A Case of Schwannoma of the Lesser Omentum Diagnosed Laparoscopically and Resected

Abstract

A rare case of schwannoma of the lesser omentum diagnosed laparoscopically and resected in a 59-year-old woman is presented. Positron emission tomography-computed tomography (CT) showed a 40-mm tumor with faint uptake in the lesser curvature of the stomach. It was unclear whether there was continuity between the tumor and the stomach wall on CT ; however, endoscopic ultrasonography showed no continuity, and the tumor was very close to the stomach wall. Thus, it was suspected to be an extragastric wall lesion. Gastrointestinal stromal tumor was considered as a diagnosis. Fine-needle aspiration was not performed because of the possibility of dissemination. Laparoscopic dissection was performed for diagnosis and treatment ; however, the tumor was very close to the stomach wall, and its continuity with the stomach wall was unclear. A small laparotomy and careful exfoliation showed that there was no continuity between the tumor and the stomach wall, suggesting that the tumor originated from the lesser omentum. Pathological examination showed proliferation of spindle-shaped cells, which were positive for S-100. Therefore, the patient was diagnosed with schwannoma of the lesser omentum. Although schwannomas of the lesser omentum are rare, they should be considered in the differential diagnosis of intra-abdominal masses.