Nevus (or naevus, plural nevi, from nævus, Latin for birthmark) is the medical term for sharply-circumscribed and chronic lesions of the skin. These lesions are commonly named birthmarks and moles. By definition, nevi are benign. Histologically, nevi are differentiated from lentigines (also a type of benign pigmented macule) by the presence of nests of melanocytes, which lentigines (plural form of lentigo) lack.

Classification

• Melanocytic nevus (nevomelanocytic nevus, nevocellular nevus): benign proliferation of melanocytes, the skin cells that make the brown pigment melanin. Hence, most nevi are brown to black. They are very common; almost all adults have at least one, usually more. They may be congenital or acquired (usually at puberty).
• Epidermal lesions:
• Epidermal nevus: congenital, flesh-colored, raised or warty, often linear lesion, usually on the upper half of the body.
• Nevus sebaceus: variant of epidermal nevus on the scalp presenting as a hairless, fleshy or yellowish area.

• Connective tissue lesions:
• Connective tissue nevus: fleshy, deep nodules. Rare.

• Vascular lesions. See birthmark for a more complete discussion:
• Hemangioma (strawberry mark or nevus).
• Nevus flammeus (port-wine stain).
• Spider angioma (nevus araneus).
• Blue Rubber Bleb Nevus Syndrome: dilatation of veins anywhere in the body (both skin and internal organs), usually lethal from internal hemorrhage. It is a very rare genetic disorder.

See also

• Becker's nevus

References

External links

• Nevus risk factors, symptoms, treatment, and more information
• Atlas of Pathology Section of a melanocytic nevus