A case of IgG4-related autoimmune hepatitis incidentally found by liver injury

Abstract

A previously healthy 48-year-old woman was referred to our hospital because of liver injury. Her laboratory data on admission showed hepatocyte injury (AST 868 IU/L, ALT 1,205 IU/L. Alp 479 IU/L, γ-GTP 254 IU/L). She denied histories of alcohol intake or any medications. All viral markers related to hepatitis were negative. We suspected her having acute phase of autoimmune hepatitis despite of negative data in her serology. Liver biopsy revealed interface hepatitis with prominent infiltration of plasma cells. In addition, these plasma cells showed expressim of IgG4 by immunohistochemistry, and serum IgG4 levels were quite high (669 mg/mL). These findings leaded us to diagnose her as having IgG4-related autoimmune hepatitis (IgG4-AIH). Predonisolone (30 mg/day) promptly improved her liver injury and did not relapse even after reducing the dose. IgG4-AIH is a rare disease entity, and its precise pathogenesis is unknown yet. These issues should be addressed in the future.