Allergic and Photoallergic Contact Dermatitis: A 10-year Experience

Background Photoallergic contact dermatitis (PACD) is a hypersensitivity reaction that occurs when a previously photosensitized exogenous agent comes into contact with UV radiation. Currently, there are no studies profiling photoallergic reactions in Canada. Because the photoallergen profile changes over time, it is necessary to continually update our knowledge to ensure proper recognition of allergens and appropriate treatment of patients. Objective This study aimed to profile photoallergic reactions in Canada. Methods A retrospective chart review of all patients who underwent photopatch testing at Toronto Western Hospital between January 2001 and December 2010 was completed. Photoallergic, allergic, and irritant reactions were recorded for 26 common allergens. Results Ninety-nine patients (61.9%) had at least 1 positive reaction to the test allergens. Fifty-four patients (33.8%) had at least 1 photoallergic reaction. All 26 allergens produced at least 1 allergic or photoallergic reaction. The most common relevant photoallergens were benzophenone-3, octyl dimethyl para-aminobenzoic acid (PABA) in 5% alcohol, and butylmethoxy-dibenzoylmethane. Conclusions This study is the first to profile photoallergic contact reactions in Canada. It is clear that the culprit photoallergen in PACD can often be identified in a properly selected population. Future surveillance is necessary to continue to characterize PACD trends in Canada and to help better treat and screen this patient population.