[Synchronous gastrointestinal stromal tumors of the rectum and duodenum: a case report].

An 85-year-old woman with anemia underwent colonoscopy, which revealed a 25-mm submucosal tumor with ulceration in the lower rectum. Histological examination of a biopsy showed that the lesion was a gastrointestinal stromal tumor (GIST). Subsequent esophagogastroduodenoscopy revealed a submucosal tumor in the duodenum, and examination of a biopsy obtained by endoscopic ultrasound-guided fine-needle aspiration also confirmed that this lesion was a GIST. The rectal lesion was surgically resected to control bleeding and was confirmed as a GIST histologically. Simultaneous development of GISTs in the rectum and duodenum is extremely rare.