Nevus 934744 221537986 2008-06-24T23:14:09Z Elagatis 549749 Typing error {{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]] [[ar:شامة]] [[de:Nävus]] [[es:Nevus]] [[eo:Nevuso]] [[fr:Nævus]] [[gd:Ball-dòbhrain]] [[is:Storkbit]] [[it:Neo]] [[he:נקודת חן]] [[la:Naevus]] [[nl:Naevus]] [[ja:ほくろ]] [[pl:Znamię]] [[pt:Nevo]] [[ru:Родинка]] [[fi:Luomi]] [[sv:Naevus]] [[tl:Nunal]] [[vi:Nốt ruồi]] [[yi:פנים פימפל]]