While most cancers are on the decline, melanoma — the deadliest skin cancer of all — is on the rise.

The National Cancer Institute predicts that over 91,000 new cases of melanoma will be diagnosed in 2018, and that it will claim about 9,300 lives.

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, if you’re at high risk, are critical.

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 he or she will consider the ABCDEs:

• Asymmetry: Do you have any mole in which 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: Does any mole have two to three shades of brown, or any shade of blue, gray, red, black or white? “Those are concerning,” says Dr. 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® 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,” notes Dr. Lopez. “Just because a mole is asymmetric doesn’t mean it’s a melanoma, for instance.”

What the microscope reveals

If any moles look worrisome, your dermatologist will choose just one 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,” she explains.

The microscope will reveal whether it is 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,” says Dr. Lopez.

“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.’”

If any lesion on your skin has one or more ABCDE traits — or if it bleeds, scabs, comes and goes, or refuses to heal — see a dermatologist promptly.

Risk factors for melanoma

You’ll also want to see a dermatologist if you have lots of moles, she says, 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,” says Dr. Lopez.

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

Taking steps to stay healthy

Doing skin self-exams and getting annual mole checks if you’re at high risk will allow your doctors to find, and treat, melanoma early.

But to lower your odds of getting melanoma or other skin cancers in the first place, apply sunscreen liberally and often before going outdoors — even on cloudy days.