A 58-year-old woman was referred to our hospital because abdominal ultrasonography during a medical check-up revealed dilation of the main pancreatic duct. Contrast-enhanced abdominal computed tomography showed a contrast-enhanced mass in the duodenal papilla associated with a dilated common bile duct and pancreatic duct. Endoscopy showed a submucosal protuberance in the duodenal papilla. Endoscopic ultrasonography (EUS) revealed a hypoechoic mass 12 mm in diameter in the second and third layers at the same site. A diagnosis was not reached on mucosal biopsy. Endoscopic papillectomy was performed to achieve complete biopsy and diagnostic treatment. The tumor was diagnosed with a grade 1 neuroendocrine tumor. Pancreaticoduodenectomy was performed because the tumor measured 17 mm in diameter and had a positive vertical margin. Complications of endoscopic papillectomy were acceptable in our hospital. Endoscopic papillectomy can thus be used as a diagnostic technique.
