Incidental Finding of Gastrointestinal Stromal Tumors (GISTs) during Laparoscopic Gastric Bypass

Background: Gastrointestinal stromal tumors (GISTs) are rare tumors, accounting for <1% of all neoplasms of the alimentary tract. GISTs have not been previously reported in association with gastric bypass surgery. Methods: This study is a retrospective review of 517 consecutive morbidly obese patients who underwent laparoscopic Roux-en-Y gastric bypass (LRYGBP) between January 2002 and August 2005. Incidental intraoperative findings of gastric GIST were recorded. Results: 4 patients (0.8%) were noted to have GISTs intra-operatively upon inspection of the stomach prior to partition. All GISTs were identified along the anterior aspect of the upper third of the stomach and were removed by laparoscopic wedge excision with at least a 1 cm margin. The 4 tumors were <1 cm in size and all had immunohistochemical analysis positive for CD117 (c-kit). None of the tumors had determinants of malignant behavior (high mitotic rate, necrosis or pleomorphism). Conclusion: We have found a 0.8% incidence of gastric GISTs in our morbidly obese patients undergoing LRYGBP. All of these small, benign tumors were found incidentally in asymptomatic patients. This case series underscores the need to fully assess the stomach prior to gastric pouch formation. Without the ability to grossly determine the benign or malignant behavior of GISTs, all these tumors found incidentally should be resected with adequate margins.