The ABCDs of Skin Cancer Cancer Your ability to spot melanoma, the most I deadly form of skin cancer, could make all the difference in your prognosis. The Harvard Health Letter offers this alphabet memory tool...· Assymetry-one half of a mole doesn't match the other half.· Border irregularity-Mole edges are ragged, notched or indistinct.· Color-Mole pigmentation is uneven.· Diameter-Mole is larger than a pencil eraser or shows a sudden or progressive increase in size.If you notice any of these symptoms, make an appointment with a dermatologist, who can evaluate the moles and explain your treatment options. Want to Keep Reading? Continue reading with a Health Confidential membership. Sign up now Already have an account? Sign in