Proliferative Nodule in Small Congenital Melanocytic Naevus After Childhood

Abstract

© 2012 The Authors. doi: 10.2340/00015555-1186 Journal Compilation © 2012 Acta Dermato-Venereologica. ISSN 0001-5555 Congenital melanocytic naevi (CMNs) are divided into giant, medium-sized, and small types. Giant CMN measures more than 20 cm in maximal diameter, whereas small CMN measures less than 1.5 cm (1). The lifetime incidence of melanoma in giant CMN is estimated to be between 6.3% (2) and 12% (1). Since the prognosis is poor (3), it is generally agreed that it would be desirable for giant CMN to be excised whenever possible. Melanomas arising from giant CMN are apt to occur before puberty and are occasionally of dermal origin (4). Although the incidence of melanoma in medium-sized CMN is probably greater than that in a comparable area of normal skin, it is supposed that melanomas rarely arise from small CMN (4, 5). Some authors insist that the risk is related to lesion size (6), while other investigators disagree (4). The excision of small and medium-sized CMNs when feasible is advised by many authors (7, 8), although not all (1,5). Melanomas arising from small and medium-sized CMNs are apt to occur after puberty, to be located at the margin of the naevi, and to be exclusively of epidermal origin (4).