Intra-ductal papillary neoplasms of bile ducts (IPNB) are mucin producing papillary neoplasms arising from intra-ductal biliary mucosa, a rare variant considered a counterpart of intra-ductal papillary mucinous neoplasm (IPT) of the pancreas, recently added to the WHO classification.
Aetiology is unknown, but its association with hepatolithiasis and Clonochiis suggests chronic biliary inflammation. The main age o presentation is around the 5th and 7th decades of life with no gender predilection. It is thought to have an ethnical predilection since most cases have been described in patients from East Asia.
These tumours are similar to IPMT of pancreas with regards to histo-physiopathology and production of excessive amount of mucin. They grow slowly spreading along mucosal surface and are often multifocal. Some tumours produce a great amount of mucin, which can obstruct the normal flow within the bile, causing the characteristic clinical manifestations; this is repeated bouts of acute cholangitis, abdominal pain, fever, chills and jaundice.
Other signs include CEA increase, more likely in malignant or large mucin secreting IPNBs, elevation of ALT, AST, bilirubin and GGT.
Imaging features of IPNBs vary from one imaging modality to another, and they change in size, shape and position during or at subsequent explorations. It is this variability what makes diagnosis challenging. Several imaging techniques will provide with different and complementary information to reach a diagnosis, and 3D and MPR reconstructions are recommended for better definition.
Endoscopy (ERCP) may prove single or multiple nodular filling defects in the bile ducts with serrated walls, as well as mucin projecting from duodenal papilla hole. In addition it allows biopsies, fundamental to achieve definitive histologic diagnosis.
Surgery is the treatment of choice, but recurrence rates are high due to superficial spread and small or undetected foci in the biliary tree. Therefore, accurate preoperative delineation is crucial to assure complete resection and close follow-up is required.