This page was reviewed under our medical and editorial policy by
Frederick L. Durden Jr., MD, Plastic and Reconstructive Surgeon & Microsurgical Reconstructive Surgeon.
This page was updated on October 19, 2022.
Dysplastic nevi are abnormal but noncancerous moles on the skin. They may be referred to as atypical moles or Clark’s nevias well. (If there’s only one mole, it’s called a nevus.) Like other moles, they are surface growths that may change your skin’s color, typically to a darker one. About one in 10 people in the United States have at least one dysplastic nevus, according to the National Cancer Institute (NCI).
Common moles tend to cover most adults with about 10 to 40 small, rounded, brown or black spots or growths in areas that get sun exposure. By the time you’re 40, you’re not likely to develop many new ones. Keeping an eye out for any changes to your moles may be a critical way to prevent skin cancer. However, every mole is unique, and some look more abnormal than others.
Dysplastic nevi are worth monitoring because they have some characteristics of a normal mole, but they also have some characteristics of melanoma skin cancer, including their size, shape and color. It’s rare for dysplastic nevi to turn into melanoma, though, and melanoma may develop without dysplastic nevi ever being present.
Although most dysplastic nevi don’t turn into melanoma, having one does increase the risk of developing melanoma cancer in your lifetime.
The more dysplastic nevi you have, the higher the risk for melanoma. If you have five or more dysplastic nevi, you have a 10 times greater risk of developing melanoma in your lifetime, as compared with someone with no dysplastic nevi, according to the NCI.
If melanoma does develop, it typically begins in a new spot on the skin and not from the dysplastic nevus itself. So even though there is a connection, having a dysplastic nevus doesn’t mean it’s likely to turn into melanoma. In fact, only about 25 percent of melanoma cases start from dysplastic nevi—most melanoma appear on their own, according to a 2020 review in StatPearls Publishing.
Melanoma cancer may develop in the eyes as well as on the skin. If you have dysplastic nevus syndrome, which involves having high numbers of dysplastic nevi, you’re at higher risk of developing primary intraocular melanoma.
Dysplastic nevi stand out from normal moles in a few ways. They tend to appear on skin exposed to sun regularly, but they sometimes show up on the scalp, breasts or buttocks as well.
These atypical moles tend to be:
Dysplastic nevi that are severe may look extremely similar to early melanoma.
Dysplastic nevi are linked to a combination of environmental elements and genetics, but researchers are still studying exactly what causes them. Exposure to ultraviolet (UV) rays from the sun definitely plays a part.
You’re more likely to develop dysplastic nevi if you have:
People with very high numbers of dysplastic nevi may have dysplastic nevus syndrome to blame. This inherited condition is also called atypical mole syndrome. Since dysplastic nevi often run in families, there is a genetic component to these moles.
If a close relative has had melanoma, this syndrome is referred to as familial atypical multiple mole melanoma syndrome (FAMMM), and it signals a significant lifetime risk of developing melanoma. Regular skin checks, both self-checks and those done by health-care professionals, are key to preventing complications from melanoma.
Your doctor may be able to diagnose a dysplastic nevus with a physical exam alone. However, if the mole looks suspiciously like melanoma, as some dysplastic nevi do, your doctor may perform a biopsy to check a tissue sample for melanoma. If the initial biopsy doesn’t show melanoma, your care team likely won’t need to remove any more of the mole.
A diagnosis of dysplastic nevi is typically made if there are at least three of the following factors:
Treatment for dysplastic nevi that aren’t suspected melanoma is minimal, if any. If you have a dysplastic nevus, the majority of work may fall to you to prevent any further skin conditions.
If you have dysplastic nevi, you should:
Most people don’t need dysplastic nevi removed because these aren’t cancerous. However, that doesn’t mean you should forget about them. Keep an eye out by doing regular skin checks on yourself.
Tell your doctor if the mole: