Gastrointestinal stromal tumor mimicking arteriovenous malformation of the jejunum

There have been case reports of small intestinal gastrointestinal stromal tumors (GISTs) complicated with arteriovenous malformation (AVM) and angiodysplasia and exhibiting intense tumor staining. Herein we report a GIST of the small intestine that showed tumor staining and early venous return on imaging studies, and so the patient was suspected to have AVM. A 62-year-old male presented with intermittent pain in the left abdominal region. Contrast-enhanced computed tomography revealed a 15-mm-long spindle-shaped mass showing intense tumor staining and early venous return through the jejunal vein. In the arterial phase, the attenuation value of the tumor was 250 Hounsfield units. Color Doppler ultrasonography simultaneously delineated vessels extending from the serosal side and turbulent signals showing a mosaic pattern in the tumor. On angiography, intense staining was observed in the peripheral part of the second branch of the jejunal artery. Although these findings suggested AVM, the tumor was diagnosed as a GIST based on pathological examination of the resected specimens. In this case, no AVM or change in vascular density was noted despite the careful examination of pathological specimens, and the cause of the tumor staining remained unknown.