Psoriasis
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Psoriasis PUVA Treatment Can Increase Melanoma Risk
Medical Editor: Melissa Conrad Stöppler, MD
Psoriasis is a chronic disorder of the skin
characterized by reddish, scaly patches of inflammation, most
commonly affecting the elbows, knees, scalp, and/or groin. Psoriasis
can be mild or severe. When it is severe, it can adversely affect
functions of daily living including work and social activities.
Psoriasis has been reported to affect approximately
2% of the world's population.
The treatment of psoriasis depends on its severity
and location. Treatments range from local (cortisone cream
application, emollients, coal tar, anthralin preparations, and sun exposure)
to systemic (internal medications, including methotrexate and
cyclosporine).
PUVA (psoralen and ultraviolet A radiation) treatment
has been used for over two decades to treat severe psoriasis. In
this "combination" therapy, the psoralen, taken internally,
acts as a skin sensitizer. The "sensitized" skin affected
by psoriasis can then be treated by ultraviolet A radiation.
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What is psoriasis?
Psoriasis is a chronic (long-lasting) skin disease
characterized by scaling and inflammation. Scaling occurs when
cells in the outer layer of skin reproduce faster than normal
and pile up on the skin's surface.
Psoriasis affects 2 to 2.6 percent of the United
States population, or almost 5.8 to 7 million people. It occurs in all
age groups and about equally in men and women. People with psoriasis
may suffer discomfort, restricted motion of joints, and emotional
distress.
When psoriasis develops, patches of skin thicken,
redden, and become covered with silvery scales. These patches
are sometimes referred to as plaques. They may itch or burn. The skin
at joints may crack. Psoriasis most often occurs on the elbows, knees, scalp,
lower back, face, palms, and soles of the feet. The disease also may affect the
fingernails, toenails, and the soft tissues inside the mouth and genitalia.
About 10 percent of people with psoriasis have joint inflammation that produces
symptoms of arthritis. This condition is called psoriatic arthritis.
Psoriasis is not contagious in any way. It is not possible to "catch"
psoriasis by touching a person afflicted with it.
What causes psoriasis?
Research indicates that psoriasis may be a
disorder of the immune system. The immune system includes a type
of white blood cell, called a T cell, that normally helps protect
the body against infection and disease. Scientists now think that
psoriasis is related to an abnormal immune system that produces too many of the immune cells, called T cells,
in the skin. These T cells trigger the inflammation and excessive
skin cell reproduction seen in people with psoriasis. This leads to inflammation and flaking of skin.
In some cases, psoriasis is inherited. Researchers
are studying large families affected by psoriasis to identify
a gene or genes associated with the disease. (Genes govern every
body function and determine inherited traits that are passed from parent
to child.)
People with psoriasis may notice that there are times
when their skin worsens, then improves. Conditions that may cause
flare-ups include changes in climate, infections, stress, and
dry skin. Also, certain medicines, such as the
nonsteroidal antiinflammatory drug indomethacin and medicines used to treat high blood pressure
or depression, may trigger an outbreak or worsen the disease.
Next: How is psoriasis diagnosed? »
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From the Doctors at MedicineNet.com  |
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Last Editorial Review: 5/23/2005