HISTORY
This 38-year-old man has had recurrent episodes of focal hair loss. His scalp has been the most affected area, but he has also noticed hair loss in his beard and in the suprapubic area. Although the problem resolves in weeks to months, it is very distressing for him.
Early in each episode, he experiences a slight tingling in the area, followed by noticeable hair loss—usually in a round pattern. He has consulted a number of providers, but no one in dermatology (until now, that is).
Additional history taking reveals a strong connection between stress and these episodes of hair loss. Moreover, there is a family history of similar hair loss, as well as of thyroid disease.
EXAMINATION
Several areas of complete hair loss, in annular configuration, are noted in the patient's scalp. No epidermal changes (eg, scaling, redness, edema) are present. Two of the sites are slightly larger than 5 cm in diameter.
DISCUSSION
Hair loss (alopecia) is an exceedingly common complaint, but alopecia areata (AA) is one of the more prolific types. Stress appears to trigger the episodes. Ironically, many patients find the hair loss itself to be extremely stressful, which of course compounds the problem.
The most widely accepted theory is that AA is an autoimmune phenomenon, mediated by T-cells and occurring in genetically predisposed individuals. Support for this theory is abundant: increased levels of antibodies directed to various hair follicle structures and a perifollicular lymphocytic infiltrate seen histologically.
Likewise, the genetic basis for predisposition to AA appears valid. For example, 10% to 20% of AA patients report a positive family history. (The more severe the AA, the more likely the patient is to have that family history.) When one twin has AA, the other is quite likely to develop it during his/her lifetime. The high association of Down's syndrome with AA suggests the involvement of a gene located on chromosome 21, but other genes have also been implicated.
PROGNOSIS AND TREATMENT
In the majority of cases, AA resolves, with or without treatment, within weeks to months. As this particular case illustrates, recurrences are quite common. In a study of more than 700 patients, 90% experienced a recurrence of AA within five years.
A tiny percentage of AA patients will progress to the permanent loss of all scalp hair (termed alopecia totalis), and a small percentage of those patients will go on to lose every hair on their body (alopecia universalis). In addition to a family history of such problems, other factors that predict this outcome include youth, atopy, and the extent of involvement of the peripheral scalp (ophiasis).
Local intralesional steroid injection (triamcinolone 5 mg/cc) usually stimulates modest hair regrowth, but must be continued at regular intervals for maintenance. Many other systemic and topically applied medications have been tried, but none appear to have a curative effect.
DIFFERENTIAL DIAGNOSIS
Aside from androgenetic alopecia (the so-called male pattern baldness seen in both men and women), the next most common type of hair loss is telogen effluvium. Seen almost exclusively in women, TE involves uniform hair loss from all over the scalp; the lost hair can be found in the comb, brush, or sink.
Occasionally, AA can be so atypical as to require biopsy to distinguish it from another major item in the differential: trichotillomania. The latter condition is characterized by focal hair loss caused by obsessive twirling or other digital manipulation by the patient, who often has an obsessive-compulsive disorder. This process usually leaves hairs of unequal lengths in the affected location (whereas in AA, total hair loss is typical).
The process of evaluating patients for hair loss is often complicated by the presence of more than one diagnosis. For example, it's quite common for a woman to have longstanding, mild androgenetic alopecia, with thinning mostly confined to the crown of the scalp, but then to experience the onset of AA or TE superimposed on the chronic hair loss. This can make for a confusing clinical picture.
The potential for hair loss due to other conditions—such as connective tissue diseases (lupus is a prime example), secondary syphilis, thyroid disease, or any number of inflammatory conditions, including lichen planopilaris—further complicates the process. And as if all this were not enough, alopecia patients are usually, and understandably, anxious about their problem. Prompt referral of these patients to dermatology is often advisable.
TAKE-HOME LEARNING POINTS
• Localized, complete hair loss in a well-defined annular pattern is probably alopecia areata (AA).
• One of the more common types of hair loss, AA is polygenic in origin, with an autoimmune basis, and manifests in a genetically predisposed patient.