Presentation
Abdominal pain and constipation.
Patient Data
There is a large well-defined, intraperitoneal, heterogeneous, solid, and cystic mass on the right side of the abdominal cavity. It measures 9 x 11 x 12 cm (in TV, AP and CC dimensions respectively). The smaller solid component has soft tissue attenuation (HU: +37) and the larger cystic component has low attenuation (HU: +18). In post-contrast images, the lesion shows cyst wall enhancement with a heterogeneous enhancement of the solid component and non-enhancing central areas (likely necrosis). Multiple small enhancing mural nodules are seen along the cyst wall.
It appears to arise in an exophytic fashion from the wall of mid ileal loops. The bowel wall appears to be fused with the mass at the contact surface. The mass is displacing the small bowel loops anteromedially, and ascending colon posteriorly, with maintained fat planes between them.
Case Discussion
The large, well-defined, exophytic, heterogeneously enhancing, solid-cystic, mixed density mass arising from the small bowel wall, in this case, makes the diagnosis of gastrointestinal stromal tumor (GIST) most likely.
Gastrointestinal stromal tumors typically have necrosis, or cyst formation (as in this case) seen as low attenuation areas on CT 1. Their growth pattern is exoenteric (as in this case), with a large extraluminal component 2. Bowel obstruction is rare even with large tumors 2 and was not evident in this case too.
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