A 40-year-old woman has a thyroid nodule. FNA shows nuclear clearing ('Orphan Annie eye' nuclei), nuclear grooves, and nuclear pseudoinclusions. The MOST likely diagnosis is:
- A Follicular adenoma
- B Medullary thyroid carcinoma
- C Papillary thyroid carcinoma ✓
- D Anaplastic carcinoma
Correct answer: C. Papillary thyroid carcinoma
Explanation
The nuclear features of papillary thyroid carcinoma (PTC) are its defining cytological hallmarks: ground-glass 'Orphan Annie eye' nuclei (cleared chromatin), nuclear grooves (longitudinal folds), and nuclear pseudoinclusions (cytoplasmic invaginations into the nucleus). These features are diagnostic even without papillary architecture, making FNA highly sensitive for PTC. BRAF V600E mutation is present in ~60% of PTC cases.
Reference: Robbins & Cotran Pathologic Basis of Disease, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.