Background Acquired haemophilia A is a very rare disease caused by the development of clotting factor VIII (FVIII) inhibitors, resulting in haemorrhage and bleeding episodes. This situation has been reported during interferon therapy for chronic hepatitis C virus (HCV) infection. To eliminate FVIII inhibitors, immunosuppressive therapy with corticosteroids and cytotoxic drugs is regarded as the mainstay of therapy.

Purpose To describe a case of acquired haemophilia A refractory to conventional immunomodulatory therapy that has responded to rituximab.

Materials and methods Patient clinical history was reviewed and the following laboratory investigations were collected: haemoglobin, platelets count, coagulation tests (prothrombin time (PT) and activated partial thromboplastin time (APTT)) and FVIII and inhibitor levels.

Results A non-haemophilic 63 years old male patient with chronic HCV infection was receiving antiviral therapy with pegylated-interferon at 180 mcg weekly plus ribavirin at 400 mg twice daily. After 21 weeks of antiviral therapy, patient was admitted to hospital for a large haematoma in right lateral abdominal muscles, coagulopathy and acquired haemophilia. Haemoglobin and platelets count were decreased, PT was normal, APTT was increased, FVIII level was 0% and FVIII inhibitor level was 345 Bethesda units (BU). Immunosuppressive therapy with intravenous metilprednisolone and oral cyclophosphamide was started. After 4 weeks, a slight improvement in FVIII level and a decrease in inhibitors were obtained; for this reason, oral cyclophosphamide was replaced by intravenous rituximab. Patient received rituximab at 375 mg/m² four once-weekly doses and oral prednisone at 30 mg twice daily. Before the second dose of rituximab, FVIII level was 25% and FVIII inhibitors level, 3 BU; coagulation tests were normalised and haemoglobin and platelets count remained diminished.

Conclusions After failure of standard therapy, the use of rituximab in off label condition appears to be an effective option to eliminate FVIII inhibitors in patients with acquired haemophilia.