Definition

Moles are spots on the skin where pigmented cells have clustered together. They typically appear as light to dark brown spots on the skin that are either flat or raised. Most people have benign moles, which are harmless.

Moles that become atypical are called dysplastic nevi. They may eventually become melanoma. Melanoma is a form of skin cancer.

Causes

Moles develop from pigment-producing cells in the skin called melanocytes. Normally, these cells are evenly distributed in your skin. When you have a mole, these cells have formed a cluster.

Risk Factors

Factors that may increase your chance of developing moles:

• Moles that are present at birth increase the likelihood of more moles later in life
• Family members with moles
• Excessive exposure to sunlight, especially sunburn

Symptoms

Most people have some benign moles that appear at birth, childhood, or adolescence. Most adults have 10-40 moles.

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 grow hair

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
• A mixture of colors, often including black
• Irregular edges
• Abnormal surface that is:
  • Scaling
  • Flaking
  • Oozing
  • Bleeding
  • Open with a sore that will not heal
  • Hard with a raised lump
• Itchy, tender, or painful
• Abnormally colored skin around it

Diagnosis

Your skin will be examined. You will be asked about your symptoms and medical history.

Your bodily tissues may be tested. This can be done with a biopsy to remove all or part of the mole to be tested for cancer cells.

Treatment

Benign moles do not need to be treated. However, surgery may be done to remove those that are unsightly or irritated.

Treatment for atypical moles includes monitoring or removal. Atypical moles that are cancerous or suspected of being cancerous can be removed. The mole tissue is examined under a microscope. If cancer cells are found, more surgery is done to remove any remaining portion of the mole and surrounding tissue.

Prevention

To help prevent benign moles from becoming atypical and possibly cancerous:

• Avoid spending too much time in the sun.
• Protect your skin from the sun. For example, wear a shirt, wide brim hat, and sunglasses.
• Use sunscreen with a sun protection factor (SPF) of at least 30.

To detect atypical or cancerous moles early:

• Monitor your moles, especially atypical ones.
• Report any changes in a mole to your doctor.
• Have your doctor check and monitor atypical moles on a regular basis. Have moles checked more often if you have:
  • A large number of moles
  • A family or personal history of atypical moles or melanoma

Have moles removed if your doctor recommends it.

American Cancer Society http://www.cancer.org

Dermatologists.ca http://www.dermatologists.ca

Common Moles, Dysplastic Nevi, and Risk of Melanoma. National Cancer Institute website. Available at:
http://www.cancer.gov/types/skin/moles-fact-sheet
Updated November 1, 2011. Accessed June 4, 2015.

Sunscreen FAQs. American Academy of Dermatology website. Available at: https://www.aad.org/media-resources/stats-and-facts/prevention-and-care/sunscreens. Accessed June 4, 2015.