Performance of the 2023 Bethesda System for Reporting Thyroid Cytopathology in a pediatric cohort: a single-center experience.

BACKGROUND: Pediatric thyroid nodules are uncommon but have higher malignancy risk than adult nodules. The 2023 TBSRTC updated ROM estimates and expanded pediatric guidance, but data remain limited. METHODS: We reviewed 63 thyroid FNAs from patients aged 21 years or younger at a tertiary center (January 2023-October 2025). Cases were classified according to the 2023 TBSRTC. Observed ROM was calculated in resected nodules with exact 95% CIs. Bethesda III nodules were subclassified as AUS with nuclear atypia or AUS-other. RESULTS: Diagnoses were Bethesda I in 5/63 (7.9%), Bethesda II in 32/63 (50.8%), Bethesda III in 3/63 (4.8%), Bethesda IV in 10/63 (15.9%), Bethesda V in 13/63 (20.6%), and Bethesda VI in 0/63 (0%). Histologic follow-up was available for 36 nodules. Observed ROM among resected nodules was 0/1 (0.0%) for Bethesda I, 1/11 (9.1%) for Bethesda II, 2/3 (66.7%) for Bethesda III, 4/8 (50.0%) for Bethesda IV, and 12/13 (92.3%) for Bethesda V. The two malignant Bethesda III cases were AUS with nuclear atypia; the AUS-other case was benign. Overall malignant yield was 19/36 (52.8%). CONCLUSIONS: The 2023 TBSRTC was applicable in this pediatric cohort. Bethesda II, IV, and V ROM estimates were broadly consistent with published pediatric data, whereas Bethesda III was imprecise because only three nodules were resected. Larger multicenter studies with standardized follow-up and explicit AUS subclassification are needed.