page_title: Congenital melanocytic nevus
section_title: Signs and symptoms
hierarchical_section_title: Congenital melanocytic nevus / Signs and symptoms
caption_attribution_description: English: Converted to JPG with Gimp from the hi-res TIFF file. From an unknown location on this patient’s body, this image depicts a pigmented cutaneous lesion that was diagnosed as a congenital nevus. Note the variable coloration, and slightly irregular border of this nevus. Congenital nevi are characterized by the following criteria: - These cutaneous lesions may be small or large - When small, these nevi present an unknown risk of malignant melanoma (MM) - The prophylactic removal of these nevi during a patient’s teen years is probably reasonable
context_page_description: The congenital melanocytic nevus is a type of melanocytic nevus found in infants at birth. This type of birthmark occurs in an estimated 1% of infants worldwide; it is located in the area of the head and neck 15% of the time.
context_section_description: The congenital melanocytic nevus appears as a circumscribed, light brown to black patch or plaque, potentially very heterogeneous in consistency, covering any size surface area and any part of the body.
  As compared with a melanocytic nevus, congenital melanocytic nevi are usually larger in diameter and may have excess terminal hair, a condition called hypertrichosis. If over 40 cm (16 in) projected adult diameter with hypertrichosis, it is sometimes called giant hairy nevus; more usually these largest forms are known as large or giant congenital melanocytic nevus. The estimated prevalence for the largest forms is 0.002% of births.
  Melanocytic nevi often grow proportionally to the body size as the child matures. As they mature, they often develop thickness, and become elevated, although these features can also be present from birth. Prominent terminal hairs often form, especially after puberty.  With maturity, the nevus can have variation in color, and the surface might be textured with proliferative growths.
  Neurocutaneous melanosis is associated with the presence of either giant congenital melanocytic nevi or non-giant nevi of the skin. It is estimated that neurocutaneous melanosis is present in 2% to 45% of patients with giant congenital melanocytic nevi. Neurocutaneous melanosis is characterized by the presence of congenital melanocytic nevi on the skin and melanocytic tumors in the leptomeninges of the central nervous system.
caption: Congenital nevus. Note the variable coloration and slightly irregular border
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