Signet-ring Cell Carcinoma Derived from a Main Duct-type Intraductal Papillary Mucinous Neoplasm of the Pancreas: A Case Report with Long-term Follow-up.

We herein report the case of a 74-year-old man who underwent surgery 9 years after his initial visit and who was pathologically diagnosed with signet-ring cell carcinoma (SRCC) derived from a main-duct-type intraductal papillary mucinous neoplasm (MD-IPMN). At the first imaging examination, only a small pancreatic cyst with mild dilation of the main pancreatic duct (MPD) was detected in the pancreatic head. Eventually, MD-IPMN with mural nodules and MPD dilation (30 mm) developed in the pancreatic body, while the pancreatic head cyst remained unchanged. Total pancreatectomy was performed and the MD-IPMN was pathologically diagnosed as SRCC derived from an intestinal-type MD-IPMN.