Endoscopic partial resection with the unroofing technique for reliable tissue diagnosis of upper GI subepithelial tumors originating from the muscularis propria on EUS

Abstract

Background: There is a growing body of evidence that a pathological diagnosis is necessary for small (<3 cm in diameter), asymptomatic, hypoechoic, subepithelial tumors (SETs) originating from the muscularis propria on EUS. However, the diagnostic efficacy of current tissue sampling techniques appears to be limited. Objective: To evaluate the diagnostic yield and safety of endoscopic partial resection using the unroofing technique (EPR-UT) in a subset of patients. Design: A prospective case series. Setting: A single tertiary-care referral center. Patients: Between August 2007 and March 2009, 16 patients with hypoechoic SETs of <3 cm in diameter, originating from the muscularis propria on EUS (14 gastric and 2 esophageal lesions), underwent EPR-UT. Interventions: The overlying mucosa was removed by using the unroofing technique using a conventional snare with electrical current to expose the tumor sufficiently. Next, the exposed tumor was partially resected by snaring. Main Outcome Measurements: The diagnostic yield and safety of this method. Results: EPR-UT provided specimens that were sufficient for a diagnosis and the assessment of risk for malignancy in 15 out of 16 cases (diagnostic yield 93.7% [95% CI, 80.4%-100.0%]). The pathological diagnoses were leiomyoma (7 of 15, 46.6%), GI stromal tumor (6 of 15, 40.0%), aberrant pancreas (1 of 15, 6.6%), and well-differentiated neuroendocrine carcinoma (1 of 15, 6.6%). Six cases with GI stromal tumor were classified as very low risk for malignant potential (mitotic index <5/50 high-power fields). Procedural blood oozing was relatively common (9 of 16, 56.0% [95% CI, 33.0%-77.0%]); however, this minor complication was easily controlled by argon plasma coagulation. There were no procedure-related major complications (0 of 16, 0% [95% CI, 0.0%-23.0%]). Limitations: Single-center, noncomparative study with small sample size. Conclusion: EPR-UT appears to be simple, safe, and effective for determining the definite pathological diagnosis and assessing malignant potential of small, hypoechoic SETs originating from the muscularis propria on EUS.