, 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
. 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.
- 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: