Melanoma: Signs and Symptoms

Most melanoma starts as a change you can see. Two questions guide what to look for. Is this spot new? And is it changing? A mole that has looked the same for years is unlikely to be a problem. A new spot, or one that is shifting in size, shape, or color, is what needs a closer look.

Doctors use five letters to describe warning signs in a spot:

• A — Asymmetry. One half does not match the other half.
• B — Border. The edges are irregular, ragged, notched, or blurred, instead of smooth.
• C — Color. The color varies within one spot — shades of brown and black, or patches of red, white, pink, or blue.
• D — Diameter. Larger than about 6 millimeters, roughly the size of a pencil eraser. Smaller melanomas do happen, so a small spot is not automatically safe.
• E — Evolving. The spot is changing in size, shape, color, or feel over weeks or months.

A spot does not need to match every letter to be worth checking. Any one of these on its own is a reasonable reason to see a doctor.

Most people's moles tend to look similar to each other, like siblings. Doctors use a simple check called the ugly duckling sign: a spot that looks different from all your other spots stands out, even if you cannot say exactly why. That instinct is worth trusting enough to get the spot looked at.

Melanoma does not always look like a classic dark, asymmetric mole. Other signs include:

• A sore that does not heal
• Pigment that spreads from the edge of a mole into the surrounding skin
• New redness or swelling around a spot
• A spot that becomes itchy, tender, or painful
• A surface that becomes scaly, oozes, or bleeds
• A new lump or bump under the skin

Melanoma can grow in spots that are easy to miss during a normal glance in the mirror:

• Under a nail — a dark line or streak, not caused by an injury, is worth checking.
• Palms and soles — a new dark or irregular area here should not be dismissed as a stain or callus.
• The eye — a new spot on the iris, or vision changes, can be a sign and is found through an eye exam.
• The mouth or genital area — a new dark spot or irregular patch of tissue in these areas should be checked too.

These locations get less sun, so people often assume anything found there cannot be melanoma. That assumption is wrong often enough to matter, especially for people with darker skin, where these areas are a more common site for melanoma to start.

Melanoma found early, while still thin and confined to the skin, is highly treatable, usually with surgery alone. The risk grows as a melanoma grows deeper into the skin over time. That is the entire reason for learning these signs: not to cause worry over every mole, but to know which changes are worth a prompt appointment rather than a wait-and-see approach.

• Can you check this spot, and should you also check my palms, soles, nails, and scalp?
• Is a biopsy needed, or can this be watched and re-checked later?
• Given my skin type and history, how often should I have a full skin exam?
• If a mole changes between visits, how soon should I come back?

• American Cancer Society — Signs and Symptoms of Melanoma Skin Cancer
• American Cancer Society — What Is Melanoma Skin Cancer?