[Small intestinal metastasis from renal cell carcinoma: a case report].

A 52-year-old man who had been treated with sorafenib for lung metastasis of renal cell carcinoma (RCC) presented to our hospital with iron-deficiency anemia. He had undergone right nephrectomy for RCC (clear cell carcinoma, pT1bN0M0) 11 years ago and lung metastasis developed 6 years after the surgery. Although upper gastrointestinal endoscopy and colonoscopy were performed on suspicion of gastrointestinal bleeding, no abnormality was detected. Capsule endoscopy and single balloon small bowel endoscopy disclosed a hemorrhagic submucosal tumor in the jejunum. Laparoscopic partial jejunectomy was performed, and pathological examination indicated metastatic RCC to the small intestine. After the operation, anemia improved but he died 8 months later because of intrabronchial bleeding from the metastatic lesion of the lung. Metastatic RCC of the small intestine is relatively rare, its diagnosis is difficult. Recently, new diagnostic tools such as capsule endoscopy and balloon-assisted endoscopy have been developed, and they are useful in diagnosing gastrointestinal bleeding (OGIB) which can not be detected by traditional enteroscopy. If patients with advanced RCC show gastrointestinal bleeding of uncertain etiology, we should perform aggressive examination of the digestive tract with these diagnostic tools.