Thyroid imaging reporting and data system in assessment of cytological Bethesda Category III thyroid nodules.

OBJECTIVE: To assess the usefulness of thyroid imaging reporting and data system (TI-RADS) for cytological Bethesda Category III thyroid nodules (TNs).

METHODS: This retrospective study included 121 patients with 121 TNs classified as Bethesda Category III at fine needle aspiration (FNA) cytology and thereafter underwent surgery. The TNs were classified according to US TI-RADS category and the malignancy risk of each category was calculated.

RESULTS: Surgical pathology confirmed 43 (35.5%) malignant and 78 (64.5%) benign TNs. The malignancy risks of categories 3, 4a, 4b, 4c, and 5 TNs were 0%, 4.0%, 12.5%, 62.2%, and 100%, respectively. For those >10 mm (n = 55), the malignancy risks were 0%, 6.2%, 12.5%, 73.3%, and 100%, respectively, whereas for those ≤10 mm (n = 66), the risks were 0%, 0%, 12.5%, 56.7%, and 100%, respectively.

CONCLUSION: Bethesda Category III TNs without suspicious US features or those ≤10 mm with only one suspicious US feature can be followed up with US.