Moderate sun exposure and nevus counts in parents are associated with development of melanocytic nevi in childhood: a risk factor study in 1,812 kindergarten children.

BACKGROUND: Melanocytic nevi have been identified as the most important risk factor for cutaneous melanoma. Sun exposure, sunburns, and light pigmentation have been found to be associated with their development in childhood. To the authors' knowledge, nevus proneness of parents and the exact type of ultraviolet (UV) exposure have not yet been investigated in this context. The authors' objective was to determine independent risk factors and their impact for nevus development in childhood.

METHODS: The current study was conducted by two university departments of dermatology in 49 public nursery schools in Stuttgart, Germany and in 38 public nursery schools in Bochum, Germany. The cross-sectional study included 1,812 children aged 2-7 years and their parents. Total body nevus counts in children, assessment of pigmentary features, and nevus counts on the arms of parents were performed. Parents underwent a standardized interview concerning national origin and lifestyle features, as well as habits and magnitude of sun exposure of children. Analysis was performed by multivariate linear regression analysis and by multiple logistic regression analysis.

RESULTS: The number of nevi was found to steadily increase with age from a median of 3 at age 2 years to 19 at age 7 years (P < 0.0001). High numbers of nevi in children were associated with the number of weeks on sunny holidays, outdoor activities at home, skin type, facial freckling, ethnicity of parents, and the number of nevi on the arms of parents. Previously experienced sunburns failed significance (P = 0.0620).

CONCLUSIONS: The authors found a strong association between nevus development in children and the number of parental moles, which most likely points to an inherited factor. Moderate sun exposure such as outdoor activities during a German summer without sunburns seemed to be sufficient for induction of melanocytic nevi. The authors believe that these findings will have direct impact on concepts for preventive strategies.