Dermoscopy of congenital melanocytic nevi: a ten-year follow-up study and comparative analysis with acquired melanocytic nevi arising in prepubertal age

Dermoscopic characteristics of congenital melanocytic nevi (CMN) have been reported, however, dermoscopic variation during long-term follow-up and direct comparative analyses with acquired melanocytic nevi (AMN) are poorly documented. To assess dermoscopic changes of CMN (including lesions present at birth or appearing within the first two years of age) after a long-term period and evaluate possible dermoscopic differences with AMN arising during prepubertal age. We re-analysed clinical and dermoscopic features of CMN, investigated ten years earlier. New findings were compared with those previously recorded, as well as with those of AMN appearing before puberty in the same group of patients. In total, 493 lesions (86 CMN and 407 AMN) from 71 patients were examined. Except for a greater size (median area: 73.9 vs 22.8 mm(2); p<0.001) and higher prevalence of hair (17.4% vs 4.7; p<0.001) in CMN, no significant difference was observed between the two cohorts, including global/local dermoscopic features (p>0.05). The follow-up of CMN revealed that dermoscopic pattern changed in only four lesions (4.7%) (from globular to globular-reticular or reticular) after ten years, though lesions with a globular architecture presented several "local" changes, namely an increase in circumscribed reticular areas (from 20.0% to 41.5%; p = 0.030), irregularly distributed globules (from 15.6% to 34.1%; p = 0.045), and large globules (from 46.7% to 68.3%; p = 0.043). The dermoscopic appearance of CMN is significantly stable during childhood and is similar to that of AMN arising before puberty, thus supporting a possible link between such types of nevi.