Who gets psoriasis?
Psoriasis occurs in both children and adults and may appear
at any age, although it is most commonly diagnosed between the
ages of 15 and 35. Both men and women of any race may be affected.
How common is psoriasis?
It is estimated that over seven million Americans (2.6%) have
psoriasis, with more than 150,000 new cases reported each year.
According to the National Psoriasis Foundation, 20,000 children
under 10 years of age are diagnosed with psoriasis annually.
What causes psoriasis?
The exact cause of psoriasis is unknown; however, researchers
suspect that whether a person develops psoriasis or not may
depend on a "trigger." Possible psoriasis triggers
include emotional stress, skin injury, systemic infections,
and certain medications. Studies have also indicated that a
person is born genetically predisposed to psoriasis, and multiple
genes have been discovered over the past 5 years confirming
this fact. Even so, not everyone with psoriasis will have a
family history of the disease.
What is parakeratosis, and what does it have to do
Parakeratosis is a word you may have come across when you read
about psoriasis, especially plaque-type psoriasis. It is a term
that describes the process by which psoriatic skin continuously
forms and scales off.
In normal skin, the outer layer, made up mostly of cells called
keratinocytes, is replaced every 27 to 28 days with newly formed
keratinocytes. The replacement usually occurs without a person
noticing it; if it takes place unusually quickly or in unusual
amounts, we may notice flakes and scales on our skin, clothing,
bedding, etc.In psoriasis, the process of keratinocyte production
is sped up.
New keratinocytes are formed and moved upward to the skin surface
faster than they can be incorporated into skin. Some are moved
upward so fast that they are not yet mature cells. The keratinocytes
accumulate and are scaled off. Parakeratosis is the word used
to describe the entire process.
Psoriatic plaque has other features also, including inflammatory
cells and dilated small blood vessels that contribute to both
the appearance and the symptoms of a psoriatic lesion.
In general, the cycle of psoriasis can best be described as
the body's immune system triggering excessive skin-cell reproduction.
In healthy skin, cells mature and are shed in about 28 days.
In people with psoriasis, this process is accelerated to only
3 or 4 days. This excessive reproduction causes skin cells to
build up and form abnormal scaling seen on lesions in psoriasis.
Can psoriasis occur on the sole of the foot and be mistaken
for a plantar wart?
Psoriasis can and does occur on the sole of the foot. The psoriatic
lesion can be painful to walk on, as can a plantar wart. It
can be mistaken for a plantar wart by both the patient and the
physician or podiatrist.
Psoriasis on the sole of the foot is usually of the plaque type.
A person who has had psoriasis for some time may recognize the
lesion as psoriatic plaque. Psoriasis may not be the first thing
that comes to mind in a person who has no previous experience
with the disease. Failure to recognize the lesion as psoriasis
may lead to a long period of incorrect treatment, and failure
to institute treatment for a developing case of psoriasis.
There are some diagnostic tips for differentiating psoriasis
on the sole of the foot from plantar wart:
If psoriasis is developing on the sole of the foot, there is
a good probability it is also developing on other parts of the
body. Likely places to look for developing psoriatic lesions
are the knees, elbows, hands and scalp.
Is it possible to have psoriasis and eczema at the same time?
The biology of skin limits the number of ways in which it can
manifest a disease process—by redness, flaking, swelling,
etc. Thus, many skin conditions can superficially resemble one
another and a dermatologic examination is necessary to establish
a diagnosis. Self-diagnosis of a troublesome skin condition
can delay proper treatment.
Psoriasis and eczema are two skin problems that seem to be mutually
exclusive to a degree, although this is not a hard and fast
rule. In persons with psoriasis the incidence of allergic contact
dermatitis and atopic dermatitis—two major forms of eczema—appears
to be substantially lower than in the general population. A
suggested reason is that the immune system dysregulation believed
to be a factor in psoriasis is not the same as dysregulation
of immune pathways in these forms of eczema.
