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__NOTOC__
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{{Alopecia}}
{{Alopecia}}
{{CMG}}
 
{{CMG}}; {{AE}} [[Ogechukwu Hannah Nnabude, MD]]
 
==Overview==
==Overview==
Alopecia is classified as either scarring or non-scarring.
 
Alopecia can be subdivided into two main categories: non-scarring and scarring.
 
==Classification==
==Classification==


===Hair Classification===
'''The six major categories of non-scarring alopecia are''':
*[[Anagen]]: growth phase, lasts 2-3 years (80-90% of follicles at any given time)
 
*[[Catagen]]: involutional phase, lasts 2-3 weeks (1-3% of follicles)
* '''Alopecia areata''': this can affect any part of the body. When it affects only a portion of an area of the body, it is called alopecia areata. When it affects the entire site, it is called alopecia totalis. When it involves the whole body, it is called alopecia universalis. The etiology is unknown, but it might be related to an autoimmune disease.<ref name="pmid30502419">{{cite journal| author=Lee YB, Jun M, Lee WS| title=Alopecia areata and poliosis: A retrospective analysis of 258 cases. | journal=J Am Acad Dermatol | year= 2019 | volume= 80 | issue= 6 | pages= 1776-1778 | pmid=30502419 | doi=10.1016/j.jaad.2018.11.033 | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=30502419  }} </ref>
*Telogen: resting phase, lasts 3-4 months (5-10% of follicles)
 
**Hair released from shaft and shed at end of telogen new cycle begins
* '''Androgenetic alopecia''': is a pattern of hair loss that is affected by the hormones and genes.
**Mature root sheath of telogen hair = “club” at proximal end
 
*[[Terminal hair]]s: large shaft diameters, bulbs extend into subcutaneous fat
* '''Telogen effluvium''': results from shifting of hair growth cycle from the anagen phase towards the telogen phase. It may result from an illness like hypothyroidism or hyperthyroidism. Also, it can arise from stress like major surgery or severe psychological stress <ref name="pmid26833522">Nalluri R, Harries M (2016) [https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&retmode=ref&cmd=prlinks&id=26833522 Alopecia in general medicine.] ''Clin Med (Lond)'' 16 (1):74-8. [http://dx.doi.org/10.7861/clinmedicine.16-1-74 DOI:10.7861/clinmedicine.16-1-74] PMID: [https://pubmed.gov/26833522 26833522]</ref>. Other causes include drugs, crash diet, poor feeding. <ref name="pmid30502414">Liu LY, King BA (2019) [https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&retmode=ref&cmd=prlinks&id=30502414 Response to tofacitinib therapy of eyebrows and eyelashes in alopecia areata.] ''J Am Acad Dermatol'' 80 (6):1778-1779. [http://dx.doi.org/10.1016/j.jaad.2018.11.037 DOI:10.1016/j.jaad.2018.11.037] PMID: [https://pubmed.gov/30502414 30502414]</ref>
*[[Vellus hair]]s: smaller in caliber and length, less pigmented
 
*Indeterminate hairs: size/length between that of terminal and vellus hairs
* '''Traumatic alopecia''': This results from forceful traction of the hair. It is commonly seen in children and is similar to traction alopecia. Also, trichotillomania is a type of traumatic alopecia in which the patient pulls on his/her hair repeatedly. <ref name="pmid30501438">{{cite journal| author=Chen P, Chen F, Zhou B| title=The risk of dermatological toxicities of combined BRAF and MEK inhibition versus BRAF inhibition alone in melanoma patients: a systematic review and meta-analysis. | journal=Cutan Ocul Toxicol | year= 2019 | volume= 38 | issue= 2 | pages= 105-111 | pmid=30501438 | doi=10.1080/15569527.2018.1553180 | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=30501438  }} </ref>
===Disease Classification===
 
* '''Tinea capitis''': the classical kind of tinea capitis (black-dots) causes non-scarring hair loss, unlike other types like kerion and favus.
 
* '''Anagen effluvium''': This is hair shedding that occurs during the anagen phase of the cell cycle. Seen in cancer patients who are receiving chemotherapeutic agents.
 
'''Scarring alopecia is divided into three major types''':
 
* Tinea capitis: This is the inflammatory variety of tinea capitis (favus) or kerion, which is when the fungi causes abscess formation, may culminate with scarring alopecia.
 
* Alopecia mucinosa: This occurs when mucinous material accumulates in the hair follicles and the sebaceous glands. The mucinous material causes an inflammatory response that hinders the growth of hair.
 
