Alopecia areata. Pathogenesis, diagnosis, and therapy.

Alopecia areata is a common form of non-scarring alopecia that appears equally in males and females of any age, although children and adolescents are more commonly affected. The disorder is usually characterized by limited alopecic patches on the scalp, but more severe forms may affect the entire scalp (alopecia totalis) or body (alopecia universalis). Characteristic nail changes may also accompany hair loss. Alopecia areata has been linked with certain human leukocyte antigen (HLA) class II alleles, indicating a probable autoimmune etiology. Current research implicates T lymphocytes in the pathogenetic mechanism of disease. Other autoimmune diseases are also linked with alopecia areata. The diagnosis of alopecia areata is usually made clinically, although a biopsy is diagnostic for this condition. Treatment is challenging and aims at the regrowth of hair in affected individuals. Intralesional corticosteroid injections are widely used in mild disease. Topical anthralin and minoxidil may also be clinically efficacious. Topical sensitizers, such as squaric acid dibutlyester and diphenyl-cyclopropenone, are sometimes employed. Various therapies for the disease may have efficacy in different patients, making a universal treatment algorithm difficult to implement. Patients should be handled on an individual basis, with the final outcome based on the cosmetic regrowth of hair. Maintenance therapy is also important in patients that do achieve acceptable regrowth, necessitating a highly motivated patient and good rapport with the treating physician.