Mole, Atypical (Atypical Nevus)

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Atypical moles (atypical nevi) or dysplastic moles (dysplastic nevi), are caused by collections of the color-producing (pigment-producing) cells of the skin (melanocytes) in which the cells grow in an abnormal way. Atypical moles may occur as new lesions or as a change in an existing mole. Lesions may be single or multiple. In atypical-nevus syndrome, hundreds of atypical moles may be seen. People with atypical moles may be at increased risk for developing skin cancer (melanoma), with the risk increasing with the number of atypical moles present.

Who's at risk?

  • Atypical moles may occur at any age and in all ethnic groups.
  • Atypical moles frequently run in families.
  • People with atypical moles may have a family history of melanoma.

Signs and Symptoms

  • Atypical moles may appear anywhere on the skin. The lesions can vary in size and/or color.
  • They can be larger than a pencil eraser (6 mm) and may have variations in color within the lesion ranging from pink to reddish-brown to dark brown.
  • Atypical moles may be darker brown in the center or in the edges (periphery).
  • People with atypical-nevus syndrome may have hundreds of moles of varying sizes and colors.

Self-Care Guidelines

  • Protective measures, such as avoiding skin exposure to sunlight during peak sun hours (10 AM to 3 PM), wearing protective clothing, and applying high-SPF sunscreen, are essential for reducing exposure to harmful ultraviolet (UV) light.
  • Monthly self-examination of the skin is helpful to detect new lesions or changes in existing lesions.
  • Be sure your atypical moles are not signs of skin cancer (melanoma). Remember the ABCDEs of melanoma lesions:
    A - Asymmetry: One half of the lesion does not mirror the other half.
    B - Border: The borders are irregular or vague (indistinct).
    C - Color: More than one color may be noted within the mole.
    D - Diameter: Size greater than 6 mm (roughly the size of a pencil eraser) may be concerning.
    E - Evolving: Notable changes in the lesion over time are suspicious signs for skin cancer.

When to Seek Medical Care

  • The occurrence of a new mole (pigmented nevus) in an adult is unusual; if a new pigmented lesion occurs, see your doctor for evaluation.
  • People with multiple moles and unusual (atypical) moles should be examined by a dermatologist every 4–12 months depending on their past history and family history.
  • It may be difficult to tell an atypical mole from a normal mole, so seek medical evaluation if you are unsure about the nature of a mole or if you note changes within a mole.
  • Your doctor may recommend that you have a biopsy or surgical removal (excision) of unusual-appearing moles to find out whether or not you have atypical moles or melanoma.

Treatments Your Physician May Prescribe

  • Biopsy or surgical removal (excision) may be done so the mole may be examined by a specialist (pathologist) to determine the actual diagnosis.
  • As noted previously, people with multiple moles and atypical moles should be followed regularly by a dermatologist. Whole-body photography or photographs of individual moles may be helpful in following these people.

Trusted Links

MedlinePlus: MolesClinical Information and Differential Diagnosis of Nevus, Atypical


Bolognia, Jean L., ed. Dermatology, pp.17, 1770. New York: Mosby, 2003.