The body site distribution of melanocytic naevi in 6-7 year old European children

The number and size of melanocytic naevi are the main predictors of cutaneo us melanoma. Naevus development per unit of skin surface is greatest during childhood. We assessed the body distribution of naevi 2-4.9 mm and greater than or equal to 5 mm in 649 European children aged 6-7 years old from Bru ssels (Belgium), Bochum (Germany), Lyon (France) and Rome (Italy). The numb ers of naevi 2-4.9 mm and naevi greater than or equal to 5 mm were strongly correlated, especially on the trunk. For naevi 2-4.9 mm, the highest relat ive densities were found on the face, back, shoulders and the external surf ace of the arms. The lowest relative densities were found on the hands, leg s, feet and abdomen. The relative density of naevi greater than or equal to 5 mm was higher on the trunk than on any other body site. Similar body dis tributions were observed in both sexes and at each centre. The body site di stribution of naevi 2-4.9 mm seemed to parallel the usual sun exposure patt erns of young European children. It is suggested that the development of na evi greater than or equal to 5 mm might be a marker of the vulnerability of melanocytes to the harmful effects of solar radiation. Vulnerability would be maximal on the back, and would decrease from proximal to distal skin ar eas, with melanocytes of the hands and feet having the lowest vulnerability . The number of naevi acquired on a specific area of skin would result from the combined effects of local vulnerability to solar radiation and local s un exposure history. The origin of acquired body site differences in the su sceptibility of melanocytes to ultraviolet radiation is unknown, although i t seems to parallel the body site density of sensory innervation. (C) 2001 Lippincott Williams & Wilkins.