psorisis
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 the skin reproduce faster than normal and
pile up on the skin’s surface.
Psoriasis affects between 1 and 2 percent of
the United States population, or about 5.5 million people. Although the
disease occurs in all age groups and about equally in men and women, it
primarily affects adults. People with psoriasis may suffer discomfort,
including pain and itching, restricted motion in their joints, and
emotional distress.
In its most typical form, psoriasis results in
patches of thick, red skin covered with silvery scales. These patches,
which are sometimes referred to as plaques, usually itch and may burn.
The skin at the joints may crack. Psoriasis most often occurs on the
elbows, knees, scalp, lower back, face, palms, and soles of the feet but
it can affect any skin site. The disease may also affect the
fingernails, the toenails, and the soft tissues inside the mouth and
genitalia. About 15 percent of people with psoriasis have joint
inflammation that produces arthritis symptoms. This condition is called
psoriatic arthritis.
What Causes Psoriasis?
Recent research indicates that psoriasis is
likely a disorder of the immune system. This 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, in psoriasis,
an abnormal immune system causes activity by T cells in the skin. These
T cells trigger the inflammation and excessive skin cell reproduction
seen in people with psoriasis.
In about one-third of the cases, psoriasis is
inherited. Researchers are studying large families affected by psoriasis
to identify a gene or genes that cause the disease. (Genes govern every
bodily function and determine the inherited traits passed from parent to
child.)
People with psoriasis may notice that there are
times when their skin worsens, then improves. Conditions that may cause
flareups include changes in climate, infections, stress, and dry skin.
Also, certain medicines, most notably beta-blockers, which are used to
treat high blood pressure, and lithium or drugs used to treat
depression, may trigger an outbreak or worsen the disease.
How Is Psoriasis
Diagnosed?
Doctors usually diagnose psoriasis after a
careful examination of the skin. However, diagnosis may be difficult
because psoriasis can look like other skin diseases. A pathologist may
assist with diagnosis by examining a small skin sample (biopsy) under a
microscope.
There are several forms of psoriasis. The most
common form is plaque psoriasis (its scientific name is psoriasis
vulgaris). In plaque psoriasis, lesions have a reddened base covered by
silvery scales. Other forms of psoriasis include
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Guttate psoriasis--Small, drop-like
lesions appear on the trunk, limbs, and scalp. Guttate psoriasis is
most often triggered by bacterial infections (for example,
Streptococcus).
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Pustular psoriasis--Blisters of
noninfectious pus appear on the skin. Attacks of pustular psoriasis
may be triggered by medications, infections, emotional stress, or
exposure to certain chemicals. Pustular psoriasis may affect either
small or large areas of the body.
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Inverse psoriasis--Large, dry, smooth,
vividly red plaques occur in the folds of the skin near the genitals,
under the breasts, or in the armpits. Inverse psoriasis is related to
increased sensitivity to friction and sweating and may be painful or
itchy.
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Erythrodermic psoriasis--Widespread
reddening and scaling of the skin is often accompanied by itching or
pain. Erythrodermic psoriasis may be precipitated by severe sunburn,
use of oral steroids (such as cortisone), or a drug-related rash.
Information on Psoriasis Treatment
Doctors generally treat psoriasis in steps
based on the severity of the disease, the extent of the areas involved,
the type of psoriasis, or the patient’s responsiveness to initial
treatments. This is sometimes called the “1-2-3” approach. In step 1,
medicines are applied to the skin (topical treatment). Step 2 focuses on
light treatments (phototherapy). Step 3 involves taking medicines
internally, usually by mouth (systemic treatment).
Over time, affected skin can become resistant
to treatment, especially when topical corticosteroids are used. Also, a
treatment that works very well in one person may have little effect in
another. Thus, doctors commonly use a trial-and-error approach to find a
psoriasis treatment that works, and they may switch treatments periodically (for
example, every 12 to 24 months) if resistance or adverse reactions
occur. Psoriasis treatment depends on the location of lesions, their size, the
amount of the skin affected, previous response to treatment, and
patients’ perceptions about their skin condition and preferences for
treatment. In addition, treatment is often tailored to the specific form
of the disorder.
Topical Psoriasis Treatment
Psoriasis Treatments applied directly to the skin are sometimes
effective in clearing psoriasis. Doctors find that some patients
respond well to sunlight, corticosteroid ointments, medicines derived
from vitamin D3, vitamin A (retinoids), coal tar, or
anthralin. Other topical measures, such as bath solutions and
moisturizers, may be soothing but are seldom strong enough to clear
lesions over the long term and may need to be combined with more
potent remedies.
