Case-based MCQ

🧩 Medical Mnemonics ⏳ A 65-year-old man in the hospital receiving spinal anesthesia for crush injuries to his lower extremities starts to notice labored breathing. He is afebrile but develops nausea and vomiting, and last had a bowel movement yesterday. His abdomen is distended and tympanic to percussion, although there are scattered bowel sounds. A plain upright abdominal film reveals a largely dilated colon extending from the cecum to the splenic flexure. Water-soluble enema fails to reveal mechanical obstruction. 🗓 February 13, 2020 #case_of_the_week 〰〰〰〰〰〰〰〰〰〰〰 ©Medical Mnemonics

🇨🇦 MCCQE1,2 | #Case_291 | #answer 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 ✅ B 🔎 Explanation Continuous therapy with oral terbinafine for 12 weeks has the highest cure rate and best long-term resolution rate of the therapies listed. Other agents and pulsed dosing regimens have lower cure rates. Topical creams are not appropriate for onychomycosis because the infection resides in the cell of the toenail. Antifungal nail lacquers have a lower cure rate than systemic therapy and should be used only when oral agents would not be safe. Toenail removal is reserved for patients with an isolated infected nail or in cases involving a dermatophytoma

🇨🇦 MCCQE1,2 | #Case_291 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 A 69-year-old female sees you for an annual examination. She asks you to look at her toes, and you note a fungal infection in five toenails. She says the condition is painful and limits her ability to complete her morning walks. She asks for treatment that will allow her to resume her daily walks as soon as possible. Her only other medical problem is allergic rhinitis which is well controlled. Which one of the following would be the most appropriate treatment for this patient? a. Oral griseofulvin ultramicrosize (Gris-PEG) daily for 12 weeks b. Oral terbinafine (Lamisil) daily for 12 weeks c. Topical terbinafine (Lamisil An daily for 12 weeks d. Topical ciclopirox (Pen lac Nail Lacquer) daily for 12 weeks e. Toenail removal

🇨🇦 MCCQE1,2 | #Case_290 | #answer 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 ✅ D 🔎 Explanation Acute kidney injury associated with fever, urine with low specific gravity and low molecular weight proteinuria is suggestive of acute tubulointerstitial nephritis, which is commonly caused by analgesic nephropathy. Patients with chronic joint pain (choice D) are likely to try and use specific medications, mixtures or combinations of analgesic medications that might cause interstitial nephritis. Analgesic nephropathy could be either acute or chronic and the acute form may develop months after exposure to the medication. Some patients may have fever and skin rash at diagnosis. Presence of eosinophils in urine supports the diagnosis but absence of these cells does not exclude the diagnosis. ⚠ Diabetes mellitus (choice A) causes glomerular rather than tubular disease. Thus, this disease usually presents as microalbuminuria with negative standard dipstick {as in our patient's urinalysis) and 24hour protein between 30 - 300 mg/day. As its name implies, the major protein in urine of patients with microalbuminuria is albumin and not low molecular weight protein as in tubular disease. ⚠ Having had sore throat two weeks ago (choice B) or impetigo four weeks ago (choice C) would suggest glomerular disease as a cause of acute kidney injury. However, the clinical picture (fever) and the results of lab investigations (absence of hematuria, low molecular weight proteinuria, low urine specific gravity) suggest tubulointerstitial nephritis, instead. ⚠ Having had self-limited diarrhea three weeks ago (choice E) might suggest a diagnosis of hemolytic uremic syndrome in which rena l failure and anuria may be preceded by history of diarrhea. This disorder is more common in children and in addition to red cells and red cell casts in urine, complete blood count of these patients usually reveals thrombocytopenia and features of microangipathic hemolytic anemia. 🔖 Key point: There is no specific test that is diagnostic of tubulointerstitial nephritis, which is most commonly drug-induced (70-75%). Therefore, obtaining a detailed history is of paramount importance for diagnosis of this disease

🇨🇦 MCCQE1,2 | #Case_290 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 A 54-year-old woman is admitted to emergency department with acute kidney injury. Other than body temperature of 37.9°C, vital signs are stable and the rest of physical examination is also normal. Urinalysis reveals normal pH, low specific gravity and white cell casts but is negative for white blood cells, red blood cells and protein. 24hour urinary protein shows low molecular weight proteinuria of 1.4g. Complete blood count is normal. Which of the following pieces of history might support the diagnosis suggested by the clinical picture and results of investigations? a. History of diabetes mellitus b. Having had sore throat two weeks ago c. Having had impetigo four weeks ago d. Having chronic joint pain . e. Having had self-limited diarrhea three weeks ago

