10 Ways to Tell if a Mole Is Cancerous

by Holly Pevzner Health Writer

From childhood through age 40, our skin churns out between 10 to 40 moles, which are basically clusters of pigmented cells (a.k.a. nevi). By and large, these moles are harmless. “It’s actually rare for melanoma to arise from a pre-existing mole,” says board-certified dermatologist Valerie M. Harvey, M.D., co-director of Hampton University Skin of Color Research Institute in Hampton, Virginia. Instead, 71% of melanomas appear as new spots, according to a 2017 study in the Journal of the American Academy of Dermatology. To be vigilant, “look out for new or changing moles and pay attention to moles that look distinct from the others,” says Dr. Harvey. Here, the tell-tales to home in on.

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Take Count

Having 50 or more moles is associated with an increased risk of developing melanoma (the most serious type of skin cancer), according to the American Academy of Dermatology, the National Cancer Institute, and other organizations. However, many people with melanoma don’t routinely have an increased mole count, a report in JAMA Dermatology found. Bottom line: If you have a lot of moles, you need to be on high alert, but those with fewer also need to pay attention to the following signs.

different colored moles
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Consider the Color

Healthy moles are most often solidly tan, brown, or black. In contrast, “if a mole contains different colors, like shades of brown, tan, or black, that can be cause for concern,” says Anne Marie McNeill, M.D., a board-certified dermatologist in Newport Beach, California and member of The Skin Cancer Foundation. “Cancerous spots can also look red, pinkish, white, or blue.” Finally, note any moles that are darker or a different color than surrounding moles.

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Know That Color Isn’t Everything

Don’t overlook an odd spot just because the color isn’t troubling: At times, cancerous moles can be the same color as your skin, such as in the case of amelanotic melanoma. “And for people of color, if any brown spots are also glassy, that could indicate basal cell carcinoma, which presents pink or pearly on fair-skinned individuals,” says Dr. Harvey.

asymmetrical mole
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Examine Shape and Symmetry

Non-cancerous moles are generally round or oval in shape, while melanomas are often asymmetrical. (If you were to draw a line through the center of a mole and one half did not match the other half, that mole would be asymmetrical.) Does this mean all atypical moles are skin cancer? No. “But having these types of moles is a risk factor for developing melanoma and, unfortunately, there’s no way to tell for sure if a mole is atypical or cancerous without visiting your dermatologist, so it’s important to stay on the lookout,” says Dr. McNeill.

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Beware of Pain or Itching

Often, skin cancer doesn’t cause any truly bothersome symptoms until the cancer has grown fairly large. That noted, about 28% of skin cancer lesions—usually non-melanoma skin cancers, like basal cell and squamous cell carcinoma—do involve pain and 37% are accompanied by itching, according to a study in JAMA Dermatology. However, “acral lentiginous melanoma, the most common subtype of melanoma in non-Hispanic Blacks, can be associated with pain, itching, ulceration, and bleeding,” says Dr. Harvey. Painful, itchy or tender spots that don’t feel better in a week’s time should be looked at by a dermatologist, advises the Skin Cancer Foundation.

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Explore the Border

“When mole borders are uneven, jagged, or scalloped as opposed to smooth, that’s considered a warning sign of skin cancer,” says Dr. McNeill, who also notes that the appearance of skin cancers and atypical moles can vary greatly. In other words: “A cancerous mole may not check multiple warning-sign boxes,” she says. “So the most important thing is to look for anything new, changing, or unusual on your skin and get it checked by a professional right away.”

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Assess the Size

In truth, a cancerous mole can be any size, but warning bells should for-sure sound if any lesion is a quarter inch in diameter or larger. That’s about the size of a pencil eraser. Another tell-tale: Any change in mole size, usually an increase. “Ideally, a dermatologist would catch a melanoma when it’s smaller, so if you’re concerned a mole is exhibiting any other warning sign, that’s a valid reason to get it checked,” says Dr. McNeill.

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Review the Texture

Check out the surface of the mole: Has it broken down at all? Does it look scraped or scaly? Is it hard or lumpy? Is it crusty? Is your mole elevated with a central depression? “All of these things may indicate skin cancer,” says Dr. McNeill. It’s smart to tune into skin texture changes even prior to any mole changes. The reason: Precancerous skin growths (actinic keratoses) start as rough-feeling patches or scaly bumps on the sun-exposed area of the body.

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Identify an Ugly Duckling

Just because a mole is, well, ugly, doesn’t mean it’s cancerous. However, most normal moles on the body look alike. “Any mole that sticks out among the others on your body in any way, is an Ugly Duckling and should be examined further,” says Dr. McNeill. Perhaps the offender is bigger (or smaller) than the rest. Maybe it’s darker (or lighter) than your other moles. Or perhaps it’s the sole raised mark. No matter what, if it’s different, have a dermatologist check it out.

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Flag a Spot That’s Slow to Heal

Moles and skin spots can get scraped, bumped, and cut, but an otherwise healthy mole should heal quickly. “If it doesn’t heal within three weeks, that can be a sign of skin cancer,” says Dr. McNeill, noting that this includes melanoma, basal cell, and squamous cell cancers. That cancer warning holds true even if, say, the bleeding or oozing happens only occasionally; if the skin sore heals and then comes back; or if a scab develops and the scab takes a few weeks to heal.

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Be Attuned to Any Visible Change

A change in a mole’s shape, size, or color indicates that melanoma may be brewing, notes Dr. Harvey. An uptick in mole elevation raises red flags, too, since that suggests vertical growth beneath the surface of the skin. In fact, a new bump may point to nodular melanoma, the second most common type of melanoma, accounting for 10% to 30% of all cases. “Remember, skin cancer can resemble something as nondescript as a pimple or red patch, so it’s important to check your skin often and take note of all changes,” says Dr. McNeill.

Holly Pevzner
Meet Our Writer
Holly Pevzner

Holly Pevzner specializes in creating health, nutrition, parenting and pregnancy content for a variety of publications, such as EatingWell, Family Circle, Parents, and Real Simple. Before becoming a full-time writer, Holly held senior staff positions at Prevention, Fitness, and Self magazines, covering medical health and psychology. She was also a contributing editor at Scholastic Parent & Child magazine. She resides with her family in Brooklyn, New York.