A Rare Case of Acquired Factor VIII Deficiency in an Elderly Male With a History of Rheumatoid Arthritis.

Acquired hemophilia A (AHA) or factor VIII (FVIII) deficiency is caused by autoantibodies targeting FVIII in the blood coagulation pathway; it is a rare condition making it challenging to diagnose. A timely diagnosis is crucial, without which there is a risk of catastrophic bleeding. We report a case of a patient with a history of duodenal arteriovenous malformations, previously on apixaban, who presented with four days of melena. On admission he was found to have a hemoglobin of 5.7 and elevated partial thromboplastin time (PTT), promoting further workup showing FVIII levels of <1%, with a mixing study that failed to correct suggesting the presence of inhibitors against FVIII. Other characteristics of this patient's cases included controlled rheumatoid arthritis without detectable rheumatoid factor or increased erythrocyte sedimentation rate (ESR). The patient was initially treated with prednisone and intravenous immunoglobulins, but an insufficient response prompted the initiation of recombinant factor VII, rituximab, and cyclophosphamide during hospitalization.