A Case of Robot-Assisted Pylorus-Preserving Pancreatoduodenectomy for Branch-Duct Intraductal Papillary Mucinous Neoplasms Complicated With an Annular Pancreas.

Annular pancreas is a rare congenital anatomical anomaly, in which the pancreatic parenchyma surrounds the descending duodenum. Generally, annular pancreas is diagnosed on the basis of symptoms associated with complications of peptic ulcer, pancreatitis, cholelithiasis, and rarely, malignant tumors. Herein, we report an 84-year-old man for whom, during hospitalization for a urinary tract infection, pancreatic cystic lesions and an annular pancreas were noted incidentally on computed tomography. These findings led to a diagnosis of intraductal papillary mucinous neoplasms on further examination. He safely underwent robot-assisted pylorus-preserving pancreatoduodenectomy, with an operative time of 478 min and blood loss of 37 g. He was discharged on postoperative day 8 without postoperative complications. In conclusion, it is important to note that, in this case, intraductal papillary mucinous neoplasms were detected before they became malignant, and minimally invasive surgery was performed safely despite the anatomical anomaly of an annular pancreas.