Moles (Nevi)

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Your doctor has determined that you have one or more moles, or nevi, which are very common skin growths that are usually harmless. Although certain types of moles may occasionally develop into skin cancer, the vast majority are not cancerous. Most adults have between 10 and 40 moles, and some have many more. Nearly all moles arise during the first two decades of life, although additional moles may appear between the ages of 20 and 40.

About the Condition

The skin is the largest organ of the body. Its top layer is the epidermis, which contains three types of cells that can become cancerous: melanocytes, basal cells and squamous cells. The main purpose of the epidermis is to provide protection against the environment. The second layer of the skin is the dermis, which supplies blood, oxygen, strength and support. Underneath the dermis is the hypodermis, or subcutaneous fat layer, which provides an ongoing blood supply to the dermis.

Moles occur when melanocytes  cells that produce melanin pigment, which gives the skin its color grow in a cluster along with surrounding tissue, forming a flat or raised, pigmented spot on the epidermis. They can develop anywhere on the body, either singly or in a group. Most moles are acquired, which means they develop after birth. In rare cases, moles are present at birth. They are called congenital nevi.

The appearance of moles may vary, but they are normally round or oval and no bigger than a pencil eraser. The coloring is usually brown, tan, pink or flesh-toned, but can be blue or black. Moles often darken and enlarge from sun exposure and the hormonal changes that occur during puberty, pregnancy and birth control pill use. These factors may also contribute to the development of new moles.

Moles usually fade or disappear over time, and have an average life cycle of 50 years. Some moles will completely disappear or drop off, while others may never lighten or change at all.

People who have many moles are considered to be at greater risk for developing melanoma, the least common but most aggressive form of skin cancer. Congenital nevi are also more apt to become cancerous than moles acquired after birth, especially if they are very large. In addition, those with certain types of moles called dysplastic nevi have an increased melanoma risk.

Dysplastic nevi are larger than regular moles, irregularly shaped and unevenly colored. They tend to run in families and are more likely to become cancerous than ordinary moles. Not everyone with dysplastic nevi gets melanoma, however. In fact, most moles never become cancerous.

Treatment Options

Moles can be left untreated if they are not causing any problems and cancer is not present. They may be camouflaged with makeup to make them less noticeable, if desired. If a hair grows out of a mole, it can be trimmed back close to the skin surface with scissors or a razor, or permanently removed with electrolysis.

In cases where a mole is suspicious for cancer, gets in the way of shaving, is cosmetically undesirable to the patient or becomes irritated by clothing or other sources of contact, it can be removed by a doctor.

The usual removal method for moles is to cut or shave them off with a scalpel. Stitches may be needed afterward, especially for larger moles. Serial excision may be required to treat very large moles. During this procedure, a mole is cut away a little at a time until the entire growth is removed. After serial excision, a skin graft will likely be needed.

What You Can Do

Occasionally moles come back after they are removed. If they do return, or if you develop any new moles or changes in existing moles such as bleeding, itching or a variation in appearance, be sure to promptly report them to your doctor.

To maximize your health and minimize your risk of ever developing skin cancer, you should strive to prevent skin damage from ultraviolet (UV) ray exposure. General steps you can take include:

•  Avoiding the sun, especially between 10 a.m. and 4 p.m. when UV rays are the strongest
•  Using SPF 15 or higher sunscreen that contains avobenzone (Parsol 1789), titanium dioxide and/or zinc oxide, applying it 20 minutes before going outdoors and again every two hours, or immediately after swimming or sweating
•  Wearing a wide-brimmed hat and 100% UV-blocking sunglasses when outdoors
•  Avoiding tanning salons and other UV tanning devices
•  Visiting your doctor regularly for skin checks and promptly reporting any changes in your skin

Additional Resources

American Academy of Dermatology, 888.462.3376, http://www.aad.org/
American Cancer Society, 800.227.2345, http://www.cancer.org/
Skin Cancer Foundation, 800.754.6490, http://www.skincancer.org/

This patient resource sheet is provided to you as a service of CBLPath® and is intended for information purposes only. It may not fully describe all aspects of your diagnosis and is not meant to serve as medical advice or a substitute for professional medical care. Your physician can provide you with a thorough explanation of your diagnosis and appropriate treatment options, which may vary. Only you and your physician can determine your best treatment plan.

Updated 10.07