Renal Metastasis of Small Cell Lung Cancer With Urothelial Carcinoma of the Bladder Misdiagnosed as Renal Cell Carcinoma

Metastases to the kidney from lung cancer are very rare and are usually therefore recognized at autopsy. A 71-year-old man visited the urology department due to symptoms of worsening hematuria. An abdominal computed tomography scan showed a right renal mass. After a nephrectomy, he was diagnosed with small cell lung carcinoma, and further investigation showed small cell lung cancer in the central area of the left upper lobe with hepatic, bone and brain metastases. But his hematuria was unchanged. Therefore, we additionally diagnosed urothelial cell carcinoma in the bladder by transurethral resection of the bladder tumor. He was treated with etoposide and cisplatin chemotherapy. This is a unique antemortem case report in the literature of small cell lung cancer metastasizing to the contralateral kidney, liver, bone and brain diagnosed concurrently with urothelial cell carcinoma in the bladder.