Multiple primary melanomas.

Abstract

Patients with clinically diagnosed dysplastic nevi or a family history of melanoma with or without histologically diagnosed dysplastic nevi seem to be at higher risk for the development of multiple melanomas. Our purpose was to determine which factors increased the risk for the development of subsequent melanomas. This was a retrospective study in 56 patients with 157 melanomas. Early age at onset (58.9%), clinically diagnosed dysplastic nevi (82.0%), a histologically diagnosed dysplastic nevus (64%), family history of clinically diagnosed dysplastic nevi (70.8%) or melanoma (64.7%) and a histologically diagnosed dysplastic nevus in combination with a family history of melanoma (48%) were found in a high percentage of patients. The mean age at diagnosis was 38.2 years. The mean interval between the first and second melanoma was 34.3 months. Of the second melanomas, 76.8% developed in a different anatomic region from the first melanomas. The mean tumor thickness (Breslow) decreased from 1.11 mm for the first melanomas to 0.90 mm for the second melanomas. The results suggest that genetic factors might be involved in a certain subset of patients in whom melanomas develop early and successively.