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Background: The Bethesda system for reporting thyroid cytopathology (TBSRTC) is a standardized and reproducible system. It is used worldwide to interpret fine-needle aspiration cytology (FNAC) of thyroid. A crucial issue of thyroid FNA is its accuracy comparing with the final histologic outcomes. This may vary on many factors e.g., nature of lesion, quality of the cytologic specimen, pathologist’s experience, etc.
Aim: To evaluate the accuracy of TBSRTC from FNAC. Nature of lesion which may impact the accuracy was also studied.
Method: A retrospective study evaluating data of TBSRTC in our hospital during January 2013 to June 2021 were reviewed and compared to its final histologic outcomes to determine diagnostic accuracy.
Results: 3714 FNA procedures were done at Vajira Hospital from January 2013 to June 2021, consisting of 3,266 (87.94%) females and 448 (12.06%) males. The female: male incidence ratio was approximately 7:1. The age at diagnosis was ranged from 14 to 86 years (median 53 years). A total of 527 patients (461 female; 87.5%, and 66 male; 12.5%) underwent surgical resection with available histopathology evaluation. From those cases, the FNAC reports revealed 172 (32.6%) cases as non-diagnostic/unsatisfactory (ND/US), 216 (41.0%) cases as benign, 87 (16.5%) cases as atypical of undetermined significant or follicular lesion of undetermined significance (AUS/FLUS), 4 (0.8%) cases as follicular neoplasm or suspicious for follicular neoplasm (FN/SFN), 36 (6.8%) cases as suspicious for malignancy (SM), and 12 (2.3%) cases as malignant. The risk of malignancy (ROM) in operated thyroid specimen was 15.7%, 15.3%, 33.3%, 0%, 91.7%, and 91.7%, respectively
Conclusions: The accuracy of thyroid FNAC at our hospital was high in malignant groups including category V and VI. However, the ROM in categories I, II, III, and V exceeded the suggested limit in TBSRTC. We strongly encourage medical practitioners in all professions to use TBSRTC because it is an international standard that shares a common understanding and helps guide patient management.
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