A : lesion asymmetric
B : border irregular
C : Color change especially black
-Diameter (greater than 1/4 inch)
-Evolve (anything that has changed)
You can also look for the ugly duckling sign, when something looks totally different than anything else.
Suzanne Sirota Rozenberg, DO, FAOCD
When there is any mile you are not sure about it is better to be safe than sorry. See a Dermatologist. We are the experts.