Pathogenesis of Ductal Plate Abnormalities

Abstract

Intrahepatic bile ducts (IHBDs) develop from bi-potential liver progenitor cells in contact with themesenchyme of the portal vein and thus form the plates. The ductal plates are remodeled into mature tubular ducts. Lack of remodeling results in the persistence of periportal epithelial sleeves or plate malformation (DPM). A proposal is that virtually all congenital of IHBDs represent examples of DPM. Some early, severe types of extra-hepatic bile duct atresia are characterized by DPM, a suggestion of a prenatal beginning of the disease. Several congenital are characterized by dilatation of segments of IHBDs and variable degrees of fibrosis. Such fibrocystic diseases represent DPM at different levels of the biliary tree. Autosomal recessive polycystic kidney disease represents DPM of interlobular bile ducts, associated with tubular dilatation of collecting renal tubules. Congenital hepatic fibrosis may derive from the same type of liver lesion, through a superimposed destructive type of cholangiopathy associated with scarring fibrosis. Caroliapos;sdisease represents DPM of the larger IHBDs, whereas Caroliapos;s syndrome combines the lesions of Caroliapos;sdisease and congenital hepatic fibrosis, von Meyenburg complexes represent DPM of smaller interlobular ducts; their dilatation gives rise to the liver cysts in autosomal dominant polycystic kidney disease. Finally, DPM is a component of the tissue abnormalities in socalled mesenchymal hamartoma.