What are the different types of psoriasis?
There are different types of psoriasis, although plaque psoriasis (described below) is by far the most common and typical type.
Plaque psoriasis
This is common. The rash is
made up of patches on the skin called plaques. The picture shows a
typical plaque of psoriasis next to some normal skin.
Each
plaque usually looks red with overlying flaky white scales that feel
rough. There is usually a sharp border between the edge of a plaque and
normal skin. The most common areas affected are over elbows and knees,
the scalp, and the lower back. However, plaques may appear anywhere on
the skin, but they do not usually occur on the face.
The
extent of the rash varies between different people, and can vary from
time to time in the same person. Many people have just a few small
plaques when their psoriasis flares up. Others have a more widespread
rash with large plaques. Sometimes, small plaques that are near to each
other merge to form large plaques.
Plaque psoriasis can be itchy, but does not usually cause too much discomfort. Treatment is discussed later.
Scalp psoriasis
This occurs in about half
of people affected by plaque psoriasis. It can also occur alone without
any other part of the skin being affected. It looks like severe
dandruff.
Nail psoriasis
This occurs in about half
the people with plaque psoriasis. It may also occur alone without the
skin rash. There are pinhead sized pits (small indentations) in the
nails. Sometimes, the nail becomes loose on the the nail bed.
Guttate ('drop') psoriasis
This typically
occurs following a sore throat which is caused by a bacterium (germ).
The plaques of psoriasis are small (less than 1 cm) but occur over many
areas of the body. It normally lasts a few weeks, and then fades away.
It may never return. But, if you have an episode of guttate psoriasis,
you have a higher than usual chance of developing common plaque
psoriasis at a later time.
Flexural psoriasis
This occurs on skin in
the creases of the skin (flexures) such as in the armpit, groin, under
breasts, and in skin folds. The affected skin is red and inflamed.
Unlike plaque psoriasis, affected skin is smooth and does not have the
rough scaling.
Pustular psoriasis
This is uncommon and
mainly affects the palms of the hands and and soles of the feet. In
this situation it is sometimes called palmoplantar pustulosis. Affected
skin develops crops of pustules which are small fluid filled spots. The
pustules of pustular psoriasis do not contain germs (bacteria) and are
not infectious. The skin under and around the pustules is usually red
and tender. Rarely, a form of pustular psoriasis can affect skin apart
from the palms and soles. This more widespread form of pustular
psoriasis is a more serious form of psoriasis and needs urgent
treatment.
Erythrodermic psoriasis
This is a
widespread erythema (redness) of much of the skin surface which is
painful. It is rare, but is serious and needs urgent treatment as it
can cause excessive protein and fluid loss that can lead to dehydration
and severe illness.
What causes psoriasis?
Normal skin is made up of layers of skin cells. The top layer of cells
are flattened and are gradually shed (they fall off). New cells are
constantly being made underneath to replace the shed top layer. It
normally takes about 28 days for a bottom cell to reach the top and to
be shed.
People with psoriasis have a faster turnover of skin
cells. It is not clear why this occurs. More skin cells are made which
leads to a build up of cells on the top layer. These form the flaky
plaques on the skin, or severe dandruff of the scalp seen in scalp
psoriasis.
There is also a slight change of the blood supply
of the skin. This tends to cause some inflammation in the skin. This is
why the skin underneath a patch of psoriasis is usually red and
inflamed.
The cause of the increased cell turnover and skin
inflammation of psoriasis is not known. Genetic (hereditary) factors
seem to play a part as about half of people with psoriasis have a close
relative also affected. It may be that some factor in the environment
(perhaps a virus) may trigger the condition to start in someone who is
genetically prone to develop it. Another theory is that the immune
system may be 'overreacting' in some way to cause the inflammation.
Research continues to try to find the exact cause.
Who gets psoriasis?
About 2 in 100 people
develop psoriasis at some stage of their life. It can first develop at
any age, but it most commonly starts between the ages of 15 and 25.
One
large study also found that smokers (and ex-smokers for up to 20 years
after giving up) have an increased risk of developing psoriasis
compared to non-smokers. One theory for this is that toxins (poisons)
in cigarette smoke may affect parts of the immune system involved with
psoriasis.
Aggravating factors
In most people who have psoriasis, there is no apparent reason why a
flare-up develops at any given time. However, in some people, psoriasis
is more likely to flare up in certain situations. These include the
following:
- Stress. It is difficult to measure stress and to
prove the relationship between stress and psoriasis. However, it is
thought that stress can contribute to a flare up of psoriasis in some
people. There is some evidence to suggest that the treatment of stress
in some people with psoriasis may be of benefit.
