melanoma

Highly malignant tumour of the melanin-forming cells (melanocytes) of the skin. It develops from an existing mole in up to two-thirds of cases, but can also arise in the eye or mucous membranes.

Malignant melanoma is the most dangerous of the skin cancers; it is associated with brief but excessive exposure to sunlight. It is easily treated if caught early but deadly once it has spread. There is a genetic factor in some cases.

Once rare, this disease is increasing at the rate of 7% in most countries with a predominantly fair-skinned population, owing to the increasing popularity of holidays in the sun. Most at risk are those with fair hair and light skin, and those who have had a severe sunburn in childhood. Cases of melanoma are increasing by 4% a year worldwide.

There were an estimated 38,300 new cases diagnosed in the USA in 1996.