IPMNs

Intraductal papillary mucinous neoplasms (IPMNs) are mucin-producing tumors that arise within the pancreatic ducts. They can be benign or progress to invasive pancreatic carcinoma. IPMNs are classified by the ductal involvement: main-duct IPMN (involving the main pancreatic duct), branch-duct IPMN (affecting side branches), or mixed/main-branch disease.

Most IPMNs occur in older adults and are often discovered incidentally on imaging. The risk of malignancy is higher in main-duct IPMN and in branch-duct IPMN with high-risk features. Histologically, IPMNs show several subtypes, including gastric-type, intestinal-type, pancreatobiliary-type, and oncocytic. These subtypes differ in mucin expression and associated genetic alterations. Invasive carcinoma that can arise from IPMN includes colloid and tubular types, with prognosis influenced by the extent of invasion.

Diagnosis typically involves cross-sectional imaging with magnetic resonance imaging and MR cholangiopancreatography (MRI/MRCP), supplemented by endoscopic ultrasound (EUS) with fine-needle aspiration when appropriate. Cyst fluid analysis may measure carcinoembryonic antigen (CEA) and amylase levels and may include molecular testing for mutations such as KRAS, GNAS, and RNF43. Imaging features suggesting higher risk include main-duct dilation, mural nodules, or a cyst ≥3 cm. The Fukuoka guidelines provide criteria for determining surveillance versus surgical resection based on high-risk stigmata and worrisome features.

Management aims to remove neoplasms with high malignant potential while limiting overtreatment. Resection is typically recommended for main-duct IPMN or branch-duct IPMN with high-risk features; small, asymptomatic branch-duct IPMNs without risk features may be monitored. Prognosis is favorable for non-invasive IPMNs after complete resection, whereas invasive IPMN-associated cancers carry a poorer outcome. Regular follow-up is advised for patients under surveillance.