- Infections. Psoriasis may flare up if you have a feverish
illnesses. In particular, a sore throat caused by a certain type of
bacterium is a cause of guttate psoriasis.
- Drugs. Some drugs and medicines may possibly trigger or
worsen psoriasis in some cases. Drugs that have been suspected of doing
this include: beta-blockers (propranolol, atenolol etc), chloroquine,
lithium, anti-inflammatory pain killers (ibuprofen, naproxen,
diclofenac, etc), ACE inhibitor drugs, and alcohol. In some cases the
psoriasis may not flare up until the medication has been taken for
weeks or months.
- Smoking. As mentioned, smoking may help to initially
trigger psoriasis to develop in some cases. Toxins from cigarette smoke
may also aggravate existing psoriasis.
- Trauma. Injury to the skin, including excessive scratching,
may trigger a patch of psoriasis to develop. The development of
psoriatic plaques at a site of injury is known as the Koebner reaction.
- Sunlight. Most people with psoriasis say that sunlight
seems to help ease their psoriasis. Many people find that their
psoriasis is less troublesome in the summer months. However, some
people notice the opposite with strong sunlight seeming to make their
psoriasis worse. A severe sunburn (which is a skin injury) can also
lead to a flare up of psoriasis.
- Hormone changes. Psoriasis in women tends to be worst
during puberty and during the menopause. These are times when there are
some major changes in female hormone levels. Some pregnant women with
psoriasis find that their symptoms improve when they are pregnant, but
it may flare up in the months just after having a baby. Again, this is
thought to be related to changes in hormone levels.
Joint problems
About 1 in 10 people with
psoriasis also develop inflammation and pains in some joints
(arthritis). This is called psoriatic arthritis. Any joint can be
affected, but it most commonly affects the joints of the fingers and
toes. The cause of this is not clear. See separate leaflet called 'Psoriatic Arthritis' for details.
How is psoriasis diagnosed?
Psoriasis is
usually diagnosed by the typical appearance of the rash. The rash is
often very typical, and no tests are usually needed. Occasionally, a
biopsy (small sample) of skin is taken to be looked at under the
microscope if there is doubt about the diagnosis.
What are the common treatments for plaque and scalp psoriasis?
There
is no once-and-for-all cure for psoriasis. Treatment aims to clear the
rash as much as possible. However, as psoriasis tends to flare up from
time-to-time, you may need courses of treatment 'on and off' throughout
your life.
There are various treatments that are used to treat
psoriasis. There is no 'best buy' that suits everybody. The treatment
advised by your doctor may depend on the severity, site, and the type
of psoriasis. Also, one treatment may work well in one person, but not
in another. It is not unusual to try a different treatment if the first
one does not work so well.
Many of the treatments are creams or
ointments. As a rule, you have to apply creams or ointments correctly
for best results. It usually takes several weeks of treatment to clear
plaques of psoriasis. Make sure you know exactly how to use whatever
treatment is prescribed. For example, some preparations should not be
used on the skin creases (flexures), on the face or on broken skin, and
some should not be used if you are pregnant. Do ask a doctor, nurse or
pharmacist if you are unsure as to how to use your treatment, and for
how long.
The following is a brief overview of the more commonly
used treatments for plaque and scalp psoriasis. Treatments of the less
common forms of psoriasis are similar, but are not dealt with here.
Your doctor will advise.
Not treating may be an option
Many people
have a few patches of psoriasis that are not too bad or not in a
noticeable place. In this situation, some people do not want any
treatment. If you opt for no treatment, you can always change your mind
at a later time if the rash changes or gets worse.
Moisturisers (emollients)
These are not
'active' treatments but help to soften hard skin and plaques. They may
reduce scaling and itch. There are many different brands of moisturiser
creams and ointments. A moisturiser may be all that you need for mild
psoriasis. You can also use one in addition to any other treatment, as
often as needed, to keep the skin supple and moist.
Vitamin D based creams such as calcipotriol, calcitriol and tacalcitrol
These
are popular and often work well to clear plaque psoriasis. They seem to
work by affecting the rate of cell division in skin cells. They are
easy to use, are less messy, and have less of a smell than coal tar or
dithranol creams and ointments (below). However, they can cause
irritation in some people. There is also a scalp preparation of
calcipotriol. Note: they may not be suitable for pregnant or breast
feeding women.
Coal tar preparations
These have been used
to treat psoriasis for many years. It is not clear how they work. They
may reduce the turnover of the skin cells. They also seem to reduce
inflammation and have 'antiscaling' properties. Traditional tar
preparations are messy to use, but modern formulas are more pleasant.
