PBC is characterized by chronic intrahepatic cholestasis due to chronic inflammation and necrosis of intrahepatic bile ducts, and progresses insidiously to biliary cirrhosis.
Its prevalence has been estimated to be 2.3-14.4 per 100,000. The histologic abnormalities in the liver have been divided into four stages.
The earliest changes (stage I) are most specific, and consist of localized areas of infiltration of intrahepatic bile ducts with lymphocytes and necrosis of biliary epithelial cells.
In stage II there is proliferation of bile ductules, prominent infiltration of portal areas with lymphoid cells and early portal fibrosis.
Stage III is characterized by a reduction of the inflammatory changes, paucity of bile ducts in the portal triads and increased portal fibrosis.
In stage IV, fibrosis is prominent in biliary cirrhosis and there is a marked increase in hepatic copper.
The pathologic process is therefore characterized by slowly progressive, spotty destruction of bile ducts, with associated inflammation and fibrosis and, ultimately, cirrhosis.