Interobserver Variability in the Evaluation of Urine Cytology using The Paris System for Urine Cytopathology Classification: An Institutional Experience

Summary: Introduction: The Paris System (TPS) was created to improve the diagnostic value and standardize cytologic diagnostic criteria of urine cytology (UC) by focusing on the diagnosis of high-grade urothelial carcinoma. This study was conducted to evaluate our performance using TPS. Materials and Methods: Urine cytology cases received in our department between 1/1/24 to 3/15/24 were included. Cytotechnologist (CT) and cytopathologist (CP) diagnoses were recorded. Major discrepancies constituted cases with a two-step change and changes from ""atypical"" to ""suspicious"" and vice versa because the diagnostic criteria and clinical implications are different. Cases with discrepancy were reviewed blindly by 2 cytopathologists and a diagnostic category was assigned by consensus. Results: Five-hundred eighty-nine cases were received during the study period. In 109 (18.5%) cases there were discrepancies between the CP and CT diagnoses. In 103 cases slides were available for review. Of these, 22/103 (21.3%) constituted major discrepancies (Table 1). Upon review, the consensus diagnosis (CD) agreed with the CP diagnosis in 64 cases and with the CT diagnosis in 38 cases. In one case, the CD disagreed with both, (CP/Negative, CT/Atypical, CD/Positive). This patient was being treated for urothelial carcinoma in situ. Cystoscopy revealed multiple bladder tumors. However, biopsies taken were negative. For major discrepancies, CD agreed with the CP and the CT on 11 cases each. Most common minor discrepancies were between the ""Negative"" and ""Atypical"" category. Most common major discrepancies were between the ""atypical"" and ""suspicious"" categories. Conclusions: Using the CD as the gold standard, CP performed better than the CT (64 vs. 38) in our study. However, for major discrepancy cases, there was no difference between both groups. The predominance of the diagnosis of atypia in cases with discrepancy suggest that TPS criteria may not be consistently applied and that consultation with a second CP may be valuable.