A thyroidectomy specimen from a 35-year-old woman shows diffuse lymphocytic infiltration with well-formed germinal centers, atrophic thyroid follicles lined by large cells with abundant granular eosinophilic cytoplasm, and interstitial fibrosis. These eosinophilic cells are best described as:

• A Psammoma body forming cells
• B Parafollicular C cells with neuroendocrine granules
• C Hürthle cells (oncocytes) with mitochondria-rich cytoplasm ✓
• D Squamous metaplastic cells derived from thyroglossal duct remnants

Explanation

Hashimoto thyroiditis shows lymphoid germinal centers, atrophic follicles, and prominent Hürthle cell change: follicular epithelial cells transformed into large oncocytes packed with mitochondria, giving granular eosinophilic cytoplasm. B cells are inconspicuous normal parafollicular cells and do not line follicles. Squamous metaplasia can occur in Hashimoto but does not produce granular eosinophilic cytoplasm, so it does not fit the described cell morphology.

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.