To determine the frequency of and the histologic and clinical factors associated with melanoma existing in histologic contiguity with a nevus.
Pathology reports from melanomas collected from January 1, 1993, to December 31, 1997, were retrospectively reviewed.
Independent, community-based dermatopathology laboratory.
A total of 1606 patients with a histologic diagnosis of melanoma.
Main Outcome Measures
Differences in histologic (subtype, Breslow thickness, and Clark level) and clinical (age, sex, and anatomic location) features between melanomas that are associated and unassociated with a nevus.
Twenty-six percent of the melanomas reviewed were histologically associated with nevi (dysplastic nevi, 43.0%; and other nevi, 57.0%). Factors that were significantly associated with an increased likelihood of a melanoma being histologically contiguous with a nevus included younger age, superficial spreading subtype, truncal location, Breslow thickness, and Clark level. However, after multivariate analysis, only younger age (odds ratio, 1.27; 95% confidence interval, 1.19-1.37), superficial spreading subtype (odds ratio, 2.96; 95% confidence interval, 2.17-4.02), and truncal location (odds ratio, 3.26; 95% confidence interval, 2.55-4.19) remained significant.
Most melanomas were not histologically contiguous with a nevus. Younger age, superficial spreading subtype, and truncal location are independent significant predicators of a melanoma being histologically associated with a nevus.