Nevus
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2008-06-24T23:14:09Z
Elagatis
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{{Infobox_Disease |
Name = Nevus |
Image = Graindebeaute.jpg |
Caption = Photograph of a nevus on an arm |
DiseasesDB = |
ICD10 = {{ICD10|I|78|1|i|70}} |
ICD9 = {{ICD9|448.1}}, {{ICD9|216.0}}-{{ICD9|216.9}} |
ICDO = |
OMIM = |
MedlinePlus = |
eMedicineSubj = |
eMedicineTopic = |
MeshID = D009506 |
}}
'''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 [[birthmark]]s and [[Mole (skin marking)|moles]]. By definition, nevi are [[benign tumor|benign]]. Histologically, nevi are differentiated from [[lentigo]]s (also a type of benign pigmented macule) by the presence of nests of melanocytes, which lentigines (pl. form of lentigo) lack.
==Classification==
* [[Melanocytic nevus]] (nevomelanocytic nevus, nevocellular nevus): benign proliferation of [[melanocyte]]s, 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. The melanocytic nevi are classified as such:
** '''Junctional nevus''': the nevus cells are located along the junction of the [[epithelium]] and the underlying [[dermis]]. A junctional nevus is flat and brown to black.
** '''Compound nevus''': a mixture of junctional and intradermal proliferation. Compound nevi are slightly raised and brown to black.
** '''Intradermal nevus''': the nevus cells are located in the [[dermis]] only. Intradermal nevi are raised; most are flesh-colored (not pigmented).
** [[Dysplastic nevus]] (nevus of Clark): usually a compound nevus with cellular and architectural [[dysplasia]]. They tend to be larger (more than 6 mm), with irregular borders and irregular coloration. Hence, they resemble [[melanoma]], appear worrisome and are often removed to clarify the diagnosis. Dysplastic nevi do not transform into melanoma but are a marker of risk when they are numerous ('''atypical mole syndrome''').
** '''Blue nevus''': the nevus cells are very deep in the dermis.
** '''Spitz nevus''': a distinct variant of intradermal nevus, usually in a child. They are raised and reddish (non-pigmented). A pigmented variant, called the '''nevus of Reed''', typically appears on the leg of young women.
** '''Giant Hairy Nevus''': these large, pigmented, often hairy congenital nevi can be a source of much psychological and social suffering. They are also important because [[melanoma]] may occasionally (10 to 15%) appear in them.
** '''Intramucosal nevus''': junctional nevus of the mucosa of the mouth or genital areas. In the mouth, they are found most frequently on the hard palate.
** '''Nevus of Ito''' and '''Nevus of Ota''': congenital, flat brownish lesions on the face or shoulder.
** '''Mongolian spot''': congenital large, deep, bluish discoloration on the back of Asian babies.
* 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.
==External links==
{{Wiktionary}}
* [http://www.pathologyatlas.ro/Nevus%20melanocytic%20intradermal.html Atlas of Pathology] Section of a melanocytic nevus
{{Epithelial neoplasms}}
{{Vascular diseases}}
[[Category:Dermatology]]
[[Category:Oral pathology]]
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