Immunological contact urticaria (ICU) is an immediate type 1 allergic reaction (52). The molecules of a contact urticant react with specific IgE molecules attached to mast-cell membranes. The cutaneous symptoms are elicited by vaso-active substances, mainly histamine, released from mast cells. Other mediators of inflammation may influence the degree of response. Immunological contact urticaria reaction can extend beyond the contact site and generalized urticaria may be accompanied by other symptoms, such as rhinitis, conjunctivitis, asthma, and even anaphylactic shock. The term ''contact urticaria syndrome'' was therefore suggested by Maibach and Johnson (55). Fortunately, the appearance of systemic symptoms is rare, but it may be seen in cases of strong hypersensitivity or in a widespread exposure and abundant percutaneous absorption of an allergen.
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