Summary
Angioedema is characterized by the 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 angioedema (HAE; 90% of cases) usually occurring in childhood or adolescence, and acquired angioedema (AAE) usually occurring after 50 years of age (see these terms). Patients present with white, circumscribed nonpruritic 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 syndrome, sometimes associated with ascites and hypovolemic shock. Laryngeal edema 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 edema. Edemas of the face are a risk factor for laryngeal involvement. Angioedema can be caused by quantitative or functional defects of the plasma protease C1 inhibitor (C1-INH encoded by the SERPING1 gene; 11q12-q13-1) or by gain-of-function mutations of coagulation factor XII (Hageman factor; F12). Transmission of HAE is autosomal dominant and AAE 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 C1-INH (dosages of C3 and C4, weighted and functional dosage of C1-INH, immunoblot analysis and screening for anti-C1-INH antibodies). C1q levels are low in patients with AAE but are normal in patients with HAE. Differential diagnoses include intestinal occlusion syndrome and histamine-induced angioedema (of allergenic or nonallergenic origin) generally associated with urticaria. Management includes administration of tranexamic acid, and, in case of severe attacks, icatibant therapy or intravenous administration of C1-INH concentrate. For the acquired form, management aims to treat the associated disease. With proper diagnosis and treatment, prognosis for patients with HAE is good. The prognosis of AAE depends on the underlying disorder. *Author: Dr L. Bouillet (May 2009)*.
