EUS-guided sampling of suspected GI stromal tumors

Background: The diagnostic yield of EUS-guided FNA (EUS-FNA) of suspected GI stromal tumors (GIST) has not been assessed in large series. Objective: Our purpose was to determine the diagnostic yield of EUS-FNA of subepithelial lesions with EUS features suggestive of GIST. Design: Retrospective database review. Setting: Tertiary care referral center and an urban Veterans Administration hospital. Patients: Consecutive patients referred for EUS evaluation of upper GI subepithelial lesions of the fourth endosonographic layer who underwent EUS-FNA. Main Outcome Measurements: Proportion of patients whose cytopathologic examination was diagnostic (immunohistochemical stains establish a specific diagnosis), suspicious (spindle cells identified, quantity not sufficient for specific stains), or nondiagnostic. Results: A total of 112 patients (45.5% female, mean age 61.6 years) underwent EUS-FNA (mean number of FNA passes 5.3). Tumor location was as follows: stomach 62.5%, esophagus 30.4%, and duodenum 7.1%. EUS-FNA was diagnostic in 61.6%, suspicious (spindle cells) in 22.3%, and nondiagnostic in 16.1%. The histologic results were 31.3% GIST, 26.8% leiomyomas, 22.3% spindle cell neoplasms, 3.5 % neural tumors, and 16.1% nondiagnostic. Fifteen (12.5%) patients also underwent EUS-guided core needle biopsy needle sampling; 7 were diagnostic, 2 suspicious, and 6 nondiagnostic. Twenty-four (20.0%) patients underwent jumbo forceps sampling; 5 were diagnostic, 1 suspicious, and 18 nondiagnostic. There were no cases of diagnostic core needle biopsy after nondiagnostic FNA core needle biopsy. Jumbo forceps biopsy of ulcerated masses was diagnostic in 3 GISTs in which FNA was nondiagnostic. Univariate and multivariate analyses showed that no variable was associated with an increased diagnostic yield. Conclusions: EUS-FNA sampling of subepithelial lesions was diagnostic in 61.6% and showed a spindle cell neoplasm ("suspicious") in another 22.3% (diagnostic yield 83.9%). Core needle biopsy needle sampling did not increase the yield, but in the setting of an ulcerated mass, forceps biopsy may be diagnostic.