A mole (nevus) is a pigmented (colored) spot on the outer layer of the skin (epidermis)and can be round, oval, flat, or raised. Moles can occur singly orin clusters on any part of the body. Most moles are brown, but colors can range from pinkish flesh tones to yellow, dark blue, or black.

Everyone has at least a few moles. They generally appear by the time a personis 20 and look, at first, like freckles. A mole's color and shape don't usually change. Changes in hormone levels that occur during puberty and pregnancycan make moles larger and darker. New moles may also appear during this period.

A mole usually lasts about 50 years before beginning to fade. Some moles disappear completely, and some never lighten at all. Some moles develop stalks that raise them above the skin's surface; these moles eventually drop off.

About 1-3% of all babies have one or more moles when they are born. Moles that are present at birth are called congenital nevi.

Other types of moles include:

  • Junctional moles, which are usually brown and may be flat or slightly raised.
  • Compound moles, which are slightly raised, range in color from tan to dark brown, and involve pigment-producing cells (melanocytes) in both the upper and lower layers of the skin (epidermis and dermis).
  • Dermal moles, which range from flesh-color to brown, are elevated, most common on the upper body, and may contain hairs.
  • Sebaceous moles, which are produced by over-active oil glands and are yellow and rough-textured.
  • Blue moles, which are slightly raised, colored by pigment deep within the skin, and most common on the head, neck, and arms of women.

Most moles are benign, but atypical moles (dysplastic nevi) may develop intomalignant melanoma, a potentially fatal form of skin cancer. Most atypical moles are bigger than a pencil eraser, and the shape and pigmentation are irregular. They are more apt to become cancerous than moles that develop after birth, especially if they are more than eight inches in diameter. Lentigomaligna (melanotic freckle of Hutchinson), most common on the face and afterthe age of 50, first appears as a flat spot containing two or more shades oftan. It gradually becomes larger and darker. One in three of these moles develop into a form of skin cancer known as lentigo maligna melanoma.

The cause of moles is unknown, although atypical moles are hereditary and mayalso result from exposure to sunlight. Only a small percentage of moles require medical attention. A mole that has the following symptoms should be evaluated by a dermatologist (a physician spealizing in skin diseases).

  • Appears after the age of 20
  • Bleeds
  • Itches
  • Looks unusual or changes in any way.

A doctor who suspects skin cancer will remove all or part of the mole for microscopic examination. This procedure, which is usually performed in a doctor's office, is simple, relatively painless, and takes little more than a few minutes. It does leave a scar.

If laboratory analysis confirms that a mole is cancerous, the dermatologist will remove the rest of the mole. However, moles are rarely cancerous and, once removed, unlikely to recur. A dermatologist should be consulted if a mole reappears after being removed.

Wearing a sunscreen and limiting sun exposure may prevent some moles. Anyonewho has moles should examine them every month and see a dermatologist if theychange in size, shape, color, or texture or if new moles appear. Anyone witha family history of melanoma should also see a dermatologist for an annual skin examination. Everyone, especially people who spend large amounts of timewith their skin directly exposed to the sun's rays, should know the ABCDs ofmelanoma:

  • A: Asymmetry, which occurs when the two halves of the mole are not identical
  • B: Borders that are irregular or indistinct
  • C: Color that varies in a single mole
  • D: Diameter, which should beno larger than the eraser on a pencil.

A mole exhibiting any of these characteristics should be evaluated by a dermatologist.

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