CT findings of a gastrointestinal stromal tumor arising from small bowel

Gastrointestinal stromal tumors (GISTs), the most common mesenchymal tumors of the gastrointestinal tract, arise from interstitial cells of Cajal. Most of them are composed of spindle cells and mimic leiomyoma morphologically. Nearly all GISTs demonstrate positive staining for CD-117 at immunohistochemistry examination, which helps to distinguish them from true leiomyomas. We describe the CT findings of a GIST of small bowel. At plain CT scan, the tumor was of homogeneous iso-attenuation. After intravenous administration of contrast materials, a well-defined exophytic growth mass with avid homogeneous enhancement was demonstrated. The mucosal layer over the mass was intact and fat plane between the mass and adjacent GI wall was preserved. A diagnosis of GIST was suggested and was then confirmed by positive staining for CD-117.