Alopecia areata (AA) is a medical condition in which hair 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/patchy hair loss.
Classification:
Classification is on the basis of area involvement.
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 the scalp, the disease is then
called Alopecia Totalis.
If all body hair, including pubic hair is lost, the diagnosis
then becomes Alopecia
Universalis.
Signs & Symptoms:
Typical first symptoms of
alopecia areata are small bald patches. The underlying skin is unscarred and
looks superficially normal. These patches can take many shapes, but are most
usually round or oval.
Exclamation point hairs are
often present. Exclamation point hairs are hairs that become narrower along the
length of the strand closer to the base, producing a characteristic
"exclamation point" appearance
In cases of alopecia
areata hair will tend to pull out more easily along the edge of the patch where
the follicles are already being attacked by the body's immune system than away
from the patch where they are still healthy.
Nails may have pitting.
Diagnosis is usually done by clinical features.
What causes alopecia areata?
Current evidence suggests that
alopecia areata is caused by an abnormality in the immune system. This
particular abnormality leads to autoimmunity, a misguided immune system that
tends to attack its own body. As a result, the immune system attacks particular
tissues of the body. In alopecia areata, for unknown reasons, the body's own
immune system attacks the hair follicles and disrupts normal hair formation.
Biopsies of affected skin show immune lymphocytes penetrating into the hair
bulb of the hair follicles. Alopecia areata is occasionally associated with
other autoimmune conditions such as allergic disorders, thyroid disease, vitiligo, lupus,rheumatoid arthritis, and ulcerative colitis. The diagnosis or treatment of these diseases is unlikely to affect
the course of alopecia areata. Sometimes, alopecia areata occurs within family
members, suggesting a role of genes.
