Management of Nondiagnostic Thyroid Fine Needle Aspiration Cytology Nodules Based on TI-RADS Risk Assessment

The high prevalence of thyroid nodules and the frequent occurrence of nondiagnostic (ND) results on fine-needle aspiration (FNA) necessitates malignancy risk stratification to balance cancer detection while avoiding unnecessary repeat biopsies. This study evaluated malignancy rates and management strategies for nodules with ND cytology, stratified by the American College of Radiology Thyroid Imaging Reporting and Data System (TI-RADS) score.

This retrospective study analyzed 342 consecutive patients with initial ND ultrasound-guided (USG) thyroid FNA from a high volume, two-practitioner clinic between January 2019 and June 2024. Data collected from chart review included Bethesda cytopathology classifications, management approaches, and final histopathological diagnosis when available.

Among 3717 thyroid FNAs performed during the study period, 342 (9.2%) were ND on initial sampling. TI-RADS (TR) distribution for ND nodules was: TR1 9.6%, TR2 9.9%, TR3 28.1%, TR4 45.3%, TR5 7.0%. Initial management comprised repeat FNA in 170 (49.7%) patients, ultrasound (US) surveillance in 101 (29.5%), surgery in 17 (5.0%); 54 (15.8%) patients were lost to follow-up. Of repeat FNAs, 47 (27.6%) remained ND. Among 33 surgical cases, malignancy was identified in 6 (1.8%) index nodules with initial ND cytology. Five malignancies occurred in TR4 nodules and one in a TR5 nodule. Importantly, there were no malignancies among 17 resected TR1-3 nodules.

For experienced practitioners in a high-volume clinic, ND thyroid FNA cytology carries a low overall observed risk of malignancy (1.8%). TI-RADS scores should be taken into consideration to guide management decisions for ND cytology nodules between repeat FNA, US surveillance, or surgery.