Photocontact dermatitis

Abstract

Photocontact dermatitis is not a common condition, but neither is it rare. Both photo-irritant contact dermatitis (PICD) and photoallergic contact dermatitis (PACD) are seen by most dermatologists in general practice. PICD is diagnosed on clinical grounds and is usually caused by furocoumarins in plants like limes and celery. PACD is caused primarily by sunscreens but can also be the result of fragrances and antibacterial agents. PACD can only be diagnosed by photo-patch testing that most dermatologists, even those who patch test and give phototherapy in their office, do not perform. The procedure as outlined in this manuscript is relatively simple and can easily be accomplished in the dermatologist's office.

Benzophenones

“…A large European multicenter study across 12 countries found ketoprofen to cause the most photopatch reactions of all agents tested. 38 Topical NSAIDs are frequently used in European countries but are far less common in the United States. 12 Not only do these 3 chemicals have similar structures, but also ketoprofen is broken down into various benzophenones structurally related to benzophenone-3 when it is irradiated with sunlight.…”

Phytophotodermatitis due to wild carrot decoction

“…Lesions may simply become erythematous, vesicles or bullae or appear as hyperpigmented patches without a preceding erythematous phase, and the hyperpigmentation may persist up to 6 months after exposure. [2] Phytophotodermatitis is a clinical diagnosis. [3] Photopatch testing in such patients is contraindicated, because a positive response might be severe, it would be expected to occur in the general population, and as such would not be discriminating in making the diagnosis.…”

Adverse Reactions to Sunscreen Agents

“…7,25 The prevalence of allergy to active sunscreen ingredients is low among individuals referred for patch testing, probably less than 1%. 7,28 The radiation that induces photocontact dermatitis, both toxic and allergic, almost always falls in the UVA (320Y400 nm) and visible light range (400Y800 nm). 26 In addition, inclusion of UV filters in photopatch testing series is not uniform, as the list of agents used for photopatch tests varies greatly by patch testing provider and location.…”