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 CO₂ 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]).

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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Conflict of Interest

The authors declare that they have no conflict of interest.

• References

• 1 Judson I, Jones RL, Wong NACS. et al. Gastrointestinal stromal tumour (GIST): British Sarcoma Group clinical practice guidelines. Br J Cancer 2025; 132: 1-10
• 2 Xu J-Q, Hu J-W, Chen W-F. et al. Short- and long-term outcomes of endoscopic submucosal dissection for superficial esophageal squamous cell cancer in patients with prior gastrectomy. Surg Endosc 2021; 35: 2229-2239
• 3 Kirita K. Efficacy and safety of underwater ESD with water pressure method for colorectal neoplasm: a propensity score matching. Endoscopy 2024; 56: S129-S130

Publication History

Article published online:
19 September 2025