What are moles?

Moles are small bumps or areas of skin color change that can occur on any part of the skin. Most moles are brownish but they can be flesh colored, blue, or black. The color is due to a pigment called melanin in your body's cells. Most people have at least a few moles. The average number of moles present on an adult is 15 to 20.

How do they occur?

Some moles are present at birth. Most appear on the skin during the first 20 years of life, especially during puberty. They are caused by an overproduction of melanin in clumps of skin cells. The cause of this melanin overproduction is not known.

At first moles are flat, but they may become raised. Many grow larger and some develop hairs.

Are moles unhealthy?

Most moles are harmless. Some moles, however, may be considered unsightly because of their appearance or location.

Rarely (about one in a million), a mole undergoes cancerous change to become a malignant melanoma. Malignant melanoma is the least common but most dangerous form of skin cancer. Research suggests that malignant melanoma in adults may be related to sunburn in childhood.

How are they treated?

Because most moles are harmless, they usually need no treatment. Some may be removed for cosmetic reasons. Hairs on moles that are unsightly can be kept trimmed or the hairs can be removed permanently by a dermatologist.

Malignant melanomas are removed surgically. The surgery may be followed with radiation therapy or anticancer drugs.

What changes in moles should I watch for?

You should have your doctor check any change you notice in a mole. In particular, watch for the following:

• A change in size (especially if the mole spreads and becomes broader).

• A change in border (the outline of the mole becomes irregular).

• A change in shape in which one half of the mole does not match the other.

• A change in color or different shades of color appearing in the same mole.

• A change in surface appearance (for example, the mole begins to scale, crust, ooze, or bleed).