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{{Infobox disease
 
|  Name          = Nevus
|  Image          = 1D-I-k ouC8.jpg
|  Caption        = A nevus on a leg
|  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
}}
__NOTOC__
__NOTOC__
{{SI}}
{{SI}}
{{CMG}}
{{CMG}}:{{AE}} {{KS}}


==Overview==
==Overview==


'''Nevus''' (or '''naevus''', plural '''nevi''' or '''naevi''', from ''nævus'', [[Latin language|Latin]] for "[[birthmark]]") is the medical term for sharply circumscribed<ref>{{DorlandsDict|six/000072214|nevus}}</ref> and [[chronic (medicine)|chronic]] [[lesion]]s of the [[skin]] or [[mucosa]]. These lesions are commonly named '''birthmarks''' or '''beauty marks'''. Nevi are [[benign tumor|benign]] by definition. However, 25% of malignant melanomas (a skin cancer) arise from pre-existing nevi.<ref>{{cite book |last= Sam |first= Amir H. |author2=James T.H. Teo  |title= [[Rapid Medicine]] |publisher= [[Wiley-Blackwell]] |year= 2010 |isbn= 1405183233}}</ref> 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 [[melanocyte]]s. Histologically, melanocytic nevi are distinguished from [[lentigo|lentigines]] (also a type of benign pigmented [[macule]]) by the presence of nests of melanocytes, which lentigines (plural form of lentigo) lack.
'''Nevus''' (or '''naevus''', plural '''nevi''' or '''naevi''', from ''nævus'', [[Latin language|Latin]] for "[[birthmark]]") is the medical term for sharply circumscribed<ref>{{DorlandsDict|six/000072214|nevus}}</ref> and [[chronic (medicine)|chronic]] [[lesion]]s of the [[skin]] or [[mucosa]]. These lesions are commonly named '''birthmarks''' or '''beauty marks'''. Nevi are [[benign tumor|benign]] by definition. However, 25% of malignant melanomas (a skin cancer) arise from pre-existing nevi.<ref>{{cite book |last= Sam |first= Amir H. |author2=James T.H. Teo  |title= [[Rapid Medicine]] |publisher= [[Wiley-Blackwell]] |year= 2010 |isbn= 1405183233}}</ref> 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 [[melanocyte]]s. Histologically, melanocytic nevi are distinguished from [[lentigo|lentigines]] (also a type of benign pigmented [[macule]]) by the presence of nests of melanocytes, which lentigines (plural form of lentigo) lack.
==Classification==
==Classification==
[[epidermis (skin)|Epidermal]] nevi are derived from [[keratinocyte]]s or derivatives of keratinocytes. [[Connective tissue]] nevi are derived from connective tissue cells like [[adipocyte]]s and [[fibroblasts]]. [[vascular tissue|Vascular]] nevi are derived from structures of the blood vessels. ''See [[birthmark]] for a more complete discussion''
[[epidermis (skin)|Epidermal]] nevi are derived from [[keratinocyte]]s or derivatives of keratinocytes. [[Connective tissue]] nevi are derived from connective tissue cells like [[adipocyte]]s and [[fibroblasts]]. [[vascular tissue|Vascular]] nevi are derived from structures of the blood vessels. ''See [[birthmark]] for a more complete discussion''
===Melanocytic nevus===
===Melanocytic nevus===
{{main|Melanocytic nevus}}
{{main|Melanocytic nevus}}
*[[Congenital nevus]]: a melanocytic nevus present at birth or near birth.
*[[Congenital nevus]]: a melanocytic nevus present at birth or near birth.
*Acquired melanocytic nevus: a melanocytic nevus acquired later in life, and not at or near birth.  Most melanocytic nevi are of the acquired variety.
*Acquired melanocytic nevus: 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 [[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).
*Melanocytic nevus (nevomelanocytic nevus, nevocellular nevus): the 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).
*[[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.
*[[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===
* Epidermal nevus: congenital, flesh-colored, raised or warty, often linear lesion, usually on the upper half of the body.
* 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.
<gallery>
Image:Epidermal naevi01.jpg|Epidermal naevi. <SMALL><SMALL>''[http://www.atlasdermatologico.com.br/  Adapted from Dermatology Atlas.]''<ref name="Dermatology Atlas">{{Cite web | title = Dermatology Atlas | url = http://www.atlasdermatologico.com.br/}}</ref></SMALL></SMALL>
 
 
Image:Epidermal naevi02.jpg|Epidermal naevi. <SMALL><SMALL>''[http://www.atlasdermatologico.com.br/  Adapted from Dermatology Atlas.]''<ref name="Dermatology Atlas">{{Cite web | title = Dermatology Atlas | url = http://www.atlasdermatologico.com.br/}}</ref></SMALL></SMALL>
 