🇨🇦 MCCQE1,2 | #Case_289 | #answer 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 ✅ B 🔎 Explanation This patient has a long history of beta -thalassemia major and the fatigue is most likely caused by anemia. The findings on physical examination of gray skin and lung crepitations are most likely manifestations of transfusion-induced hemosiderosis. Given the patient's iron overload, at this point an alternative therapy should be considered for his anemia, such as manipulation of globin gene expression. Hydroxyurea (choice B) increases the production and concentration of fetal hemoglobin (hemoglobin F), which reduces transfusion requirements. ⚠ Blood transfusion {choice A) is incorrect. At this point with the patient's blood transfusion induced hemosiderosis the most appropriate next step is to give hydroxyurea first to decrease the need of frequent transfusions. ⚠ Therapeutic phlebotomy {choice B) is appropriate in patients with hemochromatosis associated iron overload but is inappropriate in anemic patients with transfusion-induced iron overload. In these patients the primary goal of iron chelation therapy is to prevent the accumulation of iron reaching harmful levels by matching iron intake from blood transfusion, with iron excreted by iron chelation. ⚠ Erythropoietin (choice D) is incorrect because the problem with beta-thalassemia is not with the production of red blood cells but with the defective hemoglobi n. ⚠ Vitamin C supplementation {choice E) is considered useful in iron chelation in patients receiving deferoxamine infusion. But by itself, it is not sufficiently effective and large doses of vitamin C without concomitant infusion of deferoxamine have been reported to cause arrhythmias

🇨🇦 MCCQE1,2 | #Case_289 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 A 29-year-old male presents to your department because of fatigue. He has a long history of beta-thalassemia major and has received multiple blood transfusions throughout his life. Physical examination reveals gray skin and lung crepitations. Laboratory tests show hemoglobin of 81 g/L. What is the most appropriate next step in management? a. Blood transfusion b. Hydroxyurea c. Therapeutic phlebotomy d. Erythropoietin e. Vitamin C supplementation

🇨🇦 MCCQE1,2 | #Case_288 | #answer 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 ✅ A 🔎 Explanation This infant has the typical “flea-bitten” rash of erythema toxicum neonatorum (ETN). ETN is a benign self-limited eruption occurring primarily in healthy newborns in the early neonatal period. Erythema toxicum neonatorum is characterized by macular erythema, papules, vesicles, and pustules, and it resolves without permanent sequelae. ⚠ Transient neonatal pustular melanosis (choice B) is most common in black newborns, and the lesions lack the surrounding erythema typical of ETN. ⚠ Acne neonatorum (choice C) is associated with closed comedones, mostly on the face. ⚠ As the infant described is not ill, infectious etiologies (choice D and choice E) are unlikely

🇨🇦 MCCQE1,2 | #Case_288 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 During rounds, you notice a new rash on a full-term 2-day-old white female. It consists of 1 mm pustules surrounded by a flat area of erythema, and is located on the face, trunk, and upper arms. An examination is otherwise normal, and she does not appear ill. Which one of the following is the most likely diagnosis? a) Erythema toxicum neonatorum b) Transient neonatal pustular melanosis c) Acne neonatorum d) Systemic herpes simplex e) Staphylococcus aureus sepsis

🇨🇦 MCCQE1,2 | #Case_287 | #answer 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 ✅ E 🔎 Explanation The concern with infectious mononucleosis, a disease caused by the Epstein-Barr virus, is for splenomegaly. The issue of contact sports after a course of mono relates solely to when the risk of splenic injury has declined. No treatment other than rest is needed in the vast majority of cases. The spleen, being part of the lymphatic system, will generally regress in size in accord with the decline in physical signs, such as swollen lymph nodes. Waiting until next season is too long and, although likely to allow a large margin of safety, will unnecessarily keep the student from playing his sport. The Monospot test is the diagnostic test that detects the antibody generated against the EBV (heterophil antibody) in the blood of the patient. Since the immune response is last quite long, a negative Monospot test may take years to become present. Waiting for the patient to be symptom free is also too long as fatigue may persist for months after the resolution of the lymph node enlargement. The CBC may return to normal well before the lymph nodes have regressed in size.

