A Case of Small Bowel Inflammatory Myofibroblastic Tumor with Intussusception

Abstract

An inflammatory myofibroblastic tumor (IMT) is a tumorous lesion characterized by the proliferation of myofibroblast-like spindle cells in association with severe inflammatory cell infiltration. A 71-year-old man presented with abdominal pain that had continued for 2 months and was referred to our hospital. On abdominal computed tomography, a 30-mm, soft tissue tumor was seen in the ileum with a gradually increasing contrast effect. Intussusception had occurred at the advancing edge of the tumor. On abdominal magnetic resonance imaging, the tumor was hypointense on both T1- and T2-weighted imaging, suggesting that its main component was fibrous. During surgery, a 3-cm-long, small bowel tumor and intussusception were present 70-cm orally from the ileocecal junction, and laparoscopic partial small bowel resection was performed. Histopathologically, proliferation of spindle cells exhibiting little atypism and infiltration by lymphocytes, plasmacytes, eosinophils, and other inflammatory cells with intervening bundles of collagen fibers were evident, and IMT was diagnosed. Since IMT rarely has distant metastasis, it is classified as an intermediate-grade tumor in the WHO classification of soft tissue tumors.