Progressive plasmacytoid variant bladder cancer with retroperitoneal dissemination: An autopsy case report

INTRODUCTION: Plasmacytoid urothelial carcinoma is a rare and aggressive variant of bladder cancer. CASE PRESENTATION: A 75‐year‐old woman presented with plasmacytoid urothelial carcinoma with retroperitoneal dissemination was treated with chemotherapy. After an unsuccessful first‐line chemotherapy with gemcitabine and cisplatin, we assessed circulating tumor cells; one such cell was found to be positive for programmed death‐ligand 1. The patient received second‐line chemotherapy with pembrolizumab. However, the tumor extended to the retroperitoneal organs, and the patient eventually died. Autopsy revealed a widespread diffuse scirrhous infiltration of the carcinoma into the retroperitoneum. However, distant metastasis was not observed. CONCLUSION: The evaluation of circulating tumor cells and autopsy revealed a disease state of progressive plasmacytoid urothelial carcinoma treated with pembrolizumab.