Allergy testing in dermatology and beyond.

Allergy is a broad term referring to an acquired alteration of the immune system in reaction to an antigen and can affect every organ system including the skin. Patients, dermatologists, and nondermatologist physicians may use this term in a variety of ways that do not necessarily refer to the same biological process or clinical presentation, which creates difficulty in adequate communication and expectation setting regarding workup and management of allergic conditions. The purpose of this article is to provide a brief background on the pathophysiology of common presentations of allergic disease; discuss routinely used allergy tests and their indications; and provide a more detailed review of patch testing, the most frequently used allergy test in dermatology.