Pathophys-Day 3 Hair Flashcards
How long does the anagen hair phase last?
1-5 years
How long does the telogen hair phase last?
3 months
When does hair grow fastest and slowest?
Summer, winter
Approx what percentage of hair is in the anagen phase?
90%
Pathogenesis of Androgenic alopecia
Miniaturization of hairs with transformation of large terminal follicles to small vellus follicles (visible to invisible)
Describe the progression of male pattern baldness
Frontotemporal + vertex recession
Describe the progression of female pattern baldness
Retain frontal hairlines, but decreased density on crowns
Compare onset of male and female alopecia
Female delayed compared to males. 25-35 onset for women while 10 yrs younger for men
What should one do to confirm a diagnosis of androgenic alopecia?
Check DHEAS and testosterone blood levels
What is the inheritance pattern of androgenic alopecia?
AD or multifactorial
Tx for androgenic alopecia?
Minoxidil
Antiandrogens - finasteride
Hair transplants
Minoxidil MOA
Inducing anagen or inc anagen duration
Inc hair diameter
5% is best
Finasteride (Propecia) MOA
Type II 5-a-reductase inhibitor (conversion of testosterone into 5-DHT)
Finasteride AEs
Lingering sexual side effects even after therapy
Telegen effluvium pathogenesis
Premature switch from anagen into telogen results in shedding 20-35% of hair
Normally, how many hairs per day after shed?
100
Telegen effluvium presentation
6 wks - 3 mo after precipitating cause
Inc hair pull
Regrows within 6-12 months
What are some potential causes of telogen effluvium?
Birth Fever Surgery Drugs Autoimmune Trauma Infections Emotional Trauma
Treatment for telogen effluvium?
2% minoxidil
Anagen effluvium pathogenesis
Acute, extreme alteration of growth of anagen hair resulting in 80+% hair loss 1-2 weeks after cause
Chemo
Mercury
Thalium
Anticoagulants
How does drug alopecia present?
telogen effluvium, on scalp but can affect other hair
often over ears
What pattern of hair loss does alopecia areata cause?
Circular areas of complete hair loss with normal scalp
Can even progress to loss of all scalp hair and all body hair
What does alopecia areata show on biopsy?
‘Swarm of bees’ - lymphocytes around hair bulb
Alopecia areata prognosis and tx
hair may grow back white and change curly/straight
hair regrows
Alopecia areata treatment
Topical steroids; anthralin, minoxidil, immunotherapy
Traction alopecia pathogenesis and appearance
Rollers, weaves, perms, etc.
Peripheral fringe! Can scar if bad
Traction alopecia complications and tx
S aureus folliculitis
Dermatophyte infection
Tx: stop cause
What organism usually causes folliculitis?
S aureus
Folliculitis treatment
Oral antibiotics
Consider MRSA
Shampoos
Secondary syphillis appearance, dx?
Moth-eaten
Rapid plasma antigen test +
When a patient complains of hair loss, what should you do/check/order?
Physical exam - scalp disease
CBC (anemia)
Ferritin
TSH
