What are moles?

Moles are the familiar and normal tumors on the skin of most persons. They come at any age, usually starting in the second year of life.  Occasionally in adult life they come in large numbers.  It is thought that they tend to disappear spontaneously after a period of many years.

Moles consist of nevus cells, a cell thought to be related to both the nervous system and to the pigment forming cells of the body.  This latter relationship explains why a mole can become a melanoma, a deadly form of skin cancer.  However, many melanomas arise without any relationship to moles.

The mole is strictly a benign tumor of the skin.   The nevus cells are bunched together under the skin surface and can be flat or raised.  The color of moles varies from skin color to light yellow, to shades of brown or even blue-black.  They may be smooth or rough, and may be surrounded by redness or even absence of pigment.

Do moles need to be treated?

Generally moles may be left untreated. Unsightly moles may be removed.  It is wise to request a microscopic examination of each mole that is removed since studies have shown that most physicians are unable to distinguish a benign mole from a melanoma.

A mole may be dangerous if it changes in color, size, surface characteristics, shape, or becomes itchy, painful, or bleeds. If new moles develop close to an old one and particularly if there is swelling of the nearby lymph nodes, the mole may be dangerous.  Moles should be removed if the person continually strikes or injures them.  Moles present at birth or forming in early childhood have a significant risk of developing a melanoma and these should be removed. 

Some people have many irregular moles which when biopsied show various gradations of atypia.  This is called the dysplastic nevus syndrome.  These patients are at increased risk of developing melanoma in one of these atypical moles.  Monthly skin checks should be performed and any changes should be brought to the attention of a dermatologist.

There are many types of nevus cell tumors.  One of these is the giant hairy nevus or bathing trunk nevus, a brown tumor that covers a large area of the body.  These are usually present at birth. They demand prompt medical attention due to the increased risk of melanoma.

About 10% of people have nevi on the bottom of the feet and half that number have them on the palms.  These are not more commonly melanoma than on other areas.  They should be evaluated by a dermatologist and removed if they appear to be atypical.

Closely related to moles are freckles and age spots.  While these lesions look similar, they are different microscopically.  A dermatologist should be consulted in questionable cases.