Muhammet KOCABAS, Hulya KAYNAK, Yusuf OZTURK, Melia KARAKOSE
The Atlantic Journal of Medical Science and Research - 2026;6(1):46-52
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 AUS-preceded DTC group (45.8% vs. 29.0%, p<0.001). The frequencies of extrathyroidal extension (6.1% vs. 20.2%, p<0.001), capsular invasion (6.1% vs. 16.8%, p=0.040), and lymphatic invasion (12.2% vs. 24.7%, p=0.030) were significantly lower in the AUS-preceded group. Lymph node metastasis (16.8% vs. 32.2%, p=0.001) and distant metastasis (0.0% vs. 3.7%, p=0.026) were also less common. Only one patient (0.8%) in the AUS-preceded DTC group was classified as ATA high risk compared with 39 (10.4%) in the non-AUS-preceded DTC group (p=0.001). Conclusion: DTC preceded by AUS cytology exhibits more favorable pathological and prognostic features than the non-AUS-preceded DTC population. These tumors are typically smaller, less invasive, and associated with lower ATA risk categories. AUS cytology may therefore provide prognostic insight beyond its diagnostic role and support more individualized, conservative management strategies in low-risk patients.
