Nearly everyone has one or more moles on their skin, known as nevi.  Moles can have a wide range in appearance, and not all brown spots are moles.

Moles on the face or body may be regarded as beauty marks, and most of the time they are benign (non-cancerous), but all moles have the potential to develop into malignant tumors.

Typical moles

Moles can develop anywhere on the skin or mucous membranes, including the conjunctiva (whites) of the eyes.  They are usually light to dark-brown in color, but can also be pink or flesh-colored.  Pigment in the mole is caused by specialized cells
Moles can appear anywhere on the skin. They are usually brown in color but can be skin colored and various sizes and shapes. The brown color (melanin) is caused by melanocytes, special pigment-producing cells.

The pattern of moles is determined partly by an individual`s genetic makeup and in part by sun exposure.  Most typical moles appear before the age of 30.  Moles tend to change (become larger, darker), during periods of hormonal change, including the teen years and during pregnancy.

Moles often start off as flat areas of discoloration.  Over time, they frequently become raised and may develop hairs.  Mole may darken or lighten in color.  Some may eventually develop a stalk and develop the appearance of a skin tag.

Congenital nevi

Moles that are present at birth or shortly after birth are common and are called congenital nevi.  People with giant congenital nevi (>20 cm diameter) have a lifetime risk of approximately 7% for the development of melanoma.

Dysplastic nevi

Certain kinds of moles that have atypical features are called dysplastic nevi.  Though they technically are benign, they do have a higher risk of developing into malignant melanoma.  Individuals with dysplastic nevi (the more dysplastic nevi, the greater the risk) and numerous normal moles (greater than 100) are at greater risk for the development of melanoma.

Dysplastic nevi (and melanoma) have one or more of the following features and can be remembered by the following mnemonic (ABCDE):


  • Asymmetry (both in color and in shape)
  • Border irregularity (scalloped, uneven borders)
  • Color variation (more than one color, e.g. light and dark-brown tones)
  • Diameter (>6 mm)
  • Evolution (changes in the mole over time)



ASYMMETRY in shape and color

BORDER irregularity: ragged, scalloped or blurred borders

COLOR variation: when the color of the mole is not uniform in color but has multiple shades of brown, black, red, white and/or blue.

DIAMETER greater than 6 mm (this criterion is less important)



EVOLUTION: any changes in the ABCDs over time

Individuals should check their moles on a monthly basis for changes over time.  Recognizing the warning signs of malignant melanoma is important, since the earlier a melanoma is treated, the better the prognosis.  If a particular mole displays one or more of these signs or changes over time, you should consult a dermatologist for evaluation.

Treatment of moles

Because moles are benign and pose no threat to a person`s health, no treatment is required.  Any mole, however, that changes in the ABCDs, or behaves in an unusual fashion, for example, a mole that itches, bleeds or causes pain, should be examined by a dermatologist.  If the dermatologist is concerned, he or she may sample the mole with a simple biopsy procedure, for microscopic evaluation.