Eliminating the "Atypia of Undetermined Significance/Follicular Lesion of Undetermined Significance" Category From the Bethesda System for Reporting Thyroid Cytopathology

The "Atypia of Undetermined Significance/Follicular Lesion of Undetermined Significance (A US/FLUS)" category in the Bethesda System for Reporting Thyroid Cytology is heterogeneous and includes both specimens with borderline cellularity/compromised quality and those with genuine atypia. We have used a reporting scheme that is similar to the Bethesda System but does not include an AUS/FLUS category. We retrospectively reviewed all reports on thyroid FNA and thyroidectomy specimens submitted to the Beth Israel Deaconess Medical Center from January 2006 to December 2008. The positive predictive values for various categories and subcategories in this scheme demonstrate that the AUS/FLUS category can be eliminated to provide information for the most appropriate management of patients with thyroid nodules.