Successful diagnosis of small gastrointestinal stromal tumor using modified mucosal incision-assisted biopsy with a cold snare

Gastric subepithelial lesions (G-SELs), including malignant conditions like gastrointestinal stromal tumors (GISTs), require biopsy for diagnosis.¹ The European Society of Gastrointestinal Endoscopy guidelines recommend mucosal incision-assisted biopsy (MIAB) as the first choice for small SELs (≤20 mm),² despite its association with complications such as postoperative bleeding and perforation.³ In 2020, Zimmer and Eltze⁴ presented a modified MIAB using a cold snare to expose G-SELs. Modified MIAB allows for more reliable tissue sampling than boring biopsy by exposing a larger area of the tumor, but it can increase immediate bleeding due to the absence of electrocautery. Despite this, it avoids thermal damage to tissue samples, reduces the risk of delayed complications, and usually avoids hospitalization. However, to our knowledge, only one retrospective study has reported on this method, limited to benign conditions.⁵ Here, we report the first case of small GIST successfully diagnosed using modified MIAB (Video S1).

The G-SEL in the mid-body lesser curvature originated from the muscularis propria layer, measuring 18.1 mm on endoscopic ultrasound (Fig. 1a,b). The covering mucosa was bluntly resected with a thin-wire snare to a size equal to or at least half of the tumor diameter, and submucosal tissue was extracted several times with biopsy forceps (Fig. 1c,d). Once the G-SEL surface became irregular and adequately exposed, three biopsies were performed using biopsy forceps (Fig. 1e). If the tumor is a high-grade GIST, tumor exposure during open laparoscopic and endoscopic cooperative surgery risks peritoneal dissemination, so mucosal defects were clipped (Fig. 1f). All three biopsy procedures yielded c-kit positive tumor tissue, sufficient for a definitive histological diagnosis (Fig. 2). The procedure took 9 min, without complications.

This report indicates that modified MIAB with cold snare is effective for the histological diagnosis of GISTs and may be performed more quickly than existing methods.

Authors declare no conflict of interest for this article.

Approval of the research protocol by an Institutional Reviewer Board: This procedure and case report were approved by the Ethics Committee of Atsugi City Hospital.

Informed Consent: Informed consent was obtained from the patient after verbally explaining the purpose, method, safety considerations, and risks of the procedure.

Registry and the Registration No. of the study/trial: N/A.

Animal Studies: N/A.