Summary
Angioedema is a disease of characterized by occurrence of transitory and recurrent subcutaneous and/or submucosal edemas resulting in swelling and abdominal pain. Prevalence is estimated at 1/100,000. Two forms have been described: hereditary (90% of cases) angioedema usually occurring in childhood or adolescence and acquired angioedema usually occurring after 50 years of age (see these terms). Patients present with white, circumscribed non-pruritic edemas that remain for a period of 48 to 72 hours and recur with variable frequency. The edemas may involve the digestive tract resulting in a clinical picture similar to that seen in intestinal occlusion syndromes, sometimes associated with ascites and hypovolemic shock. Laryngeal edemas can be life-threatening with a risk of death of 25% in the absence of appropriate treatment. Dental procedures are a triggering factor for laryngeal edemas. Edemas of the face are a risk factor for laryngeal involvement. Angioedema can be caused by quantitative or functional defect in C1-INH (inhibitor of the C1 fraction of complement) or by gain function mutation of Hageman factor. Transmission of hereditary angioedema is autosomal dominant and acquired angioedema may be associated with a lymphoproliferative syndrome or the presence of anti-C1-INH autoantibodies. Diagnosis is based on clinical findings, measurement of C4 concentrations and on quantitative and functional analysis of the C1-INH (dosages of C3 and C4, weighted and functional dosage of C1Inh, immunoblot, search for anti-C1-INH antibodies). C1q levels are low in patients with AAE but are normal in patients with hereditary angioedema. Differential diagnoses include intestinal occlusion syndromes and histamine-induced angioedemas (of allergenic or nonallergenic origin) generally associated with urticaria. Management includes the use of tranexamic acid, and, in case of severe attacks, icatibant or intravenous administration of C1-INH concentrate. In the acquired form of the disease, management aims to treat the associated disease if present. With proper diagnosis and treatment, prognosis for patients with hereditary angioedema is good. The prognosis of the acquired angioedema depends on the underlying disorder. *Author: Dr L. Bouillet (May 2009)*.
