Editing Nevus (section)

==Classification==
The term ''nevus'' is applied to a number of conditions caused by [[Neoplasm|neoplasias]] and [[hyperplasia]]s of [[melanocyte]]s,<ref name=":0">{{Cite book|title=Fitzpatrick's Dermatology in General Medicine|publisher=The McGraw-Hill Companies, Inc.|year=2012|isbn=978-0-07-166904-7|chapter=Chapter 122. Benign Neoplasias and Hyperplasias of Melanocytes}}</ref> as well as a number of pigmentation disorders, both hypermelanotic (containing increased [[melanin]], the pigment responsible for skin color) and hypomelanotic (containing decreased melanin).<ref>{{Cite book|title=Fitzpatrick's Dermatology in General Medicine|publisher=The McGraw Hill Companies, Inc.|year=2012|isbn=978-0-07-166904-7|chapter=Chapter 75. Hypomelanoses and Hypermelanoses}}</ref> Suspicious skin moles which are multi-colored or pink may be a finding in [[skin cancer]].<ref name="Ba2012">{{cite book|url=https://books.google.com/books?id=ekr4Bt683c8C&pg=PT113|title=Baran and Dawber's Diseases of the Nails and their Management|last1=Baran|first1=Robert|last2=Berker|first2=David A. R. de|last3=Holzberg|first3=Mark|last4=Thomas|first4=Luc|date=2012|publisher=John Wiley & Sons|isbn=9781118286708|page=PT113|language=en}}</ref>

===Increased melanin===

==== Usually acquired ====
* [[Melanocytic nevus]]
** Melanocytic nevi can be categorized based on the location of melanocytic cells<ref name=":0" />
*** Junctional: [[epidermis]] 
*** Intradermal: [[dermis]] 
*** Compound: epidermis and dermis 
* [[Dysplastic nevus|Atypical (dysplastic) nevus]]: This type of nevus must be diagnosed based on histological features. Clinically, atypical nevi are characterized by variable pigmentation and irregular borders.<ref>{{Cite book|title=Melanocytic Lesions - Springer|year=2014|isbn=978-1-4939-0890-5|chapter=Dysplastic (Atypical) Nevi|doi=10.1007/978-1-4939-0891-2 |editor-last1=Hoang |editor-last2=Mihm |editor-first1=Mai P. |editor-first2=Martin C. }}</ref>
* [[Becker's nevus]]
* [[Blue nevus]] (rarely congenital): A classic blue nevus is usually smaller than 1&nbsp;cm, flat, and blue-black in color.<ref name=":1" />
* [[Hori's nevus]]
* [[Nevus spilus]] (speckled lentiginous nevus): This lesion includes dark speckles within a tan-brown background.<ref name=":2" />
* [[Pigmented spindle cell nevus]]
* [[Spitz nevus]]
* Zosteriform lentiginous nevus

==== Usually congenital ====
* [[Congenital melanocytic nevus]]
** These nevi are often categorized based on size, however, the lesions usually grow in proportion to the body over time, so the category may change over an individual's life.<ref name=":0" /> This categorization is important because large congenital melanocytic nevi are associated with an increased risk of [[melanoma]], a serious type of skin cancer.<ref name=":0" />
*** Small: <1.5&nbsp;cm<ref name=":0" />
*** Medium: 1.5–19.9&nbsp;cm<ref name=":0" />
*** Large: ≥ 20&nbsp;cm<ref name=":0" />
* [[Nevus of Ito]]
* [[Nevus of Ota]]

<gallery>
File:Conjunctival nevus.jpg|Conjunctival nevus of a 32-year-old male
File:Micrograph of an intradermal melanocytic nevus.jpg|Micrograph of an intradermal [[melanocytic nevus]]
File:Normal mole (1).jpg|Acquired melanocytic nevi
File:Dysplastic nevi (4).jpg|Atypical nevus
File:Becker's nevus of shoulder.JPG|Becker's nevus
File:Blue Nevus.jpg|Blue nevus
File:Naevus-spilus.jpg|[[Nevus spilus]]
File:Spitz nevus.jpg|Spitz nevus
File:Congenital nevus from CDC.jpg|Congenital melanocytic nevus
File:Nevus of Ota Before IBRITE C.jpg|Nevus of Ota
File:Compound nevus left buttock.jpg|Compound nevus, left buttock
</gallery>

