Alopecia areata is an autoimmune disease that causes discrete circular or oval areas of nonscarring alopecia. This form of alopecia has several clinical variants, including alopecia totalis, alopecia universalis, and an ophiasis pattern. Therapy is often difficult. The disease can have profound psychological impact, especially in young patients. It is critical to address this issue, because the effects on the patient’s psychological well-being are often more severe than the actual hair loss.
Clinical Findings: Alopecia areata can affect individuals of any age but is most frequently seen in children and young adults. It is estimated to affect 1% of the population. Both sexes are equally affected, and there is no race predilection. The first sign is hair loss in one specific area of the scalp. The hairs fall out in large numbers, especially when pulled. The patches of hair loss typically have an oval or circular pattern. There may be one or more than a dozen areas of involvement. The scalp hair is the most commonly affected region. The affected scalp is smooth without evidence of scarring or follicular dropout. Small, stubby hairs may be present at follicular openings and have been termed “exclamation point hairs.” All hair regions may be involved, including the eyebrows, eyelashes, and beard.
Alopecia areata has an unpredictable, waxing and waning course. Areas may begin to grow back as new patches form. It is not uncommon for a patient to have one solitary episode with spontaneous resolution and no future episodes. Some patients develop patches of alopecia intermittently over their lifetime. Complete loss of the scalp hair caused by alopecia areata is termed alopecia totalis. The rarest variant is alopecia universalis, which causes loss of all hair in all locations. These two forms of alopecia areata are very difficult to treat. Patients with both alopecia totalis and alopecia universalis need psychological assessment, because the loss of hair has severe social and self-esteem consequences. Patients often benefit from consultation with a professional psychologist or psychiatrist. Alopecia areata support groups can be extremely helpful.
The ophiasis pattern of alopecia areata is less commonly seen. It involves the parietal scalp dorsally to the occiput bilaterally. The diagnosis is typically made on clinical grounds. A skin biopsy is rarely needed. The hair pull test is a diagnostic test that can be performed at the bedside. It is positive when more than three hairs are pulled out in and around the patch of alopecia areata. If the hair is actively shedding, this test should be performed only once, because the number of hairs removed is large and can be very upsetting to the patient. The hair that regrows is often lacking in pigment and appears white or gray. Over time, these white hairs are replaced with pigmented hairs as the hair pigmentation machinery begins to work again.
Histology: Skin biopsies of the scalp of an affected area show a dense lymphocytic infiltrate surrounding all the hair bulbs in what has been termed a “swarm of bees” pattern. There are increased numbers of catagen and telogen hairs. The epidermis is normal.
Pathogenesis: Alopecia areata is believed to be an autoimmune inflammatory disease of T cells that, for unknown reasons, attacks certain hair follicles. It may be seen in association with other autoimmune diseases such as autoimmune thyroid disease. It is believed to be polygenic in nature.
Treatment: Treatment consists of proper assessment of the patient and how the disease is affecting the patient’s life in general. Some individuals tolerate the condition without adverse psychological effects; for them, the best treatment is a watch-and-wait approach. Others with mild disease may have severe self-esteem issues and should be offered therapy. However, no therapy has been shown to be uniformly effective, and most have only anecdotal reports of efficacy. Topical retinoids and corticosteroids are used, as well as intralesional steroid injections if the areas are small enough. Contact sensitization with squaric acid has had equivocal results. Oral steroids should be avoided, because the long-term side effects do not warrant their use.