RESUMO
BACKGROUND: The occurrence and number of melanocytic nevi (MN) are among the most important known risk factors for the development of cutaneous melanoma (CM). OBJECTIVES: To estimate the prevalence of MN among schoolchildren and its relationship with phenotype, body mass index (BMI), parental and sun exposure factors. METHODS: A cross-sectional study was conducted on N = 1277 schoolchildren aged 7-19 years old in Kaunas city, Lithuania. Subjects were interviewed using a self-administered questionnaire and were assessed by a dermatologist. MN of all sizes and ≥2 mm in diameter were counted; phenotypic features and skin phototype were defined. BMI and body surface area (BSA) were calculated. Whole-body MN counts were expressed both as totals and as counts per unit of BSA - MN density (MND). Biological parents completed questionnaires regarding nevus counts, family history of skin cancer and CM. RESULTS: The numbers of all sizes and ≥2 mm MN increased according to age, respectively, from median values of 44 (IQR 28, 60) and 5 (IQR 2, 8) at the age of 7-9 years to 85 (IQR 55, 128) and 16 (IQR 8, 30) at the age of 16-19 years. A higher MND was found in children with light skin colour (P < 0.001), I-II skin phototype (P < 0.001), extensive facial freckling (P < 0.005) and multiple nevi on the father's and mother's arms (P < 0.05). 20.2% of pupils were overweight or obese, 130 males and 118 females. Overweight and obese children had a higher all sizes MND (P = 0.033, P = 0.044). Acquired suntan at the end of summer was associated with a higher all sizes MND (P < 0.05), outdoor activities at midday - with a higher ≥2 mm MND (P = 0.047) respectively. CONCLUSIONS: The prevalence of MN among schoolchildren is age-dependent and strongly determined by skin colour, skin phototype, facial freckling and BMI. Parental nevus numbers, acquired suntan and outdoor activities at midday must be considered.
