Plasmacytoid urothelial carcinomas (PUC) along with micropapillary urothelial carcinoma (MPC), small cell cancer, and nested-typed tumors are among the rare variations of urothelial carcinomas. The molecular characterization of PUC and MPC is currently the focus of our research on bladder cancer which we are conducting in cooperation with the Institute of Pathology in Erlangen. PUCs account for approximately 0.9% of all urothelial carcinomas. The diagnosis of these rare variants has acquired increasing importance since this may have prognostic and possibly therapeutic consequences for the patients. By analysis of 32 PUCs we were able to demonstrate the most comprehensive results available to date on the underlying molecular and clinical characteristics of these variants. Micropapillary cancers have already been described in multiple organs. Micropapillary breast cancer represent an individual entity with characteristic genomic aberrations and corresponding clinical and pathological features.