Image:Naevus epidermal01.jpg|Naevus epidermal. <SMALL><SMALL>''[http://www.atlasdermatologico.com.br/  Adapted from Dermatology Atlas.]''<ref name="Dermatology Atlas">{{Cite web | title = Dermatology Atlas | url = http://www.atlasdermatologico.com.br/}}</ref></SMALL></SMALL>
 
</gallery>
* Nevus sebaceous: variant of an epidermal nevus on the scalp presenting as a hairless, fleshy or yellowish area.
* Darier-Like Epidermal Nevus
* Darier-Like Epidermal Nevus
<gallery>
<gallery>
Line 54: Line 48:
[[Image:Dermatoscope1.JPG|thumb|A [[dermatoscope]]]]
[[Image:Dermatoscope1.JPG|thumb|A [[dermatoscope]]]]
[[Image:Dermatoscope.jpg|thumb|A modern polarized dermatoscope]]
[[Image:Dermatoscope.jpg|thumb|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.
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 the clinical diagnosis is inadequate or when malignancy is suspected.


== Normal evolution or maturation of melanocytic nevi ==
== Normal evolution or maturation of melanocytic nevi ==


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.<ref>[http://www.pathologyresources.com/AFIP/melanocytic/chap02.htm ]{{dead link|date=August 2012}}</ref>
All melanocytic nevi will change with time - both congenital and acquired nevi.  The "normal" maturation is evident as the elevation of the lesion from a flat macule to a raised papule.  The color change occurs as the melanocytes clump and migrates 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 the differentiation between benign and malignant lesions.<ref>[http://www.pathologyresources.com/AFIP/melanocytic/chap02.htm ]{{dead link|date=August 2012}}</ref>
 


==See also==
==See also==
Line 71: Line 66:
* [http://www.medscape.com/features/slideshow/mole-melanoma eMedicine: Mole or Melanoma? Tell-Tale Signs in Benign Nevi and Malignant Melanoma: Slideshow]
* [http://www.medscape.com/features/slideshow/mole-melanoma eMedicine: Mole or Melanoma? Tell-Tale Signs in Benign Nevi and Malignant Melanoma: Slideshow]
* [http://www.nevus.org/ Nevus Outreach, Inc.]
* [http://www.nevus.org/ Nevus Outreach, Inc.]
* [http://www.nbclosangeles.com/video/#!/on-air/as-seen-on/Local-Surgeon-Helping-Little-Girl-From-Philippines-with-Life-Changing-Surgery/134481563/ Pediatric plastic surgeon helps little girl with nevus NBC LA]
* [http://www.nbclosangeles.com/video/#!/on-air/as-seen-on/Local-Surgeon-Helping-Little-Girl-From-Philippines-with-Life-Changing-Surgery/134481563/ Pediatric plastic surgeon helps a little girl with nevus NBC LA]


{{Diseases of the skin and appendages by morphology}}
{{Diseases of the skin and appendages by morphology}}

Latest revision as of 15:37, 4 December 2020


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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [2]:Associate Editor(s)-in-Chief: Kiran Singh, M.D. [3]

Overview

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 or mucosa. These lesions are commonly named birthmarks or beauty marks. Nevi are benign by definition. However, 25% of malignant melanomas (a skin cancer) arise from pre-existing nevi.[2] 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 distinguished from lentigines (also a type of benign pigmented macule) by the presence of nests of melanocytes, which lentigines (plural form of lentigo) lack.

Classification

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

Melanocytic nevus

Main article: Melanocytic nevus
  • Congenital nevus: a melanocytic nevus present at birth or near birth.
  • Acquired melanocytic nevus: 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): the 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 sebaceous: variant of an epidermal nevus on the scalp presenting as a hairless, fleshy or yellowish area.
  • Darier-Like Epidermal Nevus

Connective tissue nevus

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

Vascular nevus

Diagnosis of nevi

File:Dermatoscope1.JPG
A dermatoscope
File:Dermatoscope.jpg
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 the clinical diagnosis is inadequate or when malignancy is suspected.

Normal evolution or maturation of melanocytic nevi

All melanocytic nevi will change with time - both congenital and acquired nevi. The "normal" maturation is evident as the elevation of the lesion from a flat macule to a raised papule. The color change occurs as the melanocytes clump and migrates 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 the differentiation between benign and malignant lesions.[4]


See also

References

  1. ↑ Template:DorlandsDict
  2. ↑ Sam, Amir H.; James T.H. Teo (2010). Rapid Medicine. Wiley-Blackwell. ISBN 1405183233.
  3. ↑ 3.0 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 "Dermatology Atlas".
  4. ↑ [1][dead link]

External links

Retrieved from "https://www.wikidoc.org/index.php?title=Nevus&oldid=1676719"