Objective: The present study was undertaken to evaluate the demographic data, Endoscopic Ultra Sonography (EUS) characteristics of the sub-epithelial lesions, pathology results, complications and long term follow-up of the patients whom referred for EUS evaluation at Siriraj Hospital.
Material and Method: From January 2008-June 2011, a total of 61 cases was referred for EUS evaluation due to subepithelial lesions. The endoscopic reports, pathology results and the patients’ medical records were reviewed. The present study was approved by Siriraj Institutional Review Board.
Results: A total of 61 patients were referred for evaluation of subepithelial lesions, 6 of them were excluded. Thus, 55 cases were analyzed. The mean age was 57.7 + 13.8 years (27-87 years). Sixty seven percent were female. Only one-third of the patients had symptoms. The provisional diagnosis of the sub-epithelial lesions, regarding only clinical and endosonographic characteristics were GIST, neuroendocrine tumor (NET), pancreatic rest, lipoma, granular cell tumor and other (70.9%, 9.1%, 9.1%, 3.6%, 3.6% and 3.6% respectively). All the lesions were diagnosed as GIST originating from either the forth layer (97.4%) or the second layer (2.6%) of gastric or duodenal wall. Fine needle aspiration (FNA) was performed in 13 patients (23.6%). The positive predictive value, negative predictive value and accuracy of diagnosis of GIST made by endosonographers based on only endosonographic characteristics were 85, 100 and 86% (95% CI: 62.4%-94.4%) respectively.
Conclusion: Most of the subepithelial lesions which were referred for EUS evaluation at Siriraj Hospital were GISTs. The diagnosis of GIST can be accurately made by using the EUS based on only endosonographic characteristics. FNA should be done for the large sized GIST. For small sized GIST (< 3 cm), FNA might not be beneficial but a 1 year interval follow-up with EUS is recommended.

Keywords: Endoscopic UltraSonography, Sub-epithelial, Submucosal, Mass, Lesion, GIST