Aims : Ductal plate malformation (DPM) is the persistence of excess of embryonic bile duct structures in the portal tracts. Most of the congenital diseases of intrahepatic bile ducts represent examples of DPM at different levels of the biliary tree. The aim of the present study was to evaluate the histopathological spectrum and immunohistochemical properties of DPM in various paediatric liver diseases and compare them with those of the normal embryonic ductal plates of human fetuses.
Methods and results : All paediatric liver biopsies and autopsied livers of infant deaths and stillbirths over a 5-year period (between 1996 and June 2001) were subjected to histopathological examination to identify ductal plate malformations. A detailed immunohistochemical analysis was carried out in 35 cases of ductal plate malformation and 25 abortuses by using antibodies against cytokeratin (CK)7, 8, 18 and 19, CD34 and type IV collagen. Thirty-nine cases of ductal plate malformation were identified which consisted of extrahepatic biliary atresia with DPM (n = 20), isolated congenital hepatic fibrosis (n = 9), autosomal recessive polycystic kidney disease (n = 5), congenital hepatic fibrosis with autosomal polycystic kidney disease (n = 2), Caroli's syndrome (n = 2) and one case of Ivemark's syndrome. The ductal plate cells stained with CK7, 8, 18 and 19 but not with CD34.
Conclusion : DPM was present in all intrahepatic bile duct diseases included in this study and in about 26% of cases of extrahepatic biliary atresia. The cytokeratin immunophenotype of the ductal plate in pathological conditions is similar to that of normal embryonic ductal plates of fetuses after 20 weeks of gestation.