Modified semicosal tunneling endoscopic resection for endoscopic removal of a large semicosal leiomyoma in the gastric fundus. Semicosal tunneling endoscopic resection or STIR combines the techniques of parallel endoscopic myotomy and endoscopic semicosal dissection for the removal of gastrointestinal subepithelial lesions. Nonetheless, STIR has its limitations. Extraction of large lesions more than 3 cm through the tunnel can be very challenging. Furthermore, STIR in certain anatomical locations, such as the fundus, can be very difficult and often require conversion to exposed endoscopic full thickness resection for complete excision of the lesion. In this video, we present a case of a large subepithelial lesion in the gastric fundus successfully removed endoscopically via a modified STIR technique using a proximal and distal mucosal incision to facilitate dissection retrieval of the lesion. With the modified STIR technique, initial semicosal dissections perform in antegrade fashion through a mucosal incision proximal to the lesion. However, as with conventional STIR semicosal dissection, the posterior aspect of the lesion can be challenging in the gastric fundus due to scope positioning and angulation. With the modified technique, we make a second mucosal incision along the distal aspect of the lesion. Through the second mucosal incision, we are able to continue with the remainder of the semicosal dissection in retroflex fashion. The distal mucosal incision also provides a closer and easier route to retrieve the lesion following dissection. Following complete retrieval, both mucosal incisions can then be easily closed endoscopically. For our case, we present a 61-year-old woman who underwent endoscopic ultrasound to evaluate a subepithelial lesion in the gastric fundus with fine needle aspiration compatible with a diagnosed ileomyoma. The patient preferred to undergo resection as opposed to surveillance. After multidisciplinary tumor board discussion based on the patient's preference, the decision was to proceed with endoscopic resection. On endoscopy, a subepithelial lesion was identified in the gastric fundus immediately below the gastroesophageal junction. This was carefully examined using a clear distal attachment cap. Marks were placed immediately proximal to the lesion on the esophageal side to demarcate the site for the proximal mucosal incision. Following this, a transverse mucosal incision was made followed by entering the submucosal space. Once in the tunnel, submucosal dissection was initiated with the injection-capable ESD needle knife. Endoscopic dissection was performed through the tunnel in an anti-gray fashion. However, navigating the endoscope and ESD knife beyond the anterior aspect of the lesion was challenging due to the limited space in the submucosal tunnel as well as the natural angulation in the fundus. To facilitate ongoing resection, the decision was made to proceed with a second mucosal incision on the distal aspect of the lesion in retroflex manner. The second mucosal incision allowed us to approach the lesion from the distal aspect. The retroflex position resulted in scope stabilization within the tunnel and facilitated completion of the submucosal dissection on the posterior aspect of the lesion. Once the mucosal dissection was completed, we proceeded with closure with through the scope clips first of the distal mucosal incision followed by closure of the proximal incision on the esophageal side. The resected specimen was retrieved and blocked, measured 6 cm in longitudinal axis and 3 cm in width. Postoperative computer tomography with IV and oral contrast did not show any evidence of any contrast extravasation. The patient did well and was discharged on postoperative day number 2. She was seen in clinic 4 months after her procedure and did not report any adverse events. The modified STIR technique introduced in this case has several advantages. It facilitated dissection around the lesion in both an integrated and retroflex position. The distal mucosal incision on the gastric side allowed extraction of the large lesion which would have not been feasible via the mucosal incision in the esophagus. Lastly, as opposed to exposed EFTR, conservation of the mucosal flap by creating two separate mucosal incisions allowed for easy closure of the defect in an otherwise challenging position. In conclusion, the modified STIR technique with proximal and distal mucosal incision facilitated semicosal dissection and extraction of a large lesion in the gastric fundus. This technique may be an alternative to conventional STIR and exposed EFTR for selected lesions.

modified STIR technique

semicosal leiomyoma

gastric fundus

endoscopic resection

subepithelial lesions