Mucinous biliary papillomatosis: a tumour in need of wider recognition.

We report three cases of mucinous biliary papillomatosis occurring high in the extrahepatic bile ducts. Histological assessment of malignancy is difficult and subjective because there is no unequivocal evidence of stromal invasion. Using anti-laminin antibodies to assess the basement membranes of these tumours we have found a large number of discontinuities in the epithelial basement membrane. On this basis we consider that mucinous biliary papillomatosis should be considered a low-grade malignancy. This would correlate with the natural history of these tumours, namely recurrence but with no widespread metastasis, death resulting from liver failure usually with 5-6 years of presentation.