A 70-year-old man presents with abdominal pain and weight loss in the last few months.

Fig. 24.1 (A–D) Axial unenhanced abdominal CT scans show a hypodense, well-defined, partially lobulated lesion localized in the neck of the pancreas (arrow) that appears to be in association with the main pancreatic duct, which is focally dilated and anteriorly displaced. The ampullary tract of the main pancreatic duct is not dilated, and there is no intra- or extrahepatic biliary dilatation. The body and tail of the pancreas are otherwise unremarkable and present mild fatty replacement. No lymphoadenopathy is noticed.

Intraductal papillary mucinous neoplasia (IPMN)

• Pseudocyst
  
• Other pancreatic cystic neoplasms: serous cystoadenoma, mucinous cystic neoplasms
  
• Rare pancreatic cystic neoplasms: cystic and papillary epithelial neoplasm, acinar cell cystoadenocarcinoma, hemangioma, paraganglioma
  
• Solid pancreatic lesion with cystic degeneration: pancreatic adenocarcinoma, cystic islet cell tumor (insulinoma, glucagonoma, gastrinoma),
  
• Metastasis
  
• Cystic teratoma
  
• True epithelial cyst (associated with von Hippel-Lindau disease, autosomal dominant polycystic kidney disease, cystic fibrosis)

IPMN and other pancreatic cystic neoplasms have been increasingly identified over the last decade at cross-sectional imaging due to the recent introduction of dedicated thin-section CT protocol and magnetic resonance cholangiopancreatography (MRCP); thus, a diagnosis of these different entities is mandatory according to respective differences in clinical management. IPMNs have typical features, as they grow in a papillary fashion within either the main pancreatic duct or the side branches or both and produce thick mucinous secretions, causing diffuse or focal dilatation of the pancreatic ducts. They are frequently observed in elderly men and represent ˜3 to 5% of all pancreatic neoplasms and 20% of cystic pancreatic lesions.