is wearing contact lenses, it should be discontinued until the red eye has completely resolved

🇨🇦 MCCQE1,2 | #Case_147 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 A 24-year-old man presents to the emergency department with severe pain, redness and tearing from his right eye for 12 hours duration. He is a regular contact lens user and his visual acuity with the contact lenses on is 20/20 for each eye. How would you treat this patient? ❤Prescribe topical analgesics and review in 24 hours 💛Prescribe topical antibiotic and steroid combination and review in 24 hours 💚Prescribe topical antibiotic and steroid combination with topical anesthetics 💙Remove the contact lens and request urgent ophthalmology opinion 💜Remove the contact lens and treat with topical antibiotics

🇨🇦 MCCQE1,2 | #Case_146 | #answer 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 ✅ D 🔎 Explanation Contact dermatitis is one of the most common inflammatory skin diseases in the industrialized world. Contact dermatitis can be of four categories: irritant contact dermatitis, photocontact dermatitis, contact urticaria and allergic contact dermatitis. This is a classical patient of allergic contact dermatitis (ACD). It can appear anywhere on the body, depending on the allergen responsible. For example, the usual sites of nickel allergy are on the abdomen from snaps on pants or buckles, and the wrists and earlobes from jewelry. The symptoms usually appear after 12-48 hours after exposure, which include erythematous papules, edema, and vesiculation. There may be tremendous itching and the lesions may involve beyond the areas of first contact. A long-lasting ACD may show lichenification and hyperpigmentation of the affected skin. A patch testing is a provocation test to identify hypersensitivity (type-IV) to potential agents that may cause contact dermatitis. It takes 48-96 hours to formulate the result. After 48 hours the initial reading is taken and after 96 hours the final result is formulated. The patch test may be positive or negative. Positive results are expressed as 1+, 2+, or 3+. This test even may be +/- when only macular erythema is noted. A 2+ reaction means that patch reaction contains papules (choice D), which is a discrete elevation of skin of ≤ 1 cm diameter. ⚠ No change (choice A) or no evidence of skin changes is considered a negative reaction. ⚠ Only erythema (choice B) or redness over the area is not a definitive landmark that’s why it is not reportable. ⚠ Redness or erythema and edema (choice C) is reported as 1+ response. Here the area of skin will be red and edematous or elevated than the surrounding normal skin. ⚠ If the reaction contains vesicles or bullae (choice E), the report will be 3+. A small area (≤ 1 cm in diameter) with fluid-filled blister is termed as vesicle. When the area is larger (> 1 cm in diameter) with fluid-filled blister is termed as bullae 🔖 Key point: A patch testing is a provocation test to identify hypersensitivity (type-IV) to potential agents that may cause contact dermatitis. A 1+ reaction consists of erythema and edema, 2+ reaction contains papules, and a 3+ reaction has vesicles or bullae

🇨🇦 MCCQE1,2 | #Case_146 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 A 36-year-old female school teacher presents to you with a history of itching, swelling, and redness over the extensor aspect of forearm just above the wrist for few days, notable after wearing her new watch. She explains that the day after wearing the new watch first, the itching started and immediately the area increased beyond the watch-margin. On examination, there is hyperpigmentation over the area and itching mark is also evident. You advised a “patch test”. Suppose the report is 2+, then how will you remark it? ❤No change 💛Erythema only 💚Erythema and edema 💙Papules 💜Vesicle or bullae

🇨🇦 MCCQE1,2 | #Case_145 | #answer 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 ✅ C 🔎 Explanation This patient’s clinical picture with abdominal pain that radiates to the groin, severe lower back pain, passing crystals in urine, and costovertebral angle tenderness are suggestive of nephro-ureterolithiasis. Moreover, given his history of taking amlodipine and fenofibrate, drugs known to be secondary uricosurics, and clear KUB, the most likely chemical composition of these stones is uric acid. Uric acid kidney stones are the known most common cause of radiolucent kidney stones. Uric acid is a weak acid, with an ionization constant of acid (pK) of 5.8. At pH levels below the pK, uric acid is predominately found in a nonionized form. The urate ion is more soluble than the nonionized molecule. When the concentration of uric acid in urine exceeds its solubility at the urine pH, uric acid changes from a compound dissolved in solution to an insoluble precipitate. Like any other type of kidney stone, the initial therapy is urine dilution with large water intake. Since uric acid crystals form at acidic pH, uric acid urolithiasis management also consists of alkalinizing the urine with either potassium citrate (choice C) or bicarbonate. Sodium urate is 15 times more soluble than uric acid. At a urine pH level of 6.8, 10 times as much sodium urate as uric acid is present. At a urine pH level of 7.8, 100 times as much urate as uric acid is present. ⚠ Increased fluids and acetohydroxamic acid (choice A) would be beneficial in struvite kidney stones. Struvite stones are associated with urease positive infectious agents, the most common of which is Proteus mirabilis. ⚠ Increased fluids and pyridoxine (choice B) therapy is more beneficial in calcium oxalate kidney stones; it would not be the most effective treatment of uric acid urolithiasis. ⚠ Increased fluids and vitamin C (choice D) is incorrect. Limitation of vitamin C ingestion is advised in patients with calcium oxalate stones because it is known to increase the risks of formation of these stones. It is not the most effective therapy for uric acid kidney stones. ⚠ Increased fluids and hydrochlorothiazide (choice E) therapy is recommended for calcium oxalate stones as hydrochlorothiazide is known to decrease calcium excretion. Hydrochlorothiazide has a tendency to cause hyperuricemia and also causes potassium loss. This hypokalemic effect would lead to reduction of citrate, which would decrease urine pH and shift the balance towards uric acid formation and the worsening of the patient’s condition. 🔖 Key point: Uric acid kidney stones are radiolucent and are not visible on KUB. The best management of these stones is hydration and alkalinization of urine with potassium citrate or bicarbonate.

