Spontaneously acquired anti-factor VIII antibodies: report of a patient with adenocarcinoma of the prostate.

Anti-factor VIII antibodies, inherited or acquired inhibitors of the factor VIII molecule, have not been reported previously in the urological literature. Although more common in hemophiliac patients who have received multiple transfusions, this anticoagulant may be the cause of severe hemorrhage in nonhemophiliac patients. We describe a patient with carcinoma of the prostate and an unsuspected anti-factor VIII antibody, who experienced excessive postoperative bleeding and prolonged hospitalization following a vesicolithotomy and bilateral orchiectomy. A prolonged partial thromboplastin time and a significant decrease in measurable factor VIII clotting activity in a patient with no history of bleeding problems are essential clues in making the diagnosis of a factor VIII inhibitor. This coagulation defect is treated best with prothrombin complex concentrates, which contain vitamin K dependent clotting factors.