At present, IPMN is broadly divided into two main types: main duct and branch duct. However, as discussed below, the definition of mixed-type IPMN is gradually becoming accepted. In main duct IPMN, the main pancreatic duct is very dilated, while in branch duct IPMN, the branches of the pancreatic duct are dilated, resembling a bunch of grapes.IPMN is most frequently diagnosed in the elderly (around 65 years old), and the male to female ratio is 2:1, indicating that the incidence of the disease is twofold higher in males than in females. IPMN most commonly originates in the head of the pancreas, and approximately 70% of IPMN lesions are found in the head of the pancreas. It also tends to occur in multiple sites.With regard to imaging, endoscopy has revealed that the opening of the papilla of Vater, located in the duodenum close to the stomach, is dilated by mucus. This dilation of the papillary opening of Vater by mucus is a key characteristic of IPMN. When directly viewed by pancreatoscopy, IPMN appears as small protrusions similar to salmon roe.