How does a cancerous mole look?

See Dermatologist: There are definite characteristics for cancerous moles but the best and most definitive diagnosis is going to the dermatologist as i've seen many moles that did not fit the "description" for cancerous moles and it turned out to be cancerous.

ABCD: Just remember the abc's. A- asymmetric or irregular b- bleeds c- color changes d- diameter or size enlargement.