Congenital Melanocytic Nevus

What is a congenital melanocytic nevus (birthmark mole)?

A congenital melanocytic nevus (birthmark mole) is a brown, flat or bumpy spot, sometimes with increased hair growth, on any part of the body. It is a cluster of numerous melanocytes (cells that produce the color of the skin). It may be present at birth, or it becomes apparent shortly after the birth. Up to 3 out of 100 newborns will have it. The child can have one or more such spots. The size varies from very small to giant. When it is giant in size, it can involve large parts of the body. Technically, giant moles are considered those larger than 20 centimeters (about 8 inches).

What is the cause of my baby’s congenital melanocytic nevus (birthmark mole)?

The cause is unknown.

Should I take my baby to a health care provider?

It is always wise to see your baby’s health care provider for an initial exam and for a correct diagnosis. Sometimes congenital melanocytic nevus can turn into malignant melanoma, which is sometimes deadly skin tumor. The chance of developing melanoma increases with increase in the size of congenital melanocytic nevus. The risk is the highest in those whose mole will be over 40 centimeters (about 16 inches) in diameter by the adulthood. You should report to your health care provider any change in the appearance, as well as any development of deeper bumps under the congenital melanocytic nevus. Any baby with a giant mole or those with numerous moles, especially over the spine should be checked for neurocutaneous melanosis, which is increased growth and clustering of melanocytes (cells that produce the color of the skin) both in the skin and central nervous system (brain and its envelope). In the majority of cases, neurocutaneous melanosis may not produce any problems, but sometimes it can cause a blockage of cerebrospinal fluid circulation in the brain, causing brain cysts, increased size of the head (hydrocephalus), seizures and paralysis.

Is congenital melanocytic nevus (birthmark mole) painful to my child?

Congenital melanocytic nevus is not painful.

My baby has congenital melanocytic nevus (birthmark mole), so what is the treatment?

In the majority of cases no treatment is needed, except for watching for any change in the appearance and symptoms. It is important to mention that the mole sometimes may continue to look the same; however, the change can happen under the skin. Therefore, you also have to feel it/touch it to notice any bump under the skin. You should report any change in the mole to your health care provider. Larger moles that have a higher chance of turning into the cancer, and those that are cosmetically bothersome should be considered for surgical excision even without any changes in the appearance or symptoms.

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