PA31.1-10 | Endocrine System — Practice Quiz

A 45-year-old woman from a coastal iodine-deficient region presents with a painless, diffuse goiter of 3 years duration. She is euthyroid on examination. TSH is mildly elevated, T4 is low-normal. Histology shows follicles distended with colloid and flat lining cells. What is the most likely underlying mechanism of goiter formation?

A 28-year-old woman presents with weight loss, palpitations, heat intolerance, and exophthalmos. TSH is undetectable; free T4 and T3 are markedly elevated. Radioactive iodine uptake (RAIU) scan shows diffusely increased uptake throughout an enlarged gland. What is the most likely pathogenesis?

A 40-year-old woman presents with fatigue, weight gain, cold intolerance, constipation, and a firm, rubbery goiter. TSH is elevated; anti-TPO antibodies are strongly positive. Biopsy shows follicular atrophy, Hürthle cell (oxyphilic) metaplasia, lymphocytic infiltration, and germinal centre formation. Which of the following best characterises the underlying immune mechanism?

A 35-year-old woman presents with acute anterior neck pain radiating to the jaw, fever (38.8 °C), and a tender, firm thyroid. ESR is markedly elevated. She had an upper respiratory tract infection 3 weeks ago. Thyroid function shows low TSH and elevated free T4. RAIU is nearly zero. What is the most likely diagnosis?

A 32-year-old woman undergoes hemithyroidectomy for a 2.5 cm solitary thyroid nodule. Histology shows follicular cells with enlarged, ground-glass (Orphan Annie eye) nuclei, nuclear grooves, pseudoinclusions, and psammoma bodies. There is no capsular or vascular invasion. What is the most likely diagnosis and the most reliable prognostic marker?

A 55-year-old man presents with a thyroid mass, neck lymphadenopathy, and chronic diarrhoea. Serum calcitonin is markedly elevated (>2000 pg/mL). Fine-needle aspiration shows polygonal cells in a hyalinised stroma that stains positive with Congo red under polarised light. Genetic testing reveals a germline RET proto-oncogene mutation. What additional workup is most immediately necessary?

A 60-year-old woman with a long-standing multinodular goiter presents with rapidly progressive dysphagia and hoarseness over 6 weeks. Examination reveals a rock-hard neck mass fixed to surrounding structures. CT shows tracheal deviation and local invasion. Biopsy shows highly pleomorphic giant cells and spindle cells with frequent mitoses and necrosis. What is the prognosis and primary treatment modality?

A 38-year-old woman with known Type 1 diabetes mellitus presents to the emergency department with nausea, vomiting, and deep rapid (Kussmaul) breathing. Blood glucose is 28 mmol/L, blood pH is 7.18, bicarbonate is 10 mEq/L, and urine dipstick shows 3+ ketones. What is the primary pathophysiological defect leading to this presentation?

A 58-year-old man with Type 2 diabetes mellitus of 15 years duration is found to have proteinuria (3.2 g/24 h) and a serum creatinine of 210 µmol/L. Kidney biopsy shows nodular glomerulosclerosis at the periphery of the glomerular tuft with thickened basement membranes. PAS stain highlights the nodules. What is the name of this lesion and its pathological basis?

A 50-year-old man presents with fatigue, weight loss, abdominal pain, and a serum calcium of 3.1 mmol/L (elevated). Intact PTH is markedly elevated at 180 pg/mL (normal 10–65). Imaging shows a 2.5 cm mass in the superior parathyroid gland. Bone X-rays reveal subperiosteal resorption of the radial aspect of the middle phalanges and a 'salt-and-pepper' skull. What is the diagnosis and most likely cause?

A 62-year-old man presents with painless jaundice, weight loss of 8 kg over 3 months, and a palpable, non-tender gallbladder (Courvoisier sign). CT abdomen shows a 3.5 cm mass in the head of the pancreas obstructing the common bile duct. CA 19-9 is markedly elevated. What is the most likely histological type and its characteristic growth pattern?

A 35-year-old woman presents with progressive fatigue, weight loss, hyperpigmentation of skin creases and buccal mucosa, postural hypotension, and hyponatraemia with hyperkalaemia. Serum cortisol is low and does not rise with synthetic ACTH (Synacthen) stimulation. ACTH level is markedly elevated. What is the underlying pathology in the most common cause of this condition in resource-rich settings?

A 42-year-old man presents with central obesity, moon face, buffalo hump, purple abdominal striae, and hypertension. Serum cortisol is elevated with loss of diurnal variation. Overnight low-dose dexamethasone suppression test is abnormal (cortisol not suppressed). ACTH is elevated. High-dose dexamethasone (8 mg overnight) suppresses cortisol by >50%. What is the most likely cause of Cushing syndrome in this patient?

A 28-year-old woman presents with episodic hypertension (BP 220/130 mmHg during attacks), palpitations, severe headache, sweating, and pallor. Between attacks, blood pressure is normal. 24-hour urine shows markedly elevated metanephrines and vanillylmandelic acid (VMA). CT adrenal shows a 4 cm right adrenal mass. Which of the following statements about this tumour is most accurate?

A 3-year-old child presents with an abdominal mass that crosses the midline, periorbital ecchymosis ('raccoon eyes'), and proptosis. Urine HVA (homovanillic acid) and VMA (vanillylmandelic acid) are markedly elevated. CT shows a suprarenal mass with calcifications. Bone marrow biopsy reveals small blue round cells. N-MYC gene amplification is detected. Which of the following best describes this tumour's biological behaviour related to N-MYC amplification?