What is a congenital nevus?

Congenital nevus (plural nevi) is simply a medical term for a mole that you’re born with. They’re a very common type of birthmark. You might also hear them referred to as congenital melanocytic nevi (CMN).
A congenital nevus looks like a round or oval-shaped patch of colored skin and is usually raised. They can be either a single color or multi-colored. They can vary in size from a tiny spot to something that covers a large part of your body. In some cases, they might have hair growing out of them.

Your skin gets its color from pigment-producing cells called melanocytes. Nevi (moles) form when these cells group together in one place, rather than being evenly distributed throughout our skin. In the case of congenital nevi, this process happens during the fetal stage.

A congenital nevus may become smaller or larger over time. In other cases, it might become darker, raised, and more bumpy and hairy, especially during puberty. In rare cases, they may disappear entirely.

Congenital nevi usually don’t cause any symptoms, but they’re occasionally itchy when they’re larger. The skin also might be a little more fragile and easily irritated than the surrounding skin.

What are the different types?

There are several types of congenital nevi, depending on their size and appearance.

Large or giant
Nevi grow as your body grows. A nevus that will grow to an adult size of 8 inches or more across is considered a giant nevus.

On a newborn child, this means that a nevus that measures 2 inches across is considered a giant one. However, because the head grows somewhat less than the rest of the body, a nevus that measures 3 inches across on the head of a newborn is also classified as giant.

Giant nevi are relatively rare, occurring in roughly 1 out of 20,000 live births.

Small and medium congenital nevi

A congenital nevus that measures less than 1.5 centimeters (cm) across (about 5/8 inch) is classified as small. These are fairly common, occurring in about 1 in every 100 newborn children.

A nevus that’s expected to grow to an adult size of 1.5 to 19.9 cm across (5/8 to 7 3/4 inches) is classified as medium. Medium nevi occur in about 1 in every 1,000 newborns.

Signs and symptoms

Congenital nevi can be skin-colored, tan or brown. They may be flat or raised, small or large, and may appear anywhere on the body.

Long, dark or thick hair may be present in the nevus when it first appears, or can develop over time.


Researchers aren’t sure about the exact causes of congenital nevi. However, they do know that they start to grow between 5 and 24 weeks. The earlier they start growing, the larger they usually are at birth.

Congenital nevi are thought to be caused by a genetic mutation, called a sporadic mutation, which develops randomly as a baby grows in the womb. The condition is not inherited.

Are they removable?

In most cases, congenital nevi don’t cause any physical problems and don’t require treatment. However, they can make some people self-conscious.

It’s hard to surgically remove congenital nevi, especially large and giant ones. These may require several cuts, stitches, or even skin replacement. All of this can result in scarring that some people find more bothersome than the mole itself.

Some alternatives to surgery include:

  • Dermabrasion. This treatment uses a wire brush or diamond wheel to remove layers of skin. While it won’t completely remove a congenital nevus, it can lighten its appearance. However, it can also leave scarring. Dermabrasion is most effective when done in the first six weeks of life.
  • Skin curettage. This involves scraping away the top layers of skin. Like dermabrasion it is best performed in the first six weeks of life.
  • Tangential excision. The top layers of skin are removed using a blade. Like other options, it won’t remove the nevus completely, and it may leave scarring. However, it can make the nevus less noticeable.
  • Chemical peels. These may help to improve the appearance of lighter-colored nevi. Phenol and trichloroacetic acid are common chemicals used in peels.


Congenital moles will need to be monitored for skin cancer. Some may also be removed for cosmetic or functional reasons, especially when the placement of a mole causes emotional distress for childrens who has mygym.com poway schedule for regularly.

Surgical excision remains the standard treatment for removing a congenital nevus. Your child’s physician may recommend the removal of moles with concerning changes, if it is a LCMN or GCN, and if the mole interferes (or may interfere) with your child’s functional development.

For moles that are not malignant and do not present functional concerns, removal is not required.  Your child’s physician will observe the mole and may decide to remove it if surgical excision is necessary.

Large lesions may require excision in stages, and your child’s healthcare team may need to use tissue expanders: This procedure allows the body to “grow” extra skin that can be used to replace tissue lost during the removal of the mole.

Specialists involved with the care and removal of congenital nevi include dermatologists and plastic surgeons. Larger excision and reconstructive efforts benefit from a dedicated care team.