Applicability of the Paris System for veterans: high rates of undiagnosed low-grade urothelial neoplasia

The Paris System for Reporting Urinary Cytology (TPS) is a recently developed standardized terminology system. It is well-established that urine cytology has low sensitivity for detecting low-grade urothelial neoplasia (LGUN). Though the majority of tumors are low-grade, surveillance of these lesions is important to monitor for possible progression. Herein, we compared TPS to our veteran integrated system network (VISN) to assess its applicability. We also introduced semi-quantitative scoring to further evaluate cytomorphologic features of high-grade urothelial carcinoma (HGUC). Voided and instrumented urine cytology specimens and concurrent biopsies were reviewed from Sept 2018 – Jan 2020. Cytologic diagnoses reported using the VISN institutional system were reevaluated by staff cytopathologists and categorized according to TPS. A semi-quantitative scoring system to evaluate cytomorphologic features was devised. Cytology and surgical specimens from 105 patients were reviewed. The VISN and TPS reporting systems were compared and showed similar sensitivities and specificities for the detection of HGUC. Rates of biopsy-proven LGUN were high for the negative for high-grade urothelial carcinoma category (NHGUC; 27/53, 50.9%) and atypical urothelial cells (AUC; 14/30; 46.7%) compared to suspicious/positive (0/22, 0%) categories. Major and minor criteria as outlined in TPS were evaluated semi-quantitatively. Urine cytology has limited sensitivity for LGUN regardless of the cytologic reporting system used. There was a high rate of LGUN following NHGUC/AUC diagnoses in the Veteran population. Coarse chromatin was determined to be the least sensitive criterion for the detection of high-grade lesions and irregular chromatin rim was most specific. •Urine cytology effectively detects high-grade malignancies, but has limited sensitivity for low-grade lesions even in a Veteran population where the rates of LGUN are high.•Most LGUN cases were classified as negative for high-grade urothelial carcinoma or atypical urothelial cells on urine cytology.•Incorporating a semi-quantitative scoring system for TPS characteristics can help to clarify cytologic diagnosis.•Coarse chromatin was found to be the least sensitive criterion for the detection of high-grade lesions.•Irregular chromatin rim was most specific for the detection of high-grade lesions.