Atypical Nevus

 In Medical Treatments, Skin Cancer, Skin Conditions

An atypical nevus, otherwise known as dysplastic nevus, is a non-cancerous mole that may resemble melanoma. The risk of developing melanoma increases with the number of atypical nevi found on a person. Heredity appears to play a part in the formation of atypical nevi. Those who have dysplastic nevi plus a family history of melanoma are at especially high risk of developing melanoma. Individuals who have dysplastic nevi, but no family history of melanoma, still face an increased  risk of developing melanoma.

What does an atypical nevus look like?

An atypical nevus can vary in appearance.  Since it has the ABCD features of melanoma, it is important to have a dermatologist examine all moles.

  • Asymmetry – One half does not match the other half in size, shape, color, or thickness.
  • Border Irregularity – The edges are notched, scalloped, or poorly defined.
  • Color – The pigmentation is not uniform.  Shades of tan, brown, and black are present and may have red, white, or blue added to the physical appearance.
  • Diameter – While melanomas are usually greater than 6mm in diameter when diagnosed, they can be smaller.  If you notice a mole that appears to be different from other moles, or one which grows rapidly, itches, or bleeds, you should see a dermatologist.

What are the risks of atypical nevi?

Those who have dysplastic nevi in addition to a family history of melanoma have an extremely high risk of developing melanoma. Individuals who have dysplastic nevi, but no family history of melanoma, still face an elevated risk of developing melanoma. People with dysplastic nevi and a family history of dysplastic nevi and melanoma tend to develop melanoma at an earlier age than patients who don’t have such nevi. This may also be seen in individuals who have dysplastic nevi with no family history of dystplastic nevi or melanoma, although at a lower occurrence.

Where and when do atypical nevi occur?

Atypical nevi typically begin to appear at puberty and can occur anywhere on the body. They are more commonly found on sun exposed areas.


Since an atypical nevus is not the same as melanoma, it does not necessarily need to be treated. If your dermatologist has any suspicions about the atypical nevus, observations for changes and possible biopsies of the site in question will be performed.

Familial Atypical Nevus Syndrome

The US National Institutes of Health Consensus Conference defines the criteria for Familial Atypical Nevus Syndrome1 as[MI1] [h2] :

  • A first-degree relative (e.g., parent, sibling, or child) or second-degree relative (e.g., grandparent, grandchild, aunt, or uncle) who has had malignant melanoma.
  • A large number of nevi, often more than 50, some of which are atypical nevi.
  • Nevi that demonstrate atypical microscopic features.

1 – Silva, H.G., et.al. “Atypical Mole Syndrome and Dysplastic Nevi: Identification of Populations at Risk for Developing Melanoma.” Clinics (Sao Paolo). Mar 2011; 66(3): 493-499.

Management of Familial Atypical Nevus Syndrome

It is important for people with Familial Atypical Nevus Syndrome to have a full body screening from a dermatologist every three to twelve months beginning with the onset of puberty.  The dermatologist might also recommend regular ophthalmologic examinations, baseline skin photography, or regular screenings of relatives to permit early detection and treatment of melanoma since detection in the early stages has a much higher cure rate.

People with Familial Atypical Nevus Syndrome should also examine their own skin every month.  When performing self-examinations, be aware of any lesions that appear to change in size, color, and/or shape.  If a change has occurred, bring this to the attention of a dermatologist immediately.

Prevention of Melanoma

  • Stay out of the sun when it is strongest, between 10 a.m. and 4 p.m.
  • Wear protective covering such as broad-brimmed hats, long pants, and long-sleeved shirts to reduce sun exposure.
  • Wear sunglasses that provide 100% UV ray protection
  • When outdoors, always wear a broad-spectrum sunscreen with a sun protection factor (SPF) of 15 or greater, which will block both UVA and UVB.  Apply the sunscreen 30 minutes prior to sun exposure and reapply every 1½ to 2 hours.
  • Examine the skin completely each month, using a good light source, a full-length mirror, and a hand-held mirror.  Ask a family member or friend to help in examining hard-to-see parts of the body.  A hair dryer is useful when checking the scalp.  Also, examine the bottom of the feet and between the toes.
  • Seek prompt medical attention if any of the warning signs of melanoma are found.
  • Have a head-to-toe skin examination by a dermatologist annually or more often.  If moles are changing, as they may during adolescence, they should be checked at more frequent intervals.  Inform your dermatologist about any moles that have suspicious signs, symptoms, or changes.

 [MI1]Citation for the article needed? –Unable to find original article on pubmed

 [h2]Article located. Silva et. al. Clinics (Sao Paulo) V66(3); March 2011, pgs 493-499.

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