Pediatric angioedema.

Angioedema is a self-limited nonpitting edema generally affecting the deeper layers of the skin and mucous membranes. It is the result of increased vascular permeability causing the leakage of fluid into the skin in response to potent vasodilators released by immunologic mediators. Two main pathways are thought to be implicated in angioedema. The mast cell pathway in which preformed mediators, such as histamine, rapidly formed mediators, leukotrienes and prostaglandins, are released from mast cells through IgE or direct activation. This is the most common pathway among children, with food, medications, and infections commonly implicated. The second pathway is the kinin pathway, most notably affected by angiotensin-converting enzyme (ACE) inhibitors and hereditary forms of angioedema, which ultimately results in the formation of bradykinin, a potent vasodilator. Angioedema is being encountered with increasing frequency, particularly among children and is important to recognize and treat for its life-threatening associated manifestations such as anaphylaxis and airway obstruction. Although angioedema is still not fully understood, we have broadened our understanding of the possible causes and clinical course of angioedema. An understanding of these potential causes and mechanisms by which angioedema can occur may guide the clinician in determining the need for diagnostic testing and the extent of treatment.