Editing Skin condition

{{Short description|Any medical condition that affects the integumentary system}}
{{Infobox medical condition (new)
| name            = Skin condition
| synonyms        = Cutaneous condition
| image           = 3D medical animation skin layers.jpg
| alt             =
| caption         = 3D medical illustration showing major layers of skin
| synonym         =
| pronounce       =
| field           = [[Dermatology]]
| symptoms        =
| complications   =
| onset           =
| duration        =
| types           =
| causes          = Bacteria, viruses, fungi, parasites, insects, trauma, cancers, allergies, toxins, vitamin/nutritional deficiencies/excesses, prolonged pressure, impaired blood circulation, ingrown hairs or nails, autoimmune conditions, aging, sun exposure, radiation exposure, exposure to heat/cold,  dryness, humidity, other  organ damage or condition, substance usage or contact, hereditary conditions, etc.
| risks           =
| diagnosis       =
| differential    =
| prevention      =
| treatment       =
| medication      =
| prognosis       =
| frequency       =
| deaths          =
}}

A '''skin condition''', also known as '''cutaneous condition''', is any [[medical condition]] that affects the [[integumentary system]]—the [[organ system]] that encloses the body and includes [[skin]], [[Nail (anatomy)|nails]], and related [[muscle]] and [[glands]].<ref name="Lookingbill">{{cite book | vauthors = Miller JH, Marks JG |title=Lookingbill and Marks' Principles of Dermatology |publisher=Saunders |year=2006 |isbn=1-4160-3185-5 }}</ref> The major function of this system is as a barrier against the external environment.<ref name="pmid19221876">{{cite journal | vauthors = Lippens S, Hoste E, Vandenabeele P, Agostinis P, Declercq W | title = Cell death in the skin | journal = Apoptosis | volume = 14 | issue = 4 | pages = 549–569 | date = April 2009 | pmid = 19221876 | doi = 10.1007/s10495-009-0324-z | s2cid = 13058619 }}</ref>

Conditions of the human integumentary system constitute a broad spectrum of diseases, also known as dermatoses, as well as many nonpathologic states (like, in certain circumstances, [[melanonychia]] and [[racquet nails]]).<ref name="King">{{cite journal | vauthors = King LS |title=What Is Disease? |journal=Philosophy of Science |volume=21 |issue= 3|pages=193–203 |year=1954 |doi= 10.1086/287343|s2cid=120875348 }}</ref><ref name="Bluefarb">{{cite book | vauthors = Bluefarb SM |title=Dermatology |publisher=Upjohn Co |year=1984 |isbn=0-89501-004-6 |url-access=registration |url=https://archive.org/details/dermatology00samu }}</ref> While only a small number of skin diseases account for most visits to the physician, thousands of skin conditions have been described.<ref name="Lynch" /> Classification of these conditions often presents many [[nosological]] challenges, since underlying causes and pathogenetics are often not known.<ref name="pmid2653160">{{cite journal | vauthors = Tilles G, Wallach D | title = [The history of nosology in dermatology] | language = fr | journal = Annales de Dermatologie et de Venereologie | volume = 116 | issue = 1 | pages = 9–26 | year = 1989 | pmid = 2653160 }}</ref><ref name="pmid7026622">{{cite journal | vauthors = Lambert WC, Everett MA | title = The nosology of parapsoriasis | journal = Journal of the American Academy of Dermatology | volume = 5 | issue = 4 | pages = 373–395 | date = October 1981 | pmid = 7026622 | doi = 10.1016/S0190-9622(81)70100-2 }}</ref> Therefore, most current textbooks present a classification based on location (for example, [[List of cutaneous conditions#Conditions of the mucous membranes|conditions of the mucous membrane]]), morphology ([[List of cutaneous conditions#Chronic blistering|chronic blistering conditions]]), cause ([[List of cutaneous conditions#Resulting from physical factors|skin conditions resulting from physical factors]]), and so on.<ref name="Jackson">{{cite journal | vauthors = Jackson R | title = Historical outline of attempts to classify skin diseases | journal = Canadian Medical Association Journal | volume = 116 | issue = 10 | pages = 1165–1168 | date = May 1977 | pmid = 324589 | pmc = 1879511 }}</ref><ref name="pmid7769599">{{cite journal | vauthors = Copeman PW | title = The creation of global dermatology | journal = Journal of the Royal Society of Medicine | volume = 88 | issue = 2 | pages = 78–84 | date = February 1995 | pmid = 7769599 | pmc = 1295100 }}</ref>

