Bullous pemphigoid associated with acquired hemophilia A: A case report.

Background: Acquired hemophilia A (AHA) is a rare and potentially severe bleeding disorder caused by circulating autoantibodies against factor VIII (FVIII). In approximately 50% of the patients, the condition is associated with autoimmune diseases, cancers, medication use, pregnancy, and the post-partum period. Bullous pemphigoid (BP) is a chronic autoimmune subepidermal blistering disease associated with tissue-bound and circulating autoantibodies against BP antigens 180 (BP180) and 230 (BP230). AHA-associated BP has a high mortality rate; hence, the understanding of this disease must improve.

Case summary: A 69-year-old man presented with erythema, blisters, blood blisters, and crusts accompanied by severe pruritus for more than 20 days, and ecchymosis and swelling on his left upper arm for 3 days. Pathological examination revealed a subepidermal blister that contained eosinophils. Laboratory tests showed that the BP180 autoantibody levels had increased, isolated activated partial thromboplastin time was notably prolonged (115.6 s), and coagulation FVIII activity was extremely low (< 1.0%). Furthermore, the FVIII inhibitor titer had greatly increased (59.2 Bethesda units). Therefore, the patient was diagnosed as having BP associated with AHA, prescribed 0.05% topical halometasone cream, and transferred to a higher-level hospital for effective treatment; however, he died after 2 days.

Conclusion: AHA associated BP is rare, dangerous, and has a high mortality rate. Therefore, its timely diagnosis and effective treatment are necessary.