Distribution of congenital melanocytic naevi and congenital naevus-like naevi in a survey of 3406 Italian schoolchildren.

BACKGROUND

Scanty information is available on the prevalence of congenital melanocytic naevi (CMN) and congenital naevus-like naevi (CNLN), particularly the small ones.

OBJECTIVES

To estimate the prevalence of CMN/CNLN in Italian schoolchildren, and to assess variations according to potential risk factors for melanoma.

METHODS

We conducted a survey in 13 Italian areas on 3406 schoolchildren aged 12-17 years. Children were examined by dermatologists who assessed pigmentary traits and made a count of small (6-15 mm in diameter) and medium/large (> 15 mm) CMN/CNLN on 19 anatomical areas.

RESULTS

Overall, 592 children (17.4%) had one or more CMN/CNLN. Prevalence of small CMN/CNLN was 16.1%, and that of medium/large CMN/CNLN was 1.8%. There was no difference between age groups and sexes. CMN/CNLN were more frequent in children with a higher number of common melanocytic naevi (multivariate odds ratio, OR = 7.1 for the highest vs. the lowest quartile), consistent in small (OR = 7.2) and medium/large CMN/CNLN (OR = 6.0). Family history of malignant melanoma (OR = 1.4) and personal history of diabetes (OR = 4.4) appeared to be directly, and sun exposure inversely associated with CMN/CNLN. No relation was evident between CMN/CNLN and pigmentary traits, anthropometric characteristics, dietary habits, freckles, sunburns, sunscreen use or history of selected diseases.

CONCLUSIONS

The association with family history of melanoma, the strong association with acquired melanocytic naevi, and the lack of association with pigmentary traits and sunburns suggest that CMN/CNLN may act as an independent risk marker for subjects at increased risk for cutaneous melanoma later in life.