Alopecia areata

Alternative names:

alopecia totalis; alopecia universalis

Definition:

Various patterns of hair loss that have no known cause. Alopecia areata is characterized by the complete loss of hair within roundish patches on the scalp. Unlike mechanical damage to the hair, no stubble of regrowth can be found in the affected areas.

Causes, incidence, and risk factors:

The specific cause of alopecia areata is unknown. A family history of alopecia is present in about a fifth of all cases. Alopecia areata is occasionally associated with autoimmune diseases.

Alopecia may also occur as alopecia totalis with complete loss of scalp hair or as alopecia universalis with total loss of all body hair.