Concept

Dermite des prés

Résumé
Phytophotodermatitis, also known as berloque dermatitis or margarita photodermatitis, is a cutaneous phototoxic inflammatory reaction resulting from contact with a light-sensitizing botanical agent followed by exposure to ultraviolet light (from the sun, for instance). Symptoms include erythema, edema, blisters (vesicles and/or bullae), and delayed hyperpigmentation. Heat and moisture tend to exacerbate the reaction. A reaction may be elicited in any person who has been exposed to adequate amounts of both a photosensitizer and ultraviolet light. Phytophotodermatitis is not an immunologic response; no prior exposure to the photosensitizing agent is required. The photosensitizing substances found in phototoxic plants belong to a class of chemical compounds called the furanocoumarins, which are activated by long-wavelength ultraviolet (UVA) light. The most toxic of these organic compounds are the linear furanocoumarins, so called since they exhibit a linear chemical structure. Bergapten and xanthotoxin (also known as methoxsalen), two linear furanocoumarins derived from psoralen, are invariably found in plants associated with phytophotodermatitis. A reaction typically begins within 24 hours of exposure and peaks at 48–72 hours after exposure. Initially, the skin turns red and starts to itch and burn. Large blisters (or bullae) form within 48 hours. The blisters may leave black, brown, or purplish scars that can last for several years. This hyperpigmentation of the skin is caused by the production of melanin triggered by the furanocoumarins. Although media reports have suggested that eye exposure to the agent can lead to temporary or permanent blindness, the risk of permanent blindness is not supported by existing research. Phytophotodermatitis can affect people of any age. In children, it has sometimes been mistaken for child abuse. Plants associated with phytophotodermatitis mainly come from four plant families: the carrot family (Apiaceae), the citrus family (Rutaceae), the mulberry family (Moraceae), and the legume family (Fabaceae).
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