Follicular variant of papillary thyroid carcinoma with B-type Raf^V600E showing higher frequency of suspicious sonographic features and multifocality

Background The purpose of this study was to investigate the correlation between B-type Raf (BRAF) kinase mutation and clinicopathological features of follicular variant of papillary thyroid carcinoma (PTC). Methods Eighty-four patients with pathologically confirmed follicular variant of PTC, who underwent a preoperative BRAF^V600E study, were analyzed. Clinicopathological parameters and ultrasonographic features were compared between the BRAF^V600E-positive and negative groups. Results A total of 41.7% of the patients showed BRAF^V600E. The BRAF^V600E-positive group showed the smaller tumor size (7.3±3.6 mm vs 10.7±8.9 mm; p=.018) and the more frequent multifocality (25.7% vs 8.2%; p=.028). Follicular variant of PTC with BRAF^V600E showed suspicious ultrasonographic features (88.6% vs 57.1%; p=.002) more frequently. BRAF^V600E positivity is associated with multifocality after adjusting for age, sex, the presence of suspicious ultrasonographic features, pathological tumor size, and thyrotropin level. Conclusion BRAF^V600E was correlated with smaller tumor size and suspicious ultrasonographic features in follicular variant of PTC. BRAF^V600E was a significant parameter for predicting multifocality of follicular variant of PTC.