Non-invasive diagnosis and follow-up of autoimmune hepatitis.

Autoimmune hepatitis (AIH) is a liver disease characterised by necrotico-inflammatory lesions of hepatocytes, the presence of specific autoantibodies and response to corticosteroid treatment. AIH must be considered in any patient with acute or chronic liver disease. As there is no pathognomonic sign of AIH, the diagnosis is based on a combination of clinical, biological, immunological and histological findings, after excluding other causes of liver disease. The clinical and biological presentation of AIH is variable and AIH can be associated with an autoimmune biliary disease, primary biliary cholangitis or primary sclerosing cholangitis in an overlap syndrome. For these reasons, diagnosis of AIH can be challenging. Even if liver histology remains essential in the diagnosis of AIH, non-invasive tests can be used at different steps of the management of AIH: diagnosis of AIH, notably diagnosis of an overlap syndrome, assessment of severity of AIH, searching for extra-hepatic disease frequently associated to AIH, evaluation of response to therapy, decision of treatment withdrawal. This review aims to provide practical guidelines for the use of non-invasive tests for the diagnosis and the follow-up of AIH.