A dysplastic nevus is a benign growth on the skin that has certain clinical and pathological features that appear unusual. Dysplastic nevi are also sometimes called atypical nevi or Clark’s nevi – Dr. Clark was the first to describe them in 1978.
[ Notes: A mole is the same thing as a nevus, a benign (non-cancerous) growth on the skin. The word “nevi” is the plural of the word “nevus”. In describing a nevus, the words “atypical” and “dysplastic” can be used interchangeably: we’ll use “dysplastic” here. ]
A normal adult has 40-50 normal moles on their skin. A dysplastic mole has certain features that may resemble a melanoma but is NOT a melanoma. Most moles will never develop into a problem but moles should be inspected regularly looking for such change. Dysplastic moles can be inherited or sporadic. Studies have shown that the incidence of dysplastic nevi in the population can range from 7-20%. The presence of a dysplastic mole on the skin may be a marker for increased risk of developing melanoma. A dysplastic nevus can vary in appearance and has the ABCDE features of melanoma.
Watch for the early warning signs of melanoma by using the ABCDE criteria:
- Asymmetry (one half does not match the other half)
- Border irregularities (edges are poorly defined, ragged, scalloped and not regular)
- Color variation (different colors within the same mole)
- Diameter greater than 6 millimeters (larger than a pencil eraser)
- Evolving (a new mole developing or growth of an old one)
Dysplastic nevi are tan to dark brown and may have a mixture of colors, including tan, dark brown, and sometimes pink or black. The border is often irregular and indistinct and often fades into the surrounding skin. They may be raised or flat and can vary in size or shape. Heredity appears to play a role in their development. Most commonly, dysplastic moles appear on sun-exposed skin, but can occur elsewhere and continue to develop after age 35. People who have dysplastic nevi and a family history of melanoma (two or more relatives with melanoma) are at increased risk of developing a melanoma during their lifetime. Individuals who have dysplastic nevi and no family history of melanoma still may be at risk of developing a melanoma with the risk being 7 times higher than that of the general population.
Several studies have shown that regular cutaneous examinations combined with baseline and serial color photographs of the patient’s cutaneous surface ultimately decrease biopsies and lead to earlier diagnoses of melanoma.
Because sun exposure and UV light may modify the number, the appearance, and the progression of some cases of dysplastic moles, patients with dysplastic moles should avoid all UV-emitting tanning devices (tanning salons) and excessive sun exposure, and should routinely use a broad-spectrum sunscreen with a sun protective factor of 30 or greater.
Dysplastic Nevi can be surgically removed for a diagnosis or can be diagnosed in the office by a dermatologist with the naked eye or with the aid of a handheld dermatoscope (see photo).
Common moles do not need to be removed. Currently, no therapy is available to prevent the development of atypical moles. Because melanomas may develop de novo on the skin and because the risk of any one atypical mole changing into a melanoma is low, the prophylactic removal of all atypical moles is not recommended, because doing so would not necessarily prevent melanoma. Instead, accepted current treatment suggests removal of changing lesions and any lesion worrisome for melanoma.
Dysplastic nevi can be surgically removed after numbing with a local anesthetic; histological examination of the removed tissue to “rule out” cancer is often done. Some people choose to have them removed for cosmetic reasons, if they are raised and located in areas where clothing irritates, such as the waistline, or if they are on the scalp and are irritated by hair brushing. Most moles can be cut off in a simple in-office procedure. Dysplastic nevi do not need to be removed unless there are signs of changes observed. Moles and dysplastic nevi whose appearance suggests they may be cancerous should be removed and examined under a microscope. If they are found to be cancerous, additional skin in the surrounding area also must be taken to ensure all cancerous cells are removed. It is important for people with numerous dysplastic nevi or Familial Atypical Nevus Syndrome (that is, in a family whose members have lots of dysplastic moles) to have a full body screening from a dermatologist every three to twelve months beginning with the onset of puberty. Screening of relatives and full body photographs may also be recommended. Self exams, looking at one’s own skin monthly, wearing sunscreen and sun protection is also an important part of a person’s care.
If you have dysplastic nevi or if there is a history of melanoma in your family, you should have a dermatologist check all of your moles regularly. Your dermatologist will recommend how often you should have them checked.