It is seen more commonly if there is a family history of allergy, and begins from infancy to young adulthood.
Allergens bind to specific IgE on surface of mast cells in respiratory tissue.
Bridging of IgE triggers release of chemical mediators such as histamine, leukotrienes, C4, D4. The history is the most important part of the evaluation. The physical examination should be focused on the identification of injected conjunctivae, transverse nasal creases, pale, edematous nasal mucosa, allergic shiners, Dennie-Morgan lines, lymphoid hyperplasia and cobblestoning of the posterior pharyngeal wall. The number of tests will vary with the age of the child, but in infants the most commonly tested allergens include milk, eggs and soy. Much more extensive testing can be done in older patients depending on the symptoms, history, and physical findings.