Moles are a common type of growth on the skin. They often appear as small, dark brown spots and are caused by clusters of pigmented cells. Moles generally appear during childhood and adolescence. Most people have 10 to 45 moles, almost all of which appear before age 40. Some moles may fade or disappear as you age.
Most moles are harmless. Rarely, they become cancerous. Monitoring moles and other pigmented patches is an important step in detecting skin cancer, especially malignant melanoma.
The medical term for moles is nevi.
Moles are caused when cells in the skin, called melanocytes, grow in clusters or clumps. Melanocytes are distributed throughout your skin and produce melanin, the natural pigment that gives your skin its color.
The typical mole is a brown spot. But moles come in a wide variety of colors, shapes and sizes:
- Color and texture. Moles can be brown, tan, black, red, blue or pink. They can be smooth, wrinkled, flat or raised. They may have hair growing from them.
- Shape. They can vary in shape from oval to round.
- Size. Moles are usually less than 1/4 inch (about 6 millimeters) in diameter — the size of a pencil eraser. Rarely, moles present at birth can be much bigger, covering wide areas of the face, torso or a limb.
Moles can develop anywhere on your body, including your scalp, armpits, under your nails, and between your fingers and toes. Most people have 10 to 45 moles. Most of these develop by age 40. Moles may change in appearance over time — some may even disappear with age. Hormonal changes of adolescence and pregnancy may cause moles to become darker, larger and more numerous.
Unusual moles that may indicate melanoma
This ABCDE guide can help you determine if a mole or a spot may be melanoma:
- A is for asymmetrical shape. One half is unlike the other half.
- B is for border. Look for moles with irregular, notched or scalloped borders.
- C is for color. Look for growths that have changed color, have many colors or have uneven color.
- D is for diameter. Look for new growth in amole larger than 1/4 inch (about 6 millimeters).
- E is for evolving. Watch for moles that change in size, shape, color or height, especially if part or all of a mole turns black.
Cancerous (malignant) moles vary greatly in appearance. Some may show all of the features listed above. Others may have only one or two.
When to see a doctor
See your doctor if you have a mole that:
- Is painful
- Itches or burns
- Oozes or bleeds
- Shows any of the ABCDE characteristics listed above
- Grows back after having been removed before
- Is new and you’re over 30 years old
- If you’re concerned about any mole, see your doctor or ask for a referral to a doctor who specializes in skin conditions (dermatologist).