Alopecia areata
Alopecia areata is a nonscarring, presumed autoimmune hair loss disease that produces well-circumscribed, smooth, round patches of hair loss, most commonly on the scalp, with pathognomonic exclamation-point hairs at the margin. Limited disease is treated with topical or intralesional corticosteroids, while extensive disease (50% or more scalp involvement) adds topical immunotherapy, topical minoxidil, or, for severe refractory disease, the oral JAK inhibitor baricitinib.
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What this article covers
- Overview
Definition: alopecia areata is characterized by well-circumscribed, round patches of nonscarring, acute hair loss with a smooth, scaleless scalp.
- Epidemiology
Age of onset: onset usually occurs before age 30 years.
- Risk factors
Coexisting autoimmune disease: alopecia areata is associated with hyperthyroidism, hypothyroidism, vitiligo, pernicious anemia, and type 1 diabetes mellitus.
- Pathophysiology
Presumed autoimmune attack on the hair follicle: the pathogenesis is not fully understood, but an autoimmune process is postulated, supported by the disease's strong association with other autoimmune…
- Clinical features
Well-circumscribed, round patches of smooth, scaleless, nonscarring hair loss are the defining finding, most often affecting the scalp.
- Differential diagnosis
Androgenic alopecia: gradual, patterned hair loss beginning after puberty, with bitemporal recession and vertex thinning in men, unlike the abrupt, well-circumscribed round patches of alopecia…
- Diagnosis
The clinching diagnostic basis is the clinical pattern of well-circumscribed, smooth, nonscarring round patches with pathognomonic exclamation-point hairs at the margin, most commonly on the scalp, in a patient who is otherwise asymptomatic.
- Management
First, for limited disease (less than 50% scalp involvement), offer watchful waiting or start intralesional corticosteroid treatment: triamcinolone acetonide 2.5-10 mg/mL injected intralesionally…
- Complications
Psychosocial impact of visible hair loss: progression to alopecia totalis or alopecia universalis produces cosmetically significant, visible hair loss that can affect quality of life.
- Prognosis
Spontaneous regrowth is common in mild disease: patients with mild disease will often have spontaneous hair regrowth without treatment.
- Prevention
No preventive measure is established for onset, since the disease arises from a presumed autoimmune process rather than a modifiable exposure.
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