Utility of The Paris System (TPS) for upper urinary tract cytopathology: correlation with histology follow-up and UroVysion fluorescence in situ hybridization (FISH) analysis

Abstract

The Paris System (TPS) provides a uniform reporting system of urine cytology based on well-defined cytologic criteria. Due to their rarity, there are limited data on the utility of TPS in upper urinary tract (UUT) lesions and follow-up histology of cases with abnormal cytology. We aimed to evaluate the utility of TPS for UUT lesions by correlating the cytologic diagnoses using TPS criteria with subsequent histology. Additionally, the diagnostic utility of UroVysion (Abbott) fluorescence in situ hybridization (FISH) was assessed. A total of 148 UUT cytology specimens were retrospectively identified (2018-2022). Cytologic interpretation was performed using TPS, and then correlated with the findings of concurrent or subsequent histologic specimens. The performance of UroVysion FISH was analyzed. Sensitivity and specificity, positive predictive value (PPV) and negative predictive value (NPV) for detecting high-grade urothelial carcinoma (HGUC) were determined. Among 83 patients who had concurrent or subsequent histologic specimens, cyto-histologic discrepancy was seen in 7 cases (8.4%). The sensitivity, specificity, PPV, and NPV using TPS criteria for detecting HGUC were 87%, and 92%, 96.4%, and 73%, respectively. UroVysion FISH was performed in 21 patients with atypical cytologic findings. The sensitivity and specificity of UroVysion for detecting HGUC was 75% and 86%, respectively, while PPV and NPV were 86% and 75%, respectively. In our experience, the application of TPS criteria for reporting upper urinary cytology was reliable at detecting UUT lesions, especially HGUC. UroVysion FISH was a valuable ancillary test for detecting HGUC of UUT.