BI46 Acquired haemophilia A following biologic therapy for dermatological conditions: a systematic review of published case reports

Abstract

Acquired haemophilia A (AHA) is a rare but potentially life-­threatening bleeding disorder caused by factor VIII inhibitors. Biologic therapies are increasingly used in dermatology to treat inflammatory skin diseases, autoimmune blistering disorders and cutaneous malignancies, and have rarely been linked to AHA. Recognizing this complication early is crucial for timely diagnosis and management. We reviewed published reports of AHA occurring after biologic therapy in dermatology patients, highlighting clinical patterns and management to raise awareness of this rare but serious complication. A systematic review was carried out using PubMed, Embase and OVID MEDLINE to retrieve published reports from inception to 2026 following the PRISMA guidelines. Extracted data included patient characteristics, underlying diagnosis, biologic agent, time to onset, clinical features, treatment and outcomes. Six patients were identified in published case reports of AHA following biologic therapy for dermatological conditions. Two patients, aged 88 and 64 years, with bullous pemphigoid, developed spontaneous bruising and haematomas several weeks after initiation of omalizumab. One patient with chronic spontaneous urticaria (age 69 years) developed bleeding after multiple omalizumab doses and recovered with corticosteroid therapy. An 80-year-old man with severe eczema developed extensive bruising and mucosal bleeding shortly after initiating dupilumab. Two patients with cutaneous melanoma (aged 67 and 70 years) developed mucocutaneous bleeding and prolonged activated partial thromboplastin time after programmed death-1 inhibitor therapy, one following nivolumab and one following pembrolizumab. Across all cases, the time to onset ranged from a single dose to several weeks, yet clinical and laboratory features were remarkably consistent, characterized by spontaneous bleeding and detectable factor VIII inhibitors. All patients responded well to immunosuppressive treatment. AHA is a rare but serious complication of biologic therapy, requiring early recognition and prompt immunosuppressive management.