Alopecia classification: Difference between revisions
Jump to navigation
Jump to search
No edit summary |
|||
| Line 1: | Line 1: | ||
__NOTOC__ | __NOTOC__ | ||
{{Alopecia}} | {{Alopecia}} | ||
{{CMG}} | {{CMG}} | ||
==Overview== | ==Overview== | ||
Alopecia is classified as either scarring or non-scarring. | Alopecia is classified as either scarring or non-scarring. | ||
==Classification== | ==Classification== | ||
===Hair Classification=== | ===Hair Classification=== | ||
*[[Anagen]]: growth phase, lasts 2-3 years (80-90% of follicles at any given time) | *[[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) | *[[Catagen]]: involutional phase, lasts 2-3 weeks (1-3% of follicles) | ||
| Line 20: | Line 15: | ||
*[[Vellus hair]]s: smaller in caliber and length, less pigmented | *[[Vellus hair]]s: smaller in caliber and length, less pigmented | ||
*Indeterminate hairs: size/length between that of terminal and vellus hairs | *Indeterminate hairs: size/length between that of terminal and vellus hairs | ||
===Disease Classification=== | ===Disease Classification=== | ||
| Line 85: | Line 79: | ||
==References== | ==References== | ||
{{Reflist|2}} | {{Reflist|2}} | ||
{{WikiDoc Help Menu}} | |||
{{WikiDoc Sources}} | |||
[[Category:Primary care]] | |||
[[Category:Disease]] | |||
[[Category:Dermatology]] | |||
Revision as of 19:53, 13 March 2013
|
Alopecia Microchapters |
|
Diagnosis |
|---|
|
Treatment |
|
Case Studies |
|
Alopecia classification On the Web |
|
American Roentgen Ray Society Images of Alopecia classification |
|
Risk calculators and risk factors for Alopecia classification |
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Overview
Alopecia is classified as either scarring or non-scarring.
Classification
Hair Classification
- 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)
- Telogen: resting phase, lasts 3-4 months (5-10% of follicles)
- Hair released from shaft and shed at end of telogen new cycle begins
- Mature root sheath of telogen hair = “club” at proximal end
- Terminal hairs: large shaft diameters, bulbs extend into subcutaneous fat
- Vellus hairs: smaller in caliber and length, less pigmented
- Indeterminate hairs: size/length between that of terminal and vellus hairs
Disease Classification
Non Scarring
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)
- Stressful 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 1/1000
- 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 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 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 hairs present in areas of absent terminal hairs
- 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 lesions elsewhere on body