Extragastrointestinal Stromal Tumor Mimicking Gastric Subepithelial Tumor

ABSTRACT

Gastrointestinal stromal tumor (GIST) is the most common mesenchymal tumor of the gastrointestinal tract; however, it also occurs at a lower frequency in extra-gastrointestinal regions, such as omentum, mesentery, retroperitoneum, and undefined abdominal sites. This tumor is called an extragastrointestinal stromal tumor (EGIST). A 53-year-old woman presented with a gastric subepithelial tumor, which was incidentally detected by gastrofiberscopy. Contrast abdominal computed tomography (CT) showed a well-defined exophytic tumor with a minimally delayed peripheral enhancing nature near the gastrohepatic ligament. Surgical intervention was indicated, and laparoscopic surgery was planned. During surgery, no specific abnormality was found in the gastric wall and there was no evidence of a gastric subepithelial tumor. Based on immunohistochemical results, sensitive and specific immunostaining was observed for c-KIT, DOG-1, and PKC-theta. In this case, the tumor was positive for CD-117(c-kit) and for smooth muscle actin expression.