🧠 Case-based MCQ ✅ #MCQ_3
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A 48-year-old woman presents to the clinic with dysphagia, diarrhea, and facial flushing. Physical examination reveals a solitary thyroid nodule and cervical lymphadenopathy. Laboratory studies show elevated serum calcitonin and elevated carcinoembryonic antigen levels.

🧠 Case-based MCQ 🔸 #MCQ_3
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✔️The correct answer is B.

The production of calcitonin and carcinoembryonic antigen (CEA) is characteristic of medullary thyroid cancer, and these are useful markers for diagnosis and follow-up. Patients typically present with dysphagia, diarrhea, facial flushing, and a solitary thyroid nodule. Medullary thyroid cancer is a neuroendocrine tumor of the parafollicular or C cells of the thyroid gland. The diagnosis of medullary thyroid cancer is made after a fine-needle aspiration biopsy of the thyroid nodule. Treatment is with the removal of the affected thyroid lobes, and for nodules that are 4 cm or larger, diagnostic lobectomy is recommended over fine-needle aspiration.


❌Choice A and C are not correct:

Although most cases of medullary thyroid cancer are acquired sporadically, genetic inheritance can be seen in cases of multiple endocrine neoplasia type 2 (MEN2). MEN2 is associated with medullary thyroid cancer, pheochromocytoma. and primary parathyroid hyperplasia. Therefore, additional testing for coexisting tumors such as biochemical evaluation for pheochromocytoma and germline RET mutation testing is recommended.

❌Choice D is not correct:

Once medullary thyroid cancer is confirmed with fine-needle aspiration biopsy, further evaluation should include ultrasonography of the neck to look for lymph node involvement.

✅Summarized Points:

Thyroid Carcinoma physical exam will show a solitary hard nodule. Labs will show normal thyroid function, cold nodule. Initial Diagnosis is ultrasound, and Confirmation is Fine-needle biopsy.

🔴Papillary: most common, least aggressive
🔴Anaplastic: least common, most aggressive
🔴Medullary: associated with MEN2, calcitonin can be used as a tumor marker

🧠 Case-based MCQ ✅ #MCQ_4
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A 34-year-old man is evaluated during a follow-up visit after passing his third calcium oxalate kidney stone in 4 years despite maintaining a high urine volume. He has no other medical problems. His only medication is potassium citrate, which was initiated after passing the most recent stone. He drinks 4 cups of coffee daily and typically eats meals at fast-food restaurants. Physical examination findings, including vital signs, are normal. Laboratory studies:

 24-Hour urine studies
   Volume 2600 mL
   pH 6.5
   Calcium 7.3 mmol (2.5–7.5)
   Citrate 9 mmol (0.6–6.0)
   Oxalate 0.35 mmol (0.44)
   Uric acid 4.0 mmol (1.48–4.43)
 

The patient is counselled to start a low sodium diet.

🧠 Case-based MCQ 🔸 #MCQ_4
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✔️The correct answer is E.

This patient's urinary calcium excretion is in the high-normal range. The threshold that defines high urinary calcium excretion and when to initiate a thiazide diuretic for the prevention of calcium oxalate stones is unclear. However, the underlying principle is that the risk for stone formation is continuous with increasing amounts of calcium in the urine. Patients with ongoing stone formation despite dietary and fluid management should be considered for medical therapy with a thiazide diuretic to decrease urinary calcium excretion.

Thiazide diuretics can decrease calcium excretion by up to 50% and reduce the recurrence of calcium oxalate stones. Chlorthalidone is the preferred agent because of its long half-life. Chlorthalidone increases calcium reabsorption in the kidney primarily by causing mild volume depletion, which increases sodium and calcium reabsorption in the proximal tubule. When hydrochlorothiazide is used, twice-daily dosing is recommended. In addition to chlorthalidone, urinary calcium excretion can also be reduced by limiting sodium and protein intake.

❌Choice A is not correct:

Because calcium complexes with oxalate in the gastrointestinal tract, decreasing calcium intake allows for increased oxalate absorption and increased risk for stone formation. Therefore, unless a person is on a high-calcium diet (>1500 mg/d), intake should not be limited.

❌Choice B is not correct:

There is no evidence that excess coffee intake is associated with kidney stone disease, so reduction in coffee intake would not be expected to be beneficial.

Choice C is not correct:

Except in patients with hyperoxaluria, limiting oxalate intake has not been shown to decrease the incidence of stones, and thus the patient does not need to decrease intake.

❌Choice D is not correct:

Because uric acid may serve as a nidus for stone formation, allopurinol has been used to reduce stone occurrence, especially in patients with high levels of uric acid in the urine, which is not present in this patient.

✅Summarized Points:

Thiazide diuretics decrease calcium excretion by up to 50% and can be used to manage recurrent calcium oxalate kidney stones. In patients with recurrent calcium oxalate kidney stones, urinary calcium excretion can be reduced by limiting sodium and protein intake.

🧠 Case-based MCQ 🔸 #MCQ_5
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A 58-year-old male presents to an emergency department complaining of severe knee pain which has been worsening over the past 2 days. He denies any trauma to the area. When questioned about his medical history, the patient reports that he is being treated for hypothyroidism. On examination, the patient has a temperature of 38 C (100.3 F). His left knee is warm, erythematous, and tender. There is a large effusion in the knee joint. He has painful limitation of motion of the knee. He has no rashes, and no other joints are involved. Arthrocentesis is performed and shows 75,000 WBC/mm3. A polarizing microscope shows rhomboid, positively birefringent crystals in the fluid.

🧠 Case-based MCQ 🔸 #MCQ_4
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✔️ The Correct answer is A.

