P80 | Early rituximab in acquired haemophilia A: two cases report

Background: Acquired hemophilia A (AHA) is a rare event caused by the development of autoantibodies against factor VIII protein (FVIII). Guidelines recommend rituximab or cytotoxic agents as second-line therapy after 3-4 weeks of corticosteroids to eradicate FVIII inhibitor. We present two case reports of early rituximab use in AHA patients.Case 1: A man with myelomonocytic leukemia presented with widespread hematomas. Lab results showed anemia, prolonged aPTT, FVIII activity 0%, and an inhibitor level of 1.9 BU. Initial treatment with Methylprednisolone, APCC and rVIIa had limited response. Early rituximab therapy (375 mg/m2 weekly for 4 weeks) led to progressive hematoma resolution and eliminated the need for transfusions. After 4 weeks, aPTT was 35s, FVIII activity increased to 62%, and the inhibitor level dropped to 0.4 BU. Case 2: A man with metastatic gastric cancer in chemotherapy presented with left gluteal and abdominal swelling, severe anemia, and prolonged aPTT, reduced FVIII levels and the presence of FVIII inhibitor. CT scan showed the presence of muscular hematomas requiring embolization of the left gluteal and superficial left circumflex iliac arteries. Methylprednisolone and rVIIa were initiated with stability for two weeks. New hematomas prompted rituximab therapy, resulting in hematoma resolution, clinical improvement, normalizing aPTT, FVIII activity with FVIII inhibitor complete eradication.Conclusions: Early rituximab use, contrary to guidelines, effectively restored FVIII levels, reduced inhibitors, and resolved hemorrhagic symptoms in AHA patients.