Atypical Urothelial Cells (AUC)

Abstract

Atypia is admittedly a difficult topic to cover no matter what the organ system it is in. The most important reason for this is its subjective nature – it is in the eye of the beholder. In keeping with the mantra of The Paris System for Reporting Urinary Cytology, the goal for the “atypical urothelial cells” (AUC) category is to capture the cases worrisome for high-grade urothelial carcinoma that fall short of the “suspicious for high-grade urothelial carcinoma” (SHGUC) category. It is important to ensure that known causes of atypia such as polyomavirus change, treatment effect, etc., are classified as “negative for high-grade urothelial carcinoma” (NHGUC), and not under the AUC category. In order to make this a tangible and more objective category we have set forth criteria for AUC using four main cytomorphologic features: nuclear to cytoplasmic (N/C) ratio, nuclear chromasia, chromatin pattern, and features of the chromatinic rim. From a clinical standpoint, whenever the diagnosis of AUC is rendered on a case, this inconclusive category may create confusion and anxiety in the patient, and may lead to unnecessary procedures. Therefore, we recommend that the “AUC” interpretation should be kept at a minimum, and not be used as a waste basket.