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Richard M. Gore, Gregory P. Jackson, Kiran H. Thakrar, Robert I. Silvers, Daniel R. Wenzke
Department of Radiology, North Shore University Health System, University of Chicago Pritzker School of Medicine, Evanston, IL, 60201, USA
INTRODUCTION: Intraductal papillary mucinous neoplasms (IPMNs) are fairly prevalent pancreatic neoplasms that are characterised by intraductal papillary growths, thick mucus secretion, and pancreatic ductal dilation that are at risk for undergoing malignant transformation. The diagnosis, management, and treatment guidelines of this neoplasm are evolving. In this presentation, the etiopathogenesis, clinical, and imaging implications of this lesion are discussed.
CLASSIFICATION: The morphologic pattern of ductal dilation in IPMNs has been categorised into 4 major subtypes: diffuse main duct dilation; segmental main duct dilation, side branch dilation, and multifocal cysts with pancreatic duct communication. Each pattern has its own diagnostic, therapeutic, and prognostic implications.
FIELD DEFECT: It is well documented that patients with IPMNs are at increased risk of developing typical ductal adenocarcinoma of the pancreas both in association with and at a distance from the IPMN. Accordingly, recent ACR guidelines have extended the surveillance period for patients with IPMNs to 10 years. Discovery of an IPMN should prompt a careful search for concomitant pancreatic cancer.
PRECURSOR LESION: The reported incidence for malignant transformation of branch duct IPMNs ranges from 6-46% and 57-92% for main duct IPMNs.
IMAGING FEATURES: The following imaging features are concerning for malignancy in IPMNs: dilatation of the main pancreatic duct, particularly if larger than 7.2 mm; growing cysts and increasing main pancreatic duct diameter; cyst size larger than 3cm; enhancing mural nodules and nodules larger than 5 mm; thickened, irregular wall and septations; presence of or development of a solid enhancing component; diffusion restriction on diffusion weighted imaging; an SUV larger than 2.0 on PET/CT imaging; obstructive jaundice with a cyst in the pancreatic head.
CONCLUSIONS: CT and MRI are accurate in the diagnosis of malignant IPMNs. Future work is needed to better differentiate non-invasive and premalignant subtypes non-invasively.
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