Residual dysplastic and other nevi in superficial spreading melanoma. Clinical correlations and association with sun damage.

Excision biopsies of 500 invasive superficial spreading melanomas were examined for evidence of residual melanocytic dysplasia (remnants of dysplastic nevi). Melanocytic dysplasia was identified in 32.4% of tumors. Remnants of nevi without melanocytic dysplasia were found in 9.8%. Sun damage as evidenced by solar elastosis was histologically estimated in contiguous skin. Patients' age at diagnosis, tumor site, pathologic stage, evidence of tumor regression, and coexisting sun damage were correlated with the presence or absence of melanocytic dysplasia. Patients whose tumors displayed residual dysplasia were younger and demonstrated a more favorable tumor stage and less evidence of sun damage. Melanomas on the trunk were more likely to be associated with melanocytic dysplasia than those from other areas. The findings support the belief that dysplastic nevi have an important role in the genesis of superficial spreading melanoma. The influence of ultraviolet radiation in the development of dysplastic nevi and in their potential malignant progression is discussed.