A young woman presented to her physician with hair loss for 3 months. She is very worried that it will not grow back and that it might spread to other parts of her scalp. When she lifted her hair, one round area of hair loss was noted (Figure 195-1). The scalp was smooth, and there were no signs of scale or inflammation. Some fine white hairs were also seen growing in the area of hair loss. A few "exclamation point" hairs were also seen. The physician readily diagnosed alopecia areata (AA) based on the clinical exam. He attempted to reassure the young woman that her hair is already growing back and would likely regrow fully in the coming months. He also explained that the new hairs may be white at first but will regain their natural dark color. He also offered her the option of intralesional steroid injection of the involved scalp. The physician did explain that the intralesional steroid is not a guarantee of 100% resolution but may increase the speed and likelihood of recovery. The young woman chose to have the steroid injection because she did not want to take any chances of not regaining her hair.
Alopecia areata in a young woman with a typical round area of alopecia. The scalp was smooth without scale or visible lesions. (Reproduced with permission from Richard P. Usatine, MD.)
AA is a common disorder that causes patches of hair loss without scarring the hair follicle. This autoimmune process involves inflammation but does not damage the ability of the hair follicle to produce hairs again in the future. The areas of hair loss are often round, and the scalp is often very smooth at the site of hair loss.1 AA can occur at any age, and the extent of the disease is variable. Alopecia totalis (AT) involves the whole scalp. Alopecia universalis (AU) involves loss of all hair including the whole scalp, eyebrows, eyelashes, and body (Figure 195-2).
Alopecia universalis for more than 10 years in this man. Note that he has lost his eyebrows and eyelashes. (Reproduced with permission from Richard P. Usatine, MD.)
Alopecia affects approximately 0.2% of the population at any given time with approximately 2.1% of the population experiencing an episode during their lifetime.2,3
Men and women are equally affected.
Most patients are younger than age 40 years at disease onset, with the average age being 25 to 27 years.2,4 Children and teenagers are often affected.5
ETIOLOGY AND PATHOPHYSIOLOGY