Moles (Nevi)

What moles are

Melanocytes normally sit scattered in the bottom layer of the skin, giving it color. In a mole, they grow in clusters. Moles can be flat or raised, smooth or rough, and range from pink and skin-colored to tan, brown or black. Many fade, become paler or raised, or disappear with age.

Why moles develop

• Genetics: the number of moles is strongly inherited.
• Sun exposure in childhood: increases the number of moles.
• Fair skin: more moles, especially in people who burn easily.
• Hormones: moles can darken during pregnancy and puberty.

Types of moles

Moles vs other spots

• Freckles: flat, light brown, appear with sun and fade in winter.
• Seborrheic keratoses: waxy, "stuck-on" brown growths in older adults; harmless.
• Sun spots (solar lentigines): flat, brown, on sun-exposed skin after 40.
• Dermatofibromas: firm bumps that dimple when pinched.

When to worry: the ABCDEs

Use the ABCDE rule to spot possible melanoma:

• A: Asymmetry. One half does not match the other.
• B: Border. Irregular, ragged, notched or blurred edges.
• C: Color. Several shades of brown or black, or areas of red, white or blue.
• D: Diameter. Larger than 6 mm (a pencil eraser), though melanomas can be smaller.
• E: Evolving. Changing in size, shape, color, height, or new symptoms such as bleeding, itching or crusting.

Also look for the ugly duckling sign: a mole that looks different from all your others.

Some melanomas do not follow the ABCDEs, particularly nodular melanoma, which grows quickly as a firm, raised bump that may be pink or red. Remember EFG: Elevated, Firm and Growing for more than a month.

Who is at higher risk of melanoma

• more than 50 moles
• several atypical moles
• a personal or family history of melanoma
• fair skin, light hair and eyes, freckling
• a history of blistering sunburns, especially in childhood
• indoor tanning
• weakened immune system

Checking your skin

• Examine your skin monthly in good light with a full-length and hand mirror.
• Check everywhere: scalp, behind ears, between fingers and toes, soles, nails, genitals and back.
• Take photos of moles to track changes over time.
• Ask a partner to check hard-to-see areas.

In darker skin, melanoma most often occurs on the palms, soles, under nails and in the mouth.

How doctors assess moles

A dermatologist or primary care clinician examines moles with a dermatoscope, a magnifying light that shows patterns under the surface. People at high risk may have total body photography and regular follow-up. Suspicious moles are removed and sent for biopsy.

Mole removal

• Excision biopsy: the whole mole is cut out with a small margin and stitched; preferred when melanoma is suspected.
• Shave removal: the mole is shaved flush with the skin; used for raised benign moles, often for cosmetic reasons.
• Punch biopsy: a small circular sample.

Removed moles should always be examined under a microscope. Do not remove moles at home with creams, freezing kits or cutting; these can leave scars and miss melanoma.

Prevention

• use broad-spectrum SPF 30 or higher sunscreen daily
• wear hats, sunglasses and protective clothing
• avoid peak sun hours (10 a.m. to 4 p.m.) and never use tanning beds
• protect children from sunburn, which shapes lifelong mole count and risk

Frequently asked questions

When should I worry about a mole?

See a doctor if a mole is changing, has an irregular shape or border, multiple colors, is larger than 6 mm, bleeds or itches, or looks different from your other moles. A new mole after age 30 or a fast-growing firm bump should also be checked.

What does a cancerous mole look like?

Melanoma often looks asymmetrical with irregular borders and uneven colors such as brown, black, red, white or blue, and changes over time. Some melanomas are raised, firm, pink or red bumps that grow quickly. Only a biopsy can confirm melanoma.

Is it normal to get new moles as an adult?

New moles are common until about age 30 to 40. A new mole appearing later in life, or one that looks unusual, should be checked by a doctor because a larger share of new spots in older adults are melanomas.

Are atypical moles cancerous?

Most atypical (dysplastic) moles are not cancer and never become melanoma. However, having several atypical moles increases your overall risk of melanoma, so regular skin checks and sun protection are important.

Should I have my moles removed?

Moles only need removal if they look suspicious, are changing, or bother you cosmetically or physically. Removing normal moles does not prevent melanoma, since most melanomas arise as new spots. Any removed mole should be sent for laboratory testing.