Small subepithelial lesions (SELs) in the upper gastrointestinal tract present a diagnostic challenge; endoscopic ultrasound (EUS) often struggles to definitively differentiate between gastrointestinal stromal tumors (GISTs) and leiomyomas. This study evaluates the diagnostic yield and therapeutic efficacy of endoscopic full-thickness resection (EFTR) using a suction-based over-the-scope clip system as a definitive "total biopsy" strategy for indeterminate SELs.

We retrospectively analyzed data from 28 consecutive patients with gastric or duodenal SELs who underwent device-assisted EFTR at a regional public hospital between January 2022 and October 2024. The procedure utilized a suction-based over-the-scope clip (Padlock Clip; Steris, USA) and involved routine mucosal incision to facilitate clear tumor exposure prior to clip deployment. The primary outcome was the definitive histological diagnosis rate, and secondary outcomes included the R0 resection rate, procedure time, and adverse events.

A total of 28 patients (median age 57 years) were included. Lesions were located in the stomach (n=24) and duodenum (n=4), with a median size of 7 mm. The technique achieved a 100% technical success and R0 resection rate. Histopathological analysis provided definitive diagnoses for all cases, revealing low-grade GIST in 50.0% (14/28), leiomyoma in 42.9% (12/28), and ectopic pancreas in 7.1% (2/28). This distinction was crucial as half of the cohort harbored lesions with malignant potential (GIST) that required distinct management compared to benign leiomyomas. The median procedure time was 29 minutes. One patient (3.6%) experienced delayed bleeding, managed endoscopically, with no perforations or other serious adverse events observed.

Suction-based over-the-scope clip-assisted EFTR is a safe and effective technique that serves a dual role in diagnosis and therapy for small upper GI SELs. By providing a full-thickness specimen, it enables precise histological differentiation between GISTs and benign mimics, ensuring appropriate risk stratification and curative treatment in a single session.