Congenital Nevi

Also known as: congenital moles, congenital melanocytic nevus

What are congenital nevi?

Congenital nevus/i (plural) is the term for a single small to medium sized solitary, flat, or raised tan/dark mole or birthmark that develops from proliferation of pigmented cells. These pigmented cells, known as melanocytes, are present on or in the skin of a baby at birth or within a year or two thereafter.

There is a small risk that these may go on to becoming cancerous. A rare form of congenital mole is the large or giant melanocytic nevus which may be small at birth but grow in size as the child grows. These moles have a greater risk of becoming malignant as cancer called melanoma.

A syndrome called Neurocutaneous melanosis is the presence of small or giant congenital melanocytic nevi on the skin plus melanocytic tumors in the coverings of the brain and spinal cord.

What causes congenital nevi?

Congenital nevi are thought to be caused by a non-inherited genetic mutation that occurs randomly in the early stages of fetal development.

What are the symptoms of congenital nevi?

Congenital nevi can be big or small. They are typically skin-colored to brown, flat, or raised, with or without hairs and can occur anywhere on the body.

What are congenital nevi care options?

In many cases, no treatment is needed for congenital nevi. If a doctor is concerned about the nevi, additional monitoring may be recommended to assess potential cancer risk, or removal. Removal of the mole is typically a simple, fairly painless procedure.

Reviewed by: Jack Wolfsdorf, MD, FAAP

This page was last updated on: September 16, 2025 12:16 PM