Reclassification of urinary cytology regarding The Paris System for Reporting Urinary Cytology with cytohistological correlation demonstrates high sensitivity for high-grade urothelial carcinoma

Background Recently, The Paris System for Reporting Urinary Cytology (TPS) has led to major changes in the approach to evaluate urine cytology and pattern of reporting. The aim of this study was to reclassify urine cytology reports with TPS in order to determine the frequency of abnormal results compared with the previous system; also, we performed cytohistological correlation in abnormal cytological results. Methods In this study, the voided urine specimens from the patients referred to Shiraz University of Medical Sciences affiliated laboratories were retrieved and analyzed using the laboratory's electronic records system; slides prepared from the samples were reviewed by single cytopathologist blindly according to the proposed criteria of TPS. Results Totally, 1842 urine cytology slides from 828 patients were blindly evaluated by TPS criteria and compared with routine urine cytology classification. Then, available cytohistological correlation was done on 99 abnormal urine cytological results from 58 patients. Among the 26 cytology slides with atypical urothelial cell (AUC) in the previous classification, eight (30.70%) slides were downgraded to negative results, and four (15.30%) were upgraded to higher groups. Therefore, through the reclassification of the slides with TPS, 46% of the AUC changed to other groups. Diagnostic accuracy of the TPS classified urine cytology was 78%, including 87.88% sensitivity, 27.27% specificity, 64.44% positive predictive value, and 60% negative predictive value. Conclusion The findings of the present study confirmed the importance and utility of TPS regarding the reclassification of AUC to other groups and its high sensitivity for detecting high-grade urothelial carcinoma (HGUC).