Utility of UroVysion Fluorescence in situ Hybridization in Improving the Diagnostic Performance of Urine Cytology.

Introduction: The atypical urothelial cell (AUC) category in The Paris System (TPS) in urine cytology (UrCy) is a challenging area. This study aimed to evaluate the UroVysion fluorescence in situ hybridization (U-FISH) assay in predicting the outcome of AUC. Additionally, we explored the association of abnormal U-FISH results in high-grade urothelial carcinoma (HGUC) concerning muscularis propria invasion (MPI).

Methods: This is a retrospective study, and U-FISH was done on archived Papanicolaou-stained smears. Four cohorts were included: non-neoplastic AUC (AUC-NN), neoplastic AUC (AUC-N), muscle-invasive HGUC (HGUC-MI), and muscle-free HGUC (HGUC-MF) outcome on histopathology (HPE) and with clinical follow-up of 12-29 months. U-FISH was evaluated for diagnostic purposes, and MPI and tumor stage prediction by urine FISH score (UFS; high vs. low) based on copy number gain of chromosomes (Chr).

Results: U-FISH was performed on 70 cases (20 AUC-NN, 20 AUC-N, 15 HGUC-MI, and 15 HGUC-MF) and was successful in 58/70 (82.85%) cases. All UC cases showed polysomy of ≥2Chr, and all the AUC-NN cases reported non-neoplastic on HPE were negative for U-FISH. U-FISH picked up all carcinoma cases in the AUC-N cohort. Chr 3 polysomy was statistically significant in differentiating HGUC-MI from HGUC-MF and low-grade urothelial carcinoma cases. Chr 3 signals with a cut-off of 6 signals could identify MPI with a sensitivity of 80.95% and specificity of 41.94%. The UFS of the HGUC-MI group was significantly higher than HGUC-MF.

Conclusions: U-FISH successfully identified all cases of AUC with neoplastic outcomes. In the HGUC group, there was a difference in cases with and without MPI, which requires further confirmation in a larger prospective cohort.