In alopecia areata (AA), round patches of hair loss develop rapidly and asymptomatically. The patches are well-circumscribed, round, and without inflammation or scarring (Fig. 74-1). Hair loss occurs most commonly on the scalp, but other areas such as the eyebrows and beard are often involved. AA is a chronic, recurrent condition that often begins in childhood or in young
adults. The term alopecia totalis is used if all scalp hair is lost, and alopecia universalis is the term for complete loss of all body hair. As much as 1% of the population may have at least one spot of AA by age 50. There is a positive family history of AA in 10% to 20% of patients.

One pathognomonic sign of AA is the “exclamation point” hair, which is wide distally and narrow at the base and occurs at the periphery of a patch of hair loss (Fig. 74-2). Hairs that regrow in a patch of AA are often white. Pitting of the nails accompanies hair loss in approximately 40% of patients. Most patients are in good health, and no additional medical workup is required. In a small number of cases, however, there is an association with other autoimmune conditions such as Hashimoto’s thyroiditis, connective tissue disease, myasthenia gravis, cataracts, and vitiligo.