Moles are small growths on the skin that develop from pigment-producing cells in the skin called melanocytes. They typically appear as dark brown spots on the skin that are either flat or raised. Most people have benign moles, which are harmless.
Moles that become atypical (dysplastic nevi) can eventually become malignant melanoma (a form of skin cancer). It may be hard even for experts to distinguish atypical moles from melanoma cancer, so moles which change or look atypical need to be evaluated by a dermatologist or other physician skilled in skin diagnosis.
Benign moles develop from an excess accumulation of melanocytes. In rare cases, a benign mole, especially one that is large and varied, may turn into an atypical mole.
A risk factor is something that increases your chance of getting a disease or condition.
- Moles present at birth (this increases the likelihood of more moles later in life)
- Family members who have moles
- Excessive exposure to sunlight, especially sunburn
Most people have some benign moles that appear at birth, or during childhood or adolescence.
Benign moles, which can appear anywhere on the body, are usually:
- Dark brown, but can also be yellow-brown or flesh tone
- One color
- Round or oval with distinct edges
- Flat and smooth, but may occasionally become raised, rough, or change color over time
Signs that a mole may be atypical include:
- Sudden change in size, color, shape, texture, or sensation
- Large size (¼ inch or more across—about the size of an eraser at the end of a pencil). Remember though that many melanomas today are found when quite small–often even less than ¼ inch. While the majority of atypical moles of any size aren’t cancerous, don’t let small size keep you from seeking medical attention for a changing or irregularly-shaped mole.
- A mixture of colors, often including black
- Irregular edges
- Abnormal surface that is:
- Oozing liquid
- Open with a sore that won't heal
- Hard and raised lump
- Itchy, tender, or painful
- Abnormally colored skin around it
The doctor will examine your skin and moles and ask about your symptoms and medical history.
Tests may include:
- Biopsy–removal of all or part of the mole to be tested for cancer cells
Benign moles do not need to be treated. However, surgery may be performed to remove those that are unsightly or irritated.
Treatment for atypical moles include:
Atypical moles that are cancerous or suspected of being cancerous can be removed surgically with local anesthesia. The mole tissue is examined under a microscope. If cancer cells are found, additional surgery is performed to remove any remaining portion of the mole and surrounding tissue.
To help prevent benign moles from becoming atypical (and possibly cancerous):
- Avoid excessive exposure to the sun.
- Take proper precautions when in the sun:
- Wear a hat and protective clothing.
- Wear sunscreen with a minimum sun protection factor (SPF) of 15.
Sometimes there is no way to prevent a benign mole from becoming atypical or cancerous. The key to successful treatment is early detection. To detect atypical or cancerous moles early:
- Monitor your moles, especially atypical moles.
- Report any sudden changes in a mole to your doctor.
- Have your doctor check and monitor atypical moles every 12 months. Have them checked more frequently (every 6 months) if you have:
- A large number of atypical moles
- A family history of atypical moles that develop into melanoma
- Have an atypical mole removed if your doctor suggests it.