Is That Mole Cancerous?

Sometimes, you look at a mole and think, “That doesn’t look quite right.” Don’t ignore those suspicions. There’s a chance that what you’re seeing may be a sign of melanoma, a dangerous form of skin cancer.

So, how can you tell if you might have a cancerous mole? There are definite hints visible to the naked eye. Dermatologist Christine Poblete-Lopez, MD, explains how to spot potential trouble.

How can you tell if a mole might be cancerous?

Moles aren’t unusual. In fact, most adults have between 10 and 40 of them scattered around their bodies. These so-called “beauty marks” are typically harmless and nothing to worry about either.

But certain characteristics of a mole can offer hints when it comes to melanoma. Dr. Poblete-Lopez says the rule of thumb is to consider the ABCDEs when looking for signs of cancerous moles.

Each letter represents a warning sign of a potentially cancerous mole.

• A = Asymmetry
• B = Border
• C = Color
• D = Diameter
• E = Evolution

Let’s take a closer look at those clues, plus a few more.

1. Uneven shape (asymmetry)

Do you have a mole in which one half doesn’t quite match the other? If so, that may spell trouble, as an uneven shape could indicate the presence of cancerous cells growing and dividing.

“Normal moles are typically symmetrical,” explains Dr. Poblete-Lopez. “That can change when cancerous cells are present.”

2. Ragged edges (border)

Healthy moles usually have smooth, well-defined borders. Cancerous cells can make those edges fuzzy, poorly defined, ragged or blurred. Melanoma may also lead to a small notch or protrusion along the edge of a mole.

“Those are all red flags,” says Dr. Poblete-Lopez.

3. Inconsistent shading (color)

Healthy moles tend to be one shade of brown. If you have a mole that looks like a paint color card with two or three different variations of brown … well, that might be a bit suspicious.

Moles colored blue, gray, red, black or white may also signal possible melanoma.

4. Larger in size (diameter)

Size matters when it comes to moles. Any moles larger than 6 millimeters — roughly the size of the eraser on a pencil — tend to be more worrisome. That’s especially true if the growth is sudden or rapid.

“Moles are usually small,” emphasizes Dr. Poblete-Lopez. “If they get larger, it could be a sign of cancerous cells growing.”

5. Appearance changes (evolution)

Consider noticeable changes in a mole to be one of the biggest warning signs of all. Concerns increase if a mole bleeds or begins to ooze with minimal trauma.

“Moles shouldn’t really change,” says Dr. Poblete-Lopez. “If they do, it’s best to find out why.”

6. A new mole

More than 70% of melanomas begin as a new mole, which is why any mole that randomly appears deserves your attention. (This is especially true if the new mole checks boxes on the ABCDE list.)

But to be clear, not all new moles signal melanoma. Most are benign and nothing more than a new mark on your skin. But that doesn’t mean they should be ignored.

“It’s best to get new moles checked by your healthcare provider,” says Dr. Poblete-Lopez.

7. Moles that itch

Moles can become itchy for a variety of reasons. It might be something as simple as dry or irritated skin, for example, or an allergic reaction to whatever laundry detergent you just picked up.

But there’s also a chance that urge to scratch could be a sign of a cancerous mole, says Dr. Poblete-Lopez. Concerns increase if the mole bleeds or begins to ooze.

Bottom line? Get it looked at by a medical professional sooner rather than later.

8. An ‘ugly duckling’ mole

For someone with a lot of moles, healthcare professionals often look for atypical moles, often called “ugly ducklings.” These moles stand out and look different. They often check more than one of the ABCDE characteristics, too.

The good news? It’s extremely rare for the average atypical mole to transform into melanoma. The risk is estimated at 1 in 10,000.

But a high number of atypical moles on your body raises your skin cancer risk, says Dr. Poblete-Lopez. If you have 10 or more atypical moles, you’re statistically 12 times more likely to eventually develop melanoma.

When to see a dermatologist

It’s important to repeat that the warning signs we’ve outlined don’t guarantee melanoma in a mole. But the indicators do signal an increased possibility of skin cancer. And they deserve some attention.

“Many mole changes are nothing to worry about,” reiterates Dr. Poblete-Lopez. “But it’s best to get them checked out by your doctor just to make sure everything is OK.”

That’s because early detection is key to treating melanoma. And that’s why Dr. Poblete-Lopez recommends doing skin self-checks once a month. Use the inspection to look for new moles or any unusual changes to existing moles.

Melanoma is one of the most common forms of cancer in the United States, representing about 5% of all new cancer diagnoses. Case counts have been steadily rising for decades, too, reports the U.S. National Cancer Institute.

Fortunately, the survival rate for melanoma has recently shown an increase. That’s largely due to more attention to detection.

“The beauty of dermatology is that we can quickly see if there’s a problem on the surface and then do a skin biopsy, a simple in-office procedure,” explains Dr. Poblete-Lopez. “We may be able to find anything that’s trouble early on.”