Proposal of a new staging and grading system of the liver for primary biliary cirrhosis

AIMS: To define a new histological staging and grading system for primary biliary cirrhosis (PBC), to provide more information reflecting clinical laboratory data and the prognosis to hepatologists. METHODS AND RESULTS: First, 17 histological lesions of PBC were scored in 188 needle liver biopsy specimens. Factor analysis yielded three independent groups of factors: factor 1 (fibrosis, fibrous piecemeal necrosis, orcein-positive granules, bile plugs, Mallory bodies, feathery degeneration, bile duct loss and atypical ductular proliferation); factor 2 (portal inflammation, eosinophilic infiltration, lymphoid follicles, epithelioid granulomas, interface hepatitis and chronic cholangitis); and factor 3 (interface hepatitis, lobular hepatitis, acidophilic bodies and pigmented macrophages). The eight findings of factor 1, but not factors 2 and 3, were significantly correlated with clinical laboratory data and scores in the Mayo Clinic's prognostic model. Factor 1 lesions may reflect histological progression (staging), while factor 2 and 3 lesions may relate to necroinflammatory activity (grading). Then, we devised a staging and grading system using three lesions (bile duct loss, fibrosis and orcein-positive granules) from factor 1 and three from factors 2 and 3 (chronic cholangitis, interface hepatitis and lobular hepatitis). CONCLUSION: This new system might provide more pathological information on PBC patients for hepatologists.