The histology of "congenital features" in early acquired melanocytic nevi.

To test the specificity of certain histologic features claimed to be frequent in congenital melanocytic nevi, 66 of 313 consecutive newborn infants without congenital nevi (verified by perinatal examination) were addressed in a questionnaire 2 1/2 years after birth. Fifty children with acquired melanocytic nevi were reexamined clinically and biopsies were performed in 15. Congenital features were found in seven biopsy specimens from the indubitably acquired melanocytic nevi. These nevi were larger and more speckled in color than melanocytic nevi without "congenital features." It is concluded that the histologic features said to be specific for congenital nevi are, in fact, not specific. The possible relationship between these features and an increased melanoma risk cannot be refuted by the present study, but the risk of misinterpretation based on congenital features as the sole criterion in the prediction of the potential malignancy of melanocytic nevi is real.