Dysplastic changes in different types of melanocytic nevi. A unifying concept

We observed histopathologic changes previously described in dysplastic mela nocytic nevi in association with a dermal component characteristic of other types of melanocytic nevi or overlapping with features of other varieties of nevi. In order to determine the frequency of these changes, we studied 2 ,164 cases of compound melanocytic nevi that fulfilled the histopathologic criteria for the diagnosis of compound dysplastic nevus, including architec tural pattern, cytologic features, and mesenchymal changes. Of the 2,164 co mpound dysplastic melanocytic nevi,.1,895 (87.6%) had the histopathologic c haracteristics previously described for dysplastic nevus, 179 (8.3%) showed a dermal component with a congenital pattern, 67 (3.1%) demonstrated epide rmal and dermal characteristics of Spitz's nevus, 8 (0.3%) had features of a combined blue nevus, 13 (0.6%) had a halo phenomenon and 2 (0.1%) showed dermal neuronevus. By considering these nevi as variants of dysplastic nevi , one may apply a unified conceptual basis for their nomenclature. In order to completely describe the appearance of the nevus, we named them by addin g the term "dysplastic", to their main histopathologic subtype. Accordingly , six different varieties of dysplastic nevi were identified: 1) dysplastic nevus (original); 2) dysplastic nevus with a congenital pattern; 3) dyspla stic Spitz's nevus; 4) dysplastic combined blue nevus; 5) dysplastic halo n evus; and 6) dysplastic neuronevus. In summary, we conclude that the histop athologic criteria previously reported for the diagnosis of dysplastic nevi may be found in association with a dermal component characteristic of othe r types of melanocytic nevi or may have overlapping features with other var iants of nevi.