Check your skin once a month for any changes, especially for new growths or changes to existing moles. If you are a parent, check your child’s skin as well. Even young children are vulnerable to melanoma. Make sure to check your scalp and even places that are not exposed to the sun, such as the bottoms of your feet and the palms of your hands. If you notice any of the following changes, visit your doctor for a more thorough examination.

Asymmetry: one half of the mole does not match the other half

Border: edges are ragged, blotched or blurred

Color: uneven or mottled colors, including brown, black, tan, red, white or blue

Diameter: mole is larger than the size of a pencil eraser or is growing

Evolution (or elevation): a mole that changes or that has different thicknesses or heights

Very rarely, melanoma occurs inside the eye or in the mucous membranes of the nose or mouth. Regular checkups with your dentist and optometrist will help screen for disease in these areas.

Donald Lawrence, MD, is Clinical Director of the Center for Melanoma, Massachusetts General Hospital Cancer Center.