A congenital nevus (NEE-vis) is a mole that a baby is born with or that shows up shortly after birth. It is also called a congenital melanocytic nevus. Congenital nevi (plural of nevus) can be anywhere on the body and may be small or large. It's not clear why they form, but congenital nevi (NEE-vie) happen when melanocytes (pigment cells) group together in the skin layers. The pigment (color) can cause the moles to look different shades of tan, brown, black, or red. Sometimes they can be hairy. Usually, a congenital nevus isn't dangerous. But you and your child's health care provider should watch the mole carefully because rarely they can develop into cancer.

• Check your child's nevus regularly for any changes.
• Schedule follow-up visits with your health care provider as recommended.

Your child:

• has a nevus that changes in color, texture, size, or shape
• has a nevus that bleeds, itches, or becomes painful
• seems to be developing more marks on the skin

How are congenital nevi treated? Most nevi do not cause problems, so health care providers might recommend waiting to see what happens. Other times they may recommend a biopsy (taking a small piece of the mole to be checked under a microscope) or removing the nevus. Your health care provider may recommend that you take your child to a dermatologist (a skin care doctor). The dermatologist may take pictures of your child's nevus and watch it very closely for changes.