Two-year study on the application of the Paris system for urinary cytology in a cancer centre

Introduction: The Paris system for reporting urinary cytology (TPS) was published in order to provide clear cytomorphological criteria for urine cytology specimens, focusing on high-grade urothelial lesions. The aim of this study was to evaluate the impact of implementing TPS and to correlate with available concomitant histological samples, accessing overall sensitivity and specificity.

Methods: A retrospective analysis of urine cytology reports from 2017 to 2018 using TPS was carried out, with histological correlation to concomitant samples (up to 3 months). Statistical analysis was performed with calculation of sensitivity and specificity, positive and negative predictive values and risk of malignancy (ROM) for all TPS categories.

Results: A total of 1660 specimens were evaluated. Histological specimens were available for 611 (36.8%) cases. Urine cytology categorised by TPS had 2.4% non-diagnostic cases, 87.1% negative for high-grade urothelial carcinoma (HGUC), 4.6% atypical urothelial cells, 2.7% suspicious for HGUC, 2.7% HGUC and 0.5% cases of other malignancies. Sensitivity, specificity, negative predictive value and positive predictive value were 40.0%, 99.3%, 88.2% and 92.3%, respectively. ROM of each category was 0% for non-diagnostic, 11.1% for negative for HGUC, 32.4% for atypical, 64.9% for suspicious for HGUC and 87.9% for HGUC and other malignancies.

Conclusion: Our findings indicated that implementation of TPS provided a high specificity and predictive positive value for the detection of high-grade urothelial lesions, with proportionally increasing ROMs as categories progress from negative to positive.