Alopecia areata (AA) is thought to be an autoimmune disorder and may be associated with other autoimmune conditions such as pernicious anaemia, vitiligo, Hashimoto's thyroiditis or diabetes mellitus.
Cytokines, which reject the hair, are released by lymphocytes around the hair follicles. Patients often complain of sudden onset of patchy hair loss on the scalp. It may occur at any age, including childhood. Hair growth will usually return eventually, but intralesional steroids injected into the area affected may encourage regrowth.
Similar patches of hair loss may occur on the face. This may cause particular embarrassment for men if it affects the beard area. It may also affect the eyebrows or, in about 1 per cent of affected patients, all the body hair (alopecia universalis). Close inspection of bare patches may show short, stumpy hairs, known as exclamation mark hairs, which indicate that the condition is still active and that hair loss will continue. Some patches may regrow hair, but other patches of hair loss may still develop.
Tinea capitis is the result of a dermatophyte fungal infection of the scalp. It is usually seen in children, but, as in this case, does occasionally affect adults. A variety of fungi may cause the problem but Microsporun canis, which may affect a pet dog or cat, is a common cause and can be identified with Wood's light when it fluoresces green. The condition may present with dry scaling of the scalp, yellow crusting or inflammation. The scalp might be scaly and hairs broken off at the surface of the scalp may be seen. A skin scraping for microscopy and culture should be taken to confirm the diagnosis.
Scarring alopecia (or cicatricial alopecia) results in destruction of the hair follicles. The change is irreversible and the scarring is therefore permanent. The more common causes of this problem are dissecting cellulitis, folliculitis, lupus erythematosus, lichen planus or cicatricial pemphigoid.
Small patches of hair loss may be symptomless. On examination the scalp may appear normal or show signs inflammation. If suspected, a biopsy should be taken.
Hair regrowth in alopecia areata
Encouraging signs of hair re-growth may be heralded by the appearance of white hairs in the bald patch. This patient subsequently made a complete recovery and the hair later assumed its normal colour.
In 10 per cent of cases there will be complete loss of hair on the scalp and in about 30 per cent of cases this will occur within six months of the first signs of AA. The prognosis in alopecia totalis and those who develop AA in childhood is less good and recovery is less likely to be permanent. This man lost his hair suddenly at the age of 18. Temporary improvement was achieved following a course of oral steroids, however, the condition recurred. This man also had problems of atopic eczema, which often indicates a poorer prognosis.
Treatment of tinea capitis
Tinea capitis should respond well to an oral antifungal agent. Griseofulvin is the most commonly used, both for children and adults. Alternatively terbinafine, itraconazole or fluconazole for four to six weeks may be effective. It is suggested that an additional topical antifungal agent may help to reduce transmission. It is also important to check all contacts, including pet animals, but as some carriers of the condition will have no symptoms it may be advisable to treat the whole family. This woman responded to treatment and her hair had regrown normally eight months later.
Management of scarring alopecia
Once scarring alopecia is established, the balding is permanent. Aggressive early treatment is therefore advised. Possible approaches are topical or intralesional steroids, isotretinoin and/or antibiotics.
The problem in this case was discoid lupus erythematosus, in which hydroxychloroquine may be helpful. Once the alopecia is established and no further hair loss has occurred for some years, surgical hair transplantation or scalp reduction could be considered.