Amyloid deposition in intrahepatic large bile ducts and peribiliary glands in systemic amyloidosis

Amyloid deposition in the hepatic parenchyma and portal tracts in the liver is well known in systemic amyloidosis. We recently experienced an autopsy case of systemic amyloidosis presenting the amyloid deposits in the intrahepatic biliary tree. This experience prompted us to survey 19 autopsy cases of systemic amyloidosis. Amyloid deposition was found just under the lining epithelium of the intrahepatic large bile duct in 10 of 19 cases and around the peribiliary glandular acini in 7 of the 19 cases, respectively. Amyloid deposition in the intrahepatic large bile duct and peribiliary glands was positively correlated with the degree of amyloid deposition in the liver but not with type of amyloid protein. Double-staining of amyloid and vascular endothelium disclosed that amyloid deposition was more closely related to the inner part of the peribiliary vascular plexus and to the vascular plexus encircling the peribiliary glands than the lining biliary epithelium and peribiliary glandular acinar cells themselves. The exact pathogenesis of amyloid deposition in these anatomical components, however, remains unclear. Although our cases failed to show any overt clinical symptomatologies related to amyloid deposition in these biliary components, it seems conceivable that more massive amyloid deposition in these anatomical components could give rise to some clinical symptoms.