Three cases of acquired factor VIII: C inhibitors in non-hemophilic patients

During the last ten years we observed three non-hemophilic patients with factor(F) VIII: C inhibitors (2 women aged 68 and 80 and a man aged 51). In all three cases, a sudden bleeding tendency was observed shortly after an injury or surgery. Coagulation tests showed a prolonged aPTT and a decreased F VIII: C level. Other deficiencies of blood-clotting factors and acquired or hereditary von Willebrand's disease could be excluded. Therapy with F VIII: C concentrate, cryoprecipitate, or fresh-frozen plasma did not produce the expected increase in F VIII: C. Measurement of F VIII: C inhibitor levels (Bethesda Units, BU) revealed values in the range between 9 and 64 BU. The two patients subjected to long-term therapy with a combination of prednisone (initially 2-3 mg/kg BW) and azathioprine (2-3 mg/kg BW) responded positively; the F VIII: C concentration increased. The third patient, treated only with a low dose of prednisone (30 mg/day), did not show any reaction at all. Since hereditary hemophilia A could be excluded, the inhibitors apparently were acquired. Malignant tumors did not appear. In conclusion, long-term therapy of an acquired F VIII: C inhibitor with a combination of prednisone and azathioprine may lead to complete disappearance of the inhibitor, normalization of the coagulation tests, and complete remission of the bleeding tendency.