Coexistence of lupus anticoagulant and acquired haemophilia in a patient with monoclonal gammopathy of unknown significance.

Acquired haemophilia or factor VIII (FVIII) deficiency, caused by FVIII inhibitor antibodies, is a very rare condition that commonly results in severe haemorrhagic complications. We report a case of acquired haemophilia presenting with a left calfnontraumatic haematoma. The patient was also found to have lupus anticoagulant (LAC). The simultaneous presence of LAC and FVIII inhibitor is exceedingly rare. The differentiation between these two conditions is crucial, because both result in a prolongation of the activated partial thromboplastin time test, which does not correct when mixed with the plasma of a normal control; however, the clinical manifestations range from thrombosis in the presence of LAC to massive haemorrhage with FVIII inhibitors.