Malignancy rate of atypia of undetermined significance/follicular lesion of undetermined significance in thyroid nodules undergoing FNA in a suburban endocrinology practice: A retrospective cohort analysis.

Background: The Bethesda System for Reporting Thyroid Cytopathology (TBSRTC) was created to establish a standard terminology regarding thyroid nodules that can be shared between endocrinologists, pathologists, radiologists, and surgeons. Since its inception and use in 2009, multiple large hospitals and academic institutions have performed retrospective studies to compare their classification rates, specifically those of atypia of undetermined significance (AUS) and follicular lesion of undetermined significance (FLUS), with the recommended rates created by the National Cancer Institute. The current study compared AUS/FLUS rates at a private suburban endocrine practice with those of previous publications from large institutions and the rates established by the National Cancer Institute.