Congenital melanocytic nevi (CMN) are composed of clusters of nevo-melanocytes that are generally present at birth but occasionally arise as late as several years. These lesions arise from melanocytic stem cells that migrate from the neural crest to the embryonic dermis and upward into the epidermis. They may also migrate into the leptomeninges. Although the bulk of these lesions are small and benign, some cover large portions of the body or can be in conspicuous locations, presenting challenging reconstructive problems. Furthermore, their potential for malignant degeneration causes anxiety for the parent, primary care physician and surgeon alike. Although small pigmented nevi are present in one out of 100 births, large nevi are present in only 1 in 20,000 births, and the giant lesions are even less common. As a result, most surgeons have little experience with them and little opportunity to develop a rational protocol for their treatment.
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