Pancreas, Intraductal papillary mucinous neoplasm (IPMN, non-invasive)

There are many cystic lesions of the pancreas, of which most are pseudocysts and only 5-15% are neoplastic. Intraductal papillary mucinous neoplasm (IPMN) is a non-invasive mucin-producing neoplasm of the pancreas arising from the main pancreatic duct or side-branches. They are more common in men in the 6th decade, in the head of pancreas, and 10-20% may be multifocal. Most patients are asymptomatic but may also present with pancreatic duct obstruction and/or pancreatitis. Histologically, IPMNs are lined by flat or papillary mucinous epithelium of gastric, intestinal, pancreatobiliary, or oncocytic type, exhibiting varying degrees of dysplasia, and surrounded by dense fibrotic stroma. Mutations in GNAS, KRAS, TP53, SMAD4, and RNF43 have been reported in IPMNs. In contrast, mucinous cystic neoplasms of the pancreas occur almost exclusively in women, arise in the body/tail, do not communicate with a pancreatic duct, and exhibit dense ovarian-type stroma. Whereas serous cystic neoplasms are benign, IPMNs as well as mucinous cystic neoplasms can progress to invasive adenocarcinoma and require surgical resection.