Successful rituximab therapy of acquired factor VIII inhibitor in a patient with rheumatoid arthritis.

Acquired factor VIII deficiency due to antibody inhibition can result in life-threatening hemorrhage. Rarely such antibody inhibition of factor VIII can be associated with other autoimmune disorders including rheumatoid arthritis. We present the first case of a patient with active rheumatoid arthritis and refractory bleeding diatheses due to a factor VIII inhibitor who was successfully treated with rituximab. A 61-year-old Caucasian female with rheumatoid arthritis unresponsive to multiple therapies developed an acute hematoma while having a peripheral catheter placed. Her aPTT was prolonged at 61.4 with low factor VIII activity and an inhibitor level for factor VIII of 2.0 Bethesda Units. She received rituximab 375 mg/m in 4 weekly doses. Normalization of the aPTT and resolution of the bleeding occurred in 2 weeks. After 45 days, the levels of factor VIII inhibitor and factor VIII activity were <0.4 BU/mL and 130%, respectively. After 1 year, the aPTT remained normal and there was no further bleeding. An added benefit was the substantial improvement in her rheumatoid arthritis. Treatment of acquired factor VIII inhibitors in rheumatoid arthritis should be guided by the levels of the inhibitor. Patients with low levels of the inhibitor may respond to rituximab monotherapy, whereas higher levels may necessitate combination therapies. The dual benefit of RA disease control and resolution of bleeding makes rituximab therapy compelling in the rare patient who presents with these 2 disorders.