Malignant risk of pediatric Bethesda category III thyroid nodules subcategorized by nuclear atypia and other: A single institution experience

Abstract

AbstractBackgroundThe 2023 Bethesda System for Reporting Thyroid Cytopathology (TBSRTC) divides AUS diagnoses into two major subcategories: atypia of undetermined significance (AUS) nuclear atypia (AUS‐N) and other (AUS‐O). This study aims to compare the histological outcome and malignant rate of pediatric AUS thyroid nodules classified into AUS‐N and AUS‐O subcategories.DesignA search of our institutional electronic pathology database for the period from January 2012 to July 2023 was conducted to identify pediatric (<21 years old) thyroid nodules that were interpreted as AUS and subsequently had surgery. Cases were further divided into AUS‐N and AUS‐O subcategories. Results of follow‐up surgical resections were collected. The malignant rate was calculated and compared between AUS‐N and AUS‐O groups.ResultsThe study identified 62 thyroid nodules from 58 pediatric patients. Among these nodules, 29 and 33 were subcategorized as AUS‐N and AUS‐O, respectively. Both groups exhibited a female predominance and displayed a similar nodule size distribution. Histological analysis revealed 15 carcinomas in AUS‐N nodules, including 11 cases of classic papillary thyroid carcinoma (PTC) and four cases of follicular type of PTC. In contrast, in the AUS‐O group, a total of five carcinomas were documented, including two PTCs and three oncocytic thyroid carcinomas. Notably, the malignant rate of AUS‐N nodules (52%) is significantly higher than that of AUS‐O nodules (15%) (p = .002).ConclusionIn pediatric AUS thyroid nodules, the malignant risk in AUS‐N is significantly higher than that in AUS‐O. These findings may guide more appropriate clinical triage and/or improve management of pediatric patients with AUS thyroid nodules.