Reproducibility of dermoscopic features of congenital melanocytic nevi

The dermoscopic features of congenital melanocytic nevi (CMN) have recently been described, and some structures have been proposed as distinctive of these moles.

The aim of our study was to evaluate the agreement between observers, i.e. the reproducibility, in the identification of these features.

Fifty-two CMN, randomly selected from 127 male subjects carrying at least 1 CMN, were examined by a 1st medium-experienced observer. The image recording was performed according to the dermoscopic patterns of the Consensus Net Meeting on Dermoscopy and to the features proposed for CMN by Seidenari et al. The presence/absence of these features was recorded in a specifically developed patient's card, and the most typical dermoscopic features of the lesions were also photographed and observed again in this form by the same investigator and by a 2nd basic-experienced observer. The reproducibility of the dermoscopic features assessed directly and on photographs by the 1st observer (intraobserver agreement) and the agreement between the 1st and the 2nd observers judging nevi on photographs (interobserver agreement) were estimated by Cohen's kappa statistics.

Intraobserver agreement was highly satisfactory for all the dermoscopic features, with the exception of focal thickening of network lines and follicles (satisfactory), and hyperpigmented areas and target vessels (fairly satisfactory), which were more frequently identified on Dermaphot pictures. Interobserver agreement was highly satisfactory for network, globules/dots, blotches, focal hypopigmentation, skin furrow hypopigmentation and follicles; it was satisfactory for perifollicular hypopigmentation, vessels and target vessels, and barely satisfactory for focal thickening of network lines, target globules and hyperpigmented areas; finally, it was fairly satisfactory for target network.

The identification of dermoscopic features of CMN seems to show a good reproducibility, with a satisfactory intra- and interobserver agreement. Other studies involving a higher number of experienced and less experienced observers are requested to confirm these results.