* Alopecia neoplastica: This occurs when there is metastatic infiltration of the scalp hair with malignant cells.


'''Non Scarring'''<br>
Other causes of hair loss that occurs with scarring or inflammation include systemic lupus erythematosus, radiation therapy, and sarcoidosis.<ref name="pmid26833522">{{cite journal| author=Nalluri R, Harries M| title=Alopecia in general medicine. | journal=Clin Med (Lond) | year= 2016 | volume= 16 | issue= 1 | pages= 74-8 | pmid=26833522 | doi=10.7861/clinmedicine.16-1-74 | pmc=4954340 | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=26833522 }} </ref> <ref name="pmid26476248">Vary JC (2015) [https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&retmode=ref&cmd=prlinks&id=26476248 Selected Disorders of Skin Appendages--Acne, Alopecia, Hyperhidrosis.] ''Med Clin North Am'' 99 (6):1195-211. [http://dx.doi.org/10.1016/j.mcna.2015.07.003 DOI:10.1016/j.mcna.2015.07.003] PMID: [https://pubmed.gov/26476248 26476248]</ref> Diagnosis of hair loss is partly based on the areas affected. <ref name="pmid26476248">Vary JC (2015) [https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&retmode=ref&cmd=prlinks&id=26476248 Selected Disorders of Skin Appendages--Acne, Alopecia, Hyperhidrosis.] ''Med Clin North Am'' 99 (6):1195-211. [http://dx.doi.org/10.1016/j.mcna.2015.07.003 DOI:10.1016/j.mcna.2015.07.003] PMID: [https://pubmed.gov/26476248 26476248]</ref>
''Diffuse''
*[[Androgenetic alopecia]]
**Most common (30-40% of men and women)
**Genetically determined:  [[polygenic]] with [[variable penetrance]]
**Shortening of anagen phase, follicular miniaturization
**Men: M-shaped pattern along frontal hairline (temporal loss progresses to midscalp)
**Women:  more diffuse, can be difficult to distinguish from telogen effluvium
*[[Telogen effluvium]]
**Reversible loss of mature, terminal hairs (few hundred per day)
**[[Stress]]ful event (or [[medication]]) triggers transition of more anagen hairs into telogen phase
***[[Childbirth]], [[fever]], severe [[infection]], severe [[psychologic stress]], major [[surgery]], [[crash diet]]
***[[Drugs]]: [[heparin]], [[antithyroid agents]], [[anticonvulsants]], [[hormones]]
**Diffuse hair loss peaks 3-4 months after inciting event
**Up to 30% of hairs must be lost before cosmetically apparent
*Anagen effluvium
**Acute loss of anagen hair = 80-90% of hair
**Occurs 10-14 days after treatment with [[antimitotic agents]] ([[chemo]])
''Focal''
*[[Alopecia areata]]: incidence 100 in 100,000
**Smooth, discrete, circular areas of complete hair loss occurring over a few weeks
**Exclamation point hairs:  hair root narrower than normal with less pigment
**Can occur on any hair-bearing area; nails may also have proximal pitting
**Usually reversible: regrowth occurs over several months; 90% regrow within 2 years
**Relapse occurs in up to 1/3
**Decreased chance of regrowth/increased risk relapse if:
***Prepubertal onset
***Widespread involvement ([[alopecia totalis]] or [[Alopecia universalis|universalis]])
***Duration > 5 years
***History of [[atopy]]
**Possible [[autoimmune]] mechanism:  bx shows [[T-cell]] infiltrates around hair follicles
**Positive [[family history]] in 20%
*[[Syphilis]]
**Moth-eaten, patchy pattern of loss (may be diffuse)
**May be associated with [[skin lesions]] of [[secondary syphilis]], or may occur in [[Latent syphilis|latent stage]]
**Full hairgrowth occurs after treatment of [[infection]]
*[[Trauma]]
**[[Traction alopecia]]:  due to hairstyles that impose chronic tension on hair (braids)
**Hair loss most prominent in areas of greatest tension (margins)
**Fine, [[vellus hair]]s present in areas of absent [[terminal hair]]s
**Regrowth can occur in early disease (few months-yrs), but not in late disease (years)
**Chemical trauma: repeated use of [[lye]]-containing straightening agents or hot oils for styling
**[[Trichotillomania]]: bizarre, asymmetric pattern of broken hairs of varying length
'''Scarring'''
*Uncommon; hair loss is permanent
*Erythematous papules, [[pustules]], or scaling centered around follicles
*[[Polytrichia]] = multiple hair shafts exiting a single enlarged orifice
*Eventual obliteration of follicular orifices
*[[Tinea capitis]]
**Scaling and [[inflammation]] in patchy areas of hair loss, +/- [[lymphadenopathy]]
**Usually in children
**KOH prep positive
*Central, centrifugal scarring alopecia (a.k.a. [[follicular degeneration syndrome]], pseudopelade)
**Symmetric involvement of central portion of scalp with outward expansion over months/yrs
**May be associated with pustules (folliculitis decalvans)
**Cause unknown-> emipiric [[Rx]] with [[steroids]], [[antibiotics]]
*[[Discoid lupus]]
**[[Inflammation]] with plugged follicles, scale, abnormal scalp pigmentation
**May have discoid [[lesion]]s elsewhere on body


