Application of The Paris System to atypical urine cytology samples: correlation with histology and UroVysion ® FISH

Objectives To evaluate whether atypical urine cytology cases may be stratified more objectively using The Paris System (TPS) and whether reclassified cases correlate with histology and UroVysion ® results. Methods Atypical urine cytology cases subjected to UroVysion ® testing over a period of 6 years were reviewed. Each case was reclassified according to TPS and correlated with histology and UroVysion ® results. Results A total of 91 cases were identified; 70.3% were reclassified as ‘negative for high‐grade urothelial carcinoma ( HGUC )' and 14.3% as ‘atypical urothelial cells ( AUC )’. The histological correlation was available in 45 cases. In the ‘negative for HGUC ’ category, 67.9% had no histological evidence of malignancy, but 17.9% were diagnosed as HGUC . In the ‘ AUC ’ category, histology revealed urothelial carcinoma in 70% of the cases (of these, 71.4% were high grade). There was no histological evidence of malignancy in 30% of cases; notably, all of which were from patients under surveillance. The sensitivity and specificity of UroVysion ® were 85.7% and 33.3% in the ‘ AUC ’ group and 62.5% and 100% in the ‘negative for HGUC ’ group. Conclusions The Paris System is an objective template for reporting urine cytology specimens, and is particularly useful in identifying HGUC cases and refining the category of ‘ AUC ’.