Gruppo Italiano Ricerca Dermatiti da Contatto ed Ambientali Italian Multicenter Study of Allergic Contact Photodermatitis: epidemiological aspects.

A total of 1,050 patients with histories and clinical pictures suggestive of photoallergic contact dermatitis were seen. All the patients underwent photopatch tests with haptens proposed by the Gruppo Italiano Ricerca Dermatiti da Contatto plus other substances suggested by each patient's history. Two hundred fifty-nine patients (24.6%) were positive to at least one test substance of the standard series or to substances added. Typical photoallergic reactions were seen in 198 subjects (259 minus 40 toxic photodermatitis to chlorpromazine and 21 to promethazine), which represents 18.8% of the total population. Topical drugs represent the most involved substances in photodermatitis. The incidence in our population was about equal for antimicrobial agents, additives to fragrances, and fragrances themselves. Other allergens found were salicylanilides, whereas sun-screening agents were the fifth group of haptens but with clear-cut relevance. This study is a first attempt to organize the data about results of photopatch tests applied to Italian patients.