Clinico-pathological studies on a transitional type between extrahepatic biliary atresia and paucity of the interlobular bile ducts

Among the neonatal and infantile cases of obstructive jaundice seen at Niigata and Yamagata University Hospitals between 1976 and 1990, extrahepatic bile ducts were visualized in 19 cases by either preoperative endoscopic retrograde cholangiopancreaticography (ERCP) or intraoperative cholangiography. Neonatal hepatitis was diagnosed in 3 of these cases by clear images of the bile duct system extending from the common bile duct to the intrahepatic bile duct. In 7 cases, the common bile duct was able to be seen, while the common hepatic duct was only slightly visualized. Four of these 7 cases were consistent with paucity of the interlobular bile ducts (PILBD) based on hepatic histology, while the remaining 3 showed fibrosis, bile ductular proliferation, and many bile plugs in the bile ductuli of the portal areas, concurrent with histological changes in extrahepatic biliary atresia (EHBA), not PILBD. In 9 cases, only the common bile duct was visualized while the common hepatic duct was not seen, 7 of these 9 cases being consistent with type III-al EHBA. In 2 cases, neither fibrosis nor proliferation of the bile ductuli was observed in the portal areas, and portal areas without any bile ductuli were also seen, in accordance with findings for PILBD. Three cases which showed similar hepatic histological findings to EHBA despite the presence of patent extrahepatic bile ducts, and 2 cases which had obstructed extrahepatic bile ducts and hepatic histological findings similar to PILBD, were thought to be of a transitional type between EHBA and PILBD. Thus, it is postulated that the entire bile duct system covering hepatocytes to extrahepatic bile ducts is affected by a certain factor, but the expression of individual disease types may be dependent upon the location of the site most seriously affected.