Objective: EUS-guided fine needle biopsy (EUS-FNB) was introduced to obtain tissue cores. However, data on the efficacy of EUS-FNB for the diagnosis of gastric subepithelial tumors (SET) are limited. This study was aimed to determine the tissue acquisition and diagnostic yield of EUS-FNB using a novel 22-gauge FNB needle.
Material and methods: Between May 2012 and February 2014, we retrieved data on 78 consecutive patients who underwent 22-gauge EUS-FNB for tissue sampling of gastric SET larger than 2 cm. Relevant tumor and EUS-related parameters were reviewed retrospectively.
Results: The median tumor diameter was 2.8 cm and tumors were punctured successfully in 77 SET (98.7%). EUS-FNB was diagnostic in 81.8% of SET (63/77), by obtaining core biopsy tissue in 96.8% (61/63) and aspirates in 27.0% (17/63). FNB specimens permitted immunostaining for the diagnosis of gastrointestinal stromal tumors (GIST) in 30 SET (47.6%), 20 leiomyomas (31.7%), and 3 schwannomas (4.8%). Diagnoses could be made without immunostaining in 10 SET (15.9%). Tissue adequacy was optimal in 85.7% of FNB specimens by endosonographers' on-site visual evaluation. Endosonographers' evaluation of tissue adequacy was the only factor significantly associated with a higher diagnostic yield in univariate analysis. No adequate high-power fields for GIST risk stratification were available in FNB specimens. There was a single case of post-procedural bleeding (1.3%).
Conclusion: EUS-FNB using 22-gauge needle obtains a high yield for the diagnosis of gastric SET ≥2 cm, mostly via core tissue acquisition. Endosonographers should pay careful attention to the adequacy of FNB specimens.
Keywords: endosonography; fine-needle biopsy; stomach; subepithelial tumors.