Congenital Nevus

Congenital Nevus

Key Points
Mole found at birth
Occurs in 1% of infants
Moles generally larger than acquired Moles
Three types

A congenital melanocytic nevus, or birthmark, is a type of mole found in infants at birth. It’s usually larger in diameter than those that occur later in life, and may present an excess amount of hair. Some of these moles are removed for cosmetic reasons, and giant nevi are often excised to prevent cancer, as 5 to 15 percent of giant congenital melanocytic nevi may develop into melanoma.  Small and medium nevi have less than a 1% chance of developing into melanoma.

There are three types of Congenital Melanocytic Nevus.

Giant congenital melanocytic nevus — Characterized by large size.  Greater than 20cm diameter and sometimes referred to as bathing trunk nevi due to size and distribution.  They darkly pigmented and sometimes hairy 
Medium-sized congenital melanocytic nevus — characterized as having a diamater larges than 2 centimeters but smaller than 20 centimeters
Small-sized congenital melanocytic nevus — characterized as having a diamater smaller than 2 centimeters

Treatment
Most nevi may be left in place and monitored for change.  Giant congenital nevi are usually excised due to their increased risk of developing melanoma.

Evaluation by a dermatologist is recommended.  Surgical excision is the proper treatment for giant nevi but is not usually necessary for small and medium nevi.