How to Check Your Own Skin: The ABCDE Rule

A skin self-exam is when you look over your own skin to check for new spots or changes in the ones you already have. You do not need special training or tools, just good light and a couple of mirrors.

The point is not to diagnose yourself. The point is to get to know your skin so you can notice when something looks different, and then tell your doctor.

Knowing what is normal for you is the whole idea.

Doctors use a simple set of letters to describe warning signs in a mole. If a spot has one or more of these, it is worth showing your doctor.

• A is for Asymmetry. One half of the mole does not match the other half.
• B is for Border. The edges are ragged, notched, or blurry instead of smooth.
• C is for Color. The color is uneven, or there is more than one color, such as brown, black, red, or white.
• D is for Diameter. The spot is larger than a pencil eraser (about a quarter inch), though some melanomas are smaller.
• E is for Evolving. The spot is changing in size, shape, color, or feel, or it is new.

Most moles are harmless. But a spot that fits several of these letters, or that simply looks different from your other spots, deserves a doctor's look.

A mole that stands out from the rest, sometimes called the "ugly duckling," is worth checking.

Give yourself a few quiet minutes in a well-lit room with a full-length mirror and a handheld mirror.

1. Face the full-length mirror and look at your face, neck, chest, and belly.
2. Raise your arms and check both sides of your body, your underarms, and both sides of your arms.
3. Look at the palms of your hands, between your fingers, and under your fingernails.
4. Sit down and check your legs, the tops and bottoms of your feet, between your toes, and under your toenails.
5. Use the handheld mirror to see the back of your legs, your buttocks, and your lower back.
6. Use the handheld mirror, or ask someone you trust, to check your upper back, the back of your neck, and your scalp. Parting your hair helps you see the scalp.

Do not skip hidden spots; skin cancer can appear where the sun rarely reaches.

It is normal to have moles, freckles, and other marks, and to gain a few over the years. Most stay about the same. What matters is change and difference.

Call your doctor if you notice a spot that:

• Is new and looks unusual
• Is changing in size, shape, or color
• Has uneven edges or more than one color
• Itches, hurts, bleeds, oozes, or does not heal
• Simply looks different from your other spots

When in doubt, get it checked; catching a change early is what self-exams are for.

A self-exam works best when it becomes routine. Many people check about once a month. Picking a regular day, like the first of the month, makes it easier to remember.

If it helps, take photos of any moles you want to track, so you can compare them over time. This is not a test you can fail. It is simply a calm, regular check-in with your own skin, and a way to know when it is time to call your doctor.

Most of what a self-exam turns up can wait for an appointment. A few findings should not wait for your next routine visit, and one needs emergency care.

• Call 911 or go to an emergency department if a spot bleeds heavily and will not stop after about ten minutes of firm, steady pressure.
• Call your care team the same day if a spot weeps or oozes and keeps restarting after pressure, or a sore opens back up instead of healing over.
• Call your care team within a day or two if a mole shifts in shape, color or height, turns hard or lumpy, becomes scaly, starts to itch or ache, or pigment creeps out from its edge into the skin nearby. Do the same for redness or swelling that spreads past the mole's border, and for a new dark stripe under a fingernail or toenail.

Sources for this section: NCI — Common Moles, Dysplastic Nevi, and Risk of Melanoma, American Cancer Society — Signs and Symptoms of Melanoma Skin Cancer.