Skin Cancer Warning Signs: A Guide to Self-Checks

How to Spot Skin Cancer

It’s not uncommon to find a new freckle or mole and ask yourself, “Is this cancer?” Almost 200,000 people were diagnosed with melanoma in 2024 in the U.S., but the total number of cases of all skin cancers is believed to be much higher. Monitoring your skin is a proactive way to take care of your health.

Not every blemish is cancerous. Let’s explore what cancer does – and doesn’t – look like.

What Does Skin Cancer Look Like?

The appearance of skin cancer varies by type, but you can use the ABCDE rule to help determine if that mole or blemish needs further evaluation.

• Asymmetry: Cancerous moles tend to be asymmetrical, meaning the shape of one side doesn’t match the other.
• Border: An ill-defined border, or one that is irregular and non-circular, could indicate cancer.
• Color: A cancerous mole may not be the same color throughout, consisting of a variety of shades of brown, black, red or blue.
• Diameter: Moles larger than 6mm, which is about the width of a standard pencil eraser, may be more concerning for cancer.
• Evolving: Your mole could be dangerous if over time it changes in shape, size or color.

It’s important to note that even non-cancerous growths can have one (or several) of the above characteristics. If you’re concerned about a new or existing growth, schedule an evaluation with your primary care provider.

Where Does Skin Cancer Usually Appear?

Skin cancer is associated with overexposure to UV radiation (usually from the sun or tanning beds). For that reason, it’s common for cancerous moles to be found in high-exposure areas of the body like the head, neck and arms.

Melanoma, considered the most aggressive form of skin cancer, can appear anywhere on the body but is more likely to be found on the torso (for men) or legs (for women).

If It’s Not Skin Cancer, What Is It?

A new rash, mole, burn, blemish or other skin condition can be unsettling, especially if it bears one or more of the above features of skin cancer. But that doesn’t necessarily mean it’s dangerous.

Several other skin conditions can look similar, such as seborrheic keratosis or cherry angiomas, which are benign conditions.

What Can You Do to Prevent Skin Cancer?

Using sunscreen can help prevent skin cancer. It’s important to apply sunscreen regularly, especially during outdoor activities with lots of sun exposure, such as hiking, swimming and going to the beach. This will help protect against UVA and UVB rays that can cause skin cancer.

It’s generally recommended to use sunscreen with an SPF of 30 or higher and reapply every two hours, especially after swimming or sweating. Covering sun-exposed areas with clothing and wide-brimmed hats can also help limit sun exposure. Consider avoiding indoor tanning as this is associated with an increased risk of skin cancer.

Doing a skin self-exam once a month in front of a mirror can help identify new or potentially concerning marks on your skin. If you notice any of the above ABCDE features of a mole or if you are uncertain, it is important to reach out to your primary care doctor.