Submucosal tunneling endoscopic resection technique with intermuscular dissection for a rectal gastrointestinal stromal tumor

A 54-year-old woman was referred to our center for evaluation of a subepithelial tumor located in the posterior wall of the rectum, 1 cm proximal to the anal verge. Endoscopic ultrasonography showed a 15-mm hypoechoic homogeneous submucosal lesion. Submucosal tunneling endoscopic resection (STER) was performed ( Video 1 ) under monitored anesthesia care, using CO ₂ insufflation, a standard gastroscope (GIF-H190) with a transparent cap (D-201-10704), DualKnife J 1.5 mm (Olympus, Tokyo, Japan), and a VIO 200D (Erbe, Tübingen, Germany). The submucosal lift was achieved with a mixture of saline solution and indigo carmine. A small horizontal incision was made at the distal margin and a submucosal pocket was created. After dissecting the subepithelial tumor from the submucosa ( Fig. 1 ), an intermuscular dissection assisted by a water-jet injection into the intermuscular space was performed ( Fig. 2 , Fig. 3 ). Finally, the larger vessels were coagulated with a bipolar forceps (HS-D2622; Pentax, Tokyo, Japan) and the mucosal defect was closed with four 11-mm through-the-scope clips (MED-204-CLP; Meditalia, Palermo, Italy). The technical duration of the procedure was 30 minutes. The patient was discharged 2 hours later with the indication to take prophylactic oral antibiotic therapy for 5 days. No complications were reported. Histology showed a 12-mm gastrointestinal stromal tumor (GIST) surrounded by thin smooth tissue, with free margins (R0) and mitotic index <5/mm ² ( Fig. 4 ).

Fig. 1.

GI stromal tumor in the tunnel after submucosal dissection was completed.

Fig. 2.

Intermuscular dissection.

Fig. 3.

Resection base showing integrity of the external longitudinal muscle.

Fig. 4.

Histological features. a DOG1 marker (immunohistochemistry, 20×). b Hematoxylin and eosin (20×); spindle cells, absence of necrosis.

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Submucosal tunneling endoscopic resection technique with intermuscular dissection for a rectal gastrointestinal stromal tumor.

Video 1

After multidisciplinary consultation, a chest and abdominal computed tomography (CT) scan with intravenous contrast was performed, which showed no pathological findings, and a postoperative follow-up observation was scheduled considering the extremely low risk of recurrence.

GISTs are rare and account for 0.6% of all rectal neoplasias ¹ . To date, the best treatment regimen remains uncertain ² and data on endoscopic resection of these tumors are scarce ^{3 4 5} . STER is emerging as a less invasive alternative to surgery for subepithelial tumors in the upper gastrointestinal tract ² and it also seems safe and effective to treat carefully selected rectal GISTs.

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