Chapter 69-Alopecia Flashcards
What are the non-scarring alopecias?
Androgenetic Telogen effluvium Alopecia areata Tinea capitis Trichotillomania Anagen effluvium Traction alopecia Pressure alopecia Secondary syphillis
Key features of androgen genetic alopecia?
- Genetically determined sensitivity of scalp hair follicles to adult levels of androgens
- Miniaturization of hairs in a symmetric “pattern” on crown, vertex and frontal regions
Epidemiology of AGA
Increases with age
50% of women by age 70
80% caucasian men
AGA genetics
- strong hereditary component
- polygenic including: androgen receptor, estrogen receptor, aromatase
- others include histone de-acetylase (HDAC 4 and 9) and WNT molecule
Pathway of 5AR and its isotopes
Testosterone–> DHT (dihydrotestosterone) via 5-alpha reductase
3 isoenzymes 5AR
-Type 1–> sebaceous glands and liver
-Type 2–> scalp, beard, chest, liver, prostate
Type 3–>epidermis/dermis (role undetermined
Pathophysiology of AGA?
Increased 5-alpha reductase and DHT levels in hair follicles (including papilla, inner/outer root sheath-type 2) and associated sebaceous glands (type I) in patients with AGA
Leads to miniaturization of hair follicles and shafts
Androgen pathways
Does AGA in pre-pubertal children indicate precocious puberty?
No
PDG-2 and AGA?
Increased PDG-2 and prostaglandin D2-synthetase may be involved (converts PGH2–> PDG-2)
Possible target in AGA
Clinical features AGA-Men
Norwood-Hamilton Classification;
- symmetric, progressive
- frontal/temporal and crown/ vertex
Clinical features Women
Women can get male pattern with fronto-temporal and vertex, but more common
Ludwig classification:
- central thinning vertex and crown
- causes widening of part often frontal predominance–>Christmas tree pattern
- preserve hair line
What does pathology show for AGA?
- Miniaturization of hairs
- Increased vellus hairs and decreased terminal hairs (thick, long, darkly pigmented)
- Normal total number of follicles
- numerous fibrous “streamers”
- fibromucinous tract remnants underneath miniaturized or telogen hairs due to a) miniaturization or anagen–>telogen shift - No inflammation
- Anisotrichosis: increased variability in hair shaft size (due to miniaturization, vellus)
- Shortened anagen phase (increase telogen:anagen ratio)
Anti-androgen drugs pathways
Treatment for male AGA
Topicals
- Topical minoxidil (2 and 5% solution, 5% foam)*
- 5-AR inhibitors: Finasteride (1 mg po daily) (or Dutasteride 0.5 mg po daily)
- Also topical finasteride - PO minoxidil: 1.25-2.5 mg qHS
- On label
Others:
- Hair transplant
- PRP
- Low level light therapy
Counselling/screening prior to 5 alpha reductase inhibitors?
- Side effects
- low libido, decreased ejaculation volume, ED
- “post-finasteride syndrome”
- decreased incidence prostate cancer but if they do get it overall higher grade - PSA check
- Semen check
