A review of urinary cytology in the setting of upper tract urothelial carcinoma.

Urothelial carcinomas of the upper urinary tract (UUT) are uncommon. Cytological examination of voided urine or washings from the UUT has been part of the standard workup for upper tract urothelial carcinoma (UTUC); however, its value remains controversial. The lack of uniform terminology and specific diagnostic criteria could also have contributed to the inferior performance of urinary cytology for detecting UTUC. The Paris System for Reporting Urinary Cytology (TPS) has provided a standardized reporting system for urinary cytology specimens with clearly defined cytomorphologic diagnostic criteria and found acceptance on an international level after its implementation in 2016. Recent studies have shown that TPS has led to improved diagnostic performance of urinary cytology; however, most of these studies had focused on the evaluation of lower urinary tract cytology specimens. Only a limited number of new research studies have analyzed the effect of TPS when applied to UUT cytology specimens. In the present report, we have summarized the current understanding and utility of UTUC, including its molecular biology, and reviewed the current literature.