A Case of Retroperitoneal Inflammatory Myofibroblastic Tumor Originating around the Duodenojejunal Flexure

Abstract

A 54-year-old woman was admitted to our hospital owing to vomiting. Imaging examinations revealed a tumor around the duodenojejunal flexure ; this was suspected to be the cause of bowel obstruction The tumor was preoperatively diagnosed as a nonepithelial tumor, such as GIST, and surgical resection was performed. The duodenojejunal flexure, mesentery, greater omentum, transverse colon, and left kidney all appeared to be invaded by the tumor. We performed a partial resection of the small intestine, wedge resection of the transverse colon, and partial resection of the left kidney. Histopathology showed an inflammatory myofibroblastic tumor, which is a distinctive type of lesion composed of proliferating myofibroblastic spindle cells and infiltrating inflammatory cells. It occurs primarily in the lungs and rarely, in the mesentery, omentum, soft tissue, and gastrointestinal tract. In this case, previous CT findings indicated that the tumor originated from the retroperitoneum. Only a few case reports have confirmed rapid tumor growth by imaging examinations. As far as we know, this is the first reported case of bowel obstruction caused by a retroperitoneal inflammatory myofibroblastic tumor in which the tumor doubling time was confirmed.