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What Is Psoriasis?
Psoriasis is a noncontagious common skin condition that causes rapid skin cell reproduction resulting in red, dry patches of thickened skin. The dry flakes and skin scales result from the rapid buildup of skin cells. Psoriasis commonly affects the skin of the elbows, knees, and scalp.
Who Can Get Psoriasis?
Psoriasis is seen worldwide, in all races, and both sexes, in approximately 125 million people. It currently affects roughly 7.5 million to 8.5 million people in the U.S. Interestingly, African Americans have about half the rate of psoriasis as Caucasians.
Although psoriasis can be seen in people of any age, from babies to seniors, most commonly patients are first diagnosed in their early adult years. Some people have such mild psoriasis (small, faint dry skin patches) that they may not even suspect that they have a medical skin condition. Others have very severe psoriasis where virtually their entire body is fully covered with thick, red, scaly skin. Psoriasis is considered a non-curable, long-term (chronic) skin condition. It has a variable course, periodically improving and worsening.
What Causes Psoriasis?
The exact cause of psoriasis remains unknown. There may be a combination of risk factors, including genetic predisposition and environmental factors. It is common for psoriasis to be found in members of the same family. The immune system is thought to play a major role. Despite research over the past 30 years looking at many triggers, the "master switch" that turns on psoriasis is still a mystery.
What Does Psoriasis Look Like?
Psoriasis typically looks like red or pink areas of thickened, raised, and dry skin. It classically affects areas over the elbows, knees, and scalp. Essentially any body area may be involved. It tends to be more common in areas of trauma, repeat rubbing, use, or abrasions.
Psoriasis has many different appearances. It may be small flattened bumps, large thick plaques of raised skin, red patches, and mildly dry pink skin to big flakes of dry skin that flake off. We'll take a look at some of the different types on the following slides.
Psoriasis vulgaris is the medical name for the most common form of psoriasis ("vulgaris" means common). About 80% of people with psoriasis have this type. It is also called plaque psoriasis because of the characteristic plaques on the skin: well-defined patches of red raised skin that can appear on any area of skin, although the knees, elbows, scalp, trunk, and nails are the most common locations. The flaky silvery white buildup on top of the plaques is called scale; it is composed of dead skin cells. This scale comes loose and sheds constantly from the plaques.
Guttate psoriasis is a type of psoriasis that looks like small, salmon-pink drops on the skin. The word guttate is derived from the Latin word gutta, meaning drop. Usually there is a fine scale on the droplike lesion that is much finer than the scales in plaque psoriasis, the most common type of psoriasis. The trigger to the disease is often a preceding streptococcal (bacterial) infection. The eruption of the lesions on the skin usually happens about two to three weeks after the person has strep throat. The outbreak can go away and not reoccur.
Inverse psoriasis consists of bright red, smooth (not scaly) patches found in the folds of the skin. The most common areas are under the breasts, in the armpits, near the genitals, under the buttocks, or in abdominal folds. These irritated and inflamed areas are aggravated by the sweat and skin rubbing together in the folds. Yeast overgrowth, common in skin folds, may trigger the skin lesions of psoriasis.
Pustular psoriasis is an uncommon form of psoriasis. People with pustular psoriasis have clearly defined, raised bumps on the skin that are filled with pus (pustules). The skin under and around these bumps is reddish. Pustular psoriasis may cause large portions of your skin to redden. The skin changes that occur before, during, or after an episode of pustular psoriasis can be similar to those of regular psoriasis.
This is the least common type of psoriasis and can be quite serious. A very large area of the body, if not most of the body, is bright red and inflamed. The body can appear to be covered in a peeling red rash. The rash usually itches or burns.
Psoriasis of the Scalp
The scalp may have fine, dry, scaly skin or have heavily crusted plaque areas. The plaque can flake off or peel off in crusted clumps. Sometimes psoriasis of the scalp is confused with seborrheic dermatitis. A key difference is that in seborrheic dermatitis, the scales are greasy looking, not dry.
Psoriatic arthritis is a specific condition in which a person has both psoriasis and arthritis. Psoriatic arthritis is an autoimmune disease, meaning that the immune system is misdirected to cause inflammation of one's own tissues. Rarely, a person can have psoriatic arthritis without having skin psoriasis. Moreover, the arthritis can precede the psoriasis by months or years, or present after years of psoriasis.
Can Psoriasis Affect Only My Nails?
Yes, psoriasis may involve solely the nails. More commonly, the nail symptoms accompany the skin and arthritis symptoms. Nails affected by psoriasis can have small pinpoint pits or large yellowish separations of the nail plate called "oil spots." Nail psoriasis is typically very difficult to treat, but it can respond to medications taken internally to treat psoriasis or psoriatic arthritis. Treatment options include potent topical steroids applied at the nail-base cuticle, injection of steroids at the nail-base cuticle, and oral or systemic medications as described below for the treatment of psoriasis.
Is Psoriasis Curable?
No, psoriasis is not currently curable. However, it can go into remission and show no signs of disease. Ongoing research is actively making progress on finding better treatments and a possible cure in the future.
Is Psoriasis Contagious?
No. Research studies have shown that it is not contagious. You cannot catch it from anyone, and you cannot pass it to anyone else via skin-to-skin contact. You can directly touch someone with psoriasis every day and never develop the skin condition.
Can I Pass Psoriasis on to My Children?
Yes, it is possible. Although psoriasis is not contagious from person to person, there is a known inherited (genetic) tendency to develop it. Psoriasis may be inherited from parents to their children or other ancestors. It does tend to run in some families, and a family history is helpful in making the diagnosis.
What Kind of Doctor Treats Psoriasis?
Dermatologists specialize in the diagnosis and treatment of psoriasis, and rheumatologists specialize in the treatment of joint disorders, including psoriatic arthritis. Many kinds of physicians may treat psoriasis, including dermatologists, family physicians, internal medicine physicians, rheumatologists, and other medical doctors.
Medical Treatment – Topical Agents
Medications applied directly to the skin are the first course of treatment options. The main topical treatments are corticosteroids (cortisone like creams, gels, liquids, sprays, or ointments), vitamin D-3 derivatives, coal tar, anthralin, or retinoids. There isn't one topical drug that is best for all people with psoriasis. Because each drug has specific adverse effects or loses potency over time, it is common to rotate them. Sometimes topical preparations are combined together. For example, keratolytics (substances used to break down scales or excess skin cells) are often added to these preparations. Some preparations should never be mixed together because they interfere with each other. For example, salicylic acid inactivates calcipotriene cream or ointment (a form of vitamin D-3). On the other hand, drugs such as anthralin (tree bark extract) may require the addition of salicylic acid to work effectively.
Medical Treatment – Phototherapy (Light Therapy)
The ultraviolet (UV) light from the sun slows the production of skin cells and reduces inflammation. Sunlight helps reduce psoriasis symptoms in some people. If psoriasis is widespread, as defined by more patches than can easily be counted, then artificial light therapy may be used. Resistance to topical treatment is another indication for light therapy. Proper facilities are required for the two main forms of light therapