alopecia
alopecia
Introduction
- scalp hair biology
- everyone is born with a fixed number of hair follicles on the scalp that produce hairs throughout life.
- unlike other areas of the body, hairs on the scalp to grow in tufts of 3–4
- anagen phase:
- hair grows from the base of the follicle at 1cm/month for about 3yrs
- catagen hair:
- once the hair stops growing it dies but remains in the follicle
- telogen phase:
- this is a dormant phase and lasts some 3 months after which a new hair follicle starts to grow in a new anagen phase and which then pushes out the old dead hair
- some medications may cause alopecia such as:
- chemotherapy agents
- clonidine (Catapres) rarely
- isotretinoin (Roaccutane) rarely
- some nutritional deficiencies may cause alopecia:
- some toxins may cause alopecia:
Patterns of alopecia
- male pattern balding
- female pattern hair loss
- a diffuse thinning of scalp hair has a polygenetic inheritance and affects 40% of women by age 50 and 55% by age 80yrs
- often no cause is found but one should consider:
- thyroid disease
- polycystic ovary syndrome (PCOS) / polyendocrine metabolic ovarian syndrome (PMOS) (although tends to cause general body hirsutism but may cause scalp thinning) or other androgen disorders
- congenital adrenal hyperplasia
- DDx includes chronic telogen effluvium which has a different Mx
- cicatricial alopecia
- hair loss due to scarring of the skin - hair will not regrow once the follicle is destroyed
- tufted folliculitis
- doll's hair-like bundling of follicular units
- surrounding white coloration and scaling around the hair follicles form a “starburst pattern” that is indicative of the fibrosis process
- there are visible blood vessels in between the hair follicles
- treat underlying cause
- may be secondary or primary neutrophilic or lymphocytic depending upon cause
- burns
- trauma
- surgery
- pemphigus
- tinea capitis
- chronic staphylococcal infection
- chronic lupus erythematosus
- lichen planopilaris
- Graham-Little syndrome
- folliculitis decalvans
- acne keloidalis nuchae
- immunobullous disorders
- dissecting cellulitis
- secondary cicatrical alopecia
- burns
- trauma
- skin infections
- recurrent scalp folliculitis / acne necrotica
- primary cicatrical alopecias
- keratosis follicularis spinulosa decalvans
- perifolliculitis capitis abscendens et suffodiens
- neutrophilic scarring alopecias
- folliculitis decalvans
- accounts for ~11% of scarring alopecias in the USA
- an inflammation of the hair follicle that leads to bogginess or induration of involved parts of the scalp along with pustules, erosions, crusts, ulcers, and scale
- begins at a central point and spreads outward, leaving scarring, sores and alopecia
- probably due to Staph aureus as this is found in most cases
- first described by Charles-Eugène Quinquaud in 1888
- usually commences between the late teens and middle adult years and in the US, mainly affects male African Americans
- no curative Rx as yet but combination therapy of Clindamycin and Rifampicin has been useful
- lymphocytic scarring alopecias
- low dose doxycycline 20mg bd as effective and with less side effects than 100mg bd 1)
- frontal fibrosing alopecia
- auto-immune; uniform linear band hair loss along the front and sides of scalp hair margin;
- skin looks pale, shiny, or mildly scarred, without visible hair follicle openings and lacking sunlight damage
- may be preceded by eyebrow thinning (madarosis)
- in men, there may be loss of beard and sideburns as initial sign
- slowly progressive although is self-limiting in most cases after several years. The hair line recedes on average of 1.8-2.6 cm. 2)
- 1st described in Australia in 1994
- incidence is increasing; mainly post-menopausal caucasian women but can affect a wide range of age/sex/ethnicities
- may be associated with: hypothyroidism, contact allergy to fragrances or sunscreen use; systemic lupus erythematosus (SLE), rheumatoid arthritis, androgenetic alopecia
- chronic cutaneous lupus erythematosus
- need to exclude systemic lupus erythematosus (SLE)
- more common in white and African American women, esp. 20-40yr olds
- solitary or multiple variable size lesions occur primarily on sun-exposed areas and on the scalp
- lichen planopilaris
- Graham-Little syndrome
- lichen planus-like skin lesions (probably a variation of this condition)
- patchy cicatricial alopecia of the scalp
- central centrifugal alopecia
- pseudopelade (Brocq)
- a flesh- to pink-colored, irregularly shaped alopecia that may begin in a moth-eaten pattern with eventual coalescence into larger patches of alopecia
- most typical location for the first lesion is the vertex. The eyebrows and beard may be impacted
- alopecia areata
- sudden appearance of one or more round areas of hair loss
- aka autoimmune alopecia
- affects 1-2% of people over their lifetime and starts in childhood in 50% and before the age of 40yrs in 80%
- appears to have an auto-immune causation and a genetic basis with at least 8 genes detected
- it may be precipitated by viral infection, trauma, hormonal change, or stress
- may be caused by immunodeficiencies such as common variable immunodeficiency (CVID) and coeliac disease
- DDx includes fungal infections such as tinea capitis
- alopecia totalis
- as with alopecia areata but involves the whole scalp and affects 5% of patients with autoimmune alopecia
- alopecia universalis
- as with alopecia areata but involves the whole body and affects 1% of patients with autoimmune alopecia
- tricotillomania
alopecia.txt · Last modified: 2026/02/15 10:15 by gary1