A case of acquired hemophilia A with massive hemothorax

Acquired hemophilia A (AHA) is an uncommon but potentially life-threatening hemorrhagic disorder caused by the development of an inhibitor against coagulation factor VIII (FVIII). AHA is very rare, affecting approximately 1 in 1 million individuals. However, the incidence may actually be higher, because diagnosis is difficult and the disease can be overlooked. We report a case of an 80-year-old man who presented with sudden onset of severe hemothorax. The patient was diagnosed with presumed AHA based on acute onset of bleeding symptoms and unexplained isolated prolonged activated partial thromboplastin time. Diagnosis was definitely established by demonstrating a decrease in FVIII activity, presence of FVIII inhibitor activity, and normal von Willebrand factor. The patient was successfully treated with recombinant activated coagulation factor VII and transcatheter artery embolization of the intercostal arteries.