Clinically, the diagnosis of any particular skin condition begins by gathering pertinent information of the presenting skin lesion(s), including: location (e.g. arms, head, legs); symptoms ([[pruritus]], pain); duration (acute or chronic); arrangement (solitary, generalized, [[Wiktionary:annular|annular]], linear); morphology ([[Skin condition#Primary lesions|macules]], [[papule]]s, [[#Vesicle|vesicle]]s); and color (red, yellow, etc.).<ref name="FitzAtlas">{{cite book| vauthors = Wolff K, Johnson RA, Suurmond R |title=Fitzpatrick's Color Atlas and Synopsis of Clinical Dermatology |publisher=McGraw-Hill Medical Pub. Division |year=2005 |edition=5th|isbn =0-07-144019-4 }}</ref> Some diagnoses may also require a [[skin biopsy]] which yields [[histologic]] information<ref name="pmid19851671">{{cite journal | vauthors = Werner B | title = [Skin biopsy and its histopathologic analysis: Why? What for? How? Part I] | language = pt | journal = Anais Brasileiros de Dermatologia | volume = 84 | issue = 4 | pages = 391–395 | date = August 2009 | pmid = 19851671 | doi = 10.1590/s0365-05962009000400010 | doi-access = free }}</ref><ref name="pmid20098854">{{cite journal | vauthors = Werner B | title = [Skin biopsy with histopathologic analysis: why? what for? how? part II] | language = pt | journal = Anais Brasileiros de Dermatologia | volume = 84 | issue = 5 | pages = 507–513 | date = October 2009 | pmid = 20098854 | doi = 10.1590/S0365-05962009000500010 | doi-access = free }}</ref> that can be correlated with the clinical presentation and any laboratory data.<ref name="isbn0-7817-7363-6">{{cite book | vauthors = Xu X, Elder DA, Elenitsas R, Johnson BL, Murphy GE |title=Lever's Histopathology of the Skin |publisher=Lippincott Williams & Wilkins |location=Hagerstwon, MD |year=2008 |isbn=978-0-7817-7363-8 }}</ref><ref name="isbn0-7020-3941-1">{{cite book |title=Weedon's Skin Pathology, 2-Volume Set: Expert Consult – Online and Print |publisher=Churchill Livingstone |location=Edinburgh |year=2009 |isbn=978-0-7020-3941-6 }}</ref> The introduction of cutaneous [[ultrasound]] has allowed the detection of cutaneous tumors, inflammatory processes, and skin diseases.<ref>{{cite journal | vauthors = Alfageme F, Cerezo E, Roustan G | author1-link= Fernando Alfageme |title=Real-Time Elastography in Inflammatory Skin Diseases: A Primer |journal=Ultrasound in Medicine & Biology |date=April 2015 |volume=41 |issue=4 |pages=S82–S83 |doi=10.1016/j.ultrasmedbio.2014.12.341|doi-access=free }}</ref>

== Layer of skin involved ==
{{Main|Integumentary system}}

The skin weighs an average of {{convert|4|kg|lb|abbr=on}}, covers an area of about {{convert|2|m2|sqft|abbr=on}}, and is made of three distinct layers: the [[epidermis (skin)|epidermis]], [[dermis]], and [[subcutaneous tissue]].<ref name="Lookingbill" /> The two main types of human skin are [[glabrous skin]], the nonhairy skin on the palms and soles (also referred to as the "palmoplantar" surfaces), and hair-bearing skin.<ref name="RooksCD">{{cite book | vauthors = Burns T, Rook A | date = 2006 | title = Rook's Textbook of Dermatology CD-ROM | publisher = Wiley-Blackwell | isbn = 1-4051-3130-6}}</ref> Within the latter type, hairs in structures called [[pilosebaceous unit]]s have a [[hair follicle]], [[sebaceous gland]], and associated [[arrector pili]] muscle.<ref name="Paus">{{cite journal | vauthors = Paus R, Cotsarelis G | title = The biology of hair follicles | journal = The New England Journal of Medicine | volume = 341 | issue = 7 | pages = 491–497 | date = August 1999 | pmid = 10441606 | doi = 10.1056/NEJM199908123410706 }}</ref> [[Embryology|In the embryo]], the epidermis, hair, and glands are from the [[ectoderm]], which is chemically influenced by the underlying [[mesoderm]] that forms the dermis and subcutaneous tissues.<ref name="isbn0-19-261253-0">{{cite book | vauthors = Goldsmith LA |title=Biochemistry and physiology of the skin |publisher=Oxford University Press |year=1983 |isbn=0-19-261253-0 }}</ref><ref name="pmid17314969">{{cite journal | vauthors = Fuchs E | title = Scratching the surface of skin development | journal = Nature | volume = 445 | issue = 7130 | pages = 834–842 | date = February 2007 | pmid = 17314969 | pmc = 2405926 | doi = 10.1038/nature05659 | bibcode = 2007Natur.445..834F }}</ref><ref name="pmid18413712">{{cite journal | vauthors = Fuchs E, Horsley V | title = More than one way to skin . . | journal = Genes & Development | volume = 22 | issue = 8 | pages = 976–985 | date = April 2008 | pmid = 18413712 | pmc = 2732395 | doi = 10.1101/gad.1645908 }}</ref>

