DISORDERS OF HAIR :

HAIR LOSS

Hair loss can be due to a disorder of the hair follicle in which the scalp skin looks normal (non-scarring alopecia) or due to a disorder within the scalp skin that causes permanent loss of the follicle (scarring or cicatricial alopecia). This latter form causes shiny atrophic bald areas in the scalp which are devoid of follicular openings. There are many causes of alopecia (Table 23.15).

Androgenic alopecia

Table 23-15. Causes of alopecia

Scarring alopecia Non-scarring alopecia

Discoid lupus erythematosus Androgenic alopecia

Telogen effluvium

Kerion (tinea capitis) Alopecia areata

Lichen planus

Dissecting cellulitis Trichotillomania (self-induced hair-pulling)

X-irradiation Tinea capitis

Idiopathic ('pseudopelade') Traction alopecia

Metabolic (iron deficiency, hypothyroidism)

Drug (e.g. heparin, isotretinoin, chemotherapy)



Androgenic alopecia (male pattern baldness) is the most common type of non-scarring hair loss and depends on genetic factors and an abnormal sensitivity to androgens. It presents in young men with frontal receding followed by thinning of the crown and there is often a positive family history. It also occurs in females but tends to occur at a later age, be milder and show little in the way of frontal recession. If acne and menstrual disturbance are also present, polycystic ovary syndrome and other endocrine disorders of androgens can be present.

Treatment.

This may not be required. Topical 5% minoxidil lotion or oral finasteride (1 mg daily) can help arrest progression and may cause a small amount of regrowth, providing it is used early in disease but the treatment needs to be continued possibly lifelong. Approximately one-third of patients will not respond to either therapy. Finasteride is a selective inhibitor of 5α-reductase type II and it can cause side-effects in 1% of patients such as loss of libido. It should not be used in females as it can affect the sexual development of a male fetus. However, antiandrogen therapy (e.g. cyproterone acetate or spironolactone) helps some women.

Alopecia areata

Alopecia areata is an immune-mediated type of hair loss. It is associated with other organ-specific autoimmune diseases. It presents in childhood or young adults with patches of baldness. These may regrow to be followed by new patches of hair loss. The presence of broken exclamation mark hairs (narrow at the scalp/wider and more pigmented at the tip) at the edge of a bald area is diagnostic. Regrowth may initially be with white hairs and often occurs slowly over months. Occasionally all of the scalp hair is lost (alopecia totalis) and rarely all body hair is lost (alopecia universalis). The nails may be pitted or roughened.

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Treatment has no effect on the long-term progression. Potent topical or injected steroids are of limited use. Topical immunotherapy with diphencyprone, PUVA or topical 5% minoxidil are occasionally tried but often do not help. Wigs can be provided for severe cases and patient support groups are often beneficial.

Traction alopecia

This refers to the 'mechanical damage' type of hair loss that arises from pulling the hair back into a bun or tight plaiting. It is more common in black Africans.

Telogen effluvium

Telogen effluvium refers to the pattern of diffuse hair loss that occurs some 3 months after pregnancy or a severe illness. It occurs because 'stress' puts all the hairs into the telogen phase of hair shedding at the same time. The hair fully recovers and the normal staggered hair growth/hair shedding cycle resumes within a few months.

Dissecting cellulitis

This is a chronic folliculitis affecting predominantly young black males. It presents with papules and pustules over the occipital region of the scalp with hair loss. If severe, the back of the scalp becomes a boggy swelling (discharging pus) with areas of scarring alopecia. It can be complicated by keloid scar formation ('acne keloidalis nuchae').

Treatment is difficult but prolonged courses of low-dose antibiotics are worth trying in early disease. Prolonged courses of isotretinoin can help a few individuals and deep surgical excision can be used in recalcitrant cases.

INCREASED HAIR GROWTH

Hirsutism (p. 1058)

Hirsutism refers to the male pattern of hair growth seen in females. The racial variation in hair growth must be considered. Certain races (e.g. Mediterranean and Asian) have more male pattern hair growth than northern European females. This is not due to excess androgens but may reflect a genetically determined altered sensitivity to them. If virilizing features (deep voice, clitoromegaly, dysmenorrhoea, acne) are present, one should carry out a full endocrine assessment. Hirsutism can cause severe psychological distress to some individuals.

Treatment involves physical methods such as bleaching, waxing, electrolysis and laser therapy. Antiandrogen therapy is occasionally helpful.

Hypertrichosis

Hypertrichosis refers to the state of excessive hair growth at any site and occurs in both sexes. It can be seen in anorexia nervosa, porphyria cutanea tarda, and underlying malignancy and is caused by certain drugs (e.g. ciclosporin, minoxidil).

FURTHER READING

Barth JH (2000) Should men still go bald gracefully? Lancet 355: 161-162.

MacDonald Hull SP et al. (2003) Guidelines for the management of alopecia areata. British Journal of Dermatology 149: 692-699.

Price VH (1999) Treatment of hair loss. New England Journal of Medicine 341: 964-973.

Wendelin DS et al. (2003) Hypertrichosis. Journal of the American Academy of Dermatology 48: 161-179.