Solitary fibrous tumor of the lesser omentum mimicking stomach gastrointestinal stromal tumor.

Solitary fibrous tumor (SFT) is a mesenchymal tumor that rarely occurs in the abdomen. We report a very rare case of an abdominal SFT in the lesser omentum. A 39-year-old Korean man was referred to our center for management of a 9 cm incidental mass in the abdominal space found on a chest computed tomography (CT) during a routine medical examination. He had no symptoms, and there were no specific findings on physical examination. A contrast enhancement CT was performed, and an extraluminal gastrointestinal stromal tumor in the stomach or a pancreatic origin mass was suspected. Surgery was performed and an enclosed mass in the lesser omentum was observed, which was resected completely. The postoperative course was uneventful. Based on microscopy, the omental tumor was diagnosed as SFT.