🇨🇦 MCCQE1,2 | #Case_145 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 A 48-year-old male presents to your department with complaints of abdominal pain that radiates to his groin the last few days. He also noticed a severe gnawing lower back pain yesterday and while urinating passed what looked like sand. Past medical history is significant for hypertension treated with amlodipine and hypertriglyceridemia treated with fenofibrate. Vital signs show temperature of 37.5°C, BP 145/75 mmHg, heart rate 110bpm, and respirations 19/min. On physical examination he has costovertebral angle tenderness. The KUB is normal. After pain management, which of the following would be the most effective combination therapy of this patient's condition? ❤Increased fluids and acetohydroxamic acid 💛Increased fluids and pyridoxine 💚Increased fluids and potassium citrate 💙Increased fluids and vitamin C 💜Increased fluids and hydrochlorothiazide

🇨🇦 MCCQE1,2 | #Case_144 | #answer 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 ✅ E 🔎 Explanation This patient is diagnosed with gastritis secondary to Helicobacter pylori infection. It usually presents with abdominal pain that worsens with food intake, heartburn or esophageal reflex, diarrhea, nausea and vomiting. Various tests can be used to make the diagnosis including esophagogastroduodenoscopy, H. pylori fecal antigen test, and H. pylori serology. Treatment should be given to patients with positive results. Treatment with triple therapy should be administered for 10-14 days. The treatment regimens are omeprazole, amoxicillin, and clarithromycin (OAC) (choice E) - for 10 days; bismuth subsalicylate, metronidazole, and tetracycline (BMT) for 14 days; and lansoprazole, amoxicillin, and clarithromycin (LAC), which is approved for either 10 days or 14 days of treatment. 4 weeks after treatment, carbon-13 urea breath test should be done to confirm eradication. ⚠ Clarithromycin, omeprazole, and fluconazole (choice A) is incorrect. Fluconazole, an antifungal is not part of the treatment regimen to eradicate bacteria. ⚠ A combination of erythromycin, esomeprazole, and metronidazole (choice B) has greater likelihood of failure, given erythromycin decreased efficacy in acid environment. Its derivative, clarithromycin is more acid-resistant and is the preferred macrolide in H. pylori eradication. ⚠ Amoxicillin-clavulanate, ranitidine, and bismuth (choice C) is incorrect. Most tested regimens that have amoxicillin also include clarithromycin, moreover, PPI are stronger acid inhibitors than antihistamines. ⚠ Bismuth, omeprazole, and metronidazole (choice D) is incorrect. Most tested regimens with metronidazole also include either tetracycline or clarithromycin. 🔖 Key point: For H. pylori eradication the most common regimens are omeprazole, amoxicillin, and clarithromycin (OAC) for 10 days; bismuth subsalicylate, metronidazole, and tetracycline (BMT) for 14 days; and lansoprazole, amoxicillin, and clarithromycin (LAC), which is approved for either 10 days or 14 days of treatment

🇨🇦 MCCQE1,2 | #Case_144 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 A 48-year-old male presents to your department because he has had pressure-like sensation in the upper abdomen for the last 3 weeks with abdominal pain that worsens with eating food. The pain sometimes radiates to the chest. Physical examination reveals upper abdominal tenderness on deep palpation. In the course of work up an endoscopy with biopsy is performed and reveals gastritis with Helicobacter pylori infection. What is the best treatment regimen to eradicate this infection? ❤Clarithromycin, omeprazole, and fluconazole 💛Erythromycin, esomeprazole, and metronidazole 💚Amoxicillin-clavulanate, ranitidine, and bismuth 💙Bismuth, omeprazole, and metronidazole 💜Omeprazole, amoxicillin, and clarithromycin