Editing Alopecia areata (section)

== Diagnosis ==

Alopecia areata is usually diagnosed based on clinical features.

[[Trichoscopy]] may aid in establishing the diagnosis. In alopecia areata, trichoscopy shows regularly distributed "yellow dots" ([[hyperkeratotic]] plugs), small exclamation-mark hairs, and "black dots" (destroyed hairs in the hair follicle opening).<ref>{{cite journal | vauthors = Rudnicka L, Olszewska M, Rakowska A, Kowalska-Oledzka E, Slowinska M | title = Trichoscopy: a new method for diagnosing hair loss | journal = Journal of Drugs in Dermatology | volume = 7 | issue = 7 | pages = 651–654 | date = July 2008 | pmid = 18664157 }}</ref>

Oftentimes, however, discrete areas of hair loss surrounded by exclamation mark hairs is sufficient for clinical diagnosis of alopecia areata. Sometimes, reddening of the skin, [[erythema]], may also be present in the balding area.<ref name="Bei2018" />

A biopsy is rarely needed to make the diagnosis or aid in the management of alopecia areata. [[Histologic]] findings may include peribulbar [[lymphocytic]] infiltration resembling a "swarm of bees", a shift in the [[anagen]]-to-telogen ratio towards telogen, and dilated follicular infundibulae.<ref name=HordinskyJunqueira2015 /> Other helpful findings can include pigment incontinence in the [[hair bulb]] and follicular stelae. Occasionally, in inactive alopecia areata, no inflammatory infiltrates are found.{{citation needed|date=March 2015}}

=== Classification ===
[[File:Fox Plate V.jpg|thumb|Varying degrees of alopecia areata, along with alopecia totalis]]

Commonly, alopecia areata involves hair loss in one or more round spots on the scalp.<ref name=draelos/><ref name="Lookingbill">{{cite book | vauthors = Marks JG, Miller J | year = 2006 | title = Lookingbill and Marks' Principles of Dermatology | edition = 4th | publisher = Elsevier Inc. | isbn = 978-1-4160-3185-7 }}.{{page needed|date=March 2015}}</ref>
* Hair may also be lost more diffusely over the whole scalp, in which case the condition is called diffuse alopecia areata.<ref name=draelos/>
* Alopecia areata monolocularis describes baldness in only one spot. It may occur anywhere on the head.
* Alopecia areata multilocularis refers to multiple areas of hair loss.
* [[Ophiasis]] refers to hair loss in the shape of a wave at the circumference of the head.
* The disease may be limited only to the beard, in which case it is called alopecia areata barbae.<ref name=draelos/>
* If the person loses all the hair on the scalp, the disease is then called [[alopecia areata totalis]].<ref name=NIH2016/>
* If all body hair, including [[pubic hair]], is lost, the diagnosis then becomes [[alopecia areata universalis]].<ref name=NIH2016/>
Alopecia areata totalis and universalis are rare.<ref name=WebMD>{{cite web | url = http://www.webmd.com/skin-problems-and-treatments/alopecia-areata | title = Skin Conditions: Alopecia Areata | archive-url = https://web.archive.org/web/20071217145113/http://www.webmd.com/skin-problems-and-treatments/alopecia-areata | archive-date=17 December 2007 | work = WebMD | access-date = 2 December 2007 }}</ref>