Autoantibodies
A number of specific antibodies found in the blood (antinuclear antibody (ANA), anti-smooth muscle antibody (SMA), anti-liver kidney microsomal antibodies (LKM-1, LKM-2, LKM-3), anti soluble liver antigen (SLA), liver–pancreas antigen (LP), and anti-mitochondrial antibody (AMA)) are of use, as is finding an increased immunoglobulin G level. The presence of anti-mitochondrial antibody is more suggestive of primary biliary cholangitis. Hypergammaglobulinemia is also of diagnostic value. Histology
Autoimmune hepatitis can be characterized histologically by the following nonspecific findings:
Portal mononuclear cell infiltrate that invades the boundary surrounding the portal triad and infiltrates the surrounding lobule. Periportal lesions, also known as interface hepatitis, that spare the biliary tree (may include centrizonal necrosis). Bile duct abnormalities (cholangitis, ductal injury, ductular reaction) can be seen and should prompt evaluation for primary biliary cholangitis or sarcoidosis if granulomas are observed. Plasma cell infiltrate, rosettes of hepatocytes, and multinucleated giant cells. Varying degrees of fibrosis (except in the mildest form of autoimmune hepatitis). Bridging fibrosis that connects the portal and central areas can distort the structure of the hepatic lobule and result in cirrhosis. Diagnostic scoring
The Internal Autoimmune Hepatitis Group developed a standardized scoring system for clinical diagnosis in population studies but lacks value in individualized cases. A simplified scoring system for clinical use incorporates titers of autoantibodies, total IgG levels, liver histology, and the exclusion of viral hepatitis for diagnostic scoring. Classification
On the basis of detected autoantibodies, autoimmune hepatitis can be classified into three subtypes but have no distinct clinical presentations. Type 1 autoimmune hepatitis.
Epidemiology
Autoimmune hepatitis can develop in people of any race or age but occurs most frequently in women. Eighty percent of cases are the type 1 subtype with women being affected 4 times more often than men; for the type 2 subtype, women are affected 10 times more often than men.European studies suggest a disease incidence of 1 to 2 people affected per 100,000 population with a prevalence of 10 to 25 people per 100,000 population.The disease has a bimodal peak occurring between the ages of 10 to 20 and then later in life between the ages of 40 to 50. History
Autoimmune hepatitis was previously called "lupoid" hepatitis due to people having an associated autoimmune disease like system lupus erythematosus at time of diagnosis, which was believed to be its cause. It was originally described in the early 1950s. References


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