Editing Dermatitis (section)

==Diagnosis==
Diagnosis of eczema is based mostly on the [[Medical history|history]] and [[physical examination]].<ref name="Mc2012" /> In uncertain cases, [[skin biopsy]] may be taken for a [[histopathologic diagnosis of dermatitis]].<ref>{{cite web |title=Eczema |url=http://umm.edu/health/medical/altmed/condition/eczema |url-status=live |archive-url=https://web.archive.org/web/20160727103505/http://umm.edu/health/medical/altmed/condition/eczema |archive-date=27 July 2016 |website=University of Maryland Medical Center}}</ref> Those with eczema may be especially prone to [[misdiagnosis]] of [[food allergies]].<ref>{{cite journal |vauthors=Atkins D |date=March 2008 |title=Food allergy: diagnosis and management |journal=Primary Care |volume=35 |issue=1 |pages=119–140, vii |doi=10.1016/j.pop.2007.09.003 |pmid=18206721}}</ref>

[[Patch test]]s are used in the diagnosis of allergic contact dermatitis.<ref>{{cite book |url=https://books.google.com/books?id=sSHIlWSOiroC&q=dermatitis+%22patch+test%22&pg=PA462 |title=Contact Dermatitis |vauthors=Johansen JD, Frosch PJ, Lepoittevin JP |publisher=Springer |year=2010 |isbn=978-3-642-03827-3 |access-date=21 April 2014 |archive-url=https://web.archive.org/web/20140705040228/http://books.google.com/books?id=sSHIlWSOiroC&pg=PA462&dq=dermatitis+%22patch+test%22&hl=en&sa=X&ei=rIxUU_2FDLDMsQTi94H4BA&ved=0CE4Q6AEwAQ#v=onepage&q=dermatitis%20%22patch%20test%22&f=false |archive-date=5 July 2014 |url-status=live}}</ref><ref>{{cite book |url=https://books.google.com/books?id=dQBAzfyCeQ8C&pg=PA57 |title=Fisher's Contact Dermatitis |vauthors=Rietschel RL, Fowler JF |publisher=BC Decker Inc. |year=2008 |isbn=978-1-55009-378-0 |edition=6th |location=Hamilton, Ontario |access-date=21 April 2014}}</ref>

===Classification===
The term ''eczema'' refers to a set of clinical characteristics. Classification of the underlying diseases has been haphazard with numerous different classification systems, and many [[synonym]]s being used to describe the same condition.<ref>{{cite journal |vauthors=Johansen JD, Hald M, Andersen BL, Laurberg G, Danielsen A, Avnstorp C, Kristensen B, Kristensen O, Kaaber K, Thormann J, Menné T |year=2011 |title=Classification of hand eczema: clinical and aetiological types. Based on the guideline of the Danish Contact Dermatitis Group |url=https://pubmed.ncbi.nlm.nih.gov/21658054/ |journal=Contact Dermatitis |volume=65 |issue=1 |pages=13–21 |doi=10.1111/j.1600-0536.2011.01911.x |pmid=21658054 |s2cid=30780460 |access-date=2 July 2021 |collaboration=Danish Contact Dermatitis Group}}</ref>

A type of dermatitis may be described by location (e.g., [[hand eczema]]), by specific appearance (eczema craquele or discoid) or by possible cause ([[varicose eczema]]). Further adding to the confusion, many sources use the term ''eczema'' interchangeably for the most common type: [[atopic dermatitis]].<ref name="auto" />

The [[European Academy of Allergology and Clinical Immunology]] (EAACI) published a position paper in 2001, which simplifies the nomenclature of allergy-related diseases, including atopic and allergic contact eczemas.<ref name="pmid11551246">{{cite journal |vauthors=Johansson SG, Hourihane JO, Bousquet J, Bruijnzeel-Koomen C, Dreborg S, Haahtela T, Kowalski ML, Mygind N, Ring J, van Cauwenberge P, van Hage-Hamsten M, Wüthrich B |date=September 2001 |title=A revised nomenclature for allergy. An EAACI position statement from the EAACI nomenclature task force |journal=Allergy |volume=56 |issue=9 |pages=813–824 |doi=10.1034/j.1398-9995.2001.t01-1-00001.x |doi-broken-date=6 February 2025 |pmid=11551246}}</ref> Non-allergic eczemas are not affected by this proposal.

====Histopathologic classification====
{{Main|Histopathologic diagnosis of dermatitis}}

By [[histopathology]], superficial dermatitis (in the epidermis, papillary dermis, and superficial vascular plexus) can basically be classified into either of the following groups:<ref name="Alsaad2005">{{cite journal |vauthors=Alsaad KO, Ghazarian D |date=December 2005 |title=My approach to superficial inflammatory dermatoses |journal=Journal of Clinical Pathology |volume=58 |issue=12 |pages=1233–1241 |doi=10.1136/jcp.2005.027151 |pmc=1770784 |pmid=16311340}}</ref>
* Vesiculobullous lesions
* Pustular dermatosis
* Non vesiculobullous, non-pustular
:*With epidermal changes
:*Without epidermal changes. These characteristically have a superficial perivascular inflammatory infiltrate and can be classified by type of cell infiltrate:<ref name="Alsaad2005" />
::*Lymphocytic (most common)
::*Lymphoeosinophilic
::*Lymphoplasmacytic
::*Mast cell
::*Lymphohistiocytic
::*Neutrophilic

