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How can you tell if a mole is cancerous? 

Most skin cancers arise as new spots. Existing moles can become cancerous, but it is more common for skin cancer to appear out of nowhere.

Unfortunately, there's not a 100% reliable way for you to know if a mole is cancerous without going to the dermatologist. Many skin spots can mimic skin cancer and not be cancerous; other skin spots that don¡¯t look particularly concerning can be cancerous. A dermatologist can examine your skin and tell you for sure what you are dealing with.

Related: 5 things to know about raised moles

The best way to determine if a mole warrants a trip to your dermatologist? Use the ABCDEs. Each letter stands for a feature of a skin cancer called melanoma. 

A: Is your mole asymmetrical? Does one side of the mole look different than the other?

B: Does your mole have a border that looks fuzzy or irregular?

C: Is your mole more than one color? Is your mole a different color than your other moles?

D: Does your mole have a diameter greater than six millimeters, or bigger than a pencil eraser? 

E: Has your mole evolved, or changed over time? This is the most important factor for determining if you should see a dermatologist. Generally, adults shouldn¡¯t be getting new moles, nor should your existing moles be growing if you¡¯re over age 40. Using your naked eye, it can be hard to tell whether a new skin spot is a mole or an age-related spot. A dermatologist can take a closer look to help you find out.

If you answered yes to any of the questions above, you should make an appointment with your dermatologist. 

However, the ABCDE rule isn¡¯t a perfect tool. It takes time for melanoma to develop features we can see, so if you only rely on the ABCDE rule, you might miss some very early melanomas. That¡¯s why I also tell patients to watch out for the following skin changes:

• New spots 
• Growing spots
• Spots that don¡¯t look like other spots
• Spots that bleed spontaneously, or without being touched

Melanoma can develop anywhere on the body, even places that don¡¯t get a lot of sun exposure, such as the feet. 

Melanoma in dark skin

If you have dark skin, the pigment in your skin provides a small amount of UV protection, but not nearly as much as sunscreen does. But because sun exposure isn¡¯t the only risk factor for melanoma, you can still get melanoma if you have dark skin. 

In people with darker skin tones, more melanomas are found in non-sun-exposed areas like the feet than they are in people with lighter skin. That¡¯s why it¡¯s important to check your entire body for new or changing spots.

How do dermatologists tell if a mole is cancerous? 

Dermatologists consider many features when determining if a mole is cancerous. Here are four tools your dermatologist may use when examining your mole.

Visual exam: Your dermatologist will look at your skin with their naked eye to see if there are any features that may be signs of melanoma, such as the ABCDEs mentioned above.

Dermoscopy: Your dermatologist may use a lit magnifying tool called a dermatoscope, or derm light, to help them see your mole up to 10x closer. This procedure can be done in your dermatologist's office during your appointment.

Monitoring: If your dermatologist is confident your mole is non-cancerous, but not 100% sure, they may choose to carefully watch it for changes over time. This might mean taking photographs and measurements of your mole to compare at a follow-up appointment. 

Biopsy: Your dermatologist will remove your mole. Next, they will send it to a lab where pathologists examine it under a microscope to determine if it is cancerous or not. Biopsy is the gold standard for diagnosing skin cancer. It can also be used to determine skin cancer type.

How quickly can a mole turn cancerous?

Different types of skin cancer grow at different rates; each case is unique and depends on the person and the type of skin cancer.

Metastatic melanomas have been reported to double in as quickly as 30 days, while basal cell cancers grow very slowly over months to years. 

In my opinion, seeing mole changes in weeks to months is a cause for concern.

What are the risk factors for melanoma?

Certain factors can put you at a higher risk for melanoma. Some examples of common melanoma risk factors include:

• Past sunburns
• Tanning bed use
• Fair complexion, such as fair skin, red or blonde hair or green or blue eyes
• Having more than 50 moles
• A first-degree relative, like a sibling or parent, with a history of melanoma 

When should someone start to worry about a mole?

Schedule a dermatology appointment as soon as you have any concerns about a new or changing spot.

It can be hard to get a timely dermatology appointment. If you can¡¯t get an appointment right away, be sure to measure and photograph the spot you¡¯re seeing a dermatologist about. If the spot continues to grow and change, call your dermatologist to see if you can get an earlier appointment.  

 or call 1-877-632-6789.