Pancreatic cystic lesions

The IPMNs

Branch-duct IPMN (intraductal papillary mucinous neoplasm) is a mucin-producing epithelial proliferation communicating with the branch ducts, sitting in the head more than the body or tail. On imaging it is a cluster of grape-like cysts that communicate with the main duct, and mural nodules may appear. Malignant potential is low to moderate, about 15-25%. Markers are a raised CEA (>192 ng/mL), mucin, and KRAS/GNAS mutations. Surveillance if low-risk; resection if high-risk, meaning symptoms, size of 3 cm or more, a mural nodule, duct dilation, or cytology. Main-duct IPMN involves the main pancreatic duct with diffuse or segmental dilation (>10 mm) over the entire gland or a segment; the picture is a fish-mouth ampulla with viscous mucin exuding and diffuse duct dilation. Malignant potential is high, about 60-70%, and surgical resection is recommended in fit patients. Mixed-type IPMN involves both branch and main duct, combines the features of both, is high at about 40-60%, and is resected as a main-duct lesion.