Initial AUS cytology is associated with favorable prognostic features in differentiated thyroid carcinoma

Aim: To evaluate whether differentiated thyroid carcinoma (DTC) cases that follow an initial fine-needle aspiration biopsy (FNAB) result of atypia of undetermined significance (AUS) differ in their clinicopathological characteristics and prognostic features compared with DTC cases without prior AUS cytology.Materials and Methods: Medical records of 936 patients with an initial FNAB result of AUS between January 2019 and December 2023 were retrospectively reviewed.Among them, 307 underwent surgery, and 139 (45.3%) were found to have malignant lesions on final histopathology.Of these, 131 were diagnosed with DTC and comprised the "AUS-preceded DTC" group, which was compared with 376 patients in the "non-AUS-preceded DTC" cohort.Data on histopathological type, invasion patterns, metastasis, Tumor-Node-Metastasis (TNM) stage, and American Thyroid Association (ATA) risk classification were analyzed.Results: Microcarcinoma (≤10 mm) was significantly more frequent in the AUSpreceded DTC group (45.8% vs. 29.0%,p