A 40-year-old woman undergoes thyroidectomy for a solitary nodule. Histology shows nests of cells with stippled chromatin and abundant stromal amorphous eosinophilic material that stains with Congo red. The amyloid in this tumor is derived from the precursor of which secreted peptide?
- A Parathyroid hormone related peptide
- B Calcitonin ✓
- C Insulin
- D Somatostatin
Correct answer: B. Calcitonin
Explanation
Medullary carcinoma of the thyroid arises from calcitonin-secreting parafollicular C cells, and stromal amyloid derived from procalcitonin is a classic diagnostic feature visible even on fine needle aspirate cytology. Insulin-derived amylin amyloid occurs in islets of type 2 diabetes, PTHrp mediates humoral hypercalcemia of malignancy, and somatostatin produces no characteristic amyloid.
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.