A NEW LOOK AT NEVUS-ASSOCIATED MELANOMAS

The frequency with which malignant melanomas arise in association with preexisting melanocytic nevi has been studied extensively. We opted t o evaluate new aspects of this association. In particular, we addresse d the relative proportions of acquired versus congenital nevi involved and categorized the acquired nevi according to morphological type. Ap proximately 23% of the melanomas (29 of 124) in this group arose in as sociation with preexisting nevi of which 55% (n = 16) were acquired an d 28% (n = 8) were congenital (small). In 17% (n = 5) a distinction co uld not confidently be made. Of the acquired nevi, the vast majority w ere of Clark's type. It is clear that a relatively small proportion of melanomas as a whole are associated with preexisting nevi, and this n umber should be kept in perspective in devising strategies for early d etection and prevention. The involvement of Clark's nevi in this regar d is known, but to date the role of small congenital nevi has been und errecognized.