Skin cancer excision wounds on the neck and back of a 76-year-old man. At top is the excision wound for a malignant melanoma (see image C047/8461). The other excision wounds are for multiple basal cell carcinomas. Both these cancers can be caused by over-exposure to sunlight. Melanoma arises from melanocytes, the cells that produce melanin, the pigment that gives skin its colour. It is an aggressive cancer that often spreads (metastasizes) to other parts of the body. Basal cell carcinoma is one of the most common forms of skin cancer, starting as a small flat nodule that grows slowly, eventually breaking down at the centre to form a shallow ulcer that persistently bleeds. Treatment of these skin cancers is with surgical excision.