Photocontact Dermatitis

Abstract

This adverse reaction is due to chemical substances coming in contact with the skin, that elicit an inflammatory response after exposure to ultraviolet rays and/or visible light. The most common substances responsible for phototoxic contact dermatitis are furocoumarins in plants, coaltar derivatives and some dyes. Clinical features are those of an exacerbation of the normal skin response to exposure to the sun, with intense erythema and edema, and sometimes bullae strictly confined to photoexposed skin sites that have come in contact with the causal agent. The causes of photoallergic contact dermatitis are antimicrobials (halogenated salicylanilides, some antimycotics, sulfanilamide and some its derivatives), furocoumarins, frangrances, sunscreens, non-steroidal anti-inflammatory drugs, and phenothiazine derivatives. The predominant clinical aspect is eczematous; the sites affected are photoexposed areas, although even covered sites can be involved. Mainly men aged 40 to 80 years may be affected by chronic actinic dermatitis, a contact dermatitis-like reaction with a pathogenic mechanism not yet entirely known. It can manifest on normal skin but is more often observed in subjects with previous allergic or photoallergic contact dermatitis. Its clinical picture is characterized by eczematous lesions, often with scaly lichenification and infiltrate plaques, in exposed areas (face, neck, scalp, upper chest, dorsal aspects of forearms and hands).