What is paediatric alopecia areata?
Paediatric alopecia areata is an autoimmune form of nonscarring hair loss defined as being in childhood if the onset is by 10 years of age, or adolescence if between 11 and 20 years.
Who gets paediatric alopecia areata?
Alopecia areata is common worldwide, affecting all races and both sexes. Approximately 2% of the general population will have alopecia areata at some point in their lives, and 60% of them will develop their first patch of hair loss before the age of 20 years. Prevalence peaks between 10 and 30 years of age. Large series have suggested paediatric-onset alopecia areata is more common in girls than boys, but is more severe in boys. Congenital alopecia areata has been reported.
Alopecia areata developing in the first ten years of life is strongly associated with atopic dermatitis (approximately one-third) and lupus erythematosus. In the teenage years, psoriasis and rheumatoid arthritis are also associated. Thyroid disease and other autoimmune conditions are not detected at increased incidence in children with alopecia areata, in contrast with adult-onset disease.
What causes alopecia areata in children?
Alopecia areata is considered to be an organ-specific autoimmune condition of the hair follicle on a genetic background.
Alopecia areata often runs in families, and has been reported in monozygotic twins. Up to 25% of children will have at least one affected family member, and many have multiple relations with alopecia areata. It is reported to be common in Down syndrome and Turner syndrome — autoimmune disease is particularly common in Turner syndrome. This suggests a genetic predisposition to developing alopecia areata. However, investigations suggest the association is complex and polygenic.
Many hypotheses have been proposed attempting to explain the development of alopecia areata, but at this time the detailed pathogenesis is not understood.
What are the clinical features of alopecia areata in children?
Children typically present with a sudden onset of a solitary patch of hair loss, most commonly on the scalp, characterised by:
- Well-defined round or oval shape
- Completely bald smooth surface
- Normal skin appearance
- Exclamation mark hairs at the edge
- Positive hair tug test at the edge if disease is active.
Alopecia areata can present with multiple patches on any hair-bearing body site, including eyebrows and eyelashes.
Patterns of alopecia areata include:
- Patchy
- Reticular
- Ophiasis (occipital) or sisapho (frontal)
- Diffuse
- Alopecia totalis and alopecia universalis.
Alopecia areata patterns of hair loss in children
Nail changes were seen in almost 50% in one large series of children with alopecia areata, particularly pitting and trachyonychia (see Nail terminology). Nail changes do not correlate with the severity of the alopecia areata.
Nail changes in alopecia areata
What are the dermoscopy features of alopecia areata?
- Yellow dots — sebum and keratin in follicular openings
- Black dots — broken hairs on the scalp surface
- Exclamation mark hairs — narrow at the base, wider at the distal end
- Short regrowing hairs.
Dermoscopy features of alopecia areata
What are the complications of paediatric alopecia areata?
Social and psychological effects are common with any form of hair loss in children and can have a serious impact on quality of life. Social isolation, humiliation by peers, low self-esteem, anxiety, stress, and depression are often associated with alopecia areata. Paediatric alopecia areata also has a significant impact on the family as a whole (see Psychological effects of hair loss).
How is alopecia areata diagnosed in children?
Alopecia areata is usually a clinical diagnosis confirmed using trichoscopy. Wood light examination and examination of plucked hairs or skin scrapings may be required to exclude tinea capitis (see Laboratory tests for fungal infections). Skin biopsy is rarely required in children. Blood tests may be considered if there are concerns about coeliac disease or other associated autoimmune conditions.
What is the differential diagnosis for alopecia areata in children?
The two most important differential diagnoses in children presenting with patchy nonscarring hair loss are:
- Tinea capitis — scaling and inflammation are typically seen
- Trichotillomania — rough, oddly shaped patches of hair loss with broken hairs of varying length.
What is the treatment for alopecia areata in children?
No treatment changes the natural history of alopecia areata. ‘Wait and see’ is a reasonable option in young children with limited disease, as up to 50% show regrowth within one year. Treatment options for alopecia areata in children include:
- Potent topical steroids are the mainstay of treatment in children
- Intralesional steroids may be considered in older children, and short-term systemic corticosteroids in acute rapidly progressive disease
- Other topical therapies, such as minoxidil, dithranol, calcineurin inhibitors, and immunotherapy such as diphenylcyclopropenone
- Janus kinase (JAK) inhibitors, either topical or systemic (such as tofacitinib).
A wig may be necessary for extensive hair loss. Referral to a psychologist should be considered when there is significant psychological distress.
What is the outcome for paediatric alopecia areata?
Up to 50% of patients show regrowth within one year without treatment, but the course is unpredictable. Relapse is common even after apparently successful regrowth after treatment. Young age at first presentation is associated with a poor prognosis.
Other poor prognostic factors include:
- Extensive hair loss at presentation, including alopecia totalis and universalis
- Ophiasis pattern of hair loss
- Long duration of hair loss
- Atopy
- Positive family history
- Other autoimmune disease
- Nail involvement.