Small cell carcinoma of the kidney: a case report and analysis of data from the Surveillance, Epidemiology, and End Results registry.

BACKGROUND: Primary small cell carcinoma of the kidney is an extremely rare neoplasm. The clinical features of small cell carcinoma of the kidney are not well established due to its rarity and scarcity of case reports. We present an unusual case of small cell carcinoma of the kidney complicated by syndrome of inappropriate antidiuretic hormone secretion. We identify cases using a population-based dataset from the Surveillance, Epidemiology, and End Results registry and compare small cell carcinoma of the kidney with small cell carcinoma of the lung. CASE PRESENTATION: A 69-year-old Filipino man presented with hematuria for 1 month. A computed tomography scan demonstrated a large left kidney mass with biopsy demonstrating small cell carcinoma. Within 2 months he developed dizziness and was found to have a metastatic lesion to his brain. He was hyponatremic due to syndrome of inappropriate antidiuretic hormone secretion. He did not receive chemotherapy due to his poor functional status. He died within 8 months of presentation. RESULTS: From 1973 to 2013, 60 cases with small cell carcinoma of the kidney were identified in the Surveillance, Epidemiology, and End Results registry. Most (62%) presented with extensive stage, which occurred predominantly in white men in their seventh decade. The median overall survival with extensive stage small cell carcinoma of the kidney was 3 months versus 11 months with limited stage of small cell carcinoma of the kidney; this was worse than small cell carcinoma of the lung with a median survival of 5 and 13 months, respectively. CONCLUSION: We present a rare case of small cell carcinoma of the kidney complicated by syndrome of inappropriate antidiuretic hormone secretion. This adds to our understanding of the clinical features of small cell carcinoma of the kidney. Furthermore, this is the first population-based study of small cell carcinoma of the kidney using the Surveillance, Epidemiology, and End Results database. Analysis shows that overall survival is worse in small cell carcinoma of the kidney relative to that of small cell carcinoma of the lung. Small cell carcinoma of the kidney presents very aggressively, and further studies are needed to develop a standard of care.