Assessment of Thyroid Fine Needle Aspirates Using 2023 Bethesda System.

Abstract

Background: Thyroid nodules are common, with about 5% being malignant, necessitating accurate evaluation to avoid unnecessary surgeries. Fine-needle aspiration cytology (FNAC) is a crucial diagnostic tool, and the 2023 Bethesda System for Reporting Thyroid Cytopathology (TBSRTC) refines FNAC's diagnostic accuracy and risk stratification for thyroid lesions.

Materials and methods: This retrospective study re-classified thyroid FNAs performed at a tertiary care center from January 2023 to June 2024 using the 2023 TBSRTC and compared with available histopathological diagnoses. FNAC slides were reviewed and reclassified according to the 2023 TBSRTC categories by two cytopathologists. Statistical analysis included sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and overall diagnostic accuracy.

Results: The study included 387 patients (female-to-male ratio of 4:1), with 8% non-diagnostic, 61.5% benign, 9% AUS, 7.5% FN, 8% SFM, and 6% malignant cases. Histopathological correlation was available for 190 cases, revealing 126 benign and 64 malignant lesions. Considering NIFTP as benign on histopathology, the ROM for benign, FN, and SFM categories was 10%, 38%, and 69.2%, respectively. The highest sensitivity (88.2%) was achieved when AUS, FN, SFM, and malignant categories were considered positive for malignancy. The highest diagnostic accuracy (85.4%) was observed when SFM and malignant categories were considered positive.

Conclusion: FNAC, guided by the 2023 TBSRTC, is a reliable diagnostic tool for thyroid lesions, offering high sensitivity and specificity.