Other skin diseases that superficially resemble psoriasis can
coexist with psoriasis. These include fungal and yeast infections,
scabies, cutaneous (skin) lymphoma, and cutaneous manifestations
of syphilis. Many skin lesions that superficially resemble psoriasis
lack the unique appearance of psoriasis:
||Psoriatic lesions have
||The surface of a psoriatic lesion
has silvery scales that easily flake off.
||The skin under the scales has a shiny
Can psoriasis be cured?
No. The tendency to develop psoriasis is inherited through a
person’s genes. We hope to be able to safely modify these
genes in the future, but the technology is not yet developed.
We do foresee a time, when we will have more specific and more
effective therapies for the various forms of psoriasis. Also,
while psoriasis cannot be cured, it can often be completely
cleared for periods of months or even years. Occasionally, it
never returns at all. In most patients, however, it is a chronic,
life-long condition with alternating periods of flaring and
Is risk for skin infections higher in people with psoriasis
than in people with normal skin?
Studies have shown that psoriatic plaques and adjacent normal
skin usually have the same type of bacteria, but the number
of bacteria per square millimeter is higher in the psoriatic
plaques. This, in itself, is usually not an increased risk for
Risk is increased when skin and/or plaques or guttate pustules
are colonized by the highly invasive Staphylococcus aureus,
a species of bacteria capable of causing serious skin and systemic
Risk for secondary infections may also be increased by hard
scratching that abrades the skin and opens it to bacterial invasion.
Hard scratching should be avoided for this reason, and also
because abrasion of the skin can be a trigger for formation
of new psoriatic lesions.
A skin hygiene program recommended by a dermatologist is usually
adequate to keep bacterial populations in check. Specific anti-bacterial
measures may be prescribed by a dermatologist when such measures
Symptoms of secondary infection are redness of skin around a
psoriatic lesion or increased redness of the lesion, increased
warmth in the skin and/or pus in the skin in the area of a lesion.
Fever, malaise and light-headedness can be symptoms of more
serious, systemic infection.
Will psoriasis shorten my life?
Psoriasis itself does not appear to shorten a person’s
life. Patients with psoriasis should be able to live full lives
into their senior years.
Will psoriasis cause my hair to fall out?
Psoriasis itself will not cause the hair to fall out. However,
very thick scales in the scalp can entrap hair and as you attempt
to remove the scales, you can loose hair in the process. In
addition, some medications such as salicylic acid can temporarily
damage the hair.
Should I change my psoriasis skin care regimen during
It’s important to increase your use of moisturizing creams
and ointments during the winter, applying heavy layers, especially
over the skin affected by psoriasis. It is helpful to apply
the moisturizing cream while your skin is damp. Also, be sure
to pat yourself dry after bathing—don’t rub yourself
with the towel.
During the winter months, the humidity is generally lower, especially
in homes with forced air heating. This tends to cause dry, itchy
skin. Scratching affected skin will worsen your psoriasis and
can even cause new lesions to form. Thus, it is important not
to scratch, pick, or scrub psoriasis lesions.
Is it true that getting a skin scrape can lead to a
Yes. Psoriasis patients can develop lesions at the site of significant
skin trauma, especially during a period of active disease. Psoriasis
worsens in areas of skin scrapes, scratches, and cuts (such
as surgical wounds). That’s why it is so important not
to pick, scratch, or scrub the lesions and scales. The development
of a psoriatic lesion at the site of skin trauma is called Koebner’s
Can you control psoriasis with diet?
Unfortunately no. However, the healthier the diet the better.
Especially a diet that includes regular exercise. For more information
about exercise and psoriasis, visit the web site of the National
For African-Americans and other darker-skinned people,
is the treatment for psoriasis different than for people with
The immunologic dysfunctions that are a major predisposing factor
in psoriasis are believed to be the same in all persons regardless
of skin color. The patterns of genetic inheritability for the
predisposing factors may vary in different groups.
The pigmentation of skin is controlled by hormonal processes
that are unrelated to the immune and inflammatory processes
that underlie psoriasis. It is interesting to note that all
humans, regardless of skin color, have about the same number
of melanocytes (pigment-containing cells) at any given site
on the skin. Variations in skin color are due to differences
in hormonal regulation of pigment formation within the melanocytes,
and transfer of the pigment from melanocytes to keratinocytes
(the cells that make up the majority of the outer layer of skin).
