Congenital Melanocytic Nevi (CMN)

What Is Congenital Melanocytic Nevi (CMN)?

Moles present from birth, or that develop within the first few months after birth, are called congenital melanocytic nevi (CMN).

They are fairly common and, in most cases, they do not cause health problems. However, they can carry risks. Most cases of CMN never require treatment, but there are some cases in which the moles may be removed. This is usually done to lower the risk of skin cancer or to improve appearance.

You and your child’s doctor can learn how to monitor the moles and follow up with a dermatologist if there are any concerns. There are also many strategies for coping with CMN so that families and children can learn to accept these lesions as a unique part of who they are.

What Causes CMN?

Congenital melanocytic nevi are caused by a change in color (pigment) cells of the skin. The moles happen by chance. CMN is not passed down from the parents. There is no way to prevent your child from being born with moles.

In very rare cases, CMN can indicate a condition called neurocutaneous melanosis. Neurocutaneous melanosis can occur when the CMN are large and found on the back. In this case, the moles can affect the spine and brain, and may cause seizures. This type of CMN is also usually just due to chance and is not passed down from the parents.

What Are the Symptoms of CMN? How Is It Diagnosed?

Symptoms of CMN include the presence of moles on the skin from birth or that appear in the first few months of life. These birthmarks range in color from light brown to black. They may darken, get thicker or grow hair as your child ages. They are usually painless.

Diagnosis of CMN involves a physical exam. The health care provider will also ask about your child or family’s medical history. If the moles are very large, located in areas that may indicate other concerns, or as part of the work-up for neurocutaneous melanosis, an imaging test called an MRI may be done. This can help the health care team find out if the mole impacts your child’s health, rather than just his or her appearance.

When Does CMN Need Treatment?

Signs that CMN may need treatment include:

  • Pain, itchiness or burning of the mole
  • Red or irritated skin around the mole
  • Blood or pus coming from the mole
  • A change in color to black, blue or red
  • Rapid growth in size of the mole
  • Irregular or uneven borders around the mole
  • A significant change in texture of giant CMN

Very large CMN are more likely to turn into skin cancer. Children with so-called “giant” CMN may need treatment sooner than others to reduce the risk of skin cancer in the areas affected by the CMN.

Moles that are highly visible, such as those on the face, neck or hands, may also be treated if children are significantly bothered by them.

Finally, cases of neurocutaneous melanosis usually require treatment to avoid health problems affecting the brain and spine.

How Is CMN Treated?

For most cases of CMN, watching and working to prevent skin cancer is the only treatment needed. This involves regular skin checks from a parent and physician. It also means taking steps to avoid skin damage. These include:

  • Use broad-spectrum (UVA/UVB), water-resistant sunblock during outside time. This means SPF 30 or higher whenever your child is outdoors between 10 a.m. and 4 p.m.
  • Reapply sunblock every 2 hours and after swimming or sweating.
  • Wear protective clothing, sunglasses and hats to avoid sun exposure and sun burns. When possible, stay in the shade.
  • Do not let your child use tanning beds.
  • Call the doctor if you notice any changes in your child’s moles.

When a mole is considered high risk for cancer — and in some cases when the mole causes significant emotional distress — it can be removed surgically. This helps lower the risk of cancer and can improve appearance. Large or giant CMN often require multiple stages of surgery to remove as much of the affected skin as possible. These are usually done through a process called tissue expansion.

CMN can also be lightened with laser therapy or chemical peels. However, these treatments may not be permanent. Furthermore, lightened moles may also be harder to track for skin cancer risk. The only true “cure” for skin cancer risk of CMN is to remove the mole.

Undergoing Tissue Expansion: Chloe's Story

Our cameras follow Chloe into the operating room as she undergoes her fourth round of tissue expansion to remove a a mole she's had since birth-- containing abnormal cells. At Nationwide Children's Hospital, we have a team of experts to help kids like Chloe not only from a physical standpoint, but from an emotional standpoint as well.

Learn More About Tissue Expansion

Coping with CMN

Many children with CMN are not bothered by the appearance of their skin. For some children, however — especially in cases where there are many or large moles, or when they are highly visible — the condition can cause embarrassment or lead to poor self-image and self-esteem. Some children may also be teased or feel that their appearance causes others to stare or treat them differently.

It is important for families to know that CMN is not caused by anything they did wrong. It does not result from anything the mother did or didn’t do during pregnancy. CMN is also not caused by a skin injury during birth. There is nothing that parents can do to avoid CMN in their children.

How Can I Help My Child Cope with CMN?

The best way to help your child cope with moles is to help your child learn to accept CMN as a normal part of them that is nothing to be ashamed of. By expressing acceptance and love of the child, including their birthmarks, you can model attitudes that teach your child that they are more than their CMN. Speak openly and simply about it when you talk with your child.

Tips to help your child cope with birthmarks include:

  • Teach them to smile and look people in the eye when others stare. This helps show confidence and also shifts the focus of whoever is staring.
  • When people ask about the birthmark, teach them to respond and then shift the conversation to another topic.
    • “I’ve had this since I was born. It doesn’t hurt or keep me from having fun.”
    • “This is just a birthmark. I was born with it.”
    • “This part of me is just different, the same way people have different eyes and ears and noses.”
    • After this brief information, you child can then ask something such as “What games do you like to play?” or “What are your favorite books?”, etc.
  • Respond simply and confidently when questions are addressed to you as well. Children learn how to cope with staring and remarks by watching their parents do it.
  • If someone becomes rude or intrusive, change the conversation by saying “Let’s talk about something else” or “There are lots of other things that are interesting about me/my child…” and then give an example to change the subject. If need be, end the conversation directly, ignore further questions about the birthmark or walk away.

If you, your child or others in your family have difficulty coping with the emotional consequences of CMN, reach out to a health care provider. Psychologists, counselors and social workers can provide you with resources — including birthmark support groups or other organizations — to help you cope.