Assessing The Paris System for Reporting Urine Cytopathology- A Year Long Evaluation with Histopathology and NMP 22 Correlation in Atypical Cases

Summary: Introduction: Urine cytology is widely acclaimed as a non-invasive screening modality in the detection of high-grade urothelial carcinomas. The Paris System (TPS) has introduced uniformity in urine cytology reporting and also narrows down the diagnostic categories in which ancillary testing will be most valuable to improve diagnosis. This study assessed the diagnostic accuracy of urine cytology when reported according to TPS with ancillary testing of atypical samples and histopathological correlation. Materials and Methods: 84 cases were assessed according to The Paris System. Cases reported as atypical were subjected to NMP22 BladderChek test and the results were correlated with histopathology findings wherever available. Statistical analysis was done using SPSS 16.0. Results: Voided urine samples from 84 cases were evaluated. Histopathology was available in 67 cases. Urine cytology had a sensitivity of 77.27%, specificity of 91.30% and diagnostic accuracy of 82.08%. The urine cytology when categorized by TPS had 9.5% unsatisfactory cases, 28.5% negative for high grade urothelial carcinomas, 16.6% atypical , 23.8% suspicious for high grade urothelial carcinoma and 21.4% high grade urothelial carcinomas. The risk of high grade malignancy of categories II, III, IV and V was 0%, 35.7%, 88.8% and 100% respectively. Out of 14 cases reported as atypical, NMP22 was positive in 12; 10 of which proved to be true positive after histopathology. Conclusions: Urine cytology shows a high specificity and positive predictive value for detection of urothelial carcinomas and there can be a potential increase in diagnostic accuracy if combined with ancillary testing by NMP22 in cases with atypical urinary cytology.