There are various modern brands and types of creams which contain
between 0.4% and 2% crude coal tar. Tar based shampoos which have a
coal tar content of up to 2.5%.are popular for scalp psoriasis.
Dithranol
This has been used for many years
for psoriasis. In most cases a daily application of dithranol to a
psoriasis plaque will eventually cause the plaque to go. However,
dithranol irritates healthy skin. Therefore, you need to apply it
carefully to the psoriasis plaques only. To reduce the chance of skin
irritation, it is usual to start with a low strength and move onto
stronger ones gradually over a few weeks. When applying dithranol, you
should protect your hands with gloves, or wash your hands thoroughly
afterwards.
Dithranol preparations come in different brands and
strengths. 'Short contact therapy' is popular. This involves putting a
higher strength dithranol preparation on the plaques of psoriasis for
15-60 minutes each day, and then washing it off. Dithranol may stain
skin, hair, clothes, bedding, baths, etc.
Steroid creams or ointments
These work by
reducing inflammation. They are easy to use and may be a good treatment
for difficult areas such as the scalp and face. However, one problem
with steroids is that in some cases, once you stop using the cream or
ointment, the psoriasis may 'rebound' back worse then it was in the
first place. Also, side-effects may occur with long term use,
especially with the more potent (stronger) preparations.
Therefore,
if a steroid is used, a doctor may prescribe it for a limited period
only (a few weeks or so, and less for a strong steroid), or on an
intermittent basis. As a rule, a steroid cream or ointment should not
be used regularly for more than four weeks without a review by a
doctor. Steroid lotions are useful for flare-ups of scalp psoriasis.
Tazarotene
This is another cream that is
sometimes used. It is a vitamin A based drug. Irritation of the normal
surrounding skin is a common side-effect. This can be minimised by
applying tazarotene sparingly to the plaques and avoiding normal skin.
Salicylic acid
This is often combined with
other treatments such as coal tar or steroid creams. It tends to loosen
and 'lift' the scales of psoriasis on the body or the scalp. Other
treatments tend to work better if the scale is lifted off first by
salicylic acid.
For scalp psoriasis
A tar-based shampoo is
often tried first and often works well. Some preparations combine a tar
shampoo with either a salicylic acid preparation, a coconut
oil/salicylic acid combination ointment, a steroid preparation,
calcipotriol scalp application, or more than one of these.
Combinations
Some preparations use a
combination of ingredients. For example, calcipotriol combined with a
steroid may be used when calcipotriol alone has not worked very well.
As mentioned, it is not usually wise to use a steroid long-term.
Therefore, one treatment strategy that is sometimes used is
calcipotriol combined with a steroid for four weeks, alternating with
calcipotriol alone for four weeks.
Other combinations such as
a tar preparation and a steroid are sometimes used. Other 'rotating'
treatment strategies are sometimes used. For example, a steroid for a
few weeks followed by a course of dithranol treatment.
Scalp treatments often contain a combination of ingredients such as a steroid, coal tar, and salicylic acid.
Other treatments
If you have severe
psoriasis then you may need hospital based treatment. Phototherapy
(light therapy) is commonly used in hospitals. This may involve
treatment with UVB light. Another type of phototherapy is called PUVA
(Psoralen and Ultra Violet light in the A band). This involves taking
tablets (psoralen) which enhances the effects of ultraviolet light on
the skin, and then attending hospital for regular sessions under a
special light which emits UVA.
Sometimes people with severe
psoriasis are given intense courses of treatment using the creams or
ointments described above, but in stronger strengths and with special
dressings.
If psoriasis is severe and is not helped by the
treatments listed above then a powerful medicine which can suppress
inflammation is sometimes used. For example, methotrexate, ciclosporin,
acitretin, infliximab, etanercept or efalizumab. There is some risk of
serious side-effects with these medicines, so they are only used on the
advice of a specialist.
Further information and support
Psoriasis Association
Dick Coles House, 2 Queensbridge, Bedford Road, Northampton, NN4 7BF
Tel (helpline): 0845 6 760 076
Web: www.psoriasis-association.org.uk
Founded in 1968 the Association has three fundamental aims: to support
those who have psoriasis; to raise awareness about psoriasis; to fund
research into the causes of and treatments for psoriasis.
PAPAA - The Psoriasis and Psoriatic Arthritis Alliance
PO Box 111, St Albans, Hertfordshire, AL2 3JQ
Tel: 0870 770 3212
Web: www.papaa.org
Provides support and information for people with psoriasis and psoriatic arthritis.
References
© EMIS and PiP 2008 Updated: 5 Feb 2008
