Acquired hemophilia in association with ANCA-associated vasculitis: response to rituximab.

We describe a patient with end-stage renal disease secondary to antineutrophil cytoplasmic antibody-associated vasculitis who subsequently developed acquired hemophilia A with autoantibodies to factor VIII. This is a novel association. Previous vasculitis therapy with the anti-CD52 monoclonal antibody Campath-1H may have contributed to the development of a second autoimmune disease in this patient by inadvertent depletion of regulatory T cells. The hemophilia followed a relapsing course under oral corticosteroid therapy, but B-cell depletion with anti-CD20 monoclonal antibody (rituximab) was effective in inducing a prolonged remission.