Current status and diagnostic values of the Bethesda system for reporting thyroid cytopathology in a papillary thyroid carcinoma–prevalent area

Background: Most studies validating the Bethesda system for reporting thyroid cytopathology (TBSRTC) have been conducted in Western countries. We explored the current status of TBSRTC in an area where most thyroid malignancies are papillary carcinomas. Methods: Fine-needle aspirations (FNAs) of thyroid nodules performed in 2013 were retrospectively analyzed and the results were compared to final pathology on resection. Results: Of 1947 FNAs, 1925 (98.9%) were reported using TBSRTC. Among 381 resected lesions, 27.3% of nondiagnostic, 19.6% of benign, 56.0% of atypia of undetermined significance/follicular lesion of undetermined significance (AUS/FLUS), 33.3% of follicular neoplasm/suspicious for a follicular neoplasm (FN/SFN), 97.7% of suspicious for malignancy, and 100.0% of malignant lesions were malignant on pathology. The sensitivity and specificity of FNA using TBSRTC were 96.7% and 84.1%, respectively. Conclusion: TBSRTC works well in an area in which papillary thyroid cancer is prevalent; however, it may underestimate malignancy rates in AUS/FLUS, benign, and nondiagnostic categories.