Utility of The Paris System for Reporting Urinary Cytology in upper urinary tract specimens

Abstract

Introduction: Diagnosing upper urinary tract (UUT) lesions using cytology has been historically difficult because of a lack of standardized terminology, cytomorphologic criteria, and the presence of instrumentation artifact. The goal of The Paris System for Reporting Urinary Cytology (TPSRUC) was to provide standardized terminology and cytomorphologic criteria. The aim of this study was to evaluate the utility of TPSRUC in UUT cytology specimens at our institution.

Materials and methods: Single ThinPrep archival slides from 30 UUT cytology cases with corresponding histological follow-up were reviewed using TPSRUC. Those results were compared with the original cytology diagnoses.

Results: The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) for high-grade urothelial carcinoma (HGUC) using TPSRUC were 71%, 100%, 100%, and 71%.

Conclusions: The TPSRUC was reliable at identifying HGUC. These data showed that this system had a lower sensitivity (71% versus 100%) and NPV (71% versus 100%) for UUT specimens compared with original cytology diagnoses. TPSRUC had a sensitivity and specificity that were comparable to reported overall sensitivity and specificity of UUT cytology for detection of HGUC. A major cause of discrepancy with TPSRUC was the classification of urine samples (n = 8) from histologically proven HGUC cases as only atypical (n = 6) or negative (n = 2), mainly owing to nuclear hypochromasia rather than hyperchromasia. Thus, hyperchromasia, a criteria used in TPSRUC, may not be as relevant in UUT specimens.

Keywords: Cytology; Hypochromasia; The Paris System; Upper urinary tract; Urine; Urothelial carcinoma.