Alopecia areata is the name for a
condition in which round patches of hair
loss appear suddenly. The hair-growing
tissue is attacked by the patient's own
immune cells for unknown reasons. There
are three stages: first, there is sudden
hair loss, then the patches of hair loss
enlarge, and last, new hair grows back.
This process takes months, sometimes more
than a year, but rarely does the hair
never grow back.