=== Epidermis ===
{{Main|Epidermis (skin)}}

The epidermis is the most superficial layer of skin, a [[epithelium|squamous epithelium]] with several [[stratum|strata]]: the [[stratum corneum]], [[stratum lucidum]], [[stratum granulosum]], [[stratum spinosum]], and [[stratum germinativum|stratum basale]].<ref name="Fitz" /> Nourishment is provided to these layers via [[diffusion]] from the dermis, since the epidermis is without direct blood supply.<ref>{{cite web | vauthors = Amirlak B, Shahabi L | veditors = Talavera F, Stadelmann WK, Caputy GG |title=Skin Anatomy|url=http://emedicine.medscape.com/article/1294744-overview|publisher=Medscape|access-date=3 June 2013}}</ref> The epidermis contains four cell types: [[keratinocyte]]s, [[melanocyte]]s, [[Langerhans cell]]s, and [[Merkel cell]]s. Of these, keratinocytes are the major component, constituting roughly 95% of the epidermis.<ref name="RooksCD" /> This stratified squamous epithelium is maintained by cell division within the stratum basale, in which differentiating cells slowly displace outwards through the stratum spinosum to the stratum corneum, where cells are continually shed from the surface.<ref name="RooksCD" /> In normal skin, the rate of production equals the rate of loss; about two weeks are needed for a cell to migrate from the basal cell layer to the top of the granular cell layer, and an additional two weeks to cross the stratum corneum.<ref name="bolognia">{{cite book | vauthors = Bolognia JL, Jorizzo JL, Rapini RP |title=Dermatology |publisher=Mosby |location=St. Louis |year=2007 |isbn=978-1-4160-2999-1 }}</ref>

=== Dermis ===
{{Main|Dermis}}

The dermis is the layer of skin between the epidermis and subcutaneous tissue, and comprises two sections, the [[papillary dermis]] and the [[reticular dermis]].<ref name="Rapini">{{cite book | vauthors = Rapini RP |title=Practical dermatopathology |publisher=Elsevier Mosby |year=2005 |isbn=0-323-01198-5 }}</ref> The superficial papillary dermis [[wikt:interdigitate|interdigitates]] with the overlying [[rete ridge]]s of the epidermis, between which the two layers interact through the basement membrane zone.<ref name="Rapini" /> Structural components of the dermis are [[collagen]], [[elastic fiber]]s, and [[ground substance]] also called extra fibrillar matrix.<ref name="Rapini" /> Within these components are the pilosebaceous units, arrector pili muscles, and the [[eccrine gland|eccrine]] and [[apocrine gland]]s.<ref name="Fitz" /> The dermis contains two vascular networks that run parallel to the skin surface—one superficial and one deep plexus—which are connected by vertical communicating vessels.<ref name="Fitz" /><ref name="Grant-Kels">{{cite book | vauthors = Grant-Kels JM |title=Color Atlas of Dermatopathology (Dermatology: Clinical & Basic Science) |publisher=Informa Healthcare |year=2007|page=163| isbn=978-0-8493-3794-9 }}</ref> The function of blood vessels within the dermis is fourfold: to supply nutrition, to regulate temperature, to modulate inflammation, and to participate in wound healing.<ref name="LAG">{{cite book | vauthors = Ryan T |chapter=Cutaneous Circulation | veditors = Goldsmith LA |title=Physiology, biochemistry, and molecular biology of the skin |publisher=Oxford University Press |location=New York |edition= 2nd |year=1991 |page=1019 |isbn=0-19-505612-4 }}</ref><ref name="pmid8423379">{{cite journal | vauthors = Swerlick RA, Lawley TJ | title = Role of microvascular endothelial cells in inflammation | journal = The Journal of Investigative Dermatology | volume = 100 | issue = 1 | pages = 111S–115S | date = January 1993 | pmid = 8423379 | doi = 10.1038/jid.1993.33 | doi-access = free }}</ref>