A principal hormone in the regulation of human skin color is
melanocyte-stimulating hormone (MSH).
The incidence of psoriasis is much lower in dark-skinned West
Africans and African-Americans than in light-skinned people
of European ancestry. Incidence is also low in Japanese and
Eskimos, and is extremely low to non-existent in Native Americans
in both North and South America. The reasons for this epidemiologic
disparity are not known, but are believed to involve genetic,
geographic and environmental factors.
The treatment of psoriasis in African-Americans is largely the
same as treatment in light-skinned patients. An adjustment is
therapy is made in the use of photochemotherapy (PUVA) and phototherapy.
In PUVA, both the chemical photosensitizer and the ultraviolet
dose are adjusted for skin type and pigmentation.
Are homeopathic treatments effective for psoriasis?
There is no scientific evidence that homeopathic treatments
are effective for treating psoriasis. However, it’s not
impossible that some of these treatments might be helpful. Scientific
studies need to be done in order to resolve this issue.
Is there a way to curb scratching? I have had psoriasis
for 20 years and my husband has been very supportive, but recently
he has started to complain about my constant scratching. He
knows I need to scratch to relieve itching, but it seems to
bother him more now. I’m afraid we’re heading for
marital problems unless I can stop scratching or he can stop
letting it bother him. Any suggestions?
Psoriasis in a spouse can be difficult for both marriage partners.
The spouse with psoriasis not only suffers from the disease
and perhaps from problems with self-image, but also may be acutely
aware of the partner’s struggles to be supportive. Over
time, it is the "little things" that can come between
partners—for example, flaked-off skin that must be shaken
from bed sheets every morning, or in this case the spouse’s
constant scratching that becomes a "last straw" for
an otherwise supportive husband.
The husband’s growing irritation may actually be a message
worth heeding, however. While scratching is effective in temporarily
relieving pruritus, hard scratching can also be a trigger for
formation of new psoriatic lesions or worsening of existing
lesions. Especially during active phases of psoriasis, abrasion
of the skin is one of the causes of Koebner’s phenomenon—the
induction of psoriatic lesions by injury to the skin. Hard,
constant scratching can cause the type of skin injury that leads
to development of Koebner’s phenomenon.
Since pruritus has become a major issue for both husband and
wife, the issue should be discussed with the patient’s
dermatologist. Pruritus control should perhaps be made a focus
of psoriasis treatment, along with educational counseling of
both marriage partners. As discussed in May’s Update,
general measures for control of pruritus include keeping the
skin cool and moisturized and avoiding irritating fabrics. Ice
packs may help stop the itching. A heavy moisturizing cream
applied twice daily will help control scaling and pruritus.
Specific pharmacologic measures should be prescribed by the
dermatologist on the basis of the patient’s history of
psoriasis and overall medical condition.
What should I look for in an OTC psoriasis shampoo?
There are numerous shampoos available at most drug stores. Look
for a shampoo that contains tar or salicylic acid. Be sure to
treat your scalp gently, as harsh shampoos, scalp messages or
scratching can aggravate psoriasis.
Is Skin-Cap® effective for controlling psoriasis?
Skin-Cap® is an over-the-counter zinc spray preparation
that contains a prescription-strength corticosteriod (clobetasol
propionate). It was marketed without disclosing this ingredient
on the product label. Numerous potentially harmful side effects
of clobetasol propionate include stretch marks, thinning skin
and dilation of tiny blood vessels. The U.S. Food and Drug Administration
(FDA) cautioned that users should not stop treatment with this
product without a dermatologist’s help because an abrupt
halt could cause serious, even life-threatening, flare-ups.
What effect does the sun have on psoriasis?
Natural sunlight can have a positive effect on psoriasis. The
long-known benefits of sunlight provided the basis for the development
of ultraviolet light therapy for treating psoriasis and other
skin diseases. However, you should never get enough sun exposure
to turn your skin red or cause a sunburn, which can actually
cause psoriasis to flare and worsen.