Acquired factor VIII inhibitor in a patient with chronic myelogenous leukemia receiving interferon-alfa therapy

OBJECTIVE: To report a case of an acquired factor VIII inhibitor associated with the use of interferon-alfa. CASE SUMMARY: A 58-year-old white man with newly diagnosed chronic myelogen ous leukemia (CML) was initially treated with hydroxyurea. Interferon-alfa therapy was started six weeks later in order to enhance the response, with gradual reduction and eventual discontinuation of hydroxyurea. Interferon-a lfa was continued for one year. Following bone marrow aspiration at one yea r, the patient developed significant bleeding and bruising at the site of e xtraction. His hemoglobin decreased from 11.3 to 9.3 g/dL and his activated partial thromboplastin time was elevated at 72 seconds. The factor VIII co ncentration was 0.02 units/mL; factor VIII inhibitor concentration was 58 B ethesda units. A diagnosis of an acquired factor VIII inhibitor was made, a nd the patient was treated with activated factor VII concentrates and predn isone. Interferon-alfa was discontinued, and the inhibitor subsequently dis appeared over the next sex weeks. The patient did not have any further blee ding problems. DISCUSSION: Acquired for VIII inhibitors other than in patients with hemoph ilia are rare. To date, there are no reported cases of factor VIII inhibito rs associated with CML. Moreover, the temporal association with interferon- alfa administration suggests a causal relationship. There are only two prev ious case reports suggesting interferon-alfa as a cause of factor VIII inhi bitors. CONCLUSIONS: Induction of factor VIII inhibitors is a serious potential com plication of therapy with interferon-alfa. We suggest that a diagnosis of a n acquired factor VIII inhibitor be considered in patients who experience u nexplained bleeding with interferon-alfa therapy.