Dysplastic nevi as a melanoma risk factor in patients with familial melanoma.

Background: Familial melanoma has been associated with "clinically atypical moles" or "dysplastic nevi," (DN) which are markers for increased melanoma risk. In addition, melanomas in these kindreds present at a younger age, and tend to be multiple.

Methods: Melanoma incidence rates were determined for 710 members of 311 melanoma families, defined as kindreds in which melanoma had occurred in two or more blood relatives. Patients were classified either clinically or histologically as expressing DN. Melanomas that occurred before the first examination were recorded, and patients were followed prospectively for new melanomas.

Results: In prospective follow-up, the age-adjusted melanoma incidence rate was 1710/100,000 patient-years in family members with DN. In contrast, the rate was zero (no melanomas occurred) in family members without DN. For family members with DN, but without a history of melanoma, the age-adjusted incidence rate of melanoma was 413/100,000 patient-years, whereas the rate was 2779/100,000 patient-years in family members with DN and a history of melanoma.

Conclusions: Dysplastic nevi and a history of melanoma are strong risk factors for subsequent melanoma. Prognostic factors are greatly improved for patients with melanomas diagnosed in follow-up compared with the first two melanomas in each kindred. These findings warrant surveillance of individuals with DN who are members of familial melanoma kindreds.