Hair Flashcards
3 hair types
Lanugo
Vellus
Terminal
What is Lanugo hair
fine long hairs covering a foetus
shed about 1 month before birth
What is Vellus hair
short fine hairs covering most of body surface
replace lanugo hairs
What is Terminal hair
long course hairs e.g. scalp and pubic area
growth influenced by androgen levels
Location of sebaceous glands in hair follicle unit
Lie adjacent to hair follicle and open up into follicle to secrete sebum for lubrication
Role of arector pili muscle
contraction makes hair stand on end
What are the 3 phases of the hair cycle
Anagen
Catagen
Telogen
What is the anagen phase of the hair cycle
growing phase
How long does the anagen phase last for
2-6 years scalp
1-6 months eyebrows and eyelashes
What is the catagen phase of the hair cycle
Transitional phase
What is the telogen phase of the hair cycle
Resting phase
How many hairs is it normal to lose/day
50-150
Is hair growth synchronised in humans
No -asynchronous
List 7 causes of generalised hair loss
- Telogen effluvium
- Endocrine e.g. thyroid
- Drugs
- Iron deficiency
- Diffuse alopecia areata
- Malnutrition
- Androgenetic alopecia
Localised hair loss can be split into what 2 categories
Scarring and non-scarring
List 5 causes of scarring localised alopecia
- burns
- kerion
- Cutaneous discoid lupus erythematous
- Lichen planus
- Frontal fibrosing alopecia
List 5 causes of non-scarring localised alopecia
- Alopecia areata
- Androgenetic
- trichotillomania
- Traction alopecia
- Tinea capitis
What investigations are carried out for hair loss
Skins craping and hair pluckings
Wood’s lamp (?tinea)
Scalp biopsy and IMF (?inflammatory cause)
Blood tests (?systemic cause)
What is alopecia areata
A non-scarring localised alopecia that is autoimmune caused
Autoimmune disorders associated with alopecia areata
T1DM, autoimmune thyroiditis
Presentation of alopecia areata
well-demarcated areas of hair loss
no scarring
“exclamation hair”
What is “exclamation hair”
seen in alopecia areata
hair is dark and thick distally, loses pigmentation towards the follicle and the follicle itself is a dark spot, so giving the appearance of an exclamation mark
Treatment of alopecia areata
None
Topical/Systemic steroids
PUVA
How long can hair take to grow back in alopecia areata
Months to years
What is alopecia totalis
Whole scalp hair loss
What is alopecia universalis
Whole body hair loss
What is trichotillomania
A non-scarring localised alopecia caused from pulling of hair
Presentation of trichotillomania
unilateral, sharply demarcated hair loss
small fine hair regrowth
underlying psychological problem
What is tinea capitis
Scalp ringworm
Presentation of tinea capitis
non-scarring localised alopecia
with erythematous, scaly patch on scalp
Ix for tinea capitis
skin scarpings
hair pluckings
Wood’s lamp
Tx of tinea capitis
Griseofulvin - oral anti-fungal (the only one licensed for children)
What is Kerion
Inflammatory tinea capitis, where the patient has a hypersensitivity reaction to the fungus
Presentation of Kerion
painful, boggy mass on scalp
+/- lymphadenopathy
scarring localised alopecia
What is cutaneous discoid lupus erythematosus (CDLE)
a scarring chronic inflammatory skin disease that can present elsewhere other than hair
Ix for CDLE
skin biopsy with DIF
Mx CDLE
- photoprotection,
potent topical steroids,
hydroxychloroquine
What is androgenetic hair loss
generalised hair loss seen in post menopausal women or women with high androgen levels developing male pattern baldness
Ix for androgenetic hair loss
hormone levels, iron, zinc
Mx androgenetic hair loss
Minoxidil (Regaine)
Anti-androgens
Wig
What is hirsutism
androgen dependent hair growth i.e. male growth pattern
Causes of hirsutism
familial/constitutional adrenal hyperplasia or tumour PCOS pituitary hyperprolactinaemia iatrogenic - glucocorticoids, danazol
What is hypertrichosis
Excessive hair growth in non-androgenic distribution
Drugs causing hypertrichosis
Minoxidil
Phenytoin
Ciclosporin
