(See also Alopecia.)
Alopecia areata is typically sudden patchy nonscarring hair loss in people with no obvious skin or systemic disorder.
The scalp and beard are most frequently affected, but any hairy area may be involved. Hair loss may affect most or all of the body (alopecia universalis). Alopecia areata is thought to be an autoimmune disorder affecting genetically susceptible people exposed to unclear environmental triggers, such as infection or emotional stress. It occasionally coexists with autoimmune vitiligo or thyroiditis.
Diagnosis is by inspection. Alopecia areata typically manifests as discrete circular patches of hair loss characterized by short broken hairs at the margins, which resemble exclamation points. Nails are sometimes pitted or display trachyonychia, a roughness of the nail also seen in lichen planus.
Differential diagnosis includes tinea capitis, trichotillomania, traction alopecia, lupus, and secondary syphilis. If findings are equivocal, further testing can be pursued with KOH preparation, fungal culture, screening for syphilis, or biopsy. Patients with clinical findings suggesting associated autoimmune diseases (particularly thyroid disease) are tested for those diseases.
If therapy is considered, intralesional corticosteroid injection is the treatment of choice in adults. Triamcinolone acetonide suspension (typically in doses of 0.1 to 3 mL of 2.5 to 5 mg/mL concentration q 4 to 8 wk) can be injected intradermally if the lesions are small. Potent topical corticosteroids (eg, clobetasol propionate 0.05% foam, gel, or ointment bid for about 4 wk) can be used; however, they often do not penetrate to the depth of the hair bulb where the inflammatory process is located. Oral corticosteroids are effective, but hair loss often recurs after cessation of therapy and adverse effects limit use.
Topical anthralin cream (0.5 to 1% applied for 10 to 20 min daily then washed off; contact time titrated as tolerated up to 1 h/day) may be used to stimulate a mild irritant reaction. Minoxidil 5% solution may be helpful as an adjuvant to corticosteroid or anthralin treatment.
Induction of allergic contact dermatitis using diphenylcyclopropenone or squaric acid dibutylester (topical immunotherapy) leads to hair growth due to unknown mechanisms, but this treatment is best reserved for patients with diffuse involvement who have not responded to other therapies.
Alopecia areata may spontaneously regress, become chronic, or spread diffusely. Risk factors for chronicity include extensive involvement, onset before adolescence, atopy, and involvement of the peripheral temporal and occipital scalp (ophiasis).
Drug NameSelect Trade
anthralinNo US brand name