Acquired Hemophilia A Presenting with Infectious Aortic Aneurysms Due to an Underlying Helicobacter cinaedi Infection

Acquired hemophilia A (AHA) is a bleeding disorder caused by the acquired appearance of inhibitor for factor VIII. Approximately half of all patients with AHA have some type of underlying disease. We herein report the case of a 72-year-old Japanese man with AHA who presented with infectious aortic aneurysms due to an underlying Helicobacter cinaedi infection. To our knowledge, this is the first report of AHA triggered by a bacterial infection; however, there may be similar cases that remain undiagnosed because this pathogen is difficult to identify. Clinicians should consider the possibility of H. cinaedi as a causative pathogen in patients presenting with a fever of unknown origin.