==References==
==References==

Revision as of 01:16, 12 December 2020


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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Ogechukwu Hannah Nnabude, MD

Overview

Alopecia can be subdivided into two main categories: non-scarring and scarring.

Classification

The six major categories of non-scarring alopecia are:

  • Alopecia areata: this can affect any part of the body. When it affects only a portion of an area of the body, it is called alopecia areata. When it affects the entire site, it is called alopecia totalis. When it involves the whole body, it is called alopecia universalis. The etiology is unknown, but it might be related to an autoimmune disease.[1]
  • Androgenetic alopecia: is a pattern of hair loss that is affected by the hormones and genes.
  • Telogen effluvium: results from shifting of hair growth cycle from the anagen phase towards the telogen phase. It may result from an illness like hypothyroidism or hyperthyroidism. Also, it can arise from stress like major surgery or severe psychological stress [2]. Other causes include drugs, crash diet, poor feeding. [3]
  • Traumatic alopecia: This results from forceful traction of the hair. It is commonly seen in children and is similar to traction alopecia. Also, trichotillomania is a type of traumatic alopecia in which the patient pulls on his/her hair repeatedly. [4]
  • Tinea capitis: the classical kind of tinea capitis (black-dots) causes non-scarring hair loss, unlike other types like kerion and favus.
  • Anagen effluvium: This is hair shedding that occurs during the anagen phase of the cell cycle. Seen in cancer patients who are receiving chemotherapeutic agents.

Scarring alopecia is divided into three major types:

  • Tinea capitis: This is the inflammatory variety of tinea capitis (favus) or kerion, which is when the fungi causes abscess formation, may culminate with scarring alopecia.
  • Alopecia mucinosa: This occurs when mucinous material accumulates in the hair follicles and the sebaceous glands. The mucinous material causes an inflammatory response that hinders the growth of hair.
  • Alopecia neoplastica: This occurs when there is metastatic infiltration of the scalp hair with malignant cells.

Other causes of hair loss that occurs with scarring or inflammation include systemic lupus erythematosus, radiation therapy, and sarcoidosis.[2] [5] Diagnosis of hair loss is partly based on the areas affected. [5]

References

  1. ↑ Lee YB, Jun M, Lee WS (2019). "Alopecia areata and poliosis: A retrospective analysis of 258 cases". J Am Acad Dermatol. 80 (6): 1776–1778. doi:10.1016/j.jaad.2018.11.033. PMID 30502419.
  2. ↑ 2.0 2.1 Nalluri R, Harries M (2016) Alopecia in general medicine. Clin Med (Lond) 16 (1):74-8. DOI:10.7861/clinmedicine.16-1-74 PMID: 26833522
  3. ↑ Liu LY, King BA (2019) Response to tofacitinib therapy of eyebrows and eyelashes in alopecia areata. J Am Acad Dermatol 80 (6):1778-1779. DOI:10.1016/j.jaad.2018.11.037 PMID: 30502414
  4. ↑ Chen P, Chen F, Zhou B (2019). "The risk of dermatological toxicities of combined BRAF and MEK inhibition versus BRAF inhibition alone in melanoma patients: a systematic review and meta-analysis". Cutan Ocul Toxicol. 38 (2): 105–111. doi:10.1080/15569527.2018.1553180. PMID 30501438.
  5. ↑ 5.0 5.1 Vary JC (2015) Selected Disorders of Skin Appendages--Acne, Alopecia, Hyperhidrosis. Med Clin North Am 99 (6):1195-211. DOI:10.1016/j.mcna.2015.07.003 PMID: 26476248

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