The most important sign a mole might be melanoma is a change in its appearance such as a change in shape, size or color, explains the American Cancer Society. Another sign of melanoma is a spot on the skin that looks different than the spots around it.
Most doctors advise their patients to use the ABCDE rule to determine if their mole is showing signs of melanoma, according to the American Cancer Society. The letter A means to look at the mole for asymmetry. If one-half of the mole is different from the other, it could be a sign of melanoma. The letter B indicates a patient should look at the border of the mole. If it is jagged or irregular, it could be a sign of cancer.
The letter C means the patient should look at the color of the mole, reports the American Cancer Society. If it is not the same color through and through, it is necessary to see a doctor. The letter D indicates the diameter of the spot. If it is larger than 6 millimeters, it is advisable to seek out medical attention. The letter E stands for evolving, and this means the mole may be changing its appearance rapidly. If this occurs, patients are urged to reach out to a doctor for further testing.