Endoscopic subserosal dissection combined with the pocket-creation method for the treatment of exophytic gastric gastrointestinal stromal tumor

A 72-year-old female patient presented with abdominal pain. Gastroscopy revealed a submucosal tumor at the junction of the gastric antrum and body on the greater curvature, measuring approximately 1.5 cm × 2.0 cm, with a smooth surface ([Fig. 1] a). Endoscopic ultrasound showed a hypoechoic mass originating from the muscularis propria, with clear boundaries. Elastography indicated a hard texture, and color Doppler flow imaging revealed no significant blood flow signals ([Fig. 1] b). The lesion was diagnosed as an exophytic gastric gastrointestinal stromal tumor (GIST). Enhanced abdominal CT confirmed no metastasis. After obtaining informed consent, we performed endoscopic subserosal dissection (ESSD) combined with the pocket-creation method (PCM) ([Fig. 2], [Fig. 3], [Video 1]). First, a transverse mucosal incision was made on one side of the lesion. Then, a submucosal injection of a mixture (saline + methylene blue + epinephrine) is performed to separate the mucosa from the tumor surface, creating a "pocket-like" tunnel that fully exposed the tumor and provided an optimal surgical field. Next, the tumor muscle layer was then incised circumferentially, the mixture was injected subserosally several times, the base of the tumor was carefully peeled off along the subserosal layer, and the defect was closed with a metal clip on the retained mucosal layer. Postoperative histopathology confirmed a gastric GIST with negative resection margins (1.8 cm × 1.8 cm × 1.3 cm), mitotic count <5/5 mm2 (very low risk), and WHO prognostic group 1.