ABCD's of Melanoma: A sudden or continuous change in the appearance of a mole is a sign that you should see your doctor. The ABCD rule can help you remember the symptoms of melanoma:
A for Asymmetry
One half is different than the other half.
B for Border Irregularity
The edges are notched, uneven, or blurred.
C for Color
The color is uneven. Shades of brown, tan, and black are present.
D for Diameter
Diameter is greater than 6 millimeters.