🇨🇦 MCCQE1,2 | #Case_287 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 A 20-year-old man returns to the office for a follow up visit 4 weeks after being diagnosed with mononucleosis. At his initial visit, he had a sore throat, nausea and a temperature of 39.4°C (103°F). Physical examination at that time showed pharyngitis, submandibular and posterior cervical lymphadenitis, and splenomegaly. Complete blood count (CBC) done at that time showed a leukocyte count of 18,000 with an elevated number of monocytes, and a Monospot test was positive. He asks you, "When can I play again?" Which of the following is the most appropriate response to the patient regarding when he may return to contact sports? a) Next season b) When a Monospot test is negative c) When he is no longer symptomatic d) When his CBC is normal e) When his physical examination is normal

🇨🇦 MCCQE1,2 | #Case_286 | #answer 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 ✅ B 🔎 Explanation Hypoglycemia unrelated to exogenous insulin therapy is an uncommon clinical syndrome characterized by low plasma glucose level, symptomatic sympathetic nervous system stimulation, and CNS dysfunction. Many drugs and disorders cause it. A diagnosis of hypoglycemic disorder can be suggested by the Whipple's triad (choice B). Essential conditions of this triad are: ▪ Symptoms are known or likely to be caused by hypoglycemia ▪ A low plasma glucose measured at the time of the symptoms ▪ Relief of symptoms when the glucose is raised to normal ⚠ Cushing's triad (choice A) is characterized by bradycardia, bradypnea, and hypertension, which are often associated with head injuries. ⚠ Samter's triad (choice C) is seen in aspirin-induced asthma and is characterized by aspirin sensitivity, nasal polyps,and asthma. ⚠ Virchow's triad (choice D) is composed of stasis, hypercoagulability, and vessel injury. It is associated with venous thrombosis. ⚠ Beck's triad (choice E) is characterized by muffled heart sound, distended neck veins, and hypotension; it is diagnostic of cardiac tamponade

🇨🇦 MCCQE1,2 | #Case_286 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 A 45-year-old woman is brought to the Emergency Department after she fainted in a supermarket. After evaluation the patient's glucose is found to be 2.5 mmol/l. Which one of the following criteria is most in favor of the diagnosis of hypoglycemic disorder? a) Cushing's triad b) Whipple's triad c) Samter's triad d) Virchow's triad e) Beck's triad

🇨🇦 MCCQE1,2 | #Case_285 | #answer 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 ✅ A 🔎 Explanation Lithium therapy can elevate calcium levels by elevating parathyroid hormone secretion. This duplicates the laboratory findings seen with mild primary hyperparathyroidism. If possible, lithium should be discontinued for 3 months before reevaluation. This is most important for avoiding unnecessary parathyroid surgery. Vitamin D and calcium supplementation could contribute to hypercalcemia in rare instances, but they would not cause elevation of parathyroid hormone. Raloxifene has actually been shown to mildly reduce elevated calcium levels, and furosemide is used with saline infusions to lower significantly elevated calcium levels.

🇨🇦 MCCQE1,2 | #Case_285 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 A 49-year-old female who takes multiple medications has a chemistry profile as part of her routine monitoring. She is found to have an elevated calcium level. All other values on the profile are normal, and the patient is not currently symptomatic. Follow-up testing reveals a serum calcium level of 2.8 mmol/L and a parathyroid hormone level of 80 pg/mL (N 10-65). Which one of the following should be discontinued for 3 months before repeat laboratory evaluation and treatment? a) Lithium b) Furosemide c) Raloxifene d) Calcium carbonate e) Vitamin D

🇨🇦 MCCQE1,2 | #Case_284 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 A 43-year-old chronically mentally ill man was admitted to the medical floor for ketoacidosis. His previously prescribed antipsychotic haloperidol was stopped and not restarted when he was transferred to an extended care facility several weeks later. A routine follow-up examination by his primary care physician finds the patient with tic-like movements of his face and tongue and lip smacking. Based on this information, what is the most likely diagnosis? a) Diabetic neuropathy b) Tourette's disorder c) Parkinson's disease d) Akathisia e) Tardive dyskinesia

