ABSTRACT
Diagnostic in vivo skin tests are used in dermatology to detect and defi ne the possible exogenous chemical agent that causes a skin disorder, and hence are critical in their scientifi c documentation. These chemical agents often cause skin disorders by hypersensitivity mechanisms, which can thus be diagnosed by a provocative test (1). The anatomical advantage of studying skin disorders is that the skin is a foremost frontier of the human body and, therefore, easily accessible for testing. Although differences in the reactivity of different skin sites exist, many causative agents may be tested locally on one skin site, thus exposing only limited areas of skin to the diagnostic procedures. Such procedures include patch, intradermal, prick, scratch, scratch-chamber, open, photo, photopatch, and provocative use tests. In cases of some generalized skin reactions, however, systemic exposure to the external agent may be necessary for diagnosis.
