A heterogenous group of lesions causing altered architechture of intrahepatic billiary tree. They are : Von Meyenburg complexes   Congenital hepatic fibrosis Polycystic liver disease Caroli disease Alagille syndrome is absence of portal tract, bile duct peculiar facies, vertebral anomalies and CVS defects. In cystic fibrosis — bile canaliculi are plugged by mucinous material when longstanding, can cause biliary cirrhosis. It cause ductular proliferation and portal inflammation.