Alopecia areata.

Alopecia areata is an asymptomatic, nonscarring hair loss with spontaneous remissions and exacerbations. Although the etiology is unknown, the disorder is associated with vitiligo, atopy, pernicious anemia, Down syndrome and thyroiditis. The area of hair loss may remain localized or may involve the entire scalp or all body hair. Treatment is difficult to assess because of individual response and spontaneous remissions, as well as a high rate of relapse. Intralesional injection of corticosteroids is the most common mode of treatment, although systemic steroid therapy, contact allergens, minoxidil, psoralens plus ultraviolet light, and other agents have been tried.