A Case of a Huge Gastrointestinal Stromal Tumor with Extraluminal Growth Arising in the Small Intestine Diagnosed as an Ovarian Tumor

We report a case of a gastrointenstinal stromal tumor(GIST)of the small intestine with extraluminal growth that was difficult to distinguish from an ovarian tumor. A 73-year-old woman presented to a nearby hospital for lower abdominal pain. A computed tomography(CT)scan showed a 17 cm ovarian tumor in the pelvis, and she was referred to the gynecology department of our hospital. Following examinations(enhanced CT and magnetic resonance imaging), she was referred to our department in suspicion of a small intestinal GIST in which the superior mesenteric artery/vein was the feeding blood vessel, and intraperitoneal tumor resection was performed. A large cystic tumor occupied the abdominal cavity and was in contact with the small intestinal wall. As the tumor was not in contact with the uterus or bilateral adnexa, only partial resection of the small intestine was performed. Histopathological examination showed c-kit positivity and she was diagnosed with small intestinal GIST; as a result, a course of imatinib was started.