In the current study, we observed a high prevalence of NECTIN4 protein positivity in non-invasive areas of urothelial HG bladder tumor samples, including CIS and papillary HG tumors with and without a history of LG disease (91%, N = 342), with a relatively high level of NECTIN4 protein expression (77% of samples showing moderate to strong NECTIN4 protein levels according to the recently described H-score groups [9]). This evidence concerns the gene NECTIN4 and in situ carcinoma.