Histopathology of congenital pigmented nevi.

Between 1982 and 1985, a total of 39 congenital pigmented nevi (CN) were removed from patients in the Oklahoma Children's Memorial Hospital. Multiple sections were examined from each of the lesions removed. The histologic patterns were recorded with special note of those features traditionally associated with CN. These include nevus cells in the lower reticular dermis and subcutaneous tissue, association of nevus cells with and in appendageal structures, and infiltration of nevus cells between collagen bundles. These features were primarily observed in larger CN (greater than 3 cm). Most small nevi do not show these features. The histologic patterns were consistent throughout multiple sections of the nevi. It is concluded that the histology traditionally associated with CN relates primarily to the size of the nevus rather than to the time of its appearance.