Extrahepatic biliary atresia. Morphological study of 98 biliary remnants.

Histologic examination was performed on 98 biliary remnants. Classification into three types was made according to the presence of epithelial structure; biliary and glandular formations had to be separated. Atretic lesions were predominantly observed at the pars inferior of the remnants. These histological findings agree with the theory of a dynamic ascending process that leads to progressive, complete destruction of the biliary and glandular structure, although main ducts may remain preserved by the vicinity of the porta hepatis. Classic clinical data suggest that the damage is initiated in utero. The lesions certainly progress after birth; in some cases the fibrotic process of the remnant may have already reached completion at birth, whereas in some others it may become clinically evident after birth.