Beside polycystic kidneys liver disease is present in every patient with ARPKD. As a rule those with less severe renal involvement have more severe hepatic disease and vice versa. There is a periportal fibrosis, intrahepatal biliary duct ectasia (those signs are not pronounced in fetus). Significant liver involvement which is complicated by portal hypertension is reffered to as congenital hepatic fibrosis.
Classification is based on the onset of clinical manifestations. The categories are perinatal, neonatal, infantile and juvenile disease. Perinatal manifestation which is seen in 75% of all cases of ARPKD has poor prognosis.
Cysts are formed by dilated collecting tubules.