Lentigo maligna melanoma on the cheek of an 82 year old male patient. Melanoma is a malignant (cancerous) tumour of melanocytes, the skin cells that produce melanin, the pigment that gives skin its colour. Lentigo maligna melanoma is a melanoma that has evolved from a lentigo maligna, a non-invasive form of melanoma. Melanoma is less common than other types of skin cancer, and is typically caused by exposure to ultraviolet (UV) radiation in sunlight. However, it is an aggressive cancer that often spreads (metastasises) to other parts of the body, so it can be dangerous if not diagnosed early. Treatment is with surgical excision of the melanoma.