Most people have benign growths on their skin, such as moles and birthmarks. Birthmarks are present at birth; moles begin to appear in childhood. The majority of birthmarks are dark brown and flat at birth and may become lighter and slightly raised as time passes. There are, however, other colored lesions, most of which require no treatment unless they are unsightly. In rare cases, existing moles can become cancerous. Look for changes in the surface of a mole such as scaliness or oozing, and sensations in the area of the mole including itchiness, tenderness, or pain. Additional warning signs include when one half of a mole doesn't match the other half, the edges of a mole are ragged, or the color is not uniform. Shades of tan, brown, and black may be present, while dashes of red, white, and blue add to a mottled appearance. Watch for any mole or other growth larger than six millimeters, which is about the size of a pencil eraser. Monthly self exams of your skin and routine use of sun-protection products are good ways to lower your risk of skin cancer. Early detection is the best form of prevention, so don't hesitate to contact a healthcare provider if you notice any change in a birthmark, mole, or other spot on your skin.