A 45-year-old woman has a 2 cm thyroid nodule. FNA shows follicular neoplasm. The pathologist notes a capsule but no capsular or vascular invasion on histology. What is the correct classification?
- A Minimally invasive follicular carcinoma
- B Follicular adenoma ✓
- C Widely invasive follicular carcinoma
- D Papillary thyroid carcinoma, follicular variant
Correct answer: B. Follicular adenoma
Explanation
Follicular adenoma is distinguished from follicular carcinoma solely by the absence of capsular or vascular invasion on histology; FNA cannot reliably make this distinction. Minimally invasive follicular carcinoma shows limited capsular or vascular invasion, while widely invasive carcinoma shows extensive invasion. Since neither is present, this is adenoma.
Reference: Robbins & Cotran Pathologic Basis of Disease, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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