Comparison of classification systems for congenital melanocytic nevi.

BACKGROUND

Congenital melanocytic nevi (CMNs) are found in approximately 1% of newborn infants, but these represent only a small proportion of the total population of nevi. They vary widely in size, from a small spot to a large area. Later in childhood, these lesions become thickened, verrucous, and hairy. Giant CMNs predispose to malignant melanoma, with a reported incidence of 2% to 31%.

OBJECTIVE

To compare three different classification methods of the CMNs to determine which is most accurate.

PARTICIPANTS AND METHODS

Sixty patients were included in the study (34 male, 26 female), with an average age of 17.4 (range 3-32). The nevi were evaluated using three different classification methods: total area of the nevus (in cm(2)), greatest nevus dimension, and percentage of nevus surface area to total patient body surface area. An appropriate treatment procedure for each case was applied, and participants were followed from 1997 to 2007.

RESULTS

Malignant transformation was noted in 15.4% of participants with congenital nevi, which was confirmed histopathologically after excision.

CONCLUSION

We recommend the calculation of total nevus area as the most useful method for assessment of the risk of developing melanoma in a CMN. The authors have indicated no significant interest with commercial supporters.