A skin cancer that begins in cells called melanocytes. Melanocytes can grow collectively to create benign (not malignant) moles. A melanoma starts as a collection of cancerous melanocytes. A change in size, shape, or color of a mole may be an indication of melanoma. Melanoma can be treated if recognized early, before spread (metastasis) with other areas of the body. Diagnosis is verified with a biopsy of this abnormal skin. Sun exposure trigger skin lesions that will result in melanoma.