Abstract:

Objective To investigate the distribution characteristics of BRAF^V600E mutation in cytological diagnosis of thyroid fine-needle aspiration cytology (FNAC) and analyze the diagnostic value of combining FNAC with BRAF^V600E mutation detection for the preoperative diagnosis of papillary thyroid carcinoma (PTC). Methods A retrospective analysis was conducted on 261 consecutive thyroid nodules that underwent FNAC at Huadong Hospital Affiliated to Fudan University between November 2021 and January 2024. All nodules were tested for mutations in BRAF, TERT, RET, HRAS, KRAS, NRAS, PPARG, and NTRK genes using the amplification refractory mutation system-polymerase chain reaction (ARMS-PCR). The distribution of BRAF^V600E mutations across the Bethesda system for reporting thyroid cytopathology (TBSRTC) was analyzed. Among the 261 thyroid nodules, 69 underwent postoperative histopathological examination, including 65 diagnosed as PTC, 3 as follicular tumors, and 1 as a follicular nodule. Using postoperative histopathology as the gold standard, the diagnostic value (accuracy, sensitivity, and specificity) of FNAC combined with BRAFV600E mutation detection for preoperative PTC diagnosis was analyzed. Results Among the 261 FNAC samples, 98 thyroid nodules were BRAF^V600E -positive, with 78.6% of positive samples classified as category Ⅴ or Ⅵ in the TBSRTC. The accuracy of FNAC, BRAF^V600E mutation detection, and their combination in differentiating PTC was 76.8%, 81.2%, and 89.9%, respectively. The sensitivi-ty was 76.9%, 80.0%, and 90.8%, and the specificity was 75.0%, 100.0%, and 75.0%, respectively. The area under the ROC curve (AUC) for each method was 0.759 6, 0.900 0, and 0.828 8, respectively. Z-test results showed that the AUC of FNAC combined with BRAF^V600E mutation detection was improved compared to that of FNAC alone (P=0.008 2). Conclusion This study has found that 78.6% of BRAF^V600E mutation-positive cases were classified as categories Ⅴ and Ⅵ in the TBSRTC, indicating that BRAF^V600E mutation detection can serve as an important supplementary marker for diagno-sing high-risk PTC nodules. Compared with FNAC alone, the combination of FNAC and BRAF^V600E mutation detection improves the preoperative diagnostic accuracy of PTC.

Key words: Fine-needle aspiration cytology, BRAF^V600E mutation detection, Papillary thyroid carcinoma, Diagnostics