A 38-year-old woman presents with diarrhoea, flushing and a firm anterior neck mass. Fine needle aspiration shows sheets of amyloid-staining stroma surrounding malignant cells. The most appropriate serum tumour marker to monitor this patient is:

• A Calcitonin ✓
• B Thyroglobulin
• C CA 19-9
• D Chromogranin A

Explanation

Medullary thyroid carcinoma arises from parafollicular C cells, which secrete calcitonin; the hormone deposits as amyloid in the stroma. Serum calcitonin is the diagnostic and follow-up marker, and RET germline testing is indicated because many cases are familial (MEN 2). Thyroglobulin monitors differentiated follicular-derived carcinomas, not medullary, since C cells do not produce thyroglobulin. CA 19-9 is a pancreatic marker.

Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.