Optimal timing of repeat thyroid fine-needle aspiration biopsy

The objective of this study is to determine the optimal interval between repeat thyroid fine-needle aspiration (FNA) biopsies in children and adolescents and to evaluate whether this has any impact on the final pathological diagnosis.

The sample of this retrospective single-center study consisted of 99 patients who had thyroid nodules and underwent thyroid ultrasonography (USG) and FNA biopsy between 2013 and 2023. The interval between FNA biopsies as well as biopsy and surgical cytology results were recorded for each patient.

The mean age of the sample, 70.7 % of which were females, was 14.04 ± 3.29 years. According to the initial FNA biopsy results, 46.5 % of thyroid nodules were identified as benign, 24.2 % as nondiagnostic, 10.1 % as atypia of undetermined significance, 8.1 % as follicular neoplasm, 6.1 % as suspicious for malignancy, and 5.1 % as malignancy. It was decided to perform thyroidectomy in 34 patients.

The false-negative rate (6.5 %) we found in patients with a benign initial FNA cytology was slightly higher than the rate stated in the guidelines. Additionally, we determined that performing early (<3 months) repeat FNA biopsy for nondiagnostic nodules did not affect the diagnostic yield of subsequent samples. Therefore, we concluded that repeat FNA biopsy should not be delayed longer than 3 months in nondiagnostic nodules with suspicious USG findings and no longer than 6 months in benign nodules with suspicious USG findings. A shorter interval between FNA biopsies will allow for more timely surgical intervention, especially in patients with malignancy in nondiagnostic and benign nodules.