Portal fibrosis: intrahepatic portal vein pathology in chronic human schistosomiasis mansoni.

Thirty five cases of severe late chronic human schistosomiasis were studied. The attention was given to the portal vascular lesions. Four stages from isolated endothelial involvement to entire portal vein wall disorganization were observed. Ultrastructural evidence of smooth muscle cell dedifferentiation is noted with loss of well defined limits between periportal connective tissue and venous vascular wall. The synergistic action of hypertension, subendothelial transudation of serum and proliferation of vascular connective tissue cell lines, are considered to explain the self perpetuating character of portal fibrosis in chronic human schistosomiasis.