Congenital melanocytic nevus (1694)

What is a congenital melanocytic nevus?

Congenital means you are born with it. A melanocytic nevus is lesion or mark. It is not clear what causes the nevus to appear. The nevus:

• Is brown to black in color like a mole. 
• May be flat or feel bumpy like a piece of leather.
• Can be very small, like the size of a pea, but may be very large.
• Can be anywhere on the body.

About 1% of babies are born with small congenital nevi. Giant congenital nevi, which are larger than 8 inches, are much less common. Opinions differ about the risk of these birthmarks turning into skin cancer, called melanoma, later in life. Babies with the giant nevi have a little more risk of developing melanoma.

How is it diagnosed?

The nevi are diagnosed by the way they look. It is also important to know if they were present at birth.

How is it treated?

• Many of the nevi will not need treatment.
• All nevi need to be measured on a regular basis. Nevi need to be watched closely for changes including: 
  – Borders. Any changes in the size, shape, or color around the nevi.
  – Color. Any color change, especially if part of the mole changes color. 
  – Bleeding.

Surgery is recommended if:

• Any changes are noticed.
• It is giant congenital nevi.
• It is a small lesion in the scalp, on the back or bottom, back of thighs, or bottom of feet.