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Syn. : melanosis progressiva. A disease of the skin, usually beginning in childhood and occurring in family groups, Characterized at first by the development of an abundant crop of freckles accompanied by atrophic changes in the skin and later by the appearance of malignant growths. In its later manifestations it resembles the extreme Forms of senile atrophy of the skin. The lesions are commonly on the exposed parts of the body and generally appear early in childhood. [Gr., xeros, dry, + derma, The skin.]