Figure 1.

Images in endoscopic submucosal dissection. A: A superficial elevated type (IIa) lesion is observed in the second portion of the duodenum; B: Chromoendoscopy with indigocarmine was used to clarify the border of the tumor; C: After marking with argon plasma coagulation, submucosal injection was performed; D: Circumferential cutting was performed using an insulated-tipped knife [ITknife nano (KD-612); Olympus, Tokyo, Japan]; E: Submucosal dissection was performed; F: The lesion was successfully removed en bloc without complications; G: Histopathological analysis revealed a mucosal adenocarcinoma of 16 mm in diameter (yellow lines).