RESUMO
We report a 54-year-old male presenting with a history or recurrent nose bleeds and ecchymoses. The coagulation study showed a prolongedpartial thromboplastin time, a factor VIII of 8 percent and a high inhibitor titer (193 Bethesda units). A diagnosis of acquired hemophilia A was reached. The patient was initially treated with cyclophosphamide for seven months without response. Therefore rituximab in doses of 375 mglm²Iweek for four weeks was started. After starting treatment, the patient had a hematoma in the psoas muscle with a concomitantfactor VIII ofless than 5 percent, thatwas treated with local measures. Thereafter, aprogressive reduction in inhibitor titers was observed, until its disappearance atfive months of treatment. Factor VIII levéis normalized and the patient has not experienced abnormal bleeding episodes. The patient remains in remission after 67 months offollow up. Rituximab, a chimeric monoclonal antibody against theprotein CD 20 is an effective treatment in acquired hemophilia A.