Incidental Finding of Gastrointestinal Stromal Tumors during Laparoscopic Sleeve Gastrectomy in Obese Patients.

The frequency of incidental pathology found during laparoscopic bariatric surgery has been estimated to be 2%. Gastrointestinal stromal tumors (GISTs) are infrequent lesions and account for less than 1% of all digestive tract tumors. The reported incidence of this type of tumors during bariatric surgery is around 0.8%. The objective of this study was to evaluate incidence, characteristics, and evolution of incidentally found GISTs in patients undergoing laparoscopic sleeve gastrectomy (LSG) for the treatment of obesity.

A retrospective analysis from a prospectively collected database was conducted. Demographic data, clinical data, laboratory tests, preoperative esophagogastroduodenoscopy (EGD), postoperative pathology report from surgical specimen with tumor markers, and patient's outcomes were evaluated.

From June 2006 to January 2014, 915 patients underwent LSG at our institution. Five (0.5%) patients were found to have incidental GIST. There were four (80%) women; average age was 59.6 ± 6.3 years (range 46-63). None of them had symptoms that served as orientation for preoperative diagnosis. EGD findings were non-suggestive of this pathology in any of these cases. Superficial chronic gastritis was the most common finding in the endoscopic biopsy (60%). All the tumors found in the surgical specimen were of low or very low risk of malignancy, with less than 5 mitoses per 50 fields, less than 2 cm in diameter, and disease-free surgical margins. Cluster of differentiation (CD) 117 and CD 34 were positive in 100% of the cases. None of the patients required adjuvant therapy after the surgery. At 5-year follow-up, all patients were asymptomatic and disease free.

The incidence of unsuspected GIST in LSG specimens in our series was low and similar to what has been reported. The lack of symptoms and the preoperative EGD findings were not suggestive of this diagnosis in any case. The degree of tumor malignancy was low in all patients and LSG was the definitive treatment, without recurrence at 5-year follow-up.