Radiologic spectrum of intraductal papillary mucinous tumor of the pancreas.

"Intraductal papillary mucinous tumor" is now the preferred term to describe a spectrum of proliferation of the pancreatic ductal epithelium. The tumor produces an excessive amount of mucin and results in progressive dilation of the main pancreatic duct or cystic dilation of the branch ducts, depending on the location of the tumor. This tumor is small and localized in a segment of the main pancreatic duct or in branch ducts, particularly in the branch ducts of the uncinate process, but it may also be diffuse, involving a wide area of the pancreatic ducts. Excessive mucin may impede the pancreatic duct flow and, in turn, produce symptoms of chronic pancreatitis. The following findings are seen on imaging studies: lobulated multicystic dilatation of the branch ducts, diffuse dilatation of the main pancreatic duct, intraductal papillary tumors, elongated or globlike mucous plugs in the dilated ducts, and bulging of the papilla into the duodenal lumen. The diagnosis is suggested at ultrasonography, computed tomography, or magnetic resonance cholangiopancreatography. Endoscopic retrograde cholangiopancreatography is the imaging modality of choice for the diagnosis, because it depicts the communication between the cystically dilated branch ducts and the diffusely dilated main pancreatic duct, as well as intraductal papillary tumor and mucous plugs.