[Plasmacytoid urothelial carcinoma of the urinary bladder. A study of 7 cases]. / Carcinoma urotelial plasmocitoide de vejiga urinaria. Estudio de 7 casos.

OBJECTIVE: Plasmacytoid urothelial carcinoma is a rare and aggressive variant of bladder cancer that mimics plasmacytoma histologically and that can be confused with hemolymphoid neoplasms secondarily affecting the urinary bladder. Only single cases and short series have been described so far. PATIENTS AND METHODS: Seven cases of plasmacytoid urothelial carcinoma have been found among 720 high grade urothelial carcinomas of the urinary bladder. RESULTS: In our series, 0.97% of high grade urothelial carcinomas of the urinary bladder show plasmacytoid phenotype. All the cases were smoking males between 58 and 75 years old. Histologically, two cases showed pure plasmacytoid features, while in the other five cases the plasmacytoid phenotype was mixed with conventional transitional cell or glandular histologies. By immunohistochemistry, all the plasmacytoid areas showed fair epithelial differentiation. The clinical behaviour was aggressive in all the cases, with distant metastases at diagnosis in three cases and early tumor recurrence after chemotherapy in four of them. CONCLUSIONS: In our experience, the plasmacytoid urothelial carcinoma of the urinary bladder is a rare tumor that can also be detected in association with areas of conventional urothelial carcinoma. It is mandatory to recognize this histological subtype due to the clinical and prognostic implications of this diagnosis.