Changes in a Mole or Skin

This page is for anyone who has noticed a new or changing spot on their skin. It explains the warning signs of skin cancer, when to see a doctor, and what to track before your visit.

Most moles are harmless. But a mole or skin spot that changes over time, or a sore that will not heal, can be a warning sign of skin cancer, including melanoma.

The National Cancer Institute uses a five-letter checklist to describe early melanoma:

• A — Asymmetry. The shape of one half does not match the other half.
• B — Border. The edges look ragged, notched, or blurred, instead of smooth.
• C — Color. Shades of black, brown, and tan may show up together. Areas of white, gray, red, pink, or blue can appear too.
• D — Diameter. The spot changes size, usually growing larger. Melanomas are often bigger than 6 millimeters wide, about a quarter inch, roughly the size of a pencil eraser.
• E — Evolving. The mole has changed over the past few weeks or months.

Not every melanoma shows all five signs. Some show only one or two. That is why any one of these changes is worth a doctor's look.

Melanoma is not the only skin cancer to watch for. Basal cell and squamous cell cancers look different from melanoma. Watch for:

• A new growth or bump on the skin that was not there before.
• A sore that does not heal, or that bleeds, oozes, or forms a crust.
• A firm bump, flat sore, or scaly patch.

On darker skin, skin cancer often shows up in less expected places and colors. A dark patch on the palm or the sole of the foot, or a dark band under a nail, can be the first sign of melanoma. Basal cell cancer can look like a brown or glossy black bump with a rolled edge, and squamous cell cancer can appear as a firm bump or scaly patch that may look black or brown rather than red. On darker skin, melanoma is often found under the fingernails or toenails (often a pigmented streak in the nail), on the palms, or on the soles. Tell your doctor about any new mole or change in an existing mole, regardless of skin tone.

Skin changes can often be seen, so you may be the first to notice one.

Tell your doctor about any new mole or a change in an existing mole, such as a change in color, size, shape or texture, or itching, bleeding or oozing. This also includes a mole that is changing, a new growth, a sore that will not heal, or a nail with a new dark streak. NCI says to see a doctor if a symptom does not get better after a few weeks, and that cancer often does not cause pain, so do not wait to feel pain before getting a skin change checked.

At the visit, the doctor examines the spot and may take a biopsy. This means removing some or all of the tissue so a pathologist can look at it under a microscope. A biopsy is the only way to know for certain whether a spot is cancer.

Take a photo of any spot you are watching, with something for scale, like a coin, next to it. Note when you first noticed it and anything that has changed since. If you are not sure whether something looks different from your other moles, bring it up anyway. Getting a new or changing spot checked is worth doing.

• National Cancer Institute — Common Moles, Dysplastic Nevi, and Risk of Melanoma.
• National Cancer Institute — Skin Cancer on Black and Brown Skin.
• National Cancer Institute — Skin Cancer Screening (PDQ).