Application of the Paris Reporting System for Urine Cytology: The Three-Year Experience of a Single Tertiary Care Institute in Thailand

Introduction: Urothelial carcinoma is one of the most common human cancers, both in Thailand and worldwide. Urine cytology is a screening tool used to detect urothelial carcinoma. The Paris System for Reporting Urinary Cytology (TPSRUC) was first published in 2016 to standardize the procedures, reporting, and management of urothelial carcinoma. Diagnostic categories include negative for high-grade urothelial carcinoma (NHGUC), atypical urothelial cells (AUCs), suspicious for HGUC (SHGUC), HGUC, low-grade urothelial neoplasm, and other malignancies. Material and methods: In a retrospective review, urine cytology specimens from 2016 to 2019 were reevaluated using the TPSRUC. The risk of high-grade malignant neoplasm (ROHM) for each diagnostic category was calculated. The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy of prediction of high-grade malignant neoplasms were evaluated for cases with histological follow-up specimens. Results: In total, 2,178 urine cytology specimens were evaluated, of which 456 cases had follow-up histological specimens. The ROHM in each diagnostic category was as follows: NHGUC, 17.4%; AUC, 49.9%; SHGUC, 81.2%; HGUC, 91.3%; and other malignant neoplasms, 87.5%. The sensitivity, specificity, PPV, NPV, and accuracy for high-grade malignant neoplasm prediction were 63%, 92.8%, 89%, 73.1%, and 78.5% when AUC was included as malignant in the comparison and 82.6%, 74.7%, 75.1%, 82.3%, and 78.5% when AUC was not considered malignant. Conclusions: TPSRUC provides reliable results that are reproducible by different interpreters and is a helpful tool for the detection of HGUC.