Angioedema. Pathogenesis, differential diagnosis, and treatment.

Angioedema is a constellation of syndromes that present a great challenge to the clinician. The term "angioedema" describes the localized, transient, episodic edema of the deeper layers of the skin or of the mucosa of the gastrointestinal tract. Although angioedema may affect any part of the body, the skin and gastrointestinal tract are involved most commonly by far. Episodic abdominal pain arising from angioedema affecting any intra-abdominal organ may occur without skin angioedema; therefore, angioedema must be included in the differential diagnosis of intermittent, unexplained abdominal pain. Angioedema is caused by extravasation of plasma in the affected areas, which at times is accompanied by nonspecific, minimal cellular infiltrate. The most commonly identified causes of angioedema are medications, allergens, and physical agents, but most angioedema is idiopathic. Rare forms of angioedema associated with either hereditary or acquired faulty activation of the complement and kallikrein-kinin systems have been extensively described. Taking a comprehensive personal and family history, performing a physical examination, and compulsively monitoring the response to therapy are the most rewarding and cost-effective diagnostic and treatment tools. Diligent and knowledgeable follow-up by the attending physician spares patients costly and unnecessary tests as well as harmful treatment. The most effective treatment depends on the identification of the causative mechanism and--especially when the mechanism is not identified--on the clinician's knowledge and experience with innovative therapeutic regimens.