Autoimmune hepatitis: review of histologic features included in the simplified criteria proposed by the international autoimmune hepatitis group and proposal for new histologic criteria.

Simplified criteria for diagnosis of autoimmune hepatitis are based on autoantibodies, serum immunoglobulin G, histologic features, and negative viral serology. A score of 6 points is necessary for the designation of probable autoimmune hepatitis and 7 points or more for definite autoimmune hepatitis. The presence of three histologic features is required for categorizing a case as typical (2 points): interface hepatitis with portal lymphocytic/lymphoplasmacytic cells extending into lobule, emperipolesis, and rosettes. In the absence of all three features, a chronic hepatitis picture is considered compatible with autoimmune hepatitis (1 point). This study examines the validity of these histologic features for the diagnosis of autoimmune hepatitis. Clinical data and liver biopsies were reviewed for 88 autoimmune hepatitis, 20 primary biliary cholangitis, and 13 non-autoimmune acute hepatitis cases. Interface/lobular activity, number of plasma cells, copper/CK7 stains, and presence/absence of biliary features were assessed in autoimmune hepatitis and primary biliary cholangitis cases. The simplified criteria score was calculated. Modified histologic criteria were formulated on the basis of interface/lobular activity, number of plasma cells, and presence/absence of biliary features. Using the proposed histologic features, histologic score of 2 increased from 8 to 77%, while total simplified score of >6 increased from 69 to 86%. There was no increase in total simplified score for primary biliary cholangitis or non-autoimmune acute hepatitis. Rosettes and emperipolesis are difficult to interpret, and lack sensitivity and sensitivity for autoimmune hepatitis diagnosis. The current histologic criteria used in the current simplified score lead to underscoring of autoimmune hepatitis cases. The modified histologic criteria based on the inflammatory activity, extent of plasma cells, and results of copper/CK7 staining increased the histologic score in autoimmune hepatitis and led to a probable/definite diagnosis of autoimmune hepatitis in 17% of cases that would have otherwise been classified as non- autoimmune hepatitis by simplified score.