Primary sclerosing cholangitis: Histopathology and aetiopathogenesis

Abstract

Primary sclerosing cholangitis (PSC) is a chronic liver disease which primarily affects the bile ducts. We summarize currently available information about histopathology and aetiopathogenesis of PSC. This disease is characterized by non-specific inflammatory fibrosis in the wall of the biliary tree leading to irregular stenosis, usually of both the intra - and extrahepatic bile ducts, combined by multifocal segmental dilatation of the biliary tree. Four histological stages of PSC have been identified. First represents the initial lesion and characterized by portal hepatitis and degeneration of epithelial cells of the bile ducts. Stage 4 is the end stage, and it is characterized by frank biliary cirrhosis. The pathognomonic sign of PSC is the onion skin lesion. However, it is rarely seen on percutaneous biopsy of the liver. The diagnosis is therefore usually made by typical cholangiographic findings: bile duct dilatations proximal to areas of stricture. Histologic examination of the liver is used for confirmation and to determine the stage of the disease. The aetiopathogenesis of the PSC is unknown, but there is an evidence that genetic and immunologic factors are involved. Portal bacteriemia, viral infections, and toxic and ischemic factors have also been implicated in the pathogenesis of PSC.