Anatomic pathology selected abstracts
May 2024—The Bethesda System for Reporting Thyroid Cytopathology described four subclasses of atypia within the atypia of undetermined significance category: nuclear (AUS-Nuc), architectural (AUS-A), oncocytic (AUS-Onc), and atypia not otherwise specified (AUS-NOS). Accumulating evidence supports the use of a binary AUS subclassification scheme based primarily on the presence of nuclear atypia only. The authors conducted a study to compare the risk stratification of binary versus four-tier AUS subclassification systems among AUS nodules with molecular or histologic follow-up, or both. The study included thyroid aspirates classified as AUS and tested using Afirma (Veracyte Inc.) between June 2013 and July 2021. Histological classification was considered the final outcome for resected nodules.