Classification of Alopecia

A..Scarring alopecia

Also known as cicatricial alopecia,is hair loss that can occure as a result of complications from another condition. In this type of alopecia the hair follicle is completely destroyed. Conditions that can cause scarring alopecia are:

a.  Growth disorders and inherited diseases(epidermal nevi-darier disease)etc

b . Damages from natural causes ( mechanical trauma-burns ) etc

c.  Infections microbial or viral

d.  Neoplasia

e.  Various other skin diseases of unknown etiology. 

B..Non -scarring alopecia



Physiologic alopecia: daily hair loss 50-150 hairs(NORMAL) ,as a result of reaction of the hair folicles to seasonal environmental influences.

Androgenic alopecia: (male- and female-pattern baldness):Most common cause of hair loss
Localized and systemic hair loss, which usually begins with the frontoparietal scalp and then the vertex
Male-pattern baldness in females is indicative of androgen excess and may be accompanied by hirsutism in mild cases and virilization in more serious ones
Female-pattern baldness is similar but more diffuse, usually without complete baldness and maintaining the frontal hairline

Alopecia areata:Second most common presentation of nonscarring alopecia
Hair is rapidly lost in circular or oval patches or less commonly, may be diffuse involving the scalp
May include facial or body hair
May be episodic or persistent

Telogen effluvium:Diffuse alopecia following a triggering event, such as surgery, childbirth, emotional stress, hormonal fluctuations, or medication use
Hair loss occurs approximately 3 months after the event
Usually affects less than 50% of the scalp
Recovery is often complete once triggering factor is resolved 

Anagen effluvium:Diffuse hair loss that occurs as a result of exposure to certain toxins
Following toxic exposure, hair growth is abruptly interrupted and anagen hair is shed after 1 to 4 weeks
Rapidly affects 80% to 90% of the scalp
Complete recovery can be expected once triggering factor are  removed 

Traction alopecia:Hair loss that is caused by direct insult to hair
Associated with such styling techniques as using hot rollers or braiding
Pattern of hair loss may relate directly to technique used
More common in black patients
If continued, may progress to scarring alopecia 

Trichotillomania (subtype of traction alopecia):Self-inflicted loss of hair, typically from frontoparietal region progressing backwards

Regrowth of up to 1.5 cm may also be visible before hair is long enough to pull again

Tinea capitis:Fungal infection that causes hairs to break off close to the scalp leaving a 'black dot' effect
Often a result of a secondary bacterial infection
Scalp is intensely pruritic or painful
Predominantly affects children; more commonly, inner city African populations 

Alopecia neoplastica:Hard nodules/tumors or flat unchanged skin with loss of hair
Can be secondary to primary skin cancer of scalp or metastatic tumor 

Alopecia mucinosa: A form of localized hair loss sometimes seen in patients with mycosis fungoides, but may occur alone