Small cell carcinoma of the kidney treated with immune checkpoint inhibitor/tyrosine kinase inhibitor

INTRODUCTION: Small cell carcinoma (SCC) of the kidney is extremely rare. Although the majority of patients with advanced renal small cell carcinoma were treated with a combination of cisplatin and etoposide, the efficacy was limited. We report the first case with renal small cell carcinoma who received nivolumab and cabozantinib. CASE PRESENTATION: A 57‐year‐old woman was referred to our hospital with a massive left kidney mass and several bone, lymph nodes, liver, and lung metastases. A left renal mass biopsy made the diagnosis of small cell carcinoma. Nivolumab and cabozantinib were used in combination therapy. The tumors were stable during the treatment for 4 weeks. However, the treatment was halted due to a serious adverse event, immune‐related hemophagocytic lymphohistiocytosis. Although immune‐related hemophagocytic lymphohistiocytosis was resolved with corticosteroids, the patient died 3 months after the initiation of nivolumab and cabozantinib. CONCLUSION: We reported the first case of renal small cell carcinoma treated with nivolumab and cabozantinib.