Abstract
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.