How can you tell if a mole on your body is benign or if it has started to develop malignant changes? The following methods may help you to do a self-examination. The ABCDE rule of skin cancer summarizes the characteristics of abnormal moles: Asymmetry: A normal mole or freckle is perfectly symmetrical. By drawing a line through a normal mole, you can divide the mole into two symmetrical halves. In the case of skin cancer, the two sides are not symmetrical. Border: Irregular moles have uneven borders or edges that are fuzzy or jagged. Color: A normal mole is uniform in color. If multiple colors are present on a mole, it is considered abnormal, including darkening or lightening of the color. Diameter: A mole is considered abnormal if its diameter is larger than an eraser (about 1/4 inch or 6 mm). This abnormal mole may not show any other abnormal features (color, borders, asymmetry, etc.). Evolution: Evolution is any change in symmetry, borders, color and diameter of an already existing mole.