IPMN of the Bile Ducts, “The Myth about the Cyst”: A Systematic Review

Background and Aim: Intraductal papillary mucinous neoplasm of the bile ducts (IPMN‑B) is a distinct pathologic entity and a true precancerous lesion. This entity shares common features with pancreatic IPMN. IPMN of the pancreas is well described and diagnostic criteria and guidelines have been formulated. In contradiction, IPMN-B is still relatively an under-described entity.
The purpose of the study was to systematically review the literature emphasizing the role of MRI in its detection.

Materials and Methods: We adhered to the recommendations of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). We searched PubMed database for Original Articles and Case Series of MR Imaging features of IPMN-B, published in the English literature, using the search words: "IPMN OR intraductal papillary mucinous neoplasm, AND Biliary, biliary cancer, hepatic cystic lesions, MRI”. The search included studies published from December 1, 1994 up to September 1, 2021. Risk of bias and applicability were evaluated using the QUADAS-2 tool.

Results: Of 448 Retrieved studies, seven satisfied the inclusion criteria, and included MR features of 79 patients. All the studies were retrospective.
The imaging findings described included cystic intra and extrahepatic lesions communicating with the biliary tree. Biliary dilatation, and/or an intra-luminal enhancing mass were reported as well. Signs differentiating IPMN-B from other hepatic or biliary cystic lesions or from intraductal cholangiocarcinoma were not well elaborated.
The QUADAS-2 tool identified high risk of bias and concerns regarding applicability in 42.9% and 57.1% of the studies, respectively.

Conclusions: The MRI features of IPMN-B need to be further studied. Guidelines regarding reporting the imaging findings should be established and published.
Radiologists should be acquainted with IPMN-B so that a diagnosis can be made in an early stage leading to improved prognosis.

Keywords: Biliary Tract, IPMN, Cystic Tumors, Mucinous Tumors, Papillary Tumors