Fig. 1

a Plain abdominal computed tomography (CT) showed a cystic lesion of 7 cm in size in the lumen near the second part of duodenum. The cystic lesion showed high density inside. b Gastrointestinal endoscopy revealed that the lumen of the duodenum was deformed by a submucosal tumor-like mass. Active bleeding was not seen in the lumen of the duodenum. c Contrast-enhanced CT demonstrated a high-density spot on the wall of the cystic lesion (yellow arrow). d A pseudoaneurysm was identified in the branch of the anterior superior pancreaticoduodenal artery (ASPDA) by angiography (yellow arrowhead)