De novo autoimmune hepatitis after living donor liver transplantation in a 25-day-old newborn baby: a case report.

De novo autoimmune hepatitis (AIH) has been described recently as a new type of graft dysfunction in pediatric patients receiving liver transplantation. Herein we have reported the case of a boy, diagnosed as neonatal hemochromatosis, who received a reduced left lateral graft 25 days after birth. Pretransplantation autoantibodies and serological tests were negative. The postoperative course was smooth. No episode of vascular or biliary complication or acute cellular rejection was observed. The maintenance immunosuppressant was tacrolimus only. Liver dysfunction occurred 13 months after living donor liver transplantation. Liver biopsies showed no acute cellular rejection, but severe apoptosis and regeneration of liver cells at the centrolobular area. At that time, various autoantibodies including anti-nuclear, anti-double-stranded DNA, and anti-smooth muscle antibodies were positive. In addition, serum immunoglobulin G (IgG) was elevated. Based on these findings, he was diagnosed as de novo AIH. The treatment consisted of reducing the tacrolimus dose and reintroduction of steroids. After 12 months of treatment, liver dysfunction improved, serum autoantibodies became negative, and serum IgG level normalized. Currently his immunosuppressive therapy consists of low-dose tacrolimus and prednisolone. In conclusion, the present case demonstrated that de novo AIH can appear in living donor liver transplant patients despite appropriate immunosuppression. Reducing the tacrolimus dose and reintroduction of prednisolone sustained the graft and prevented retransplantation.