A 28-year-old woman with Graves disease has a diffusely enlarged thyroid. The pathological finding on histology that reflects the effect of TSH receptor-stimulating antibodies is:

• A Large colloid-filled follicles with flattened follicular epithelium
• B Nodular fibrosis replacing most follicular tissue
• C Riedel thyroiditis with dense fibrosis extending into adjacent soft tissues
• D Follicular epithelial hypertrophy and hyperplasia with scalloping of colloid and lymphocytic infiltration ✓

Explanation

In Graves disease, TSH receptor-stimulating antibodies (TRAb) chronically stimulate follicular cells, causing diffuse hyperplasia. Histologically this manifests as follicular epithelial hypertrophy (columnar cells), hyperplasia with papillary infoldings, and scalloping (vacuolation) of the colloid at the epithelial-colloid interface reflecting active reabsorption. A lymphoid infiltrate with germinal centres reflects the autoimmune background. Flattened epithelium and large colloid-filled follicles characterise hypothyroid (colloid) goitre.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.