Significance of FNAC, BRAF mutation, and intraoperative frozen section in surgical decision‐making of thyroid nodules

Abstract

A preoperative method is desired to discriminate benign from malignant thyroid nodules. This retrospective study evaluated the diagnostic performance of BRAF (B-Raf proto-oncogene) mutation (BRAFV600E ) positivity and fine-needle aspiration cytology (FNAC) relative to intraoperative frozen section pathology. Patients underwent preoperative FNAC of thyroid nodules. Cytology specimens were classified according to the Bethesda System for Reporting Thyroid Cytopathology (BSRTC), and analyzed for BRAFV600E using an amplification-refractory mutation system (ARMS). Thyroid tissue was surgically removed and frozen sections processed for histology. The sensitivities and specificities of each analysis were compared, alone and in combination. Among 346 patients, 333/358 FNACs (93%) showed malignant nodules; 322 (93%) patients received a pathological diagnosis of papillary thyroid carcinoma (PTC). The sensitivity and specificity of BSRTC VI for malignancy was the highest among the BSRTC categories. Compared with FNAC, the BRAFV600E analysis had significantly higher sensitivity and specificity. The diagnostic efficacy of frozen section pathology was significantly higher than that of either BSRTC category or BRAFV600E analysis alone. Combining methods variably improved diagnostic performance. BRAFV600E was not associated with capsule infiltration, neurovascular infiltration, mono- or multifocal PTC, lymph node metastasis, or clinical stage. The diagnostic performance of preoperative BRAFV600E determination was better than that of the BSRTC-FNAC category; combining both improved sensitivity and specificity. Patients with positive malignancy scores from both should be recommended for surgery; those with negative scores require close monitoring. Surgical treatment should include comprehensive intraoperative frozen section assessment. BRAF mutations cannot indicate aggressive treatment.