A 45-year-old woman undergoes thyroidectomy for a thyroid nodule. Histology shows follicles filled with colloid, nuclear features of ground-glass 'Orphan Annie eye' nuclei, nuclear grooves, intranuclear pseudoinclusions, and psammoma bodies. The diagnosis is papillary thyroid carcinoma (PTC). Psammoma bodies in PTC represent what pathological process?
- A Metaplastic ossification due to stromal bone formation
- B Calcium pyrophosphate crystal deposition within the thyroid stroma
- C Dystrophic calcification in foci of individual cell necrosis within tumour papillae ✓
- D Amyloid calcification from calcitonin deposits
Correct answer: C. Dystrophic calcification in foci of individual cell necrosis within tumour papillae
Explanation
Psammoma bodies in PTC are concentric laminated calcification (calcospherites) that form through dystrophic calcification of individual necrotic tumour cells within papillary stalks; they virtually never occur in follicular carcinoma or adenoma and serve as a diagnostic clue for PTC or metastatic PTC. Calcitonin-derived amyloid with calcification is seen in medullary thyroid carcinoma.
Reference: Robbins & Cotran Pathologic Basis of Disease, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.