Earlier terms for this condition include lupoid hepatitis and autoimmune chronic active hepatitis. Like other autoimmune disorders it is a disease of unknown cause that occurs in persons with a genetic predisposition. Ninety percent of patients are women and three quarters are positive for HLA-B8 , DR3 or DR4. Initially considered to be a disease of young women, it clearly can affect all age groups and can include males. A chronic fluctuating course is usual. Cirrhosis is often already present at first clinical presentation. Occasionally there is acute or even fulminant presentation. The typical clinical and laboratory test pattern is that of chronic active hepatitis. Chronicity is indicated by a firm liver edge, vascular spiders, often a palpable spleen, decreased serum albumin, raised gamma globulin (polyclonal pattern), and prolonged prothrombin time. Acute features are moderate to marked elevation of serum transaminases and mild to moderate hyperbilirubinemia. Most patients have autoimmune serological markers, both antinuclear antibodies (ANA) and antismooth muscle antibodies (SMA) preferably tested by immunofluorescence on rodent tissue sections. A few have additional serological test markers such as positive Coombs test, or a false positive VDRL.

A variant subtype of autoimmune hepatitis (Type 2) occurs in young females with serum antibody to a microsomal antigen in liver and proximal renal tubules (Anti-LKM antibody).

Histology of autoimmune hepatitis has elements of chronic liver diseases: portal fibrosis progressing to macro nodular cirrhosis, and active liver disease: portal and parenchymal lymphocyte and plasma cell infiltrates with piecemeal necrosis.

Extrahepatic manifestations are sometimes seen including arthralgia and arthritis, glomerulonephritis, and Coombs-positive hemolytic anemia and are responsible, along with a positive lupus erythematosus cell test, for the original designation of "Lupoid Hepatitis" coined by Ian Mackay. Perhaps the most important diagnostic feature of autoimmune hepatitis is its almost invariably excellent response to corticosteroid therapy. Serum transaminases return to normal or near normal levels within a few weeks of treatment, serum albumin improves and prothrombin time decreases. Many authorities use large doses of prednisone (1mg/kg) with rapid tapering as transaminases improve. I have been content with the effect of initial doses of 30 mg/day. Azathioprine has a similar beneficial effect at 50 - 100 mg daily and when added to the therapeutic regimen allows maintenance doses of prednisone to be reduced to relatively non-toxic levels of 5-10 mg/day. After 2-3 years of normal or near normal transaminase levels prednisone can be discontinued and disease control maintained with 100 - 150 mg azathioprine daily. The threat of relapse is always present so that regular monitoring of transaminases is important indefinitely. Side effects of prednisone include obesity, diabetes and osteoporosis while chronic azathioprine use had the potential threat of lymphoproliferative malignancy.

A small proportion of patients, more often those with a relatively acute presentation, fail, for unclear reasons, to respond to corticosteroid treatment. They do however respond to cyclosporine. Patients who are intolerant of azathioprine can be treated with cyclophosphamide.

Some hepatologists use repeated liver biopsy for evaluation of hepatic inflammation. Most however use regular measurement of serum transaminases.

Some patients with autoimmune hepatitis have such advanced disease at diagnosis that life-threatening complications are present. They are suitable subjects for liver transplantation with little likelihood of recurrence of the process, probably because of the post-transplant immunosuppressive regimen.

Autoimmune cholangiopathy is a recently introduced appellation for a small group of patients, usually female, with features that overlap autoimmune hepatitis and primary biliary cirrhosis. Hepatic histological changes are consistent with primary biliary cirrhosis but the antimitochondrial antibody test is negative. Liver blood tests have both cholestatic features and moderate elevation of serum transaminase. Antinuclear and antismooth muscle antibodies are strongly positive. These patients respond well, both biochemically and histologically, to corticosteroid and azathioprine therapy.