Dysplastic nevi and melanoma

Abstract

Dysplastic nevi are described as being on a continuum between common acquired nevi and melanoma because they are morphologically and biologically intermediate between these 2 entities. Since initially being reported as histologic lesions observed in melanoma-prone families, there has been considerable debate about the definition of dysplastic nevi, the histologic and clinical criteria used to define them, and their biologic importance. Their role as precursor lesions for melanoma is not their primary role in their relationship to melanoma because of the rarity of transformation of any individual nevus to a melanoma. Although there is still no single, universally agreed upon histologic or clinical definition or even name for these nevi, dysplastic nevi should be considered important because of their association with an increased risk for melanoma.

figure 1. Examples of dysplastic nevi defined based on clinical criteria

A. The lesion is 8 mm in greatest diameter. The lesion is partially flat with an irregular and indistinct outline and variable pigmentation. Because of changes to the lesion, it was excised and diagnosed as a dysplastic nevus with severe melanocytic dysplasia. B. The lesion is 7 mm in diameter and is very irregular with indistinct borders, variable pigmentation, and an asymmetric configuration. Excision of the lesion resulted in a histologic diagnosis of dysplastic nevus with severe melanocytic dysplasia. C. The lesion is 14 mm in greatest diameter. It has an irregular, asymmetric scalloped-shaped outline. The lesion is partially flat with indistinct borders and variably pigmented. D. The lesion is 8 mm × 5 mm. It is partially flat with an irregular outline and indistinct borders.