TREATMENT OF ACQUIRED HEMOPHILIA

Introduction: Acquired hemophilia (AH) is an autoimmune disease. The organism produces sufficient quantities off factor (F) VIII, but it is inhibited by the appearance of autoantibodies, which creates hemorrhages. Despite its low incidence, mortality remains high (8-22%). In some cases, it is related to autoimmune diseases, pregnancy, etc.; being cancer the most common of them. Pathogenesis and diagnose: The neutralization of FVIII follows a second-order kinetics, with a fast initial phase, followed by a slower second one, which allows for an FVIII residual activity. Second-order kinetics will become one of the main differences for aloantibodies developed in patients with congenital hemophilia treated with FVIII, given that these last ones act with a first-order kinetics, with the complete activation of the administered FVIII. Differently from congenital hemophilia, whose main symptom is hemarthrosis, AH is characterized by hemorrhage in soft tissues: epistaxis, purple-colored hemorrhage, hematuria, muscular bleeding, and gastrointestinal and intracerebral hemorrhages. Diagnose is bused on the clinical practice and laboratory tests. Just in case, a hemostasis study, should be conducted to rule out any other causes like von Willebrand disease, heparin contamination, or the presence of lupus anticoagulant. Treatment: Depending on hemorrhage severity, there could be used anti-fibrinolytic drugs, desmopressin, or coagulation factor concentrates. Immunosuppression to eliminate the inhibitor is performed with corticoids, with or without cytostatics (mainly, cyclophosphamide). Rituximab has been used with encouraging results, as well as the immunotolerance induction, effective in congenital hemophilia. With respect to intravenous immunoglobulins, there is little Scientific evidence that supports their use.