Comparison of nonfamilial and familial melanoma.

There has been concern that individuals with nonfamilial melanoma and dysplastic melanocytic nevi (DMN) are not directly comparable to patients with hereditary melanoma and DMN. Because we have conducted a comprehensive study of nonfamilial melanoma over the past several years, we have addressed the above issue by directly comparing the characteristics of 145 nonfamilial patients, 6 patients with familial melanoma and the information available for familial melanoma in the literature. All 6 patients with familial melanoma had at least one first-degree blood relative with cutaneous melanoma. A large number of clinical and histologic variables were compared for both groups. Some pertinent variables included mean age at melanoma diagnosis 46.7 versus 52.3 years, mean Breslow thickness 2.11 versus 1.54 mm, mean total body nevi per patient 20.6 versus 18.3, mean total clinically atypical nevi per patient 2.0 versus 1.7 and total histologically confirmed DMN per group 22 (18.3%) versus 2 (33%), for patients with nonfamilial versus familial melanoma, respectively. No substantial differences were observed between the two groups. A review of the medical literature failed to reveal any quantitative data for melanocytic nevi, either clinical or histologic, at present that would allow distinction of patients with sporadic versus familial melanoma. We conclude that studies concerning the clinical characteristics of patients with DMN and nonfamilial melanoma are relevant to other persons with DMN including familial melanoma.