Histological staging of PBC on liver biopsy (after Scheuer9)
| Stage | Key histological features | |
| I: The florid duct lesion | Expansion of some, but often not all, portal tracts around septal and interlobular bile ducts by aggregates of lymhocytes and plasma cells. Formation of often poorly defined granulomas within or close to affected tracts | |
| Irregularities or rupture of biliary epithelium, often with relative preservation of remaining portal architecture | ||
| Histological evidence of cholestasis usually absent | ||
| II: Ductular proliferation | Changes in all portal tracts. Expansion of portal tracts by immature connective tissue, mononuclear and neutrophil aggregates and, to a lesser extent than in stage I, by lymphocyte aggregates | |
| Bile ducts scanty with proliferation of biliary ductules. Occasional biliary plugging | ||
| Mild piecemeal necrosis at limiting plate | ||
| III: Septal stage | Inflammation less severe, although the sites of bile ducts may be marked by lymphocyte collections | |
| Formation of dense fibrous tissue extending from portal tracts, but the absence of regeneration nodules | ||
| Cholestasis frequent | ||
| IV: Cirrhosis | Formation of regenrative nodules and a “true” cirrhosis | |
| Gross reduction in number of bile ducts | ||