PD-L1 pathway as a novel target in carcinosarcoma of the kidney and renal pelvis.

Carcinosarcoma of the kidney and renal pelvis (CSKP) is a rare and highly-aggressive malignancy characterized by rapid progression and widespread metastases. To date, few studies describe the natural history of the disease. We present a patient placed on pembrolizumab therapy for suspected metastatic colon cancer. The patient was found to have a right renal mass with caval extension on surveillance and ultimately underwent radical surgery revealing carcinosarcoma with positive PD-L1 expression with no evidence of recurrence to date. To our knowledge, this is the first case describing PD-L1 expression in CSKP and presents a novel pathway for future treatment algorithms.