Intraductal papillary neoplasm of the bile duct (IPN-B): also a disease of western Caucasian patients. A literature review and case series.

Cholangiocarcinoma (CCa) is an aggressive malignancy, which often presents with advanced, inoperable disease. Early detection of any premalignant condition could improve the dismal prognosis of cholangiocarcinoma (5% 5-year survival). There are two premalignant precursors of CCa: biliary intraepithelial neoplasia (BilIN) and intraductal papillary neoplasm of the bile duct (IPN-B). BilIN is only visible microscopically; imaging has no role in identification. IPN-B is a recent diagnostic entity, arising from a World Health Organization (WHO) reclassification of tumours. IPN-B is visible macroscopically, and can be identified on imaging. With its propensity to spread preferentially along the biliary epithelium, only infiltrating the duct wall at a late stage, it may be more amenable to complete resection than typical CCa. The lead time with early detection, during which dysplasia could progress to invasive carcinoma, is an opportunity where resection may be curative. The literature on IPN-B has originated from Asia, but awareness of this condition in the western world is limited. We report a case series of IPN-B occurring in Caucasian patients from the UK, with radiological-pathological correlation. The protean imaging appearances present a unique challenge, but also a great opportunity, for radiologists. Early identification and resection of lesions, even in asymptomatic or minimally symptomatic patients, should be considered.