🇨🇦 MCCQE1,2 | #Case_283 | #answer 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 ✅ D 🔎 Explanation This patient presents with Basal Cell Carcinoma (BCC). The unresponsiveness to topical creams supports this diagnosis. The site of ulcer on the side of the nose is the commonest site for BCC. Being a farmer who is exposed to sunrays all day is a risk factor for BCC. A typical BCC has a rolled out edge, often beaded and the floor shows scabbing at some places and breaking at others. The treatment of choice for this patient is Mohs micrographaic surgery (choice D). The goal of this surgery is to remove the cancerous cells completely with the least possible cosmetic damage. This technique can save the greatest amount of healthy tissue and has the highest cure rate, 99 percent or better. It is often used for tumors in cosmetically important areas around the eyes, nose, lips, and ear. Using local anasthesia, the surgeon removes the cancer layer by layer, examining each one microscopically until the margin around the cancer is free of cancer cells. The clinical quotes for cure rate of Mohs surgery is from 97% to 99.8% after 5 years for newly diagnosed BCC, decreasing to 94% or less for recurrent basal cell cancer. Radiation oncologists quote cure rate from 90 to 95% for BCCs less than 1 or 2 cm, and 85 to 90% for BCCs larger than 1 or 2 cm. Surgical excision cure rate varies from 99% for wide margin (4 to 6 mm) and small tumor, to as low as 70% for narrow margins applied to large tumors. ⚠ Radiotherapy (choice A) is also used in treatment of (BCC), but radiation may be used for tumors that are hard to manage surgically and for elderly patients or others who are in poor health. Cure rates are around 90 percent, but the technique can involve long-term cosmetic problems and radiation risks. ⚠ Cryosurgery (choice B) can be used in treatment of BCC, but it is the treatment of choice for patients with bleeding disorders or an intolerance to anathesia. This method is used less commonly today, and has a lower cure rate than the surgical techniques, approximately 85-90 percent depending on the physician’s expertise. ⚠ The effectiveness of the excisional surgery (choice C) does not match that of Mohs and produces cure rates around 90 percent. ⚠ Topical 5-fluorouracil (5-FU) (choice E) has been FDA-approved for superficial BCCs. 🔖 Key point: Choice of treatment for BCC is based on type, size, location, depth of penetration of the tumor, patient’s age, general health, and the expected outcome to his or her appearance. Mohs surgery allows for the removal of a skin cancer with very narrow surgical margin and a high cure rate. The cure rate with Mohs surgery cited by most studies is between 97% and 99.8% for primary basal cell carcinoma, the most common type of skin cancer.

🇨🇦 MCCQE1,2 | #Case_283 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 A 48-year-old farmer presents to your office with skin ulcer on the side of his nose. He said that this ulcer started as a nodule and then ulcerated one year ago. His dermatologist prescribed topical creams but there was no response. On examination, the ulcer was deep, rounded with rolled beaded edges, and indurated base. Cervical lymph nodes were not enlarged. What is the treatment of choice for this patient? a) Radiotherapy b) Cryosurgery c) Excisional surgery d) Mohs micrographic surgery e) Topical 5-fluorouracil (5-FU)

🇨🇦 MCCQE1,2 | #Case_282 | #answer 〰〰〰〰〰〰〰〰〰〰〰〰〰〰 ✅ E 🔎 Explanation This patient’s chest wall motion on spontaneous breathing is known as paradoxical chest wall motion and is characteristic of flail chest (choice E). This occurs when 3 or more ribs are broken compromising the structural stability of the chest wall. Paradoxical chest wall motion is unlikely to be noted if less than 3 ribs are involved. The best initial study to confirm 3 broken ribs is chest X-ray. Respiratory insufficiency in these patients may be minimal or severe and tachypnea is often present. The degree of respiratory insufficiency is typically related to the underlying lung injury (pulmonary contusion), rather than the chest wall abnormality. ⚠ Cardiac tamponade (choice A) is incorrect. Consider cardiac tamponade in a patient with Beck’s triad of hypotension, jugular venous distension, and distant, muffled heart sounds. Other clues are pulsus paradoxus, which is a drop of 10 mmHg systemic blood pressure on inspiration and electrical alternans on ECG. ⚠ Diaphragmatic rupture (choice B) occurs in about 5% of chest wall trauma and majority of diaphragmatic rupture cases are related to motor vehicle crashes. The left side is more likely to rupture and is involved in 75% of cases. Common symptoms are chest pain, abdominal pain, and dyspnea. Physical examination has limited diagnostic value but it may reveal decreased breath sounds, auscultation of bowel sounds in the chest, and dullness to percussion of the chest. ⚠ Tension pneumothorax (choice C) is characterized by decreased breath sounds on auscultation of the affected side of the chest and contralateral deviation of the trachea. ⚠ Tracheal rupture (choice D) presents with hemoptysis, dyspnea, dysphonia, and subcutaneous emphysema (air bubbles that can be palpated underneath the skin of the chest). 🔖 Key point: Flail chest results from chest injury with 3 broken ribs or more. It is characterized by paradoxical chest wall motion