The use of The Bethesda System for Reporting Thyroid Cytopathology in a Chinese population: An analysis of 13 351 specimens

AIMS: The Bethesda System for Reporting Thyroid Cytopathology (TBSRTC) has been widely adopted since its introduction. In this study, we aimed to report our experience using this reporting system at a College of American Pathologists (CAP)-accredited hospital laboratory in a large series of Chinese patients. METHODS: All patients who underwent preoperative ultrasound-guided thyroid fine-needle aspiration (FNA) from January 2011 to August 2016 were retrospectively analyzed. Thyroid FNAs were classified according to the Bethesda System. For patients who underwent subsequent surgery at our institution, the diagnostic performance of the preoperative FNA was further analyzed according to four different calculation criteria. All of the follicular variants of papillary thyroid carcinoma specimens were reviewed to exclude NIFTP (noninvasive follicular thyroid neoplasm with papillary-like nuclear features). RESULTS: A total of 13 351 thyroid FNAs were included in this analysis. Of the 12 530 sampled patients, 3594 (28.7%) underwent thyroidectomy, and the malignancy rates for each cytological category were as follows: 66.7% unsatisfactory, 14.2% benign, 53.5% undetermined significance, 30.2% follicular neoplasm, 82.0% suspicious, and 99.1% malignant. Only 12 (0.36% of all PTC) patients were reclassified as having NIFTP. The sensitivities of the preoperative FNAs were all above 95.0% and were as high as 99.0%. The specificities ranged from 50.3% to 63.9%, depending on which criteria were used. The positive predictive value was 95.4% for criteria 1 and 2 and was 94.2% for criteria 3 and 4. The negative predictive values ranged from 64.5% to 85.8%. The diagnostic accuracies all exceeded 90.0%, with the highest being 94.8%. CONCLUSION: This study revealed the great efficacy and accuracy of TBSRTC in a large Chinese population for the first time.