===Decreased melanin===

==== Acquired ====
* [[Nevus anemicus]]

==== Congenital ====
* [[Nevus depigmentosus]]

<gallery>
File:Nevus anemicus.jpg|Nevus anemicus
File:Nevus Depigmentosus.jpg|Nevus depigmentosus
</gallery>

Additional types of nevi do not involve disorders of pigmentation or melanocytes. These additional nevi represent hamartomatous proliferations of the epithelium,<ref name=":3">{{Cite book|title=Fitzpatrick's Dermatology in General Medicine|publisher=The McGraw-Hill Companies, Inc.|year=2012|isbn=978-0-07-166904-7|chapter=Chapter 118. Benign Epithelial Tumors, Hamartomas, and Hyperplasias.}}</ref> connective tissue,<ref name=":4">{{Cite book|title=Fitzpatrick's Dermatology in General Medicine|publisher=The McGraw-Hill Companies, Inc.|year=2012|isbn=978-0-07-166904-7|chapter=Chapter 66. Dermal Hypertrophies and Benign Fibroblastic/Myofibroblastic Tumors.}}</ref> and vascular malformations.<ref>{{Cite book|title=Fitzpatrick's Dermatology in General Medicine|publisher=The McGraw Hill Companies, Inc.|year=2012|isbn=978-0-07-166904-7|chapter=Chapter 172. Vascular Malformations.}}</ref>

===Epidermal nevi===
These nevi represent excess growth of specific cells types found in the skin, including those that make up oil and sweat glands.<ref name=":3" />
* [[Verrucous epidermal nevus]]
* [[Nevus sebaceous]]
* [[Nevus comedonicus]]
* [[Eccrine nevus]]
* [[Apocrine nevus]]

===Connective tissue nevi===
[[Connective tissue nevus|Connective tissue nevi]] represent abnormalities of [[collagen]] in the dermis, the deep layer of the skin.<ref name=":4" />
* Collagenoma
* Elastoma

===Vascular nevi===
These nevi represent excess growth of blood vessels, including capillaries.<ref>{{Cite book|title=Fitzpatrick's Dermatology in General Medicine|publisher=The McGraw-Hill Companies, Inc.|year=2012|isbn=978-0-07-166904-7|chapter=Chapter 107. Neonatal, Pediatric, and Adolescent Dermatology}}</ref>
* '''Nevus simplex''' ([[nevus flammeus nuchae]]), also known as a ''stork bite'' or ''salmon patch''.
<gallery>
File:NaevusSebaceus res.jpg|Nevus sebaceous
File:Nevus flammeus nuchae ("stork bite" "Storchenbiss").JPG|Nevus flammeus nuchae
</gallery>

===Intramucosal nevi===
An ''intramucosal nevus'' is a nevus within the [[mucosa]] as found in for example the mouth and genital areas. In the mouth, they are found most frequently on the hard palate. They are typically light brown and dome-shaped.<ref>{{cite web|title=Oral Nevi|url=https://emedicine.medscape.com/article/1079272-overview|website=MedScape|access-date=23 January 2018}}</ref> Intramucosal nevi account for 64% of all reported case of oral nevi.<ref name="BuchnerMerrell2004">{{cite journal|last1=Buchner|first1=A.|last2=Merrell|first2=P. W.|last3=Carpenter|first3=W. M.|title=Relative frequency of solitary melanocytic lesions of the oral mucosa|journal=Journal of Oral Pathology and Medicine|volume=33|issue=9|year=2004|pages=550–557|issn=0904-2512|doi=10.1111/j.1600-0714.2004.00238.x|pmid=15357676}}</ref>