A 76-year-old man was admitted to our hospital with dyspnea on exertion, diarrhea, and anemia. Abdominal ultrasonography and computed tomography showed a tumor in the abdominal cavity. Capsule endoscopy (CE) and double-balloon enteroscopy (DBE) revealed an elevated mass with an ulcer in the ileum. Histopathological examination showed a spindle-cell tumor, and the spindle cells were immunopositive for c-kit and CD34. Thus, a definitive diagnosis of gastrointestinal stromal tumor (GIST) was made before surgery. After the diagnosis was confirmed by both CE and DBE, single-incision laparoscopic surgery with partial resection of the segment of the small intestine with tumor was performed via a single 2.5-cm umbilical incision. The postoperative course was uneventful. CE and DBE may be useful diagnostic tools in patients with diseases of the small intestine.
