Diagnostic Value of Endoscopic Ultrasound-Guided Tissue Acquisition With Rapid On-Site Evaluation in Small Gastric Subepithelial Lesions.

Background: Gastric subepithelial lesions (SELs) measuring <20 mm without high-risk features are typically managed with periodic surveillance, while surgical resection is recommended for gastrointestinal stromal tumors (GISTs) per the Japanese guideline. Recent advancements in endoscopic ultrasound-guided tissue acquisition (EUS-TA) needles have improved tissue collection, but few studies have assessed the utility of EUS-TA for SELs <20 mm. This study aimed to evaluate the usefulness of EUS-TA for gastric SELs <20 mm. Methods: We retrospectively analyzed patients who underwent EUS-TA for SELs at Tonan Hospital between June 2012 and March 2025. Variables including needle type, number of passes, histological diagnosis, and diagnostic accuracy were compared between SELs <20 and ≥20 mm. Rapid On-Site Evaluation (ROSE) was performed for all specimens. Results: A total of 163 patients were included: 50 with SELs <20 mm and 113 with SELs ≥20 mm. Median lesion size was 15.5 and 31.7 mm, respectively. The <20 mm group required more passes to obtain adequate samples (2.5 vs. 2.0, p = 0.03). GIST was the most common diagnosis in both groups, with no significant difference (56% vs. 61.9%). Fine needle biopsy did not significantly improve sample adequacy or diagnostic accuracy. Diagnostic accuracy for SELs <20 mm was comparable to that for SELs ≥20 mm (88% vs. 93.8%). Conclusions: EUS-TA with ROSE for gastric SELs <20 mm yields diagnostic accuracy comparable to that for SELs ≥20 mm. Given the high GIST prevalence in small SELs, EUS-TA may be a valuable diagnostic strategy.