Cutaneous malignant melanoma is the third most common variety of skin cancer. Basal cell carcinoma and squamous cell carcinoma take first and second places respectively. Like the other two types of tumour, malignant melanoma occurs more commonly in sunny areas and the highest incidence rates are reported in countries near the equator. Basal and squamous carcinomas show a clear-cut relationship with chronic sun exposure occurring mainly in older age groups and on habitually exposed sites. Malignant melanomas, however, present in individuals with a mean age of only 48 years and may occur in both exposed and unexposed sites
