Immunoglobulin G4-associated autoimmune hepatitis later complicated by autoimmune pancreatitis: A case report.

Immunoglobulin G4 (IgG4)-associated autoimmune hepatitis (AIH) is a new disease entity with elevated levels of serum IgG4 and marked IgG4 positive plasma cell infiltration of the liver, and its clinical course remains unknown. A patient with IgG4-associated AIH who later developed autoimmune pancreatitis (AIP) is reported. A 73-year-old man was admitted to our hospital due to elevated liver transaminase levels, hypergammaglobulinemia and positive antinuclear antibody. A liver biopsy specimen showed severe interface hepatitis with marked lymphoplasmacytic infiltration without damage to the interlobular bile ducts, and a diagnosis of AIH was made. Abdominal computed tomography showed no abnormalities in the pancreas. Prednisolone therapy normalized the transaminase levels. Two years later, the patient developed AIP, which recurred after 5 years due to a reduction in the prednisolone dose. Three years later, he had a recurrence of AIH after discontinuation of prednisolone treatment. Evaluation of serum IgG4 levels and IgG4-bearing plasma cell infiltration of the liver at both the onset and recurrence of AIH showed that the serum IgG4 levels were 284 and 208 mg/dL, respectively, and the IgG4-bearing plasma cell infiltration levels were 30-40 cells/high-power field (HPF) per portal area and 4-10 cells/HPF per portal area, respectively. From these results, this case was finally diagnosed as IgG4-associated AIH. The course of this patient demonstrates two important clinical lessons: (i) IgG4-associated AIH can later be complicated by AIP; and (ii) discontinuation of prednisolone treatment can cause recurrence of IgG4-associated AIH.