Melanoma is one of the least common forms of skin cancer, but it’s also the deadliest type because of its potential to spread to other parts of the body.
Each year, about 91,000 people are diagnosed with melanoma, and more than 9,000 people die from it. Rates of melanoma are on the rise, especially among children and teens.
There are several factors that can make you more likely to develop melanoma, which include:
- getting sunburned frequently, especially if the sunburn was severe enough to cause your skin to blister
- living in locations with more sunlight, such as Florida, Hawaii, or Australia
- using tanning beds
- having fairer skin
- having a personal or family history of melanoma
- having a large amount of moles on your body
Just about everyone has at least one mole — a flat or raised colored spot on the skin. These spots are caused when skin pigment cells called melanocytes assemble into clusters.
Moles often develop in childhood. By the time you reach adulthood, you may have 10 or more of them on your body. Most moles are harmless and don’t change, but others can grow, change shape, or change color. A few can turn cancerous.
The biggest clue that a spot on the skin might be melanoma is if it’s changing. A cancerous mole will change in size, shape, or color over time.
Dermatologists use the ABCDE rule to help people spot the signs of melanoma on their skin:
Keep reading to see what each of these melanoma signs looks like on the skin.
A mole that’s symmetrical will look very similar on both sides. If you draw a line through the middle of the mole (from any direction), the edges of both sides will match each other very closely.
In an asymmetrical mole, the two sides won’t match in size or shape because cells on one side of the mole are growing faster than cells on the other side. Cancer cells tend to grow more quickly and more irregularly than normal cells.
The edges of a normal mole will have a clear, well-defined shape. The mole is set apart from the skin around it.
If the border seems fuzzy—like someone has colored outside of the lines—it could be a sign that the mole is cancerous. Ragged or blurred edges of a mole also have to do with the uncontrolled cell growth of cancer.
Moles can come in many different colors, including brown, black, or tan. As long as the color is solid throughout the mole, it’s probably normal and noncancerous. If you’re seeing a variety of colors in the same mole, it could be cancerous.
A melanoma mole will have different shades of the same color, such as brown or black or splotches of different colors (e.g., white, red, gray, black, or blue).
Moles usually stay within certain size limits. A normal mole measures about 6 millimeters (1/4 inch) or less in diameter, which is roughly the size of a pencil eraser.
Bigger moles can indicate signs of trouble. Moles should also remain consistent in size. If you notice that one of your moles is growing over time, consider having it examined.
Change is never a good thing when it comes to moles. That’s why it’s important to do regular skin checks and keep an eye on any spots that are growing or changing shape or color.
Beyond the ABCDE signs, look out for any other differences in the mole, such as redness, scaling, bleeding, or oozing.
Although rare, melanoma can also develop under the nails. When this happens, it appears as a band of pigment across the nail that:
- causes thinning or cracking of the nail
- develops nodules and bleeding
- becomes wider by the cuticle
Melanoma doesn’t always cause pain when it’s under the nails. Talk to your doctor if you notice any changes in your nails.
By doing regular skin checks, you can spot possible skin cancer early enough for it to be treated.
People who have a lot of moles and a family history of skin cancer should see their dermatologist regularly. A dermatologist can map your moles and keep track of any changes that happen.
They might take a sample of the mole, called a biopsy, to check for cancer. If the mole is cancerous, the goal will be to remove it before it has a chance to spread.