获得性血友病A

获得性A血友病A(AHA; 2017 ICD-10-CM: D68.311)是一种罕见但可危及生命的系统性自身免疫性疾病。获得性血友病的最常见类型为针对内源性凝血因子(F)VIII 的自身抗体（AHA），然而，针对其他凝血因子（包括I、II、V、VII、 IX、X、XI及XIII）的自身抗体亦有报道.¹ 

该疾病通常见于无家族史或既往出血史的患者，以突发出血或非预期出血为首发表现。由于患者就诊时常常由缺乏该类疾病诊治经验的医师接诊，进而导致误诊、漏诊或诊治延误的发生。因此一旦疑诊AHA，应立即延请抑制物管理经验丰富的血友病中心会诊，以确保迅速而准确的诊断、及时有效治疗和防止不当干预增加的额外出血风险。 ^2,3

据估计获得性血友病A年发病率约为1.5/100万。⁴约半数AHA可继发于自身免疫病、各种恶性肿瘤、药物或妊娠；约半数患者为特发性。³AHA可发生于任何年龄或性别。除了一部分女性患者在围产期发病，AHA更多发生于老年患者。⁵报道的死亡率约为3%~40%，尽管一些早期研究中可能包含了有效治疗受限的患者。^4-7

AHA的出血特征不同于先天性血友病A(HA)或血友病B(HB)。其常见的出血表现包括皮肤瘀斑、软组织出血、肌肉和粘膜、消化道、颅内、咽后、腹膜后和手术部位出血。关节出血并不常见。

超过70%的患者可有严重、危及生命的出血。⁵ 然而30%的患者出血轻微，可无需止血治疗。^4,6 例如皮肤瘀斑和皮下血肿，即便范围较广，也可能只需密切观察而不必给予特殊治疗。⁸

AHA患者出血表现的严重程度和出血风险与其FVIII活性水平或抑制物滴度并无明显相关。^2,9 即使发病初期患者无出血表现或出血轻微，但只要体内自身抗体持续存在，患者就有自发性、致命性出血风险。^2,8 与先天性HA或HB患者替代治疗后可出现的同种抗体不同，AHA患者体内的自身抗体表现为II型动力学特征，因此可检测出残余FVIII活性。

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9. Baudo F, de Cataldo F. Acquired haemophilia in the elderly. In: Balducci L, Ershler W, de Gaetano G, eds. Blood Disorders in the Elderly. Cambridge: Cambridge University Press; 2007:389-407.