Factors associated with the sensitivity of fine-needle aspiration cytology for the diagnosis of follicular variant papillary thyroid carcinoma

Background The purpose of this study was to evaluate the factors associated with diagnostic accuracy of preoperative fine-needle aspiration (FNA) for follicular variant papillary thyroid carcinoma (FVPTC). Methods The patients with FVPTC who underwent thyroidectomy were divided into 2 groups: "group A" (Bethesda category II, III, or IV) versus "group B" (category V or VI). Results A total of 225 patients (117 in group A and 108 in group B) were included. Group B was associated with older age, malignant ultrasonographic features, smaller tumor size, extrathyroidal extension, higher stage, and B-type Raf (BRAF)^V600E mutation compared with group A. In multivariable analysis, malignant ultrasonographic features and tumor size ≤3.0 cm were independent predictive factors for group B. Conclusion FVPTCs >3.0 cm are unlikely to be diagnosed as category V or VI. Clinicians should keep FVPTC in mind and consider diagnostic lobectomy for the nodules regardless of FNA or ultrasonographic findings.