Alopecia

Overview

Hair grows in small clusters of 3-4 hairs per follicle unit. Hair grows through 3 phases. The follicle can move through this process and back again based on hormonal signalling. Normally, an individual loses about 50 – 100 hairs per day

Phases of hair growth

Phase of hair growth	Description	Duration
Anagen	The main period of hair growth. Old hair is shed and new hair starts to grow. 92 % of hairs are in anagen at any time.	3 – 6 years
Catagen	Slowing down or starting up	2 – 3 weeks
Telogen	Hair that is not currently growing	3 – 4 m

• Signs of abnormal hair loss
  • Hair on the pillow in the morning
  • Clogged drain after a shower

Classification of alopecia: Cicatricial (scarring) vs non-cicatricial (non-scarring

Types of alopecia	Examples
Primary cicatricial alopecia	Lichen planopilaris, discoid lupus
Secondary cicatricial alopecia	Fungal infection, sarcoidosis, metastatic cancer, burns
Primary non-scarring	Anagen enfluvium, telagen, androgenic alopecia, alopecia areata, trichotillomania, tractional alopecia, non-inflammatory tinea capitis
Secondary non-scarring	SLE, secondary syphilis, hypo/hyperthyroidism, hypopituitarism/

Telogen Effluvium

Telogen effluvium is non-scarring hair loss characterized by a greater proportion of hairs that are in telogen. It commonly occurs after periods of stress (childbirth, blood loss, high fevers and major bone fractures). Hair loss is noted when patients enter the recovery phase, as the hair follicles re-enter anagen growth phase and old hair is shed. It is commonly seen in women since they keep their hair longer. Self-limited and resolves with time.

Anagen effluvium

Anagen effluvium is non-scarring hair loss that occurs when the growth phase (anagen) is disrupted. It is reversible with hair regrowing 3 – 6 months after stopping the cause.

• Causes
  • Chemotherapy
  • Radiation therapy to the head
  • Toxins
  • Infection
• Signs and symptoms
  • Diffuse hair loss
  • Hair loss that begins 7 – 14 days after treatment

Alopecia Areata

Alopecia areata is an autoimmune, non-scarring, localised hair loss. Hair loss in alopecia areata is not always complete. It is commonly caused by tinea capitis.

• Areas involved
  • Scalp
  • Beard area (In men, this is a more common presentation than on the scalp. Sometimes mistaken for an area of depigmentation)
  • Eyelashes
• Signs and symptoms
  • Exclamation mark hairs: usually seen at the edge of an area of the alopecia. A sign of ongoing disease activity. The hair has started to grow, but this has set off inflammation around the follicle and as the hair grows, the inflammation continues and the hair becomes thinner and thinner until it falls out
  • Yellow dots (follicles without hairs) in the affected area
  • Nail pitting (much less obvious than those seen in psoriasis – not as deep, often from lines)
• Treatment
  • Topical corticosteroids
  • Intralesional corticosteroids
  • Short term systemic corticosteroids
  • Topical immunotherapy (DCP – diphenylcyclopropenone)
  • Phototherapy – PUVA
  • Lase

Androgenic alopecia

Androgenic alopecia is AKA “baldness”. Women actually lose hair at about the same rate as men. However, they don’t lose it in a male pattern – but more generally, female pattern hair loss

About 25% of women have cosmetically significant androgenetic alopecia by the age of 40

• Signs and symptoms
  • Hairs become thinner
• Treatment of female pattern hair loss
  • No cure
  • Often just a case of slowing natural progression
  • Topical minoxidil +/- tretinoin
  • Oral antiandrogens (e.g. spironolactone e.g. 25mg – 100mg BD. Can cause menstrual irregularities at higher doses. Oral contraceptives may be an appropriate alternative. Can be used in combination with spironolactone)
  • Finasteride used occasionally but often not very effective in women
• Treatment of male pattern baldness
  • Finasteride is mainstay of treatment. Other anti-androgen are associated with a high risk of side effects
    • Need to use for 6-12 months to notice an improvement
    • 1% of patients will get gynaecomastia or impotence
    • Can be started as young as age 16
    • Be wary of Family history of early onset prostate cancer. Finasteride makes PSA unreliable
  • Minoxidil – orally 0.5mg – often compounded with spironolactone
    • Can cause excess hair growth at other sites (e.g. hairier arms and chests)
  • Topical minoxidil
    • 30% will have moderate re-growth
    • 30% will slow hair loss
    • 30% will not make any difference
    • Need to use it for more than 6 months
    • Mechanism – moves hair follicles into anagen. Follicles will only remain in anagen whilst on the minoxidil!
  • If doing a biopsy of the scalp – needs to be at least 4mm, and >1 biopsy is useful for the pathologist (and often may need >1 biopsy for a diagnosis)