Cutaneous malignant melanoma in Swedish children and teenagers 1973-1992: a clinico-pathological study of 130 cases.

To assess whether there has been a change in histological features and prognostic factors of primary cutaneous malignant melanoma (CMM) in young individuals in Sweden, an unselected, population-based study was undertaken; 177 cases of primary CMM in persons below 20 years of age were reported to the Swedish National Cancer Registry between 1973 and 1992. In 87% of the cases, original tumor tissue was available for histo-pathological review. The original diagnosis was verified in 88% (n = 126) of these cases. All tumors had histological features similar to adult CMM; 17% had an associated precursor lesion. Superficial spreading melanoma (SSM) was the most common sub-type, constituting 20/36 cases in the first decade and 59/90 in the second. Corresponding figures for nodular melanoma (NM) were 11/36 and 23/90. Only 5 melanomas in situ were diagnosed. In girls, the mean thickness of SSM decreased from 1.5 to 0.6 mm (p < 0.001). Overall mortality was 10%, 22% in the group with CMM diagnosed 0-15 years of age and 8% in individuals 15-19 years. Fatal CMM cases diagnosed below 15 years of age (n = 4) were NM > 1.6 mm thick and in subjects 15-19 years (n = 9) 44% of fatal tumors were NM with a mean thickness of 2.2 mm. Breslow index was the single most important prognostic factor. However, when known prognostic factors were adjusted for in a Cox regression analysis, young age remained an independent risk factor, with a relative death rate of 0.21 for individuals aged 15-19 compared with children < 15 years of age.