Dermoscopic patterns and subclinical melanocytic nests in normal-appearing skin

Abstract

Dermoscopic patterns of normal-appearing skin have received little scrutiny. We have recently completed an analysis of dermoscopic patterns of naevi in children. To describe dermoscopic patterns in the normal-appearing skin surrounding naevi and to explore histological features of patterned background skin. Dermoscopic images of back naevi were obtained from a population-based sample of fifth grade students. The dermoscopic pattern of the background skin around the naevi was analysed. We examined histopathological features of background skin patterns in a convenience sample of seven specimens from six adult patients. We observed a dermoscopic pattern in the background of normal-appearing skin in 41% of 1192 dermoscopic images from the backs of the 443 children. The background skin pattern was less frequent in individuals with a fair skin (P < 0.001). A globular pattern was observed in 201 images (17%) and a reticular pattern was seen in 287 images (24%), of which 112 images also showed globules. Inter-rater reliability between the two observers for a random sample of 100 images was excellent (kappa = 0.77). In four specimens with a globular background pattern, microscopic melanocytic nests were observed in the normal-appearing skin. No subclinical naevus nests were observed in three reticular pattern specimens. Dermoscopically recognized patterns are commonly present in clinically normal skin of children. Microscopic melanocytic nests may be observed in normal-appearing skin with a globular skin pattern.