Reclassification of cytologically atypical thyroid nodules based on radiologic features in pediatric patients.

Abstract

In children the percentage of "Atypia of undetermined significance/follicular lesion of undetermined significance" ("AUS/FLUS") cases is greater and the risk of malignancy is higher than expected. Our study aimed to determine if cytologically atypical nodules can be better characterized using imaging techniques for appropriate management of pediatric patients. Thyroid fine needle aspiration (FNA) specimens were reclassified using the Bethesda System for Reporting Thyroid Cytopathology (BSRTC). Cytologic-histologic correlation was performed to determine if the cytopathologic groups had different associations with the surgical outcome. The "AUS/FLUS" lesions were then subdivided based on radiologic features and the outcome was analyzed for each subgroup. Histologically benign follicular nodules showed uniform distribution between the "benign" vs. "AUS/FLUS" (p=0.09) or between the "AUS/FLUS" vs. "follicular neoplasm" ("FN") cytologic groups (p=0.27). The follicular neoplasms were also evenly distributed between the "FN" vs. "AUS/FLUS" categories (p=0.31). "Benign", "AUS/FLUS", and "FN" designations showed comparable associations with papillary thyroid carcinoma classical variant (PTC-cv). Reclassification of atypical lesions based on ultrasound findings yielded two subcategories with different risk of malignancy: one similar to the "benign" group (11% malignancy rate) and one comparable with the "FN" category (28% risk of malignant neoplasm). "AUS/FLUS" designation does not add significant value in categorization of pediatric thyroid nodules. These lesions can be reclassified based on radiologic features to provide accurate information for follow-up.