後天性血友病Aの長期経験：臨床的特徴と転帰に関する40年間の単一施設研究

Background: Acquired haemophilia A (AHA) is a rare autoimmune disorder characterized by the development of autoantibodies against Factor VIII activity, leading to a significant reduction in its functionality. Clinically, AHA presents with an unexpected prolongation of activated partial thromboplastin time (aPTT) and spontaneous bleeding episodes in patients without any personal or family history of haemorrhages. Bleeding manifestations can be severe at presentation, making early diagnosis and prompt treatment essential to reduce morbidity and mortality. Methods: We report on a single-centre cohort of 35 patients with AHA (examined from 1984 to 2024), analysing their demographics, underlying conditions, bleeding characteristics, treatment and outcome. Results: The median age of patients at diagnosis was 69 years (ranging from 18 to 92), 15 were males and 20 females. AHA was idiopathic in 37% of cases, severe bleeding was observed in 54% of patients treated with bypassing agents. Recombinant activated Factor VII (rFVIIa) was administered in 79% of cases and activated prothrombin complex concentrate (aPCC) in 10%, with no significant differences in haemostatic response and no thromboembolic complications. Occurrence of major bleeding showed no significant association with sex, age group, underlying condition, baseline Factor VIII activity or inhibitor titre at diagnosis. A total of 69% of patients were treated with corticosteroids alone, and 23% received a combination of corticosteroids and cyclophosphamide. Two patients died, six were lost to follow-up after partial remission, and one relapsed without bleeds after complete remission. Statistical analyses highlighted that the FVIII inhibitor titre > 20 BU was the only significant prognostic factor affecting time to complete remission. Conclusions: These observations emphasize the critical role of clinical suspicion and timely referral to experienced centres with adequate laboratory support for the effective management of AHA.