Alopecia areata

Also known as: Alopecia celsi, Alopecia circumscripta, Cazenave's vitiligo, Celsus' vitiligo, Jonston's alopecia, Porrigo decalvans, Vitiligo capitis, Alopecia cicatrisata
Alopecia areata is a disorder characterized by loss of hair. Sometimes, this means simply a few bare patches on the scalp. In other cases, hair loss is more extensive. Although the exact cause is not known, this is thought to be an autoimmune disorder in which the immune system, the body's own defense system, mistakenly attacks the hair follicles, the tiny structures from which hairs grow. Unpredictable hair loss is the only noticeable symptom of this disorder. Regrowth of hair may or may not occur. Hair loss is usually confined to the head and face, although the entire body may be involved.