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xeroderma pigmentosum xeroderma pig·men·to·sum (pĭg'mən-tō'səm, -měn-)
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.
rare, recessively inherited skin condition in which resistance to sunlight and other radiation beyond the violet end of the spectrum is lacking. On exposure to such radiation the skin erupts into numerous pigmented spots, resembling freckles, which tend to develop into multiple carcinomas. The condition may occur in mild or severe forms. Protection from direct sunlight and surgical destruction of precancerous or established malignant lesions are the prescribed treatment