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Corticosteroids--Available in
different strengths, corticosteroids (cortisone) are usually applied
twice a day. Short-term psoriasis treatment is often effective in improving but
not completely clearing the condition. If less than 10 percent of the skin
is involved, some doctors will begin treatment with a high-potency
corticosteroid ointment (for example, Diprolene®,*
Temovate®, Ultravate®, or Psorcon®).
High-potency steroids may also be used for treatment-resistant
plaques, particularly those on the hands or feet. Long-term use or
overuse of high-potency steroids can lead to worsening of the
psoriasis, thinning of the skin, internal side effects, and resistance
to the treatment’s benefits. Medium-potency corticosteroids may be
used on the torso or limbs; low-potency preparations are used on
delicate skin areas.
*Brand names included in this fact sheet begin with a
capital letter and are provided as examples only. Their inclusion does
not mean that these products are endorsed by the National Institutes
of Health or any other Government agency. Also, if a particular brand
name is not mentioned, this does not mean or imply that the product is
unsatisfactory.
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Calcipotriene--This drug is a
synthetic form of vitamin D3. (It is not the same as
vitamin D supplements.) Applying calcipotriene ointment (for example,
Dovonex®) twice a day controls excessive production of skin
cells. Because calcipotriene can irritate the skin, however, it is not
recommended for the face or genitals. After 4 months of treatment,
about 60 percent of patients have a good to excellent response. The
safety of using the drug for cases affecting more than 20 percent of
the skin is unknown, and using it on widespread areas of the skin may
raise the amount of calcium in the body to unhealthy
levels.
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Coal tar--Coal tar may be applied
directly to the skin, used in a bath solution, or used on the scalp as
a shampoo. It is available in different strengths, but the most potent
form may be irritating. It is sometimes combined with ultraviolet B
(UVB) phototherapy. Compared with steroids, coal tar has fewer side
effects, but it is messy and less effective and thus is not popular
with many patients. Other drawbacks include its failure to provide
long-term help for most patients, its strong odor, and its tendency to
stain skin or clothing.
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Anthralin--Doctors sometimes use a 15-
to 30-minute application of anthralin ointment, cream, or paste to
treat chronic psoriasis lesions. However, this treatment often fails
to adequately clear lesions, it may irritate the skin, and it stains
skin and clothing brown or purple. In addition, anthralin is
unsuitable for acute or actively inflamed eruptions.
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Topical retinoid--The retinoid
tazarotene (Tazorac) is a fast-drying, clear gel that is applied to
the surface of the skin. Although this preparation does not act as
quickly as topical corticosteroids, it has fewer side effects. Because
it is irritating to normal skin, it should be used with caution in
skin folds. Women of childbearing age should use birth control when
using tazarotene.
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Salicylic acid--Salicylic acid is used
to remove scales, and is most effective when combined with topical
steroids, anthralin, or coal tar.
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Bath solutions--People with psoriasis
may find that bathing in water with an oil added, then applying a
moisturizer, can soothe their skin. Scales can be removed and itching
reduced by soaking for 15 minutes in water containing a tar solution,
oiled oatmeal, Epsom salts, or Dead Sea salts.
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Moisturizers--When applied regularly
over a long period, moisturizers have a cosmetic and soothing effect.
Preparations that are thick and greasy usually work best because they
hold water in the skin, reducing the scales and the itching.
Phototherapy
Ultraviolet (UV) light from the sun causes the
activated T cells in the skin to die, a process called apoptosis.
Apoptosis reduces inflammation and slows the overproduction of skin
cells that causes scaling. Daily, short, nonburning exposure to
sunlight clears or improves psoriasis in many people. Therefore,
sunlight may be included among initial treatments for the disease. A
more controlled form of artificial light treatment may be used in mild
psoriasis (UVB phototherapy) or in more severe or extensive psoriasis
(psoralen and ultraviolet A [PUVA] therapy).
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UVB phototherapy--Some artificial
sources of UVB light are similar to sunlight. Newer sources, called
narrow-band UVB, emit the part of the ultraviolet spectrum band that
is most helpful for psoriasis. Some physicians will start with UVB
treatments instead of topical agents. UVB phototherapy is also used to
treat widespread psoriasis and lesions that resist topical treatment.
