Determining the Association Between Melanomas and Fields of Melanocytic Dysplasia.

Some have proposed that melanomas in situ may be associated with fields of melanocytic dysplasia, particularly on sun-damaged skin, whereas others maintain that the atypical junctional melanocytic hyperplasia (MH) at the periphery of melanomas is simply background junctional MH of sun-damaged skin. The biological potential of atypical junctional MH at the periphery of melanomas is uncertain. We examined whether atypical junctional MH was intrinsic to the melanoma itself (ie, melanoma-associated field of melanocytic dysplasia) or was simply the predictable junctional MH associated with long-standing sun exposure. We retrospectively compared 106 cutaneous melanoma excisions without residual tumor with 105 nonmelanoma cutaneous tumor excisions (ie, basal cell or squamous cell carcinomas) without residual tumor. MH with atypia occurred significantly more frequently in melanoma than in nonmelanoma cutaneous tumor excisions (55.7% vs. 24.8%, P < 0.001). Solar elastosis occurred significantly less frequently in melanoma than in nonmelanoma cutaneous tumor excisions; 33.0% of melanoma excisions and 8.6% of nonmelanoma excision samples exhibited no solar elastosis, respectively (P < 0.001). After controlling for solar elastosis using multivariable linear regression, the association between MH with atypia and melanoma excisions remained significant (P < 0.001). Our results, therefore, demonstrate that melanomas were associated with atypical junctional MH that could not solely be accounted for by the extent of sun damage as measured by solar elastosis.