The tumor appears as a mucosal growth (Fig. 1) that is extending deep through the muscularis propria into perivesical fat and around the right fallopian tube (Fig. 2). The adjacent urothelium is unremarkable with no papillary urothelial carcinoma or urothelial carcinoma in situ component. This tumor shows different patterns of differentiation. Superficially, the tumor cells are arranged in sheets and show plasmacytoid histology (Fig. 3) with relatively uniform round nuclei with coarsely stippled chromatin located paracentrically within abundant amphophilic cytoplasms. In other areas the tumor shows glandular differentiation (Figs. 5, 6) with tumor cells having more pleomorphic partially cleared nuclei with prominent nucleoli. Deep within the vesical wall, the tumor cells appear to be aggregated in lacunae (Figs. 7, 8, 9) and in other areas the tumor has a micropapillary filiform architecture with plasmacytoid histology (Fig. 4).
On immunohistochemical staining the tumor is strongly positive for Cytokeratin 20 (Fig. 10) and epithelial membrane antigen (EMA) (Fig. 11). It is weekly positive for Cytokeratin 7 (Fig. 12) and CA125 (Fig. 13).