ABSTRACT
The contact urticaria syndrome comprises a heterogeneous group of inflammatory reactions that appear, usually within minutes, after contact with the eliciting substance. They include not only wheal and flare but also transient erythema and may lead to eczema. Symptoms can be classified according to morphology and severity: Itching, tingling, or burning accompanied by erythema are the weakest type of immediate contact reaction and are often produced by cosmetics and fruits and vegetables. There has been confusion in using terms such as contact urticaria, immediate contact reactions, atopic contact dermatitis, and protein contact dermatitis. The mechanisms underlying contact reactions are divided into two main types, namely, immunologic (IgE-mediated) and nonimmunologic immediate contact reactions. In skin challenge, the molecules of a contact reactant penetrate the epidermis and react with specific IgE molecules attached to mast cell membranes. The diagnosis of immediate contact reactions is based on a full medical history and on skin tests with suspected substances.
