A 20-year-old woman presents with a 4-week history of dry mouth, fatigue, fever, and yellow sclerae. Physical examination shows mild jaundice and hepatomegaly Serum total bilirubin is 3.3 mg/dL. Serologic markers for viral hepatitis are negative. The anti-mitochondrial antibody test is negative. A liver biopsy discloses parenchymal and periportal inflammatory cell infiltrates composed primarily of lymphocytes and plasma cells. The patient's signs and symptoms abate following 2 months of treatment with steroids. Which of the following is the most likely diagnosis?

Autoimmune hepatitis is a type of chronic hepatitis, which is associated with circulating autoantibodies (e.g., antinuclear antibodies) and high levels of serum immunoglobulins. The disease typically affects young women but occasionally afflicts older women and men. It is often accompanied by other autoimmune diseases (e.g., Sjogren syndrome, systemic lupus erythematosus). None of the other choices respond to steroids. Primary biliary cirrhosis (choice C) features anti-mitochondrial antibodies. Primary biliary cirrhosis (choice C) and primary sclerosing cholangitis (choice D) do not manifest the described histologic findings.Diagnosis: Autoimmune hepatitis