THE INCIDENCE OF MELANOCYTIC NEVI IN ADOLESCENT CHILDREN IN QUEENSLAND, AUSTRALIA

The aim of this study was to assess longitudinally the development of melanocytic naevi in children around the time of their puberty. In Que ensland, Australia, 102 schoolchildren born mostly in 1977 or 1978, we re examined annually an four occasions from 1990. All naevi on the bod y except for the scalp and parts covered by a bathing suit were counte d by an experienced research nurse or trained assistant according to a set protocol. In addition, each subject's pigmentary characteristics were recorded and height, weight and pubertal status were assessed ann ually. The findings confirmed that the average number of naevi and ave rage density of naevi (count per m(2)) on the whole body in boys and g irls increase significantly with increasing age and increases were als o seen on each of the following anatomic sites: face and neck, back an d shoulders, and upper and lower limbs. Children who had a high baseli ne naevus count, or a large increase in skin surface area during the 3 -year follow-up period had the highest absolute increases in naevus co unt but the smallest proportionate increases. Associations between bas eline naevus counts and male sex, light brown or blonde hair, blue or hazel eyes, facial freckling and a tendency to sunburn, which have bee n previously reported, were also found. However, the independent relat ions of each of these factors to the increase in new naevi were more c omplex, once the effects of high naevus counts at baseline and increas es in skin surface area were taken into account. No association was fo und between the incidence of naevi and height, body mass index or time of onset of puberty in this group of adolescent subjects. Beyond pers onal characteristics, period of birth may also influence the developme nt of naevi, since there has been an apparent increase in naevi in the Australian children in this and other recent studies compared with na evus counts among Australian children of previous generations of compa rable age living in similar environments.