[A Case of Progressive Sarcomatoid Renal Cell Carcinoma Treated with Second-Line Nivolumab after Surgery].

A 69-year-old man visited a local doctor for fever, pain in the left abdomen, and macroscopic hematuria. Computed tomography (CT) revealed hydronephrosis of the left kidney, and he was referred to our hospital. Detailed examinations suggested left-side pyonephrosis due to urothelial cancer, and left-side total nephroureterectomy was performed. Pathological diagnosis was sarcomatoid renal cell carcinoma. Sunitinib administration was started postoperatively for para-aortic lymph node metastasis, which disappeared. However, metastasis to the common iliac lymph node and liver appeared newly 11 months later. Nivolumab was started in combination with radiation thepapy for the lymph node metastases. The patient remains in a stable disease state as of 21 months after nivolumab administration.