Malignant melanoma occurring in those aged under 30 in the west of Scotland 1979-1986: a study of incidence, clinical features, pathological features and survival.

The study population consisted of the 95 patients who presented with cutaneous malignant melanoma in the west of Scotland between 1979 and 1986 and who were aged under 30 at the time of diagnosis. Over this 7-year period, 1299 melanomas were diagnosed in all age groups in this geographical area, increasing in incidence by 82% from 135 in 1979 to 246 in 1986. The proportion of melanomas diagnosed before the patients' thirtieth birthday remained constant at 6%. None were diagnosed in the under-15 age-group, and none developed on giant congenital naevi. Forty-two of the 95 melanomas (44%) in the under-30 group developed on a small naevus present either from birth or early childhood. These melanomas were thicker than those apparently developing on normal skin, but once controlled for tumour thickness and sex the presence of a pre-existing naevus did not affect 5-year survival. The overall 5-year survival was 76% with poorer survival associated with thicker tumours and male sex. This study suggests that small early onset naevi may have a higher potential for post-pubertal malignant change than has been previously recognized.