De novo autoimmune hepatitis after liver transplantation.

Allograft dysfunction with clinical, serologic, and histologic features resembling autoimmune hepatitis (AIH) may develop in pediatric and adult patients who have received a liver transplant (LT) for end-stage diseases other than AIH. This condition is now known as de novo AIH, although its pathophysiology is still uncertain and whether it represents a specific type of rejection or a genuine form of AIH is under debate. The occurrence of de novo AIH seems to be unrelated to the etiology of the disease necessitating liver transplantation, but it has been correlated with antiviral treatment in cases of hepatitis C virus (HCV) infection recurring after LT. Several investigators have reported adverse outcome of de novo AIH, including graft failure, particularly in cases with late diagnosis. Prompt treatment with prednisone, with or without azathioprine (in addition to the basic immunosuppressive regimen), seems to be the best option. The histology of de novo AIH is characterized by an infiltrate rich in plasma cells with significant interface hepatitis and perivenular necro-inflammatory activity. These features are not specific for autoimmune damage; therefore, other causes of graft dysfunction must be excluded. The final diagnosis may be a challenge in patients with recurrent hepatitis C, and requires careful clinical and pathologic assessment.