Common and dysplastic naevi as risk factors for cutaneous malignant melanoma in a Swedish population.

Common naevi, dysplastic naevi (DN) and other phenotypic features were evaluated as melanoma risk factors in a Swedish case-control study. One-hundred and twenty-one prevalent melanoma cases and 378 randomly selected controls participated. The mean total body naevus count was 115 in the cases and 67 in the controls. Fifty-six per cent of the cases and 18% of the controls had clinical DN. The corresponding figures for histologically diagnosed DN were 40% and 8% respectively. Clinical DN was as good as histologically diagnosed DN in identifying individuals at risk for melanoma. Subjects with sun-sensitive skin, greater than or equal to 150 naevi and presence of DN have 50 times higher melanoma risk than those without these characteristics.