===Common types===
====Atopic====
[[Atopic dermatitis]] is an allergic disease believed to have a hereditary component and often runs in families whose members have [[asthma]]. Itchy [[rash]] is particularly noticeable on the head and scalp, neck, inside of elbows, behind knees, and buttocks. It is very common in developed countries and rising. Irritant [[contact dermatitis]] is sometimes misdiagnosed as atopic dermatitis. [[Stress (biology)|Stress]] can cause atopic dermatitis to worsen.<ref>[https://nationaleczema.org/eczema/types-of-eczema/atopic-dermatitis/ Atopic Dermatitis]  National Eczema Association.</ref>

====Contact====
[[Contact dermatitis]] is of two types: allergic (resulting from a delayed reaction to an [[allergen]], such as [[poison ivy]], [[nickel]], or [[Balsam of Peru]]),<ref name="dermnetnz1">{{cite web |date=28 December 2013 |title=Balsam of Peru contact allergy |url=http://dermnetnz.org/dermatitis/balsam-of-peru-allergy.html |url-status=live |archive-url=https://web.archive.org/web/20140305094411/http://dermnetnz.org/dermatitis/balsam-of-peru-allergy.html |archive-date=5 March 2014 |access-date=5 March 2014 |publisher=Dermnetnz.org}}</ref> and irritant (resulting from direct reaction to a detergent, such as [[sodium lauryl sulfate]], for example).

Some substances act both as allergen and irritants (wet cement, for example). Other substances cause a problem after sunlight exposure, bringing on [[phototoxic dermatitis]]. About three-quarters of cases of contact eczema are of the irritant type, which is the most common occupational skin disease. Contact eczema is curable, provided the offending substance can be avoided and its traces removed from one's environment. (ICD-10 L23; L24; L56.1; L56.0)

====Seborrhoeic====
[[Seborrhoeic dermatitis]] or seborrheic dermatitis is a condition sometimes classified as a form of eczema that is closely related to [[dandruff]]. It causes dry or greasy peeling of the scalp, eyebrows, and face, and sometimes trunk. In newborns, it causes a thick, yellow, crusty scalp rash called [[cradle cap]], which seems related to lack of [[biotin]] and is often curable. (ICD-10 L21; L21.0)

There is a connection between seborrheic dermatitis and ''[[Malassezia]]'' fungus, and [[antifungal]]s such as anti-dandruff shampoo can be helpful in treating it.<ref name="Bor2019" />

===Less common types===
====Dyshidrosis====
[[Dyshidrosis]] (dyshidrotic eczema, pompholyx, vesicular palmoplantar dermatitis) only occurs on palms, soles, and sides of fingers and toes. Tiny opaque bumps called [[Cutaneous conditions#Morphology|vesicle]]s, thickening, and cracks are accompanied by itching, which gets worse at night. A common type of hand eczema, it worsens in warm weather. (ICD-10 L30.1)

====Discoid====
[[nummular dermatitis|Discoid eczema]] (nummular eczema, exudative eczema, microbial eczema) is characterized by round spots of oozing or dry rash, with clear boundaries, often on lower legs. It is usually worse in winter. The cause is unknown, and the condition tends to come and go. (ICD-10 L30.0)

====Venous====
[[stasis dermatitis|Venous eczema]] (gravitational eczema, stasis dermatitis, varicose eczema) occurs in people with impaired circulation, [[varicose veins]], and [[edema]], and is particularly common in the ankle area of people over 50. There is redness, scaling, darkening of the skin, and itching. The disorder predisposes to [[venous ulcer|leg ulcers]]. (ICD-10 I83.1)

====Herpetiformis====
[[Dermatitis herpetiformis]] (Duhring's disease) causes an intensely itchy and typically symmetrical rash on arms, thighs, knees, and back. It is directly related to [[celiac disease]], can often be put into remission with an appropriate diet, and tends to get worse at night. (ICD-10 L13.0)

====Hyperkeratotic====
Hyperkeratotic hand dermatitis presents with hyperkeratotic, fissure-prone, erythematous areas of the middle or proximal palm, and the volar surfaces of the fingers may also be involved.<ref name="Andrews2005">James, William; Berger, Timothy; Elston, Dirk (2005). ''Andrews' Diseases of the Skin: Clinical Dermatology''. (10th ed.). Saunders. {{ISBN|0-7216-2921-0}}.</ref>{{rp|79}}

====Neurodermatitis====
[[Neurodermatitis]] ([[lichen simplex chronicus]], localized scratch dermatitis) is an itchy area of thickened, pigmented eczema patch that results from [[habit (psychology)|habitual]] rubbing and scratching. Usually, there is only one spot. Often curable through behaviour modification and anti-inflammatory medication. [[Prurigo nodularis]] is a related disorder showing multiple lumps. (ICD-10 L28.0; L28.1)

====Autoeczematization====
[[Autoeczematization]] (id reaction, auto sensitization) is an eczematous reaction to an infection with [[parasite]]s, [[fungi]], [[bacteria]], or [[virus]]es. It is completely curable with the clearance of the original infection that caused it. The appearance varies depending on the cause. It always occurs some distance away from the original infection. (ICD-10 L30.2)

====Viral====
There are eczemas overlaid by viral infections ([[eczema herpeticum]] or [[eczema vaccinatum|vaccinatum]]), and eczemas resulting from underlying disease (e.g., [[lymphoma]]).

Eczemas originating from ingestion of medications, foods, and chemicals, have not yet been clearly systematized. Other rare eczematous disorders exist in addition to those listed here.