[Dysplastic nevus syndrome of familial type. A family study].

A family with heritable occurrence of dysplastic nevus syndrome has been studied through 20 years and five generations. The intention was to study how the disease is inherited, how often malignant melanomas developed from such moles, and which factors caused this change. 59 out of 103 family members had dysplastic nevus syndrome. Occurrence was distributed equally between males and females. The moles were not present at birth, but first appeared in childhood and adolescence. The moles differ clinically from common moles by being flat, irregularly coloured, and irregularly delimited in relation to the surroundings. There are also large variations between moles in the individual. 20% of the patients developed hereditary malignant melanoma from these particular moles. Dysplastic nevus syndrome was inherited autosomally dominant and might develop into malignant melanoma many years later in life. In some cases the development was provoked by sunshine. Patients who suffer from dysplastic nevus syndrome are in danger of developing malignant melanoma and should therefore be careful of exposure to sun and should regularly examine their moles for possible changes.