ABCDE is a tool for checking moles. It helps you know when to show a mole to your care team. It is not a way to diagnose melanoma yourself. Each letter stands for a warning sign doctors look for in a mole: Asymmetry: one half of the mole does not match the other half. Border: the edges are ragged, blurred, or irregular instead of smooth. Color: the color is uneven, with shades of black, brown, or tan. Diameter: the mole has grown larger than it used to be. Evolving: the mole has changed over the past few weeks or months. Often, the first sign of melanoma is a change in a mole. That change can be in size, shape, color, or feel. Most melanomas have a black or black-blue area. Melanoma can also appear as a new, unusual-looking mole. Most people have between 10 and 40 moles. About 1 in 10 people has an unusual mole, called a dysplastic nevus. It can look different from a typical mole. It may be more likely to develop into melanoma. If a mole looks unusual, grows, or changes, your care team can check it.