Urticaria is defined by the appearance of wheals (hives or individual urticae) of any size and configuration on any part of the skin. The wheals consist of a circumscribed, slightly elevated, erythematous, usually pruritic, edematous swelling of the upper dermal tissue which disappears within minutes to hours, leaving a basically unaltered, normal appearing skin (restauratio ad integrum). Similarly transient, erythematous swellings of the deeper cutaneous and the subcutaneous tissue are called angioedema and appear in about 50 % of patients in association with ordinary urticaria (see Chapter 4, p. 47).
KeywordsMast Cell Food Allergy Chronic Urticaria Chronic Idiopathic Urticaria Serum Sickness
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