Follow up or FNAB?: Malignancy Rates of ACR TI-RADS 4 and 5 Thyroid Nodules <10 mm in Diameter.

Abstract

The aim of this study is to ascertain the rate of malignancy in nodules that are less than 10 mm in diameter in the TR-4 and TR-5 categories, as defined by the American College of Radiology Thyroid Imaging and Reporting Data System 2017 whitepaper and to open a discussion on the strategy of approach to PTMCs. Prospective cohort study. Single academic medical center. All thyroid ultrasound examinations were performed by 2 senior radiologists with consensus. The fine-needle aspiration biopsy procedure was performed under the guidance of ultrasound. All patients underwent surgery, except for those with benign cytology. Among 60 nodules, 15 nodules (25%) were classified as TR-4 and 45 nodules (75%) as TR-5. Based on cytological analysis, 12 of the 15 nodules classified in the TR-4 category (80%) were benign, while 3 nodules (20%) were classified as nonbenign. In the assessment of 45 TR-5 nodules, 30 (66.7%) were identified as nonbenign, while the remaining 15 (33.3%) were classified as benign. Surgery was performed on all 33 patients with nonbenign FNAB results, and the histopathological results confirmed malignancy in 3 TR-4 nodules (20%) and in 29 TR-5 nodules (64.4%). Our study highlights that TR-4 and TR-5 thyroid nodules smaller than 10 mm exhibit high malignancy rates. Despite limitations such as small sample size and single-center design, our findings support the consideration of FNAB in selected <10 mm nodules, particularly when active surveillance is unsuitable.