A 35-year-old woman has a thyroid nodule. FNA cytology shows cells arranged in a papillary configuration with characteristic nuclear features: nuclear grooves, intranuclear pseudoinclusions (Orphan Annie eye nuclei), and powdery chromatin. Molecular analysis would most likely reveal:
- A RAS point mutation
- B BRAF V600E mutation ✓
- C RET/PTC rearrangement only
- D PAX8-PPARγ fusion
Explanation
The nuclear features described (nuclear grooves, intranuclear pseudoinclusions, ground-glass/Orphan Annie nuclei, powdery chromatin, nuclear overlap) are pathognomonic of papillary thyroid carcinoma (PTC). BRAF V600E mutation is the most common molecular alteration in PTC, found in approximately 45-60% of cases. RET/PTC rearrangements are found in ~10-20%, particularly in radiation-associated PTC in children. RAS mutations are more common in follicular thyroid carcinoma (FTC) and follicular-patterned PTC variants. PAX8-PPARγ fusion characterises follicular carcinoma.
Reference: Robbins & Cotran Pathologic Basis of Disease, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.