RESUMO
Interferon is used to treat chronic viral hepatitis because of low drug resistance and a high remission rate. However, its propensity to induce and modify autoimmunity has been reported. We used pegylated interferon α-2a to treat a patient with chronic viral hepatitis B. After 5 months of this therapy, the patient developed membranous nephropathy. Complete remission of his nephrotic syndrome was achieved after 1 year of cyclosporine and corticosteroid therapy. During this same period, his chronic viral hepatitis B was controlled by entecavir. To our knowledge, this is the first case in which membranous nephropathy developed during pegylated interferon α-2a therapy for chronic hepatitis B. The autoimmune modulation induced by interferon is the most likely mechanism for this complication.