Autoimmune hemorrhaphilia resulting from autoantibody against the a subunit of factor XIII

Abstract

A 65-year-old woman was admitted with acute intramuscular hemorrhage of the left gluteus medius and piriformis muscles and associated anemia. Blood tests showed low plasma factor XIII (FXIII) antigen and activity. A cross-mixing test revealed a concave “inhibitor” pattern and anti-FXIII-A subunit antibody was detected. The patient was diagnosed with autoimmune hemorrhaphilia resulting from anti-FXIII antibody. The bleeding has not recurred since the initiation of treatment with oral immunosuppressive agents. Although hemorrhagic acquired FXIII deficiency is a rare disorder, prompt recognition of the underlying mechanism can save lives.