Autoimmune C1 inhibitor deficiency and angioedema.

C1 inhibitor (C1-INH) deficiency results in bouts of mucocutaneous edema and may be inherited (hereditary angioedema) or acquired (acquired angioedema). The syndrome of acquired angioedema, characterized by the adult onset of angioedema and by the lack of evidence of inheritance of the disease, may be associated with lymphoproliferative or other malignant diseases (type I) or with the presence of autoantibodies to C1-INH (type II); this is a rare variant form of C1-INH deficiency with angioedema. We report here a case of acquired C1-INH deficiency with angioedema, hypotension and abdominal discomfort observed in a 71-year-old man in whom complement abnormalities and autoantibodies against C1-INH have been observed and who was classified as having an autoimmune C1-INH deficiency. From the therapeutic point of view after resolution of the acute attacks, high doses of tranexamic acid have been able, at first, to decrease the frequency and the severity of the symptoms, and subsequently to provide a long symptom-free time.