September 5, 2022

When Should You Worry About a Mole?

An irregular border, large size or asymmetrical appearance are all signs to watch out for

A melanoma on the skin.

While most cancers are on the decline, melanoma — the deadliest skin cancer of all — is on the rise. The National Cancer Institute currently ranks melanoma as the fifth most common cancer, with over 100,000 newly diagnosed cases per year.


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The good news is that most skin cancers are highly treatable when detected early, says dermatologist Christine Poblete-Lopez, MD. So, self-exams of your skin and annual skin exams from a doctor or dermatologist are critical — especially if you’re at high risk.

Dr. Poblete-Lopez outlines for us what to look for when doing these checks and what to know when examining your own moles.

Cancerous mole warning signs

Whether you’ve had a mole for your entire life or if it’s relatively new, there are plenty of reasons to keep an eye on them. Here are a few of the most important things to look for.

A change in an existing mole: The ABCDEs of melanoma

When you have your exam, the dermatologist will ask if you’ve noticed any changes in a mole or other skin lesion. Then they’ll consider the ABCDEs:

  • Asymmetry: Do you have a mole where one half doesn’t match the other? Asymmetry is a red flag.
  • Border: Is a mole’s border fuzzy, or does it have a small notch or protrusion? Poorly defined, ragged or blurred edges are also red flags.
  • Color: Do any moles have two to three shades of brown, or any shade of blue, gray, red, black or white? “Those are concerning,” says Dr. Poblete-Lopez.
  • Diameter: Is any mole bigger than 6 millimeters (about the size of the top of your pencil eraser)? Although larger moles are more worrisome, “I’ve certainly seen pinpoint melanomas that were Sharpie® pinpoint black in color,” she says.
  • Evolution: Has any mole changed over time? Evolution is the biggest red flag of all.

“We’ll consider all of the ABCDEs together,” says Dr. Poblete-Lopez. “Just because a mole is asymmetric doesn’t mean it’s a melanoma, for instance.”

A new mole

A new mole isn’t necessarily a sign of melanoma. But only around 30% of melanomas begin as an existing mole; the rest begin on normal skin. So, if you notice a new mole, particularly one that meets the above ABCDEs, contact a healthcare provider right away.

Moles that itch or bleed

There are several reasons a mole may itch:

  • Dry skin.
  • Allergic reaction to detergent or soap.
  • Irritated skin.

But, yes, a cancerous mole is also a possible cause, so it’s important to see a healthcare provider if you notice one of your moles begins itching. You should also call a doctor if any mole that bleeds or oozes doesn’t properly heal within a few weeks.

An ‘ugly duckling’ mole

If any moles look worrisome, your dermatologist will choose just one or a couple to sample for study under the microscope. “We’ll look for the mole that stands out the most — what we call the ‘ugly duckling’ mole,” Dr. Poblete-Lopez says.

The microscope will reveal whether it’s mildly, moderately or severely atypical (abnormal). “What we find under the microscope will guide how aggressive we’ll need to be in checking your moles,” she adds.

“We may say, ‘OK, you’ve got a higher chance of developing cancer based on what we see, so we’ll need to see you every six months instead of every year or every two years.’”

Who has the highest risk of developing melanoma?

You’ll also want to see a dermatologist if you have lots of moles or any of these risk factors for melanoma:

  • A history of indoor tanning.
  • Fair skin or skin that easily burns, freckles or reddens.
  • A personal history of skin cancer.
  • A family history of melanoma.
  • Heavy sun exposure at work or play.
  • Lots of sunburns early in life.
  • Blue or green eyes.
  • Blonde or red hair.
  • Certain types of moles.

“The beauty of dermatology is that we can quickly see if there’s a problem on the surface and then easily sample the skin to study under the microscope,” explains Dr. Poblete-Lopez.

If a cancerous mole is found, dermatologists can treat it in a variety of ways, including surgery, chemotherapy, immunotherapy and targeted therapy.


What you can do for protection

The biggest key to treating melanoma is early detection. Doing skin self-checks once a month, examining existing moles and looking for new ones, is a good way to keep track. Checking your whole body can be tricky, so use a full-length mirror, check areas like your neck and scalp and even ask for help from a trusted friend or family member for an extra set of eyes in hard-to-see places.

Making regular appointments with your doctor and a dermatologist is also a good rule of thumb. Not only can they help you in looking for any irregularities, but they also have a keener eye on what to look for and may be able to spot trouble before you do.

Protecting your skin is also essential, especially if you:

  • Have fair skin.
  • Have many moles on your body.
  • Have immediate families with many moles, atypical moles or a history of melanoma.

Use plenty of strong sunscreen, reapplying often, when you’re out in direct sunlight for long periods. You can also wear light-colored clothing that covers your extremities like your arms and legs to protect exposed skin.

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