Melanoma. Ulcerated malignant melanoma found on a lower leg. Melanoma is the most serious type of skin cancer; it arises from melanocytes the cells that produce melanin, the pigment which colours the skin, hair and the iris of the eyes. Melanomas are most common in middle-aged and elderly people with pale skin who have been exposed to strong sunlight for many years. The melanoma usually grows from an existing mole which may enlarge, become lumpy, bleed and change colour. The tumour is highly malignant and often spreads to other parts of the body. Treatment consists of surgical removal of the melanoma. Radiotherapy or anticancer drugs may also be necessary.