Acquired hemophilia A: an illustrated review based on the French National Guidelines.

Acquired hemophilia A is a rare but potentially life-threatening autoimmune bleeding disorder caused by the sudden development of neutralizing autoantibodies against factor VIII (FVIII), predominantly affecting older adults. Because of the risk of severe bleeding and excess mortality, prompt hospitalization and immediate management are essential to avoid diagnostic and therapeutic delays. Diagnosis relies on the association of an isolated prolonged activated partial thromboplastin time, reduced FVIII activity, and detection of a FVIII inhibitor quantified using the Bethesda or Nijmegen assay. Management has 2 complementary objectives. First, hemostatic therapy combines preventive measures with treatment of acute bleeding episodes, using bypassing agents (recombinant activated FVIII or activated prothrombin complex concentrate) or recombinant porcine factor VIII as first-line options. More recently, prophylaxis with emicizumab has emerged as a promising strategy to reduce recurrent bleeding, with early clinical data suggesting favorable efficacy and safety. Second, inhibitor eradication relies on immunosuppressive therapy, typically corticosteroids alone or in combination with agents such as cyclophosphamide or rituximab, guided by baseline FVIII activity and inhibitor titer. Close and prolonged follow-up is mandatory, combining clinical assessment of bleeding control, recurrence risk, and treatment toxicity, with laboratory monitoring of hemoglobin, factor VIII activity, von Willebrand factor levels, and inhibitor titers. Surveillance should be maintained for at least 2 years after complete remission.