Psoriasis is a chronic autoimmune disease that affects the skin, usually in the form of thick, red, scaly patches. It occurs when the immune system sends out faulty signals that speed up the growth cycle of skin cells. There are five types of psoriasis: plaque, guttate, inverse, pustular and erythrodermic. The most common form, plaque psoriasis, appears as raised, red patches or lesions covered with a silvery white buildup of dead skin cells, called scale. Psoriasis can occur on any part of the body, but most commonly appears on ellbows, knees and scalp. Psoriasis is not contagious.
Up to 30 percent of people with psoriasis also develop psoriatic arthritis. Psoriasis can be associated with other serious conditions such as diabetes, heart disease and obesity.
Psoriasis is a persistent, long-lasting disease. You may have periods when your psoriasis symptoms improve or go into remission alternating with times when your psoriasis worsens. For some people, psoriasis is just a nuisance. For others, it's disabling, especially when associated with arthritis.
There is no cure, but psoriasis treatments may offer significant relief. Lifestyle measures, such as nutritional intervention, applying certain cremes, reducing stress and exposing your skin to small amounts of natural sunlight, can improve psoriasis symptoms.
Symptoms
Psoriasis signs and symptoms can vary from person to person but may include one or more of the following:
- Red patches of skin covered with silvery scales
- Small scaling spots (commonly seen in children)
- Dry, cracked skin that may bleed
- Itching, burning or soreness
- Thickened, pitted or ridged nails
- Swollen and stiff joints
Psoriasis patches can range from a few spots of dandruff-like scaling to major eruptions that cover large areas.
Immune System Cause
The cause of psoriasis is related to the immune system, in particular, the white blood cells called a T lymphocytes or T cells. Normally, T cells travel throughout the body to detect and fight off foreign substances, such as viruses or bacteria. If you have psoriasis, however, the T cells attack healthy skin cells by mistake as if to heal a wound or to fight an infection.
These overactive T cells trigger other immune responses including dilation of blood vessels in the skin around the plaques and an increase in other white blood cells that can enter the outer skin layer (epidermis). These changes result in an increased production of both healthy skin cells and more T cells and other white blood cells. This results is an ongoing cycle in which new skin cells move to the outermost layer of skin too quickly, in days rather than weeks. Dead skin and white blood cells can't fall off quickly enough and build up in thick, scaly patches on the skin's surface. This usually doesn't stop unless treatment interrupts the cycle.
The exact cause of this T cells malfunction in people with psoriasis isn't entirely clear, although researchers think genetic and environmental factors both play a role
Psoriatic Arthritis
Psoriatic arthritis is a painful, inflammatory condition of the
joints that usually (but not always) occurs in association with
psoriasis. About 30% of people with skin psoriasis have
some signs of psoriatic arthritis.
Symptoms of psoriatic arthritis come and go but it is a
lifelong condition. It may result in severe damage to the joints and
can be as severe as rheumatoid arthritis.
People with psoriatic arthritis usually have some skin signs eventually.
In about 70% of sufferers of psoriatic arthritis skin psoriasis precedes arthritic symptoms. In the other 30% of patients simultaneous onset of
skin and joint psoriasis occurs or joint symptoms precede any skin problem.
The severity of the skin diseases does not predict the severity of the
joint disease.
Plaque psoriasis
is the most common form of skin psoriasis seen with psoriatic
arthritis. Joint symptoms may flare with a flare in skin psoriasis but
quite commonly the skin symptoms behave independently of joint
symptoms. Most people with psoriatic arthritis have mild skin psoriasis. |
Knowledge Links:
NZ Dermatologocal Society Inc.
National Psoriasis Foundation, Portland, Oregon, USA
National Institute of Arthritis and Musculoskeletal and Skin Diseases, USA
MedlinePlus:
Psoriasis
Mayo Clinc Psoriasis Info:
 All about Psoriasis
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