A thyroidectomy specimen from a 35-year-old woman shows a diffusely enlarged gland with a firm, tan-white cut surface. Microscopy reveals a dense lymphoplasmacytic infiltrate with well-formed germinal centers and thyroid follicles lined by large cells with abundant granular eosinophilic cytoplasm. The follicular epithelial change described is:

• A Squamous metaplasia
• B Hurthle cell (oncocytic) metaplasia ✓
• C C-cell hyperplasia
• D Papillary nuclear atypia

Explanation

Hashimoto thyroiditis is characterized by a dense lymphocytic infiltrate with reactive germinal centers, atrophic follicles, and transformation of follicular epithelium into Hurthle cells, which are large cells with abundant granular eosinophilic cytoplasm packed with mitochondria. Squamous metaplasia may occur but is not the defining epithelial change. Psammoma bodies suggest papillary carcinoma, and granulomas would indicate subacute thyroiditis.

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.