Congenital nevi are tan, brown to dark brown macules, papules or plaques present at birth. Texture can range from smooth, nodular, verrucous, or rough cobblestone-like texture. Hair may or may not be present on the lesions and does not indicate malignancy potential. Congenital nevi range in size and are categorized as small, intermediate, and large or giant. Size assessments are based on adult size. Small nevi are defined as 1 to 1.5 cm or less. The size for intermediate nevi ranges from 1 to 1.5 cm up to 20 cm. Giant melanocytic nevi are uncommon nevi, greater than 20 cm in adults or greater than 5% of the body surface area in children. Oftentimes, numerous smaller nevi called "satellite lesions" are located at skin sites distant from the large nevi and may arise throughout childhood. Neurocutaneous melanosis is the association of a giant melanocytic nevus overlying the scalp or spine with central nervous system involvement.

Differential diagnosis

Café au lait spots can be confused with congenital nevi because a congenital nevus is often flat at birth but becomes raised with time. Congenital smooth muscle and pilar hemartomas present as light brown plaques with fine hair. Histologic examination can differentiate between the lesions.

Pathophysiology

Nests of melanocytes are found within the epidermis and dermis on histologic exam. In giant congenital nevi, the pigment cells may populate the entire dermis and extend around hair and eccrine sweat glands. It is hypothesized that congenital nevi are produced due to developmental errors in melanocyte proliferation and migration.

Treatment

This is a controversial topic. Many patients with giant congenital nevi are at risk for developing malignant melanoma, however oftentimes these melanomas do not occur in the skin. It is advisable to consider the potential for cosmetic improvement and surgical risk in assessing these lesions. The parent should be encouraged to have the patient followed annually for the lesion and include additional visits for any change in the nevus that is not proportional with the child's growth. The child with spine and scalp involvement should be evaluated by a neurologist if there are any signs of CNS abnormalities.