Pseudogout is joint inflammation caused by calcium pyrophosphate crystals. it happens in Elderly and Osteoarthritis joint. Its Presentation is similar to gout cause redness, swelling, tenderness, but typically occurs in larger joints (knee).

Three main conditions that may increase crystal deposition include hemochromatosis, hyperparathyroidism, hypothyroidism (3 H’s).


❌Choice B is not correct:

The uric acid crystals of gout are needle-shaped and negatively birefringent.

❌Choice C is not correct:

This patient WBC count in the synovial fluid over 55.000 which suggest a septic arthritis, but the crystals point to pseudogout.

❌Choice D is not correct:

Rheumatoid arthritis is symmetrical arthritis and usually involve hands.

❌Choice E is not correct:

Osteoarthritis not come with fever, and synovial fluid WBC in osteoarthritis is less than 2000 and there is no crystal.

💠 Summarized Points:

Fever and single joint pain next step is joint aspiration. Rhomboid crystal associated with Pseudogout. Risk factors for Pseudogout are hypothyroidism, Hemochromatosis, hyperparathyroidism. Pseudogout happen in Elderly and Osteoarthritis joint.

🧠 Case-based MCQ 🔸 #MCQ_5
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A 68-year-old male presents to the emergency department with a complaint of right upper extremity weakness and slurred speech. His symptoms started 5 hours ago and have not improved. He has a medical history significant for hypertension and diabetes. His physical examination is notable for weakness in the right arm only and dysarthria, Right biceps reflex is brisk. The rest of the examination is normal. His temperature is 37.5, blood pressure is 190/100 mm Hg, the pulse is 75/min, respiratory rate is 12 /min.

🧠 Case-based MCQ 🔸 #MCQ_5
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✔️The Correct answer is D.

This patient has symptoms of an acute stroke. Strokes can be ischemic, caused by embolic events cutting cerebral blood flow, or hemorrhagic. CT scan of the head without contrast is the first best initial imaging study that needs to be ordered. This differentiates an ischemic from a hemorrhagic infarction.

Ischemic strokes appear as dark areas on the CT scan
Hemorrhagic strokes appear as white areas on the CT scan

❌Choice A is not correct:

MRI of brain is more sensitive than CT scan. Identifies all infarcts, and does so earlier than CT scan. 95% of infarcts identified on MRI within 24 hours. However, not preferred in an emergency setting because it is time consuming and is not suitable for potentially unstable patients.

❌Choice B, C, E are not correct:
First we need to identify with noncontract CT of head that patient has hemorrhagic or ischemic stroke. because they are contraindicated in the setting of a hemorrhagic stroke.

✅ Summarized Points:

In all patient with suspicion of stroke first stabilize patient in primary survey doing ABC, Order labs like Noncontrast-CT scan of the brain, ECG, chest radiograph, CBC, platelet count, PT, PTT, Serum electrolytes, Glucose level, Bilateral carotid ultrasound and Echocardiogram. Noncontrast-CT scan will decide further treatment.

🧠 Case-based MCQ 🔸 #MCQ_6
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A 4-year-old boy is brought to the physician for evaluation of a rash. The rash has been present for at least a month and became more prominent as the child spent more time playing outside during the summer. He has not used any new soaps, lotions, or detergents. Examination shows several hypopigmented macules on each cheek. Each macule is approximately 1 cm in diameter and is covered with a fine-scale. No other rashes or lesions are seen.

🧩 Medical Mnemonics

🟦CASES of Bloody Diarrhea have increased recently, haven't they?

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🧠 Case-based MCQ 🔸 #MCQ_6
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The correct answer is E.

This child's clinical presentation is classic for tinea versicolor (i.e., pityriasis versicolor). Tinea versicolor is a superficial fungal infection caused primarily by Malassezia globosa. Although Malassezia yeasts are part of normal skin flora, overgrowth causing clinical disease is common in temperate climates. The rash can have a variety of appearances and may present as either hyperpigmented or hypopigmented macules sometimes covered by a fine scale. Affected children usually have facial lesions; adolescents and adults typically have lesions on the trunk and proximal upper extremities. Diagnosis is confirmed by the presence of hyphae and yeast cells in a "spaghetti & meatballs" pattern on potassium hydroxide (KOH) preparation.

The preferred treatment for tinea versicolor includes topical ketoconazole 2% cream or shampoo or selenium sulfide 2.5% lotion or foam. A 2-week course is often effective, but some cases take several months to resolve. Recurrence is also very common. Tinea versicolor is not contagious and children can return to school or daycare with no restrictions.


❌Choice A is not correct:

Diluted bleach water soaks may be used as part of the treatment of eczema to reduce the risk of bacterial skin infections in these patients. Bleach baths have also been used to decrease skin colonization of methicillin-resistant Staphylococcus aureus; however, they do not play a role in the prevention of tinea versicolor.

❌Choice B is not correct:

Oral antifungal agents (e.g., ketoconazole, itraconazole) can be used for recalcitrant or widespread tinea versicolor but are associated with increased side effects (e.g., transaminitis).

❌Choice C is not correct:

Vitiligo can be differentiated from tinea versicolor by completely depigmented macules and patches. Treatment of vitiligo includes topical and oral corticosteroids, topical calcineurin inhibitors, and ultraviolet light.

❌Choice D is not correct:

Permethrin is used in the treatment of lice and scabies but not tinea versicolor.

✅Summarized Points:

Tinea versicolor is a common fungal infection in temperate climates and manifests as hypopigmented or hyperpigmented lesions. First-line treatment includes topical ketoconazole or selenium sulfide.