High-Grade Urothelial Carcinoma with Divergent Prostatic Differentiation Mimicking a Collision Tumor in a Bladder Diverticulum

were identified and were identical and shared among the two histologically distinct components. These findings suggest that the two components are part of the same neoplastic process and, given the presence of urothelial carcinoma in situ, possibly represent the first reported example of urothelial carcinoma with divergent prostatic differentiation. Awareness of divergent differentiation in urothelial carcinomas has important diagnostic, prognostic and therapeutic implications and can be resolved with the use of ancillary molecular studies.