Autoimmune hepatitis: Contrasts and comparisons in children and adults - a comprehensive review

This review concentrates on autoimmune hepatitis (AIH), a liver disorder affecting both children and adults, characterized by inflammatory liver histology, elevated transaminase levels, circulating non-organ-specific autoantibodies, and increased levels of immunoglobulin G, in the absence of a known aetiology. Two types of AIH are recognized according to seropositivity: smooth muscle antibody and/or antinuclear antibody define AIH type 1, while antibodies to liver-kidney microsome type 1 and/or liver cytosol type 1 define AIH type 2. AIH type 1 affects both adults and children, while AIH type 2 is mainly a paediatric disease, though it does occasionally affects young adults. There is a female predominance in both types. AIH is particularly aggressive in children/adolescents, progressing rapidly unless immunosuppressive treatment is started promptly. With appropriate treatment 80% of patients achieve remission and long-term survival. In childhood/adolescence, sclerosing cholangitis with strong autoimmune features, including interface hepatitis and serological features identical to AIH type 1, is as prevalent as AIH, but it affects boys and girls equally. The differential diagnosis relies on cholangiographic studies. In autoimmune sclerosing cholangitis, liver parenchymal damage responds satisfactorily to immunosuppressive treatment, whereas bile duct disease progresses in 50% of cases, leading to a worse prognosis and higher transplantation requirement; it has a higher recurrence rate after transplant than AIH. AIH can arise de novo in patients transplanted for non-autoimmune liver disease. Post transplant de novo AIH affects children and adults and responds well to the same treatment schedule used for classical AIH, but not to that used for acute rejection.