Diagnostic utility of EUS-guided FNA in patients with gastric submucosal tumors

Background Submucosal tumors (SMTs) comprise both benign and malignant lesions, and most of the gastric lesions tend to be malignant. The addition of EUS-guided FNA (EUS-FNA) has the potential to improve this distinction, but published series are limited. Objective To evaluate the yield of EUS-FNA in gastric SMTs with referral to a criterion standard final diagnosis. Design Retrospective study. Setting Tertiary-care referral center. Patients This study involved 141 consecutive patients with gastric SMTs, who underwent EUS-FNA from January 2000 to December 2008. Immunohistochemical staining with c-kit, CD34, actin, and S-100 antibodies was done if a spindle cell tumor was found. Based on FNA sample adequacy, and whether a specific diagnosis could be established, EUS-FNA results were categorized as diagnostic, suggestive, or nondiagnostic. The criterion standards for final diagnosis were the surgical histopathological results or the follow-up course for malignant, inoperable cases. Intervention EUS-FNA. Main Outcome Measurements Diagnostic yield of EUS-FNA and factors related to sampling adequacy for cytological and immunohistochemical evaluation. Results A total of 141 patients (52% female, mean age 56.7 years) underwent EUS-FNA (range 1-5 passes). The overall results of EUS-FNA were diagnostic, suggestive, and nondiagnostic in 43.3%, 39%, and 17.7% of cases, respectively. Adequate specimens were obtained in 83% of cases, and 69 cases (48.9%) had a definitive final diagnosis. The most common gastric SMT was GI stromal tumor (59.5%). EUS-FNA results were 95.6% accurate (95% confidence interval [CI], 87.5%-99%) for the final diagnosis and 94.2% (95% CI, 85.6%-98.1%) accurate for differentiating potentially malignant lesions. A heterogeneous echo pattern was the only independent predictor for sampling adequacy (adjusted odds ratio 6.15; P = .002). There were no procedure-related complications. Limitations Possibility of selection bias. Conclusion EUS-FNA is an accurate method for diagnosis of gastric SMTs and for differentiating malignant lesions.