Immediate-Type Testing: Immunologic Contact Urticaria and Immunologic Contact Urticaria Dermatitis

Abstract

We note a relative paucity of literature on immunologic contact urticaria (ICU) and protein contact dermatitis (now preferentially neologized-immunologic contact urticaria dermatitis). Immunologic contact urticaria differs from nonimmunologic contact urticaria in that the former requires previous exposure to a substance to induce a wheal and flare response on the skin. Contact urticaria can be divided into four clinical stages, ranging from a localized reaction to a systemic, possibly fatal response. To test for ICU, we advise starting with open application testing and moving onto prick testing if negative results ensue. The prick test is a simple, straightforward method used to diagnose ICU and also poses less of a threat for inducing anaphylaxis. In our experience, applying the following tips with prick testing yields less false negatives than with commercial allergens.