Moles are a common type of skin growth. 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 40 moles, some of which may change in appearance or fade away over time.
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.
The typical mole is a brown spot. But moles come in different 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. Most moles are oval or 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 (congenital nevi) 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 40 moles. Many of these develop by age 50. Moles may change in appearance or fade away over time. Hormonal changes of adolescence and pregnancy may cause moles to become darker and larger.
Unusual moles that may indicate melanoma
This ABCDE guide can help you determine if a mole or a spot may indicate melanoma or other skin cancers:
- 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 a mole 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. Moles may also evolve to develop new signs and symptoms, such as itchiness or bleeding.
Cancerous (malignant) moles vary greatly in appearance. Some may show all of the features listed above. Others may have only one or two.