A case of acute hepatitis with positive autoantibodies who actually had hepatitis E virus infection.

Hepatitis E virus (HEV) is one of the major causative agents of acute hepatitis in many developing countries. On the other hand, recent intensive investigation has revealed the existence of non-imported cases in industrialized countries. We encountered a sporadic patient with hepatitis E in 1999, who had had no recent travel abroad. He was a 67-year-old Japanese, and his laboratory data were negative for serum markers of hepatitis A, B and C virus infection and positive anti-nuclear antibody, anti-smooth muscle antibody and high level of serum immunoglobulin G. He scored as probable autoimmune hepatitis (AIH) with the scoring system by the international AIH group. He was given a diagnosis of acute cryptogenic hepatitis including acute onset AIH in those days, but the recent retrospective examination with frozen stocked serum revealed his exact diagnosis. In conclusion, we must take HEV infection into consideration for the diagnosis of cryptogenic acute hepatitis even in the developed countries, and some patients with hepatitis E could demonstrate positive for autoantibodies similar to clinical features of AIH. This case demonstrated the needs for further studies about clinical feature of acute hepatitis E virus infection.