Prepyloric Submucosal Tumor Endoscopic Resection

Endoscopic ultrasonography (EUS) was routinely performed to determine the lesion origin. Patients were maintained in the left lateral position, and general anesthesia was administered using mechanical ventilation. All procedures were carried out by three experienced endoscopists with experience with over 300 ESD cases and 300 STER cases. ESD procedure was carried out using the following steps: marking–injection–circumferential incision–submucosal dissection. Of note, the post-ESD wound was closed using metal clips if the GWD occurred during the procedure.
The P-STER procedure was carried out as follows: (1) Several milliliters of a mixture solution (100 mL saline + 2 mL indigo carmine + 1 mL epinephrine) was injected 3–4 cm proximal to the prepyloric SMTs with an injection needle (NM-4L-1, Olympus; Figures 1(a), 1(b), and 1(c)); (2) an inverted T incision as described previously was made as the tunnel entrance [5 (link)] (Figure 1(d)); (3) a tunnel was created between the mucosal and MP layer with the triangular knife and the tunnel ended at 1 cm distal to the prepyloric SMTs (Figures 1(e) and 1(f)); (4) an insulation-tip knife (KD611L, IT2, Olympus), a triangular knife, or a snare (ASM-1-S or ASJ-1-S, Cook, Limerick, Ireland) was used to remove the prepyloric SMT after it was completely exposed (Figures 1(g) and 1(h)); and (5) the incision was closed with clips (HX-610-135, Olympus) after examination of the tunnel (Figure 1(i)). Of note, the endoscopists could chose the full-thickness resection of MP if the lesion originated from the MP layer. The specimen was routinely pinned at a rubber plate for size measurement followed by fixing into formalin for histopathological evaluation.
Moreover, the snare could be used to remove the lesion at the discretion of the endoscopists in both the ESD and P-STER procedures, if operation difficulty was encountered in the final stage of the procedure.