This type of phototherapy is normally administered in a doctor’s
office by using a light panel or light box, although some patients can
use UVB light boxes at home with a doctor’s guidance. Generally at
least three treatments a week for 2 or 3 months are needed. UVB
phototherapy may be combined with other treatments as well. One
combined therapy program, referred to as the Ingram regime, involves a
coal tar bath, UVB phototherapy, and application of an
anthralin-salicylic acid paste, which is left on the skin for 6 to 24
hours. A similar regime, the Goeckerman treatment, involves
application of coal tar ointment and UVB phototherapy.
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PUVA--This treatment combines oral or
topical administration of a medicine called psoralen with exposure to
ultraviolet A (UVA) light. Psoralen makes the body more sensitive to
this light. PUVA is normally used when more than 10 percent of the
skin is affected or when rapid clearing is required because the
disease interferes with a person’s occupation (for example, when a
model’s face or a carpenter’s hands are involved). Compared with UVB
treatment, PUVA treatment taken two to three times a week clears
psoriasis more consistently and in fewer treatments. However, it is
associated with more short-term side effects, including nausea,
headache, fatigue, burning, and itching. Long-term treatment is
associated with an increased risk of squamous cell and melanoma
skin cancers. PUVA can be combined with some oral medications
(retinoids and hydroxyurea) to increase its effectiveness.
Simultaneous use of drugs that suppress the immune system, such as
cyclosporine, have little beneficial effect and increase the risk of
cancer. In very rare cases, patients who must travel long distances
for PUVA treatments may, with a physician’s close supervision, be
taught to administer this treatment at home.
Systemic Treatment
For more severe forms of psoriasis, doctors
sometimes prescribe medicines that are taken internally:
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Methotrexate--This treatment, which
can be taken by pill or injection, slows cell production by
suppressing the immune system. Patients taking methotrexate must be
closely monitored because it can cause liver damage and/or decrease
the production of oxygen-carrying red blood cells, infection-fighting
white blood cells, and clot-enhancing platelets. As a precaution,
doctors do not prescribe the drug for people with long-term liver
disease or anemia. Methotrexate should not be used by pregnant women,
by women who are planning to get pregnant, or by their male partners.
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Cyclosporine--Taken orally,
cyclosporine (Neoral®) acts by suppressing the immune
system in a way that slows the rapid turnover of skin cells. It may
provide quick relief of symptoms, but it is usually effective only
during the course of treatment. The best candidates for this therapy
are those with severe psoriasis who have not responded to or cannot
tolerate other systemic therapies. Cyclosporine may impair kidney
function or cause high blood pressure (hypertension), so patients must
be carefully monitored by a doctor. Also, cyclosporine is not
recommended for patients who have a weak immune system, those who have
had substantial exposure to UVB or PUVA in the past, or those who are
pregnant or breast-feeding.
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Hydroxyurea
(Hydrea®)--Compared with methotrexate and
cyclosporine, hydroxyurea is less toxic but also less effective. It is
sometimes combined with PUVA or UVB. Possible side effects include
anemia and a decrease in white blood cells and platelets. Like
methotrexate and cyclosporine, hydroxyurea must be avoided by pregnant
women or those who are planning to become pregnant.
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Retinoids--A retinoid, such as
acitretin (Soriatane®), is a compound with vitamin A-like
properties that may be prescribed for severe cases of psoriasis that
do not respond to other therapies. Because this psoriasis treatment also may
cause birth defects, women must protect themselves from pregnancy
beginning 1 month before through 3 years after treatment. Most
patients experience a recurrence of psoriasis after acitretin is
discontinued.
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Antibiotics--Although not indicated in
routine psoriasis treatment, antibiotics may be employed when an infection, such
as Streptococcus, triggers the outbreak of psoriasis, as in
certain cases of guttate psoriasis.
What Are Some Promising
Areas of Psoriasis Research?
Researchers continue to search for genes that
contribute to the inherited and other causes of psoriasis. Scientists
are also working to improve our understanding of what happens in the
body to trigger this disease. In addition, much psoriasis research is focused on
developing new and better treatments. Some of these experimental
treatments, such as agents directed at the specific types of T cells
involved, work to improve the disease with less overall suppression of
the immune system.
How Can People
Contribute to Psoriasis Research?
The National Psoriasis Tissue Bank, which is supported
by the National Psoriasis Foundation, is helping researchers worldwide
study the inherited tendency toward psoriasis. The tissue bank has DNA
from the white blood cells of more than 250 families affected by the
disease. There is particular interest in large families in which
psoriasis is both common and spans two or more generations. More
recently, the tissue bank has begun research involving families having
at least two siblings with psoriasis. People seeking more information
or families interested in participating in a study should contact
Keeping on Top of Your Condition
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