Bruce P.Robinson, MD

Atypical Nevus | Dysplastic Nevus

An atypical nevus or dysplastic nevus (mole) is a benign growth that may share some of the features of a melanoma, but is NOT a melanoma or any other form of cancer. The presence of an atypical nevus, however, may increase the risk of developing a melanoma, or be a marker for it. A single atypical nevus may indicate a small risk; this risk increases with the number of atypical nevi present.

What does an atypical nevus look like?

An atypical nevus can vary in appearance. Since it has the ABCDE features of a melanoma, it is important ot 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 ragged, scalloped, or poorly defined.

Color - The pigmentation is not uniform. Shades of tan, brown, and black are present. Dashes of red, white, and blue add to the mottled appearance.

Diameter - While melanomas are usually greater than 6mm in diameter (the size of a pencil eraser) when diagnosed, they can be smaller. If you notice a mole different from others, or one which changes, itches, or bleeds (even if it is small), you sould see a dermatologist.

What are the risks of atypical nevi?

The lifetime risk of a person in the United States developing melanoma is 1 in 75. A patient with one to four atypical nevi without a personal or family history of melanoma is at a slightly higher risk than the general population. The risk of developing melanoma is higher if a patient with atypical nevi has a personal or family history of melanoma. A patient who has multiple atypical and normal nevi (moles) may have Familial Atypical Nevus Syndrome, and is at an increased risk for developing a melanoma, especially if a relative had melanoma.
Where and when do atypical nevi occur?

Atypical nevi begin to appear at puberty and can occur anywhere on the body, but are more common in sun-exposed areas, the back, and the legs.


Since an atypical nevus is not the same as a melanoma, it does not need to be treated aggressively but should be observed for changes, biopsied, or conservatively excised.

Familial Atypical Nevus Syndrome

The National Institute of Health Consensus Conference defines the Familial Atypical Nevus Syndrome as those persons meeting the following criteria:

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

Management of Familial Atypical Nevus Syndroms

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. Information on the early signs of melanoma is available from the dermatologist or the American Academy of Dermatology.
Prevention of Melanoma

  • Apply a broad-spectrum sunscreen which protects against ultraviolet light (UVA and UVB) and has an SPF of 15 or higher daily.
  • Reapply every 2 hours during prolonged sun exposure
  • Seek shade whenever possible, especially during peak sun hours between 10 a.m. and 4 p.m.
  • Never use a tanning bed, booth, or artificial tanning devices
  • Wear a wide-brimmed hat, sunglasses, and other protective clothing like long-sleeved shirts and pants when outdoors
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