A Case of Gastrointestinal Stromal Tumor in the Mesenterium of the Ileum with Formation of a Colorectal Fistula and Abscess

Abstract

A 71-year-old man was referred to our hospital with a history of right lower abdominal pain and melena. Laboratory findings revealed evidence of inflammatory reaction. Abdominal contrast-enhanced CT showed a 13-cm cystic lesion with an air- fluid level in the ileocecal region, and enhancement of the cyst wall. Based on the findings, the patient was diagnosed as having an abdominal abscess, of tumor or infectious origin. Treatment by drainage was not effective. Colonoscopy and irrigoscopy revealed fistula formation between the tumor abscess and the sigmoid colon. Subsequently, the patient’s condition became worse and he developed peritonitis, necessitating emergency operation. Intraoperative exploration revealed a huge tumor originating from the ileal mesentery directly invading the small intestine and sigmoid colon with hemorrhagic ascites and scattering of the cellular debris from the ruptured tumor. We performed wide resection of the small intestine, sigmoid colectomy, colostomy and abdominal irrigation. Immunohistochemical examination revealed positive staining of the tumor cells for c-kit and CD34. Based on the findings, the patient was diagnosed as having a gastrointestinal stromal tumor arising from the mesenterium of the small intestine forming a fistula with the sigmoid colon. Gastrointestinal stromal tumor with intratumor abscess forming a fistula with the colon is very rare. Herein, we report this rare case with a review of the literature.