The impact of thyroid imaging reporting and data system on the management of Bethesda III thyroid nodules

Objectives: Atypia of undetermined significance (AUS) or follicular lesion of undetermined significance (FLUS) is a heterogeneous category of fine needle aspiration cytology (FNAC); the management of this condition re-mains controversial. The clinical significance of such patients relies on the exclusion of malignancy. In this study, we aimed to determine the validity of the Amer-ican College of Radiology Thyroid Imaging Reporting and Data System (ACR TI-RADS) (2017) for predicting malignancy in this specific category of patients.Methods: In this study, we analysed a cohort of patients from our previous retrospective study. This four-year retrospective cohort study included all cases undergoing surgery with a cytological diagnosis of AUS/FLUS. We enrolled 110 cases with documented final histopatholog-ical diagnoses and ultrasound examinations.Results: The study included 83 females (75.5%) and 27 males (24.5%). The overall risk of malignancy (ROM) for AUS/FLUS thyroid nodules was 47.3%. The ROMs of TI-RADS 3 (TR3), TI-RADS 4 (TR4), and TI-RADS 5 (TR5) were 43.5%, 49.4% and 40%, respectively. There was no significant association between TI-RADS and final pathological analysis.Conclusions: Repeated FNAC with initial AUS/FLUS nodules is crucial. Our findings showed that ACR TI-RADS did not contribute to the cancer risk stratifica-tion of AUS/FLUS nodules. A large prospective multi-institutional study is now required to determine the val-idity of ACR TI-RADS and whether other adjunct clin-ical, cytological, molecular, or biochemical tools could facilitate the management of patients with these hetero-geneous nodules.

Automated summary

This study aimed to determine the validity of the American College of Radiology Thyroid Imaging Reporting and Data System (ACR TI-RADS) for predicting malignancy in patients with atypia of undetermined significance (AUS) or follicular lesion of undetermined significance (FLUS). The findings showed that ACR TI-RADS did not contribute to the cancer risk stratification of AUS/FLUS nodules. Further large-scale prospective multi-institutional studies are needed to determine the validity of ACR TI-RADS and explore other potential tools for managing patients with these heterogeneous nodules.