Successful treatment of severe lung hemorrhage caused by acquired factor V inhibitor with rituximab.

Acquired coagulation factor deficiency is a rare disorder that occurs in patients with drug reactions, malignancy and collagen diseases as well as during pregnancy. Most cases are caused by factor VIII inhibitors. We herein describe the case of a 61-year-old Japanese man with acquired factor V inhibitor who developed symptoms 11 days after lung surgery for empyema. The patient required mechanical ventilation to treat acute respiratory failure due to severe pulmonary hemorrhage. He responded poorly to steroid pulse therapy; however, treatment with rituximab was successful.