Congenital hepatic fibrosis in 5 dogs.

Congenital hepatic fibrosis is a disorder of biliary system development histologically characterized by diffuse periportal to bridging fibrosis with numerous small often-irregular bile ducts and reduction in the number of portal vein branches. The condition results from abnormal development of the ductal plate, the embryonic precursor to the interlobular bile ducts. It has rarely been reported in veterinary species, and it has never been reported in dogs. This article describes 5 cases of a ductal plate malformation in dogs consistent with congenital hepatic fibrosis. On light microscopy, all 5 livers had severe bridging fibrosis with a marked increase in the number of small bile ducts, which often had irregular, dilated profiles reminiscent of the developing ductal plate. In addition, 80% (4 of 5) of cases lacked typical portal vein profiles. Cytokeratin 7 and proliferating cell nuclear antigen immunohistochemistry was performed on the 3 cases for which paraffin-embedded tissue was available. The bile du...