We encountered a 2-year-old boy with acquired haemophilia, which rarely occurs in children, who was complicated with nephrotic syndrome. In mid-August 2001, he was diagnosed to have nephrotic syndrome based on the presence of massive proteinuria and hypoalbuminaemia. Activated partial thromboplastin time (APTT) was normal at 42.4 s at that time. After starting prednisone administration of 2 mg kg(-1) day(-1), the proteinuria disappeared immediately. However, in early October the same year, subcutaneous ecchymosis and intramuscular bleeding occurred for no apparent reason, and from the examination results his APTT was 106.4 s, factor VIII (FVIII) activity was <1%, and the anti-FVIII inhibitor titre was 6.9 BU ml(-1). As a result, he was diagnosed to have acquired haemophilia. The anti-nuclear antibody and anti-phospholipid antibody were negative. With recombinant activated FVII, haemostasis was obtained, and after administering three courses of steroid pulse therapy (methyl prednisolone: 20 mg kg(-1) day(-1) x 3 days), the anti-FVIII inhibitory activity disappeared. An analysis of the immunological and coagulation properties of his FVIII autoantibodies showed the anti-FVIII inhibitory activity to be mediated by IgG(1) antibody. In other words, his FVIII inhibitor was a Th1 dominant and it provided a good response to treatment. These findings correlate with those of previous reports. The patient thereafter frequently demonstrated a recurrence of nephrotic syndrome. As a result, he is presently being managed with cyclosporine. However, no recurrence of the anti-FVIII titre has been observed.
Autoantibodies Child, Preschool