Nevus

Nevus
Classification and external resources

Photograph of a nevus on an arm
ICD-10 I78.1
ICD-9 448.1, 216.0-216.9
MeSH D009506

Nevus (or naevus, plural nevi or naevi, from nævus, Latin for "birthmark") is the medical term for sharply-circumscribed[1] and chronic lesions of the skin. These lesions are commonly named birthmarks and moles. Nevi are benign by definition. Using the term nevus and nevi loosely, most physicians and dermatologists are actually referring to a variant of nevus called the "Melanocytic nevus", which are composed of melanocytes. Histologically, melanocytic 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.

Contents

Classification

Epidermal nevi are derived from keratinocytes or derivatives of keratinocytes. Connective tissue nevi are derived from connective tissue cells like adipocyte and fibroblasts. Vascular nevi are derived from structures of the blood vessels. See birthmark for a more complete discussion

Melanocytic nevus

  • Congenital nevus implying a melanocytic nevus present at birth or near birth.
  • Acquired melanocytic nevus. Implies a melanocytic nevus acquired later in life, and not at or near birth. Most melanocytic nevi are of the acquired variety.
  • 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).
  • Dysplastic nevus usually an acquired melanocytic nevus with abnormal features making it difficult to distinguish from a melanoma. It can be a marker for an individual at risk for developing melanomas.

Epidermal nevus

  • 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 nevus

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

Vascular nevus

Diagnosis of nevi

A dermatoscope.
A modern polarized dermatoscope.

Clinical diagnosis of a melanocytic nevus from other nevi can be made with the naked eye using the ABCD guideline, or using dermatoscopy. The main concern is distinguishing between a benign nevus, a dysplastic nevus, and a melanoma. Other skin tumors can resemble a melanocytic nevus clinically, such as a seborrheic keratosis, pigmented basal cell cancer, hemangiomas, and sebaceous hyperplasia. A skin biopsy is required when clinical diagnosis is inadequate or when malignancy is suspected.

Normal Evolution or Maturation of Melanocytic Nevus

All melanocytic nevi will change with time - both congenital and acquired nevi. The "normal" maturation is evident as elevation of the lesion from a flat macule to a raised papule. The color change occurs as the melanocytes clump and migrate from the surface of the skin (epidermis) down deep into the dermis. The color will change from even brown, to speckled brown, and then losing the color and becomes flesh colored or pink. During the evolution, uneven migration can make the nevi look like melanomas, and dermatoscopy can help in differentiation between the benign and malignant lesions.[2]

See also

References

External links


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Look at other dictionaries:

  • Nevus — Clasificación y recursos externos CIE 10 I78.1 …   Wikipedia Español

  • nevus — m. dermat. Conjunto de enfermedades congénitas caracterizadas por una serie de displasias en la piel o sus anejos. Se trata de malformaciones planas, nodulares, de color marrón claro que en ocasiones pueden desarrollarse con pelos. Las pecas y… …   Diccionario médico

  • nevus — nȇvus m DEFINICIJA term. znamenka, madež na koži, nenasljedna mana kože (ima ih pigmentarnih, nepigmentarnih, dlakavih i dr.) ETIMOLOGIJA lat. naevus …   Hrvatski jezični portal

  • nevus — (Del lat. naevus, lunar1). m. Med. Alteración congénita muy localizada de la pigmentación de la piel, generalmente de color marrón o azulado …   Diccionario de la lengua española

  • nevus — (Brit. naevus) ► NOUN (pl. nevi) ▪ a birthmark or a mole on the skin. ORIGIN Latin …   English terms dictionary

  • nevus — [nē′vəs] n. pl. nevi [mē′vī΄] [ModL < L naevus, birthmark < base of genus, GENUS] a birthmark, mole, or other colored spot on the skin nevoid [nē′void΄] adj …   English World dictionary

  • nevus — nevoid /nee voyd/, adj. /nee veuhs/, n., pl. nevi / vuy/. any congenital anomaly of the skin, including moles and various types of birthmarks. [1685 95; sp. var. of L naevus mole] * * * ▪ anatomy plural  Nevi,         congenital skin lesion, or… …   Universalium

  • Nevus — ► sustantivo masculino MEDICINA Denominación genérica de las manchas de la piel y de las mucosas susceptibles de sufrir una degeneración cancerígena. IRREG. plural nevus * * * nevus m. Med. Mancha o verruga de la piel. * * * nevus. (Del lat.… …   Enciclopedia Universal

  • Nevus — A pigmented spot on the skin, such as a mole. The plural of nevus is nevi. * * * 1. A circumscribed malformation of the skin, especially if colored by hyperpigmentation or increased vascularity; a n. may be predominantly epidermal, adnexal,… …   Medical dictionary

  • nevus — {{#}}{{LM N27314}}{{〓}} {{[}}nevus{{]}} ‹ne·vus› {{◆}}(pl. nevus){{◇}} {{《}}▍ s.m.{{》}} Malformación de la piel que forma pequeñas manchas o verrugas. {{★}}{{\}}ETIMOLOGÍA:{{/}} Del latín naevus (lunar) …   Diccionario de uso del español actual con sinónimos y antónimos

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