Alopecia areata (AA) is a condition affecting humans, in which hair is lost from some or all areas of the body, usually from the scalp. Because it causes bald spots on the scalp, especially in the first stages, it is sometimes called spot baldness. In 1% - 2% of cases, the condition can spread to the entire scalp (Alopecia totalis) or to the entire epidermis (Alopecia universalis).
The most common type of alopecia areata involves hair loss in one or more round spots on the scalp.
· Hair may also be lost more diffusely over the whole scalp, in which case the condition is called diffuse alopecia areata.
· Alopecia areata monolocularis describes baldness in only one spot. It may occur anywhere on the head.
· Alopecia areata multilocularis refers to multiple areas of hair loss.
· The disease may be limited only to the beard, in which case it is called Alopecia areata barbae.
· If the patient loses all the hair on his/her scalp, the disease is then called Alopecia areata totalis.
· If all body hair, including pubic hair, is lost, the diagnosis then becomes Alopecia areata universalis..