Biliary atresia: pathology, etiology and pathogenesis

Abstract

Biliary atresia is a progressive fibrosing obstructive cholangiopathy of the intrahepatic and extrahepatic biliary system, resulting in obstruction of bile flow and neonatal jaundice. Histopathological findings in liver biopsies include the expansion of the portal tracts, with edematous fibroplasia and bile ductular proliferation, with bile plugs in duct lumen. Lobular morphological features may include variable multinucleate giant cells, bilirubinostasis and hemopoiesis. The etiopathogenesis of biliary atresia is multifactorial and multiple pathomechanisms have been proposed. Experimental and clinical studies have suggested that viral infection initiates biliary epithelium destruction and release of antigens that trigger a Th1 immune response, which leads to further injury of the bile duct, resulting in inflammation and obstructive scarring of the biliary tree. It has also been postulated that biliary atresia is caused by a defect in the normal remodelling process. Genetic predisposition has also been proposed as a factor for the development of biliary atresia.

Lay abstract

Biliary atresia is an obliterative fibrosing cholangiopathy of the intrahepatic and extrahepatic bile ducts. Even after successful surgery (Kasai portoenterostomy), most patients are likely to show progressive liver dysfunction. It is the commonest indication for liver transplantation during childhood. Liver biopsies demonstrate features of large duct obstructive cholangiopathy. Several theories have been proposed for etiopathogenesis including viral infection, immune-mediated bile duct injury and genetics. Herein, we review the pathology and etiopathogenesis.