=== Subcutaneous tissue ===
{{Main|Subcutaneous tissue}}

The subcutaneous tissue is a layer of fat between the dermis and underlying [[fascia]].<ref name="Lynch">{{cite book | vauthors = Lynch PJ |title=Dermatology |publisher=Williams & Wilkins |year=1994 |isbn=0-683-05252-7 }}</ref> This tissue may be further divided into two components, the actual fatty layer, or [[panniculus adiposus]], and a deeper vestigial layer of muscle, the [[panniculus carnosus]].<ref name="RooksCD" /> The main cellular component of this tissue is the [[adipocyte]], or fat cell.<ref name="Lynch" /> The structure of this tissue is composed of septal (i.e. linear strands) and [[Lobe (anatomy)|lobular]] compartments, which differ in microscopic appearance.<ref name="Fitz" /> Functionally, the subcutaneous fat insulates the body, absorbs trauma, and serves as a reserve energy source.<ref name="Lynch" />

== Diseases of the skin ==
{{For|a list|List of skin conditions}}

Diseases of the skin include [[skin infection]]s and [[skin neoplasm]]s (including [[skin cancer]]).<ref>{{cite journal | vauthors = Rose LC | title = Recognizing neoplastic skin lesions: a photo guide | journal = American Family Physician | volume = 58 | issue = 4 | pages = 873–84, 887–8 | date = September 1998 | pmid = 9767724 | url = http://www.aafp.org/afp/1998/0915/p873.html | access-date = 3 June 2013 }}</ref>

== History ==
{{See also|History of dermatology}}
In 1572, [[Geronimo Mercuriali]] of [[Forlì]], [[Italy]], completed {{lang|la|De morbis cutaneis}} ('On the diseases of the skin'). It is considered the first scientific work dedicated to [[dermatology]]. <!-- This text needs no citation as it is a reference unto itself. -->

== Diagnoses ==
The physical examination of the skin and its appendages, as well as the mucous membranes, forms the cornerstone of an accurate diagnosis of cutaneous conditions.<ref name="isbn0-7216-8256-1">{{cite book | vauthors = Callen J |title=Color atlas of dermatology |publisher=W.B. Saunders |location=Philadelphia |year=2000 |isbn=0-7216-8256-1 }}</ref> Most of these conditions present with cutaneous surface changes termed "lesions," which have more or less distinct characteristics.<ref name="Andrews" /> Often proper examination will lead the physician to obtain appropriate historical information and/or laboratory tests that are able to confirm the diagnosis.<ref name="isbn0-7216-8256-1" /> Upon examination, the important clinical observations are the (1) morphology, (2) configuration, and (3) distribution of the lesion(s).<ref name="isbn0-7216-8256-1" /> With regard to morphology, the initial lesion that characterizes a condition is known as the "primary lesion", and identification of such a lesions is the most important aspect of the cutaneous examination.<ref name="Andrews" /> Over time, these primary lesions may continue to develop or be modified by regression or trauma, producing "secondary lesions".<ref name="Lookingbill" /> However, with that being stated, the lack of standardization of basic dermatologic terminology has been one of the principal barriers to successful communication among physicians in describing cutaneous findings.<ref name="Fitz">{{cite book | vauthors = Wolff KD, Goldsmith LA |title=Fitzpatrick's Dermatology in General Medicine | volume = 2 |publisher=McGraw-Hill Medical |year=2008 |isbn=978-0-07-146690-5 }}</ref> Nevertheless, there are some commonly accepted terms used to describe the macroscopic morphology, configuration, and distribution of skin lesions, which are listed below.<ref name="Andrews">{{cite book | vauthors = James WD, Berger TD, Elston DM, Odom RB |title=Andrews' Diseases of the Skin: Clinical Dermatology |publisher=Saunders Elsevier |year=2006 |isbn=0-7216-2921-0 }}</ref>

== Lesions ==
=== Primary lesions ===

{{multiple image
<!-- Layout parameters -->
 | direction         = vertical
 | width             = thumb
<!-- Header -->
 | header_background =
 | header_align      = <!-- center (default), left, right -->
 | header            =
<!--image 1-->
 | image1            = TrombiculosisSores.jpg
 | caption1          = [[Trombiculidae|Chigger]] bites on human skin showing characteristic welts
<!--image 2-->
 | image2            = Macule and Patch.svg
 | caption2          = Macule and patch
<!--image 3-->
 | image3            = Papule and Plaque.svg
 | caption3          = Papule and plaque
<!--image 4-->
 | image4            = Nodules.svg
 | caption4          = Nodules
<!--image 5-->
 | image5            = Vesicles and Bulla.svg
 | caption5          = Vesicles and bulla
<!--image 6-->
 | image6            = Ulcers, fissures, and erosions.svg
 | caption6          = Fissures, erosions and ulcers
<!--image 7-->
 | image7            = Teenager-with-acne.jpg
 | caption7          = A pustule on the cheek
<!--image 8-->
 | image8            = Relative incidence of cutaneous cysts.jpg
 | caption8          = Relative incidence of skin cysts
<!-- Footer -->
 | footer_background =
 | footer_align      = <!-- left (default), center, right -->
 | footer            =
}}
* {{anchor|Macule}}'''Macule''': A macule is a change in surface color, without elevation or depression, so nonpalpable, well or ill-defined,<ref name="FitzAtlas"/> variously sized, but generally considered less than either 5<ref name="FitzAtlas"/> or 10&nbsp;mm in diameter at the widest point.<ref name="Andrews" />
* '''Patch''': A patch is a large macule equal to or greater than either 5 or 10&nbsp;mm across,<ref name="Andrews" /> depending on one's definition of a macule.<ref name="Lookingbill" /> Patches may have some subtle surface change, such as a fine scale or wrinkling, but although the consistency of the surface is changed, the lesion itself is not palpable.<ref name="isbn0-7216-8256-1" />
* '''[[Papule]]''': A papule is a circumscribed, solid elevation of skin, varying in size from less than either 5<ref name="FitzAtlas"/> or 10&nbsp;mm in diameter at the widest point.<ref name="Andrews" />
* '''[[Papule|Plaque]]''': A plaque has been described as a broad papule, or confluence of papules equal to or greater than 10&nbsp;mm,<ref name="Andrews" /> or alternatively as an elevated, plateau-like lesion that is greater in its diameter than in its depth.<ref name="isbn0-7216-8256-1" />
* {{anchor|Nodule}}'''[[Nodule (medicine)|Nodule]]''': A nodule is morphologically similar to a papule in that it is also a palpable spherical lesion less than 10&nbsp;mm in diameter. However, it is differentiated by being centered deeper in the dermis or subcutis.
* '''[[Neoplasm|Tumor]]:''' Similar to a nodule, but it is larger than 10&nbsp;mm in diameter.{{cn|date=June 2021}}
* {{anchor|Vesicle}}'''Vesicle''': A vesicle or [[Bleb (medicine)|''bleb'']] is a small [[blister]],<ref name="Dorlands">{{cite book |author=Elsevier |author-link=Elsevier |title=Dorland's Illustrated Medical Dictionary |date=23 December 2020 | edition = 33rd |publisher=Elsevier |url=https://www.dorlandsonline.com/dorland/home | isbn = 978-0-323-66148-5 }}</ref> a circumscribed, epidermal elevation generally considered less than either 5<ref name="FitzAtlas"/> or 10&nbsp;mm in diameter at the widest point.<ref name="Andrews"/>
* {{anchor|Bulla}}'''Bulla''': A bulla is a large [[blister]],<ref name="Dorlands"/> a rounded or irregularly shaped blister equal to or greater than either 5<ref name="FitzAtlas"/> or 10&nbsp;mm,<ref name="Andrews" /> depending on one's definition of a vesicle.<ref name="Lookingbill" />
{{anchor|Pustule}}{{hatnote group|{{Redirect-distinguish|Pustule|Boil}}{{for|the hieroglyph|Pustule (hieroglyph)}} }}
* '''Pustule''': A pustule is a small elevation of the skin usually consisting of necrotic inflammatory cells.<ref name="Andrews" />
* '''[[Cyst]]''': A cyst is an epithelial-lined cavity.<ref name="FitzAtlas"/>
* {{anchor|Wheal|Weal}}'''Wheal''': A wheal is a rounded or flat-topped, pale red papule or plaque that is characteristically [[evanescent (dermatology)|evanescent]], disappearing within 24 to 48 hours. The temporary raised skin on the site of a properly delivered intradermal (ID) [[injection (medicine)|injection]] is also called a welt, with the ID injection process itself frequently referred to as simply "raising a wheal" in medical texts.<ref name="FitzAtlas"/>
* '''[[Welt (bruise)|Welts]]''': Welts occur as a result of blunt force being applied to the body with elongated objects without sharp edges.
* '''[[Telangiectasia]]''': A telangiectasia represents an enlargement of superficial blood vessels to the point of being visible.<ref name="isbn0-7216-8256-1" />
* '''Burrow''': A burrow appears as a slightly elevated, grayish, tortuous line in the skin, and is caused by burrowing organisms.<ref name="isbn0-7216-8256-1" /><ref name="Andrews" />

=== Secondary lesions ===
* '''Scale''': Dry or greasy laminated masses of [[keratin]],<ref name="Andrews" /> they represent thickened stratum corneum.<ref name="isbn0-7216-8256-1" />
* '''Crust''': Dried [[Sebaceous gland#Sebum|sebum]] usually mixed with epithelial and sometimes bacterial debris<ref name="FitzAtlas"/>
* '''[[Lichenification]]''': Epidermal thickening characterized by visible and palpable thickening of the skin with accentuated skin markings<ref name="Lookingbill" />
* '''Erosion''': An erosion is a discontinuity of the skin exhibiting incomplete loss of the [[epidermis (skin)|epidermis]],<ref name="isbn0-7216-0187-1">{{cite book|title=Robbins and Cotran pathologic basis of disease | vauthors= Cotran RS, Kumar V, Fausto N, Robbins SL, Abbas AK |publisher=Elsevier Saunders|year=2005|isbn=0-7216-0187-1|location=St. Louis, Mo}}</ref> a lesion that is moist, circumscribed, and usually depressed.<ref name="Fitz" /><ref name=":0">{{Cite web |url= https://basicmedicalkey.com/alterations-in-the-integumentary-system/ |title=Alterations in the Integumentary System| vauthors = Copstead LE, Diestelmeier RE, Diestelmeier MR |date=2016-09-03|website=Basicmedical Key|language=en-US|access-date=2019-07-01}}</ref>
* '''Excoriation''': A punctate or linear [[Abrasion (medical)|abrasion]] produced by mechanical means (often scratching), usually involving only the epidermis, but commonly reaching the [[papillary dermis]].<ref name="Andrews" /><ref name=":0" />
* '''[[Ulcer (dermatology)|Ulcer]]''': An ulcer is a discontinuity of the skin exhibiting complete loss of the epidermis and often portions of the dermis.<ref name="isbn0-7216-0187-1" /><ref name=":0" />
* '''[[Skin fissure|Fissure]]''' is a lesion in the skin that is usually narrow but deep.<ref name="isbn0-7216-8256-1" /><ref name=":0" />
* {{anchor|Induration}}'''Induration''' is dermal thickening causing the cutaneous surface to feel thicker and firmer.<ref name="isbn0-7216-8256-1" />
* '''Atrophy''' refers to a loss of skin, and can be epidermal, dermal, or subcutaneous.<ref name="Andrews" /> With epidermal atrophy, the skin appears thin, translucent, and wrinkled.<ref name="isbn0-7216-8256-1" /> Dermal or subcutaneous atrophy is represented by depression of the skin.<ref name="isbn0-7216-8256-1" />
* '''[[Skin maceration|Maceration]]''': softening and turning white of the skin due to being consistently wet.
* {{anchor|Umbilication}}'''Umbilication''' is formation of a depression at the top of a papule, vesicle, or pustule.<ref>{{cite web | vauthors = Benedetti J | date = December 2021 |title=Description of Skin Lesions|url=http://www.merckmanuals.com/professional/dermatologic_disorders/approach_to_the_dermatologic_patient/description_of_skin_lesions.html|publisher=The Merck Manual|access-date=3 June 2013}}</ref>
* '''[[wikt:phyma#noun|Phyma]]''': A [[tubercle]] on any external part of the body, such as in [[rosacea#Classification|phymatous rosacea]]

=== Configuration ===
"Configuration" refers to how lesions are locally grouped ("organized"), which contrasts with how they are distributed (see next section).
{{div col|colwidth=22em}}
* '''Agminate''': in clusters
* '''Annular''' or '''circinate''': ring-shaped
* '''Arciform''' or '''arcuate''': arc-shaped
* '''Digitate''': with finger-like projections
* '''Discoid''' or '''nummular''': round or disc-shaped
* '''Figurate''': with a particular shape
* '''Guttate''': resembling drops
* '''Gyrate''': coiled or spiral-shaped
* '''Herpetiform''': resembling [[herpes]]
* '''Linear'''
* '''Mammillated''': with rounded, breast-like projections
* '''Reticular''' or '''reticulated''': resembling a net
* '''Serpiginous''': with a wavy border
* '''Stellate''': star-shaped
* '''Targetoid''': resembling a [[bullseye (target)|bullseye]]
* '''Verrucous or Verruciform''': wart-like
{{div col end}}

=== Distribution ===
"Distribution" refers to how lesions are localized. They may be confined to a single area (a patch) or may be in several places. Some distributions correlate with the means by which a given area becomes affected. For example, contact dermatitis correlates with locations where allergen has elicited an allergic immune response. [[Varicella zoster virus]] is known to recur (after its initial presentation as [[chicken pox]]) as [[herpes zoster]] ("shingles"). Chicken pox appears nearly everywhere on the body, but herpes zoster tends to follow one or two dermatomes; for example, the eruptions may appear along the bra line, on either or both sides of the patient.{{cn|date=June 2021}}

{{div col|colwidth=30em}}
* '''Generalized'''
* '''Symmetric''': one side mirrors the other
* '''Flexural''': on the front of the fingers
* '''Extensor''': on the back of the fingers
* '''[[Intertriginous]]''': in an area where two skin areas may touch or rub together
* '''[[Morbilliform]]''': resembling [[measles]]
* '''Palmoplantar''': on the palm of the hand or bottom of the foot
* '''Periorificial''': around an orifice such as the mouth
* '''Periungual/subungual''': around or under a fingernail or toenail
* '''Blaschkoid''': following the path of [[Blaschko's lines]] in the skin
* '''Photodistributed''': in places where sunlight reaches
* '''Zosteriform''' or '''dermatomal''': associated with a particular nerve
{{div col end}}

===Other related terms===
{{div col|colwidth=30em}}
* Collarette
* [[Blackhead|Comedo]]
* [[Confluency|Confluent]]
* [[Eczema]] (a type of dermatitis)
* [[Evanescent (dermatology)|Evanescent]] (lasting less than 24 hours)
* [[Granuloma]]
* [[Livedo]]
* [[Purpura]]
* [[Erythema]] (redness)
* Horn (a cell type)
* [[Poikiloderma]]
{{div col end}}

== Histopathology ==
{{div col|colwidth=22em}}
* [[Hyperkeratosis]]
* [[Parakeratosis]]
* [[Hypergranulosis]]
* [[Acanthosis]]
* [[Papillomatosis]]
* [[Dyskeratosis]]
* [[Acantholysis]]
* [[Spongiosis]]
* [[Hydropic swell]]ing
* [[Exocytosis (dermatopathology)|Exocytosis]]
* [[Vacuolization]]
* [[Erosion (dermatopathology)|Erosion]]
* [[Ulcer (dermatology)|Ulceration]]
* [[Lentigo|Lentiginous]]
{{div col end}}
{{Clear}}

== See also ==
* [[Wound]], an injury which damages the [[epidermis]].

== References ==
{{Reflist}}

== External links ==
{{Medical resources
|  ICD10           = <!--{{ICD10|Xxx.x}}-->
|  ICD9            = <!--{{ICD9|xxx}}-->
|  ICDO            =
|  OMIM            =
|  DiseasesDB      =
|  MedlinePlus     =
|  eMedicineSubj   =
|  eMedicineTopic  =
|  MeSH            =
|  GeneReviewsNBK  =
|  GeneReviewsName =
|  Orphanet        =
}}
{{Diseases of the skin and subcutaneous tissue}}
{{Disorders of skin appendages}}
{{Diseases of the skin and appendages by morphology}}
{{Disease groups}}
{{Authority control}}

{{DEFAULTSORT:Cutaneous Conditions}}
[[Category:Cutaneous conditions| ]]