Intraductal papillary mucinous tumor is a mucus-producing tumor that grows in the lumen of the pancreatic duct, and cystic lesions of the pancreas are relatively common. The Johns Hopkins Hospital in the United States once performed abdominal CT examinations on 2932 patients without symptoms of pancreatic disease and found that 37 of them had pancreatic cysts, which means that there are 2.6 pancreatic cysts in every hundred examinations, and it should be emphasized that these patients were completely asymptomatic. Many of them are IPMN, so there are far more IPMN than we think. The main pancreatic duct is a bifurcated duct-like structure in the center of the pancreas that collects pancreatic fluid made up of digestive enzymes produced by pancreatic cells in the branch pancreatic ducts, which eventually flows into the intestinal cavity like a stream into a river to help digest food. If we could look into the lumen of the pancreas we would see that IPMN are papilla-like structures that protrude into the lumen of the pancreas, while under the microscope we can see that they are composed of tall columnar mucus-producing cells. Pathologists divide them into two groups, one infiltrative and one non-infiltrative. The reason for this division is that the infiltrative ones have a poor prognosis while the non-infiltrative ones have a better prognosis. The non-invasive ones are subdivided into three types: benign, junctional, and malignant, which usually progress from benign to junctional to malignant and finally to invasive. IPMN grows right into the lumen of the main pancreatic duct and branch pancreatic ducts. IPMN that grows in the main pancreatic duct is referred to as the main pancreatic duct type and those that grow in the branch pancreatic ducts are referred to as the branch pancreatic duct type. This typing is important because studies have shown that the main pancreatic duct type is more malignant than the branch pancreatic duct type. The presentation of IPMN is very diverse, the most common symptoms are abdominal pain, bloating and discomfort. The most common reasons for hospital visits include jaundice, wasting, acute pancreatitis, and these symptoms are not specific to IPMN. If IPMN is suspected, it will be confirmed by various imaging tests, including pancreatic CT, ultrasound endoscopy (EUS), magnetic resonance imaging (MRCP), and retrograde pancreatic ductography (ERCP), which can detect dilatation of the main or branch pancreatic ducts. Sometimes cytobrush and ultrasound endoscopic puncture (EUS-FNA) are needed for microscopic cytology to identify benign and malignant cases. Approximately 70% of main pancreatic ductal IPMN contain high-grade intraepithelial neoplasia (a high-grade pre-invasive lesion) or invasive carcinoma. Therefore, if surgery can be tolerated, main pancreatic ductal IPMN should be treated surgically. It is important that such surgery should be performed in a unit with extensive experience in pancreatic surgery. IPMN in the caudal part of the pancreatic body can be treated with caudal pancreatic resection, IPMN in the pancreatic head and pancreatic hook requires pancreaticoduodenectomy, and IPMN in the total pancreas type requires total pancreatectomy. The treatment of branched IPMN is more complicated than that of the main pancreatic duct type. Many branching IPMNs are not so malignant that surgery is more than worth the cost. For the treatment of branch pancreatic ducts, there is an international consensus in 2006, which aims to weigh the risks and benefits of surgery. The international consensus recommends that asymptomatic branching IPMN with the following three conditions: 1 less than 3 cm, 2 no main pancreatic duct dilatation, and 3 no wall nodes, can be followed up with regular review without surgery. For those with symptoms, larger than 3 cm, wall nodes, or main pancreatic duct dilatation, surgical resection is recommended. Although many studies support the international consensus, the international consensus is not perfect, and some of the branch pancreatic duct IPMN resected according to the international consensus are not cancerous, so the international consensus cannot completely identify the benignity and malignancy of IPMN. In particular, the cut-off value of 3 cm needs to be confirmed by more studies and may change in future studies. Therefore some doctors and patients will advocate for resection of branching IPMN smaller than 3 cm. Of course, even the main pancreatic duct type IPMN should be treated surgically only if the patient can tolerate surgery. Branched IPMN that cannot be treated surgically requires regular follow-up imaging and surgical resection when it becomes a mass. The follow-up includes pancreatic CT, MRCP, ERCP, and EUS. Lesions smaller than 1 cm can be followed up once a year, while lesions larger than 1 cm need to be reviewed once every six months or three months. Generally, surgery can “cure” IPMN, but a small percentage of IPMN is multiple or may recur after surgery, so regular follow-up is needed even after surgery. If there is a recurrence, the decision to operate depends on the condition of the recurrent lesion. Patients with IPMN are at a slightly higher risk of developing colon tumors than normal people.