When Should You Worry That Mole is Melanoma?

Skin cancer is the most common cancer in the United States. One in five Americans will develop skin cancer by age 70, and melanoma, the most serious type, causes the most skin cancer deaths. The good news: Melanoma is highly curable if found early.

Health Matters spoke with Dr. Larisa Geskin, director of the Comprehensive Skin Cancer Center at NewYork-Presbyterian/Columbia University Irving Medical Center, about skin cancer prevention, how to tell normal moles from melanoma, and the latest advances in skin cancer detection.

What are moles?

Moles (or nevi) are common, usually harmless growths made of melanocytes — pigment-producing cells. They can be many colors (brown, pink, blue-gray), shapes, and sizes.

Some moles are present at birth (congenital), while others appear later in childhood or early adulthood. Sun exposure and genetics both play roles in how many moles a person develops.

Are moles inherently dangerous?

Most moles are benign and not dangerous. But in people with many moles, atypical moles, a family history of melanoma, significant sun exposure, or immune suppression, the risk of a mole transforming into cancer is higher. The key is to recognize when a mole or skin spot warrants evaluation.

What is melanoma? What puts us at risk for it?

Melanoma is a type of skin cancer that develops when pigment-producing cells grow out of control. There are a few factors that may contribute to developing melanoma. The first is our hereditary disposition, or the genes we get from our parents. The second risk factor is our age — we develop more genetic mutations as we grow older, which increase our chances of developing melanoma or other forms of cancer. Finally, sun exposure can put us at risk for developing skin cancer, including melanoma.

What is the ABCDE checklist and is it still recommended?

For many years, people were taught the ABCDEs (Asymmetry, Border, Color, Diameter, Evolution) to help identify concerning moles.

Today, dermatologists emphasize something even simpler: Spots that are new and keep growing or changing need to be checked.

While ABCDE can still be useful, change over time (“evolution”) is the most critical warning sign. Even small melanomas may not meet all ABCDE criteria. You should also remember the “Ugly Duckling” rule: If one mole looks different from the others on your body, you should get it examined by a dermatologist

Can melanoma develop even if you don’t have a mole?

Yes — in fact, most melanomas (70–80%) develop on normal-looking skin, rather than within an existing mole.

Melanoma can also occur in unexpected places: under a fingernail or toenail (subungual melanoma), on the scalp, on palms and soles, on mucosal surfaces (mouth, genital skin). That’s why full-body checks, including inspecting less visible areas, are important.

What are the most common places on the body to find melanoma?

Melanoma can appear anywhere. In lighter skin, it more often arises on sun-exposed areas like the back, face, or chest. In darker skin, it more commonly appears on palms, soles, or under nails, areas that don’t usually get much sun.

Men most often develop melanoma on the back, torso, or head and neck. Women most often develop it on the legs.

Important health equity note: Outcomes are worse for patients with darker skin, largely because melanomas are often detected later. So awareness is critical for all skin tones.

What is the best way to protect our skin and prevent melanoma?

Sun protection is the foundation of melanoma prevention:

• Apply broad-spectrum sunscreen (SPF 30 or higher) every day, year-round.
• Reapply sunscreen every 2 hours and after swimming and sweating.
• Wear protective clothing, wide-brimmed hats, and UV-blocking sunglasses.
• Seek shade between 10 a.m. and 4 p.m. when UV rays are strongest.
• Avoid tanning beds entirely.
• Check the UV index before doing outdoor activities.

Some people worry sunscreen may cause a vitamin D deficiency, since your body makes vitamin D from the sun. But experts recommend sticking with sunscreen and getting vitamin D from diet or supplements — safe options that don’t raise your skin cancer risk.

What are the newest ways to detect melanoma?

Dermatologists now have powerful tools beyond the naked eye to look for skin cancer:

• Reflectance Confocal Microscopy (RCM): A non-invasive “virtual biopsy” that lets doctors see cellular details in the skin; it can reduce unnecessary surgical biopsies.
• Total-Body Photography (including 3D systems): High-resolution or 3D imaging creates a photographic map of your skin, making it easier to detect subtle new or changing lesions over time.
• Molecular tape-strip tests: A painless “peel” of the skin’s surface that can detect gene expression patterns linked to melanoma, helping identify which lesions need biopsy.
• Artificial Intelligence (AI): Dermatologists are increasingly using AI-assisted dermoscopy and image analysis to highlight suspicious spots. While these tools help doctors, they do not replace expert examination.

How often should people see a dermatologist for skin checks?

Everyone should see a dermatologist at least once in their life to assess their individual risk and determine how frequently they should be checked.

Screening is often done annually or semiannually for higher-risk people (fair skin, many atypical moles, family history, prior melanoma, immunosuppression). Mole mapping and digital imaging may be recommended for patients with many or unusual moles.

What are the key takeaways about skin cancer prevention and detection? 

Sun protection is still the most effective skin cancer prevention step.

On the detection front, new tools — from advanced imaging to molecular testing — are helping dermatologists catch melanoma earlier than ever.

You play a big role by keeping an eye on your skin. If you notice a new and growing or changing spot, be sure to get it checked by a dermatologist. Early detection saves lives.

Larisa J. Geskin, M.D., is director of the Comprehensive Skin Cancer Center at the Department of Dermatology at NewYork-Presbyterian/Columbia University Irving Medical Center and a professor of dermatology (in medicine) at Columbia University Vagelos College of Physicians and Surgeons.