Dermoscopic patterns of naevi in fifth grade children of the Framingham school system

Background: Childhood is a critical period for naevogenesis. Objective: To describe the prevalence of dermoscopic patterns of naevi using cross-sectional data from a population-based cohort of children. Methods: We obtained overview digital photography of the back of fifth graders (age 10-11 years) from all 10 schools in Framingham, MA, U.S.A. From each participant, dermoscopic images of up to four naevi were obtained, including the largest and one randomly selected naevus on the upper back and a corresponding pair from the lower back. Results: The study included 443 children, 61% boys, with 1181 back naevi analysed. Globular pattern was seen in 37% of naevi, reticular pattern in 13%, homogeneous pattern in 44% and complex (reticular-globular) dermoscopic pattern in 5%. Globular naevi were significantly more frequent and larger on the upper than the lower back. There was a significant hierarchic trend in naevus diameter by dermoscopic pattern: complex naevi (4.3 mm) > globular (3.3 mm) > reticular (3.0 mm) > homogeneous (2.8 mm). Reticular naevi were more prevalent in children with darker pigment phenotype (P < 0.0001). There was a decrease in the size of naevi in children with darker pigmentation (P < 0.0001). Conclusions: An interrelationship was observed in childhood between dermoscopic pattern, naevus size, anatomical location on the back and pigment phenotype.