**2. Epidemiology**

Alopecia areata is the most prevalent autoimmune disorder and the second most frequent disease causing hair loss after androgenetic alopecia [3]. The prevalence rate of the disease is approximately 1 in 1000 people worldwide; in the United States, the lifetime risk is estimated to be 1.7% [2, 4]. Alopecia areata is mainly a disease of young adults; as many as 60% of patients are under the age of 20 at first presentation. Pediatric cases constitute approximately 20% of alopecia areata patients [2]. However, patients of any age can be affected. There is no gender predilection [4]. Reported cases in elderly were of milder severity and had a better treatment response [5].
