Congenital melanocytic nevus

The congenital melanocytic nevus is a type of melanocytic nevus (or mole) found in infants at birth. Occurring in about 1% of infants in the United States, it is located in the area of the head and neck 15% of the time.

The appearance of the congenital melanocytic nevus is similar to those of acquired ones, but are usually larger in diameter and may have excess hair, called hypertrichosis. If large with hypertrichosis, it is called giant hairy nevus.

Microscopically, the congenital melanocytic nevus appears similar to acquired nevi with two notable exceptions. For the congenital nevus, the neval cells are found deeper into the dermis. Also, the deeper neval cells are found along with neurovascular bundles with both surrounding hair follicles, sebaceous glands, and subcutaneous fat.

Many are surgically removed for aesthetics, but larger ones are excised for prevention of cancer. 5 - 15% transform into melanoma.