Cystic masses of the pancreas can include a variety of different diseases from benign to malignant, and can generally be divided into pseudocysts, true cysts and cystic tumors, with pseudocysts being the most common. The wall of pseudocysts is fibrous tissue without epithelial tissue. True cysts commonly include congenital simple cysts, polycystic disease, dermatomal cysts, and retention cysts, etc. The inner wall of cysts is covered with epithelium. Cystic tumors are divided into 3 main categories: plasmacytoid cystic neoplasm (SCN), mucinous cystic neoplasm (MCN), and intraductal papillary mucinous cystadenoma (IPMN). Although all of these lesions are mainly cystic lesions, there are some differences in differential diagnosis and treatment due to different pathological changes. The diagnosis of pancreatic cysts is not difficult to diagnose based on history, symptoms, signs, and imaging examinations. Most of the true cysts are found accidentally during physical examination, while pseudocysts usually have a relatively clear history of abdominal trauma and live pancreatitis. The true cysts with clear diagnosis can be followed and observed without surgical treatment for the time being. Most of the true pancreatic cysts occurring in the caudal part of the pancreatic body should be selected for caudal resection of the pancreatic body, and whether to perform partial resection of the spleen or stomach and other related organs should be decided according to the specific situation; for cases with large size and heavy adhesions that cannot be surgically removed, pancreatic cyst-gastrointestinal anastomosis should be performed; cases occurring in the head and body of the pancreas should be selected for surgery according to the specific situation. 2. Pseudocysts (1) Treatment principles: It is generally believed that if the cyst is greater than 6 cm in diameter and does not subside after 4-8 weeks of observation, surgery should be considered. However, not all pancreatic pseudocysts require surgical treatment. For example, the natural regression rate of pseudocysts after acute pancreatitis is about 50% or more. If the patient is asymptomatic or has mild symptoms, the observation time or long-term follow-up can be extended appropriately if the diagnosis of pseudocyst is clear. (2) Treatment: percutaneous drainage (under CT or ultrasound guidance); endoscopic treatment (direct endoscopic puncture and drainage, endoscopic ultrasound-guided puncture and drainage and endoscopic internal drainage of the pancreatic duct through the duodenal papilla); surgical treatment: internal drainage (cystic gastric anastomosis, cystic jejunal Roux-en-Y anastomosis and cystic duodenal anastomosis), external drainage, pancreatic resection (pancreaticoduodenectomy, caudal pancreatic body resection or total pancreatectomy, etc.), and laparoscopic surgery. (The decision is based on the size and location of the pseudocyst, the condition of the cyst itself, and the nature of the pathology). 3.Cystic tumor Cystic tumor of the pancreas is not sensitive to radiotherapy and chemotherapy, and surgical treatment is the only method. Except for plasmacytoid cystic neoplasm (SCN) or small branching intraductal papillary mucinous cystadenoma (IPMN), which have been clearly diagnosed, have small tumors and no obvious symptoms, all should be actively treated surgically. Even if the malignant transformation is cystic adenocarcinoma, there is still a high rate of resection and long-term survival is often achieved after radical resection: (1) Plasmacytoid cystic neoplasm (SCN) For atypical imaging manifestations, when the diagnosis of SCN cannot be clearly made and the possibility of malignancy cannot be excluded, all pancreatic resection should be performed. Asymptomatic SCN patients with lesions less than 3 cm and a clear diagnosis can be followed up and observed with regular imaging examinations. (2) Mucinous cystic neoplasm (MCN) MCN has a high rate of malignancy and all patients should be treated surgically. Enucleation is feasible in some patients with MCN, but local excision alone may not be sufficient for potentially malignant MCN. Incomplete excision of non-invasive MCN may lead to recurrence and loss of opportunity for radical treatment. Postoperative follow-up plan: imaging every 6 months and annually after 2 years. Intraductal papillary mucinous cystadenoma (IPMN): IPMN has a significant malignant tendency and all should be treated by surgical resection. About half of IPMN occur in the head of the pancreas or in the leptomeninges, and pancreaticoduodenectomy (Whipple procedure) is the most common procedure. If it occurs in the caudal part of the body, pancreatic caudal resection is performed. Intraoperative frozen pathological sections are required to determine the adequacy of resection for IPMN resection margins with atypical hyperplasia, and the procedure emphasizes intraoperative frozen pathological examination to ensure negative margins. In 2009, Mayo Clinic experts summarized the literature to propose surgical indications for IPMN. Main pancreatic ductal type, branch pancreatic ductal type greater than 3 cm or symptomatic IPMN with less than 3 cm branch pancreatic ductal type should be surgically resected, and IPMN with less than 3 cm branch pancreatic ductal type and asymptomatic and without attached nodules can be entered into a strict follow-up program. For lesions less than 1 cm, MRI or CT examination is required every year, and if the lesion is stable and there is no mural nodule, observation should be continued; for lesions between 1 and 3 cm, ultrasound endoscopy should reveal mural nodules or dilated main pancreatic ducts, and surgical resection is required; for lesions between 1 and 2 cm that are not found above by ultrasound endoscopy, CT or MRI examination should be performed between 6 and 12 months, and for lesions between 2 and 3 cm, examination should be performed every 3 to 6 months; during follow-up Surgical resection is required for symptomatic lesions, lesions larger than 3 cm, or other high-risk factors.