Source: NCI Visuals Online. Skin Cancer Foundation. http://visualsonline.cancer.gov/about.cfm

The ABCDEs of melanoma skin cancer are:

• Asymmetry. One half doesn't match the appearance of the other half.
• Border irregularity. The edges are ragged, notched, or blurred.
• Color. The color (pigmentation) is not uniform. Shades of tan, brown, and black are present. Dashes of red, white, and blue add to a mottled appearance.
• Diameter. The size of the mole is greater than 1/4 inch (6 mm), about the size of a pencil eraser. Any growth of a mole should be evaluated.
• Evolution (not shown in the picture). There is a change in the size, shape, symptoms (such as itching or tenderness), surface (especially bleeding), or color of a mole.