xeroderma pigmentosum (redirected from Light allergy)

xeroderma /xe·ro·der·ma/ (zēr″o-der´mah) a mild form of ichthyosis, marked by a dry, rough, discolored state of the skin.xerodermat´ic

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xeroderma pigmento´sum  a rare pigmentary and atrophic autosomal recessive disease in which extreme cutaneous sensitivity to ultraviolet light results from an enzyme deficiency in the repair of DNA damaged by ultraviolet light. It begins in childhood, with early development of excessive freckling, telangiectases, keratomas, papillomas, and malignancies in sun-exposed skin, severe opthalmologic abnormalities, and, in some cases, neurological disorders.

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xeroderma pig·men·to·sum (pgmn-tsm, -mn-)

n.

A rare hereditary skin disorder caused by a defect in the enzymes that repair DNA damaged by ultraviolet light and resulting in hypersensitivity to the carcinogenic effect of ultraviolet light.

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xeroderma pigmentosum (XP),

a rare, inherited skin disease resulting from faulty DNA repair, characterized by extreme sensitivity to ultraviolet light, exposure to which results in freckles, telangiectases, keratoses, papillomas, carcinoma, and, possibly, melanoma. Keratitis and tumors developing on the eyelids and cornea may result in blindness. Exposure to sunlight must be avoided. See also Kaposi's disease.

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xeroderma,

n a chronic skin condition characterized by dryness and roughness.

xeroderma pigmentosum,

n an eruption of exposed skin occurring in childhood and characterized by numerous pigmental spots resembling freckles, larger atrophic lesions eventually resulting in glossy white thinning of the skin surrounded by telangiectases, and multiple solar keratoses that undergo malignant changes at an early age. This results from a single-gene autosomal recessive disorder.

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xeroderma pigmentosum 

An autosomal recessive inherited disease in which there is progressive pigmentary degeneration of the skin, especially in sun-exposed areas. It results from a deficient enzyme used in the repair of DNA damaged by ultraviolet light. The condition begins in infancy and is characterized by the appearance of numerous pigmented spots resembling freckles and telangiectases. Eventually atrophic patches appear as well as wart-like excrescence and often squamous cell carcinoma. Patients are photophobic and the eyelids are frequently affected with atrophy and ectropion, which may be accompanied with conjunctival inflammation and corneal ulceration. Protection of the eyes and skin is essential as well as surgical removal of the carcinomatous tumours, but many patients eventually succumb to metastases.