Melanocytic nevi in children. I. Anatomic sites and demographic and host factors.

A survey of benign melanocytic nevi was conducted among schoolchildren in Perth, Western Australia, in 1985, with the aim of describing the prevalence and causes of nevi. Children were recruited from Perth public schools that were chosen to be representative of the socioeconomic and geographic distribution of the population. Of 4,898 eligible children, 2,595 (53%) had all of their nevi counted by one member of a team of five nurses. Analysis was restricted to 2,552 children aged 5-14 years. Children of European origin (i.e., white children), who comprised the majority of the sample (2,376 children), had many more nevi than did children of other ethnic origins. Among white children, the prevalence of nevi increased progressively with age, although the number of nevi per unit of skin area reached a plateau at about 9 years of age. Boys had more nevi at all ages than did girls. The number of nevi per unit of area was highest on the lateral surfaces of the upper limbs and the face and neck, and was lowest on the lower limbs. Children whose parents had been born in Southern Europe were likely to have few nevi. Children with red hair had relatively few nevi, but children with light skin generally had more nevi than children with darker skin. Ability to tan and propensity to burn were also associated with number of nevi, although not in a simple fashion; numbers of nevi were highest in intermediate categories of these two variables. The relation with freckling was also complex; the mean number of nevi increased with increasing freckling until the freckling became moderate to heavy, after which it fell.