Unusual moles, sores, lumps, blemishes, markings, or changes in the way an area of the skin looks or feels may be a sign of melanoma or another type of skin cancer, or a warning that it might occur.
Normal moles
A normal mole is usually an evenly colored brown, tan, or black spot on the skin. It can be either flat or raised. It can be round or oval. Moles are generally less than 6 millimeters (about ¼ inch) across (about the width of a pencil eraser). Some moles can be present at birth, but most appear during childhood or young adulthood. New moles that appear later in life should be checked by a doctor.
Once a mole has developed, it will usually stay the same size, shape, and color for many years. Some moles may eventually fade away.
Most people have moles, and almost all moles are harmless. But it’s important to recognize changes in a mole – such as its size, shape, color, or texture – that can suggest a melanoma may be developing.
Possible signs and symptoms of melanoma
The most important warning sign of melanoma is a new spot on the skin or a spot that is changing in size, shape, or color.
Another important sign is a spot that looks different from all of the other spots on your skin (known as the ugly duckling sign).
If you have one of these warning signs, have your skin checked by a doctor.
The ABCDE rule is another guide to the usual signs of melanoma. Be on the lookout and tell your doctor about spots that have any of the following features:
- A is for Asymmetry: One half of a mole or birthmark does not match the other.
- B is for Border: The edges are irregular, ragged, notched, or blurred.
- C is for Color: The color is not the same all over and may include different shades of brown or black, or sometimes with patches of pink, red, white, or blue.
- D is for Diameter: The spot is larger than 6 millimeters across (about ¼ inch – the size of a pencil eraser), although melanomas can sometimes be smaller than this.
- E is for Evolving: The mole is changing in size, shape, or color.
Some melanomas don’t fit these rules. It’s important to tell your doctor about any changes or new spots on your skin, or growths that look different from the rest of your moles.
Other warning signs are:
- A sore that doesn’t heal
- Spread of pigment from the border of a spot into surrounding skin
- Redness or a new swelling beyond the border of the mole
- Change in sensation, such as itchiness, tenderness, or pain
- Change in the surface of a mole – scaliness, oozing, bleeding, or the appearance of a lump or bump
Be sure to show your doctor any areas that concern you. It’s sometimes hard to tell the difference between melanoma and an ordinary mole, even for doctors, so it’s important to show your doctor any mole that you are unsure of.
Remember, too, that a small portion of melanomas start in places other than the skin, such as under a fingernail or toenail, inside the mouth, or even in the colored part of the eye (iris). These might look different from melanomas on the skin. For example, a melanoma under a nail might appear as a dark line (streak) in the nail, while a melanoma in the eye might appear as a dark spot in the colored part of the eye. It’s important to show a doctor anything that concerns you in these areas as well.
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- References
The American Cancer Society medical and editorial content team Our team is made up of doctors andoncology certified nurses with deep knowledge of cancer care as well as journalists, editors, and translators with extensive experience in medical writing.
Mitchell TC, Karakousis G, Schuchter L. Chapter 66: Melanoma. In: Niederhuber JE, Armitage JO, Doroshow JH, Kastan MB, Tepper JE, eds. Abeloff’s Clinical Oncology. 6th ed. Philadelphia, Pa: Elsevier; 2020.
National Cancer Institute. Melanoma Treatment (PDQ)–Health Professional Version. 2023. Accessed at https://www.cancer.gov/types/skin/hp/melanoma-treatment-pdq on September 19, 2023.
Swetter S, Geller AC. Melanoma: Clinical features and diagnosis. UpToDate. 2023. Accessed at https://www.uptodate.com/contents/melanoma-clinical-features-and-diagnosis on September 19, 2023.
Last Revised: October 27, 2023
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