ALOPECIA

Table of content

• Alopecia Areata
• Androgenetic Alopecia
• TELOGEN EFFLUVIUM
• Postpartum Effluvium
• Anagen effluvium
• TRICHTILLOMANIA
• Scaring Alopecia

Alopecia

Dr Sami Aldaham

Hair Biology

Hair Follicle Components (4 MM)

• Sebaceous Gland
• Arrector Pili Muscle
• Bulge
• Hair Bulb
• Follicular Papilla

Hair Follicle Components

Hair Types

1. Vellous: A. in the whole body B. bright in color C. thin, and short.

2. Terminal: A. Thick hair like the hair on the: B. scalp, eyebrow, axilla.

3. Androgen dependant terminal: In the androgen dependent areas as axilla, groin.

HAIR TYPES

Fetal hair -

• Lanugo hair : soft, fine, lightly pigmented hairs.

Adult hair -

• Vellus hair : fine hairs cover most of the bodyof youngsters and adults.
• Terminal hair: long, coarse, pigmented hairs with larger diameters.

NUMBER OF HAIRS

Scalp : about 1,00,000 hairs. Face : about 600 hairs /cm². Rest of the body : about 60 hairs/cm².

LENGTH, WIDTH AND GROWTH RATE

Length : range from <1mm to > 1 meter. Average uncut scalp hair : 25 – 100 cm.

Width : from 0.005 to 0.06mm. Growth rate: about 1 cm/ month (terminal hair).

FUNCTIONS

1. Protects body surface from external injury.
2. Helps in sensory function. 3. Psycho – social importance. 4. Forensic importance.
   • i. Identification of race, sex, age and religion.
   • ii. Cause of death- can be determined.
   • iii. Time of death- can be determined.
3. Assist thermo- regulation: mainly in lower animals.

HAIR CYCLE

It is believed that each hair follicle goes through 10-20 hair cycle in a life time. There are four phases-

1. Anagen : growing phase.
2. Catagen: involuting phase. transition into quiescence
3. Telogen : resting phase.

The hair cycle is divided into 3 stages:

1. Anagen (growth phase):
   • 70-80% of the hair follicle is in this phase.
   • The length of this phase determines the length of the hair.
   • The average is 3 years in the scalp
2. Catagen (resting phase)
   • 5% of the hair is present in this phase (the least).
   • It last for 3 weeks
3. Telogen (shedding phase):
   • 15% of the hair is in this phase
   • shortening of the hair & the epidermal papillea atrophies.
   • And then the hair starts to grow in the Anagen phase.
   • It last for 3 months and normally the person loss 150 hair a day
   • So any disturbance in this cycle will result in the hair disease

ANAGEN (GROWING PHASE)

➤Last for about 1000 days. ➤Follicular cells grow, divide and become keratinized to form growing phase. ➤A darkly pigmented portion is evident just above the hair bulb.

CATAGEN

• Lasts for about 10 days.
• Scalp hairs show a gradual thinning and decrease of the pigment.
• Melanocytes cease producing melanin.

TELOGEN

• Lasts for about 100 days.
• Club-shaped proximal end shed from the follicle during telogen or subsequent anagen.
• Growth of a new anagen hair leads to shedding of any remaining telogen hair.
• But new hair does not “push out” the hair from the previous cycle.

Scarring vs Non-Scarring Alopecia

Alopecia

• Non-Scarring (Reversible) - ✓
• Scarring (Irreversible) - ✗

Non-scarring vs Scarring Alopecia Explained

1. Non-scarring alopecia (reversible):
   • The skin is normal, so there is hope for the hair to grow again and it is treatable.
   • It is called non-scarring because there is no fibrosis.
   • In this type the hair follicles are Intact
2. Scarring alopecia (irreversible):
   • There is fibrosis and severe inflammation,
   • there is no hope for hair re-growth
   • In this type the hair follicles are damaged

NB : How to differentiate between them clinically ? By looking for ( hair ostia ) by the scope→ if they intact then the alopecia is Non scaring and vise versa

Causes of non-scarring alopecia

1. Telogen effluviu : post- pregnancy, post-medication.
2. Anagen effluvium: It occurs after chemotherapy.
3. Alopecia Areata: Loss of hair in a well defined area
4. Androgenetic alopecia: more in male.
5. Hair shaft abnormality: Due to a genetic disease.
6. Trauma: Some people when they are in stress they pull their hairs.
7. Infectious disorder: e.g. Tinea pedis could be scarring or non- scarring ( more usually ). If there is inflammation, then there is scarring.
8. Infections: Severe infections.

Causes of scarring alopecia

1. Neoplastic disorders: Basal Cell Carcinoma.
2. Trauma: 2nd & 3rd degree burns.
3. Lichen planus: It’s a common cause of scarring hair loss.
4. Discoid lupus erythematosus

Hair Excess

1. Hirsutism
2. Hypertrichosis