A 45-year-old man with a history of good health visits the office to have a neck tumor examined. While shaving a month ago, the patient first noticed the bulge, which has since gotten bigger. He hasn't experienced a fever, neck discomfort, hoarseness, or any breathing or swallowing issues. The patient does not consume alcohol, tobacco, or illegal substances. Blood pressure is 110/70 mm Hg, temperature is 36.7 C (98 F), and pulse is 78 beats per minute. A nontender, hard nodule is visible on physical examination in the upper left thyroid lobe. Laboratory tests show high serum calcitonin levels and normal serum TSH. A 2-cm hypoechoic thyroid nodule with microcalcifications is shown on a neck ultrasound. Spindle-shaped cells are visible in the nodule's fine-needle aspiration against an amorphous backdrop. Which of the following gene alterations most likely contributed to this patient's current condition?

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Quizplus · Accepted Answer

Eductional Objective: A neuroendocrine tumor, medullary thyroid cancer develops from C (parafollicular) cells that secrete calcitonin. Although most occurrences are sporadic, it is frequently observed in the context of multiple endocrine neoplasia type 2 (A and B). Mutations in the RET proto-oncogene are linked to both sporadic and familial medullary thyroid tumors.

A 45-Year-Old Man with a History of Good Health Visits