Incidence of congenital melanocytic nevi in newborn babies in Denmark.

Three hundred fourteen unselected babies were examined within 96 hours of delivery. Three (1%) of the infants had clinically recognizable pigmented lesions. Two of the lesions (mean, 0.6%; range, 0.1%-2.3%; 95% confidence limits) proved histologically to be compound melanocytic nevi. The histology displayed almost identical patterns, with large nests of melanocytes at the dermoepidermal junction and only few nevus cells in the papillary dermis. A 0.6% incidence rate corresponds to 330 congenital melanocytic nevi in Denmark each year (range, 55-1265; 95% confidence limits). Because histology does not seem to be an accurate diagnostic tool to sort out the malignant potential of the small congenital melanocytic nevi, prospective studies are needed to characterize the premalignant melanocytic nevi, whether congenital or acquired.