How Can We Predict Malignancy of Thyroid Nodules with AUS/FLUS from Ultrasonographic Features?

Purpose: Atypia/follicular lesions of undetermined significance (AUS/FLUS) as Bethesda System category 3, cannot be classified as benign or malignant. The purpose of this study was to identify which clinical factor increases the risk of malignancy in patients with AUS/FLUS. Methods: A total of 158 patients with AUS/FLUS, who underwent thyroid surgery at the au-thors’ institution, were examined retrospectively. Chi square analyses were performed to compare the benign and malignancy group based on their final pathology to assess the in-dependent effects of risk factors, such as age, sex, size of nodule, the number of FNAC, ultrasonography findings, and the number of malignancy ultrasonography findings in a single nodule. Results: In the analyses, age, sex, the number of FNAC, contents, and shape were not significantly related to the cancer diagnosis. Marked hypoechogenicity, spiculated margin, mi-crocalcification, and showing three or more ultrasonographic risk features were significantly related to an increased malignant risk. Conclusion: Surgical resection of thyroid nodules should be considered in an AUS group showing three or more ultrasonographic risk findings.