Malignant melanoma (MM) arises from epidermal melanocytes. These tumours may arise within long-standing or new pigmented lesions. Melanoma occurs in any age in adults and can be unpredictable, with metastasis and death in a significant proportion of patients. Noticing an irregular pigmented lesion is key to early recognition and excision of a melanoma leading to the best opportunity for curative treatment.

Epidemiology

The incidence of melanoma has increased steadily. The incidence in the UK is around 10–15 cases per 100,000 population and has quadrupled in the last four decades. Thirty per cent of cases present at <50 years of age. Melanoma in childhood is extremely rare. Melanoma is the sixth most common cancer in women and the seventh in men. However, it is the second most common cancer presenting in the 20–40 year age group.

Malignant melanoma causes 80% of skin cancer deaths even though <10% of skin cancers are melanoma. More than 1800 deaths were reported in 2006 in the UK, with better survival rates in women because of thinner melanomas.

Risk Factors

Risk factors for MM include exposure to sunlight (especially as a child and teenager) and UV exposure intermittently (holidays and regular sun bed use).

Moderate risk factors: red hair, freckles and Celtic Caucasian skin type. Risk is 10–20 times lower in non-whites.
High risk factors: increasing numbers of melanocytic naevi >6 mm in diameter, dysplastic naevus syndrome (atypical mole syndrome), family history of melanoma and large congenital naevi.

Melanoma risk has been linked with major genes including CDKN2A gene (chromosome 9), CDK4 gene (chromosome 12) and melanoma susceptibility gene (chromosome 1).