Phytophotodermatitis

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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Clinical evaluation of the cutaneous phototoxicity of 5, 10, 15, 20-tetra (m-hydroxyphenyl)chlorin

Hubert van den Bergh, Georges Wagnières

The cutaneous phototoxic reaction induced by i.v. injection of 5,-10,-15,-20-tetra(m-hydroxyphenyl)chlorin (mTHPC) has been clin. evaluated in patients undergoing photodynamic therapy. These tests were performed on the backs of 23 patients with a solar sim ...

1998

Phototoxicity

Phototoxicity, also called photoirritation, is a chemically induced skin irritation, requiring light, that does not involve the immune system. It is a type of photosensitivity. The skin response resembles an exaggerated sunburn. The involved chemical may enter into the skin by topical administration, or it may reach the skin via systemic circulation following ingestion or parenteral administration. The chemical needs to be "photoactive," which means that when it absorbs light, the absorbed energy produces molecular changes that cause toxicity.

Psoralen

Psoralen (also called psoralene) is the parent compound in a family of naturally occurring organic compounds known as the linear furanocoumarins. It is structurally related to coumarin by the addition of a fused furan ring, and may be considered as a derivative of umbelliferone. Psoralen occurs naturally in the seeds of Psoralea corylifolia, as well as in the common fig, celery, parsley, West Indian satinwood, and in all citrus fruits.