Discrimination between gastric ectopic pancreas and mesenchymal tumours, including GIST - From 12 years' surgical experience in one institute

Background: Although recent immunochemical analysis enabled the discrimination of gastrointestinal stromal tumour (GIST) to other mesenchymal tumours, preoperative diagnosis of these tumours is not always easy. Aim: To discriminate between ectopic pancreas (EP) and mesenchymal tumours, including GIST, 12 years surgical experience at Keio University Hospital was reviewed. Methods: Clinicopathological findings were analysed for 131 patients with gastric submucosal tumours (SMT), including GIST (67 cases), myogenic tumour (21 cases), Schwannoma (11 cases), EP (12 cases) and others (20 cases) surgically treated at Keio University Hospital since 1993. Results: Analysis of clinicopathological findings of these tumours showed that GIST, myogenic tumour and Schwannoma mimic each other from the standpoint of size and location of the tumour. In contrast, comparison of mesenchymal tumours showed that, compared with gastrointestinal mesenchymal tumour, EP tends to exist at middle or lower third of the stomach (P = 0.004), and the tumour size was smaller than 3 cm (P = 0.0006). All EPs were laparoscopically resected and no malignant features were evident. Conclusion: To avoid unnecessary surgery for EP, SMT smaller than 3 cm occurring in the middle or lower third of the stomach should be carefully selected as a candidate of surgical resection.