[A Case of Metastatic Urothelial Carcinoma with Pseudoprogression of Liver Metastasis during the Treatment with Pembrolizumab].

A 75-year-old woman with a complaint of gross hematuria was referred to our hospital. The patient was diagnosed as having bladder cancer (cT3bN1M0) and received two cycles of chemotherapy with gemcitabine and cisplatin. Radical cystectomy with pelvic lymph node dissection and bilateral ureterostomy was performed after achieving partial response in a lymph node metastasis following chemotherapy. Based on the pathological diagnosis of high-grade (G3) urothelial carcinoma (ypT3aN2), two more cycles of adjuvant chemotherapy with gemcitabine and cisplatin were administered. Four months after completing adjuvant chemotherapy, pulmonary and hepatic metastases appeared, and treatment with pembrolizumab was initiated. The size of the lung metastasis decreased, while that of the liver metastasis increased 2 months after administering pembrolizumab. However, considering treatment beyond progression using checkpoint inhibitors, pembrolizumab was continued, resulting in marked tumor shrinkage of the liver metastasis. After that, pembrolizumab treatment was temporarily discontinued, and radiation therapy was administered for a new lymph node metastasis at the tracheal bifurcation. Eventually, the lymph node metastasis shrank, and the treatment with pembrolizumab was recommenced for 1 year and the metastases remained shrumken.