Melanocytic nevi in Lithuanian schoolchildren: the role of phenotype, body mass index, parental and sun exposure factors

Abstract

Background: Melanocytic nevi (MN) are well known risk markers and precursors of cutaneous melanoma (CM). Recent studies revealed a strong positive correlation between body mass index (BMI) and the incidence of CM. However, there was no investigated the relationship between BMI and the prevalence of MN. 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 in Kaunas city, Lithuania. Subjects were interviewed using self-administered questionnaire and were assessed by a dermatologist. MN of all sizes and ≥2mm in diameter were counted, phenotypic features and skin phototype were defi ned. BMI and body surface area (BSA) were calculated. Whole-body nevus counts were expressed both as totals and as counts per unit of BSA – MN density (MND). Biological parents completed questionnaires about nevus counts, family history of skin cancer and CM. Results: The number of all sizes and ≥ 2mm MN increased sequentially with 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. Higher MND was found in children with light skin color (p < 0.001), I-II skin phototype (p < 0.001), extensive facial freckling (p < 0.005), and multiple nevi on father‘s and mother‘s arms (p < 0.05). Acquired suntan at the end of summer was associated with a higher all sizes MND (p < 0.05), correspondingly, outdoor activities at the midday – with a higher ≥ 2mm MND (p = 0.047). Overweight and obese children had a higher all sizes MND (p = 0.033, p = 0.044). Conclusions: The prevalence of nevi among schoolchildren is age-dependent and strongly determined by skin color, skin phototype, facial freckling, and BMI. Parental nevus numbers, acquired suntan and outdoor activities at the mid