Abstract
A 57-year-old woman presented with upper abdominal pain. Abdominal ultrasonography showed a hypoechoic mass, 45 mm in diameter. Computed tomography revealed a well-defined mass adjacent to the inferior surface of the liver and lesser wall of the stomach. Preoperative diagnosis was extramural gastrointestinal stromal tumor (GIST) of the stomach. Intraoperatively, the tumor approximately 25 × 20 mm in size arose from the lesser omentum and adhered to the inferior surface of the liver and lesser wall of the stomach. The tumor was resected without any resection of the adjacent organs. Histologically, the tumor was composed of short spindle shaped cells, which lacked particular arrangement, capsulated by myofibroblastic cells with extensive central necrosis. Immunohistochemically, the tumor was positive for vimentine and partially positive for smooth muscle actine (SMA) and CD68 (Kp1), but negative for c-kit and CD34 antibody. It was diagnosed as mesenchymal tumor of the lesser omentum. The patient had an uneventful postoperative course. It was difficult to categorize this rare tumor originating from the lesser omentum in one classification.
