Short-tunnel submucosal tunneling endoscopic resection for the removal of a rectal gastrointestinal stromal tumor above the dentate line

The management of rectal gastrointestinal stromal tumors (GISTs) is complex, particularly for small lesions located in functional areas near the dentate line ¹ . This report describes a case of short-tunnel submucosal tunneling endoscopic resection (STER) ² for the removal of a rectal GIST near the dentate line, aiming to expand clinical insights into minimally invasive approaches.

A 72-year-old woman undergoing colonoscopy for diarrhea was found to have a hemispherical lesion (0.6 cm) on the anterior wall of the distal rectum, 2–3 cm above the dentate line on the anterior wall of the distal rectum ( Fig. 1 a ). Endoscopic ultrasound revealed a lesion measuring 6.4 mm × 3.5 mm, originating from the muscularis propria ( Fig. 1 b ).

Fig. 1.

Endoscopic resection of rectal GIST via short-tunnel STER. a Endoscopic view of a rectal tumor located 2–3 cm above the dentate line. b Endoscopic ultrasound demonstrates the lesion originated from the muscularis propria. c Transverse mucosal incision at the dentate line for tunnel entry creation. d Exposure of the muscularis propria tumor after submucosal dissection. e Underwater-assisted tumor flotation enhances visualization for en bloc resection. f Short-tunnel STER. g Titanium clip closure ensures mucosal integrity. h Resected tumor specimen with intact pseudo capsule.

The patient underwent STER under propofol sedation with CO ₂ insufflation, using a standard gastroscope (GIF-H290T) equipped with a transparent cap (D-201-11804) (Olympus, Tokyo, Japan), VDK-KM-15-195-D knife 1.5 mm (Vedkang, Jiangsu, China). After marking the tumor with methylene blue, a mucosal incision knife was used to create the tunnel entrance above the dentate line ( Fig. 1 c ). The lesion was identified at the muscularis propria during the procedure, and the underwater technique was employed to float and successfully excise the tumor. The procedure lasted approximately 20 minutes ( Fig. 1 d–h , Video 1 ).

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Short-tunnel submucosal tunneling endoscopic resection for removal of rectal gastrointestinal stromal tumor above the dentate line.

Video 1

Postoperative pathological analysis confirmed a rectal GIST with a mitotic index of <5/50 high-power fields, positive staining for CD117, DOG-1, CD34, and SDHB, and a Ki67 index of <1% ( Fig. 2 ). The tumor was classified as very low-risk, and no complications occurred. The patient was advised to undergo regular surveillance.

Fig. 2.

Pathological and immunohistochemical features of GIST.

Based on our experience, the short-tunnel technique offers simplified manipulation and predictable outcomes. Underwater dissection minimizes mucosal injury and enhances visualization during the procedure ³ . Besides, in patients with internal hemorrhoids, further experience is needed before making definitive recommendations.

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