Precursor neoplastic lesions of the biliary tract.

Recently, the precursor neoplastic lesions of the bile duct tract have been classified using the same criteria used to classify the preinvasive lesions of the pancreas. Flat dysplasia and dysplastic mass-forming lesions of the bile duct system are considered precursor lesions of the adenocarcinomas and are frequently associated with invasive adenocarcinoma of the bile duct tract. The incidence and the histopathology of these dysplastic lesions are variable in different geographical areas. The prognosis of non-invasive dysplastic mass-forming lesions is very good if compared with lesions associated with adenocarcinoma and with conventional adenocarcinoma of the bile tract. Here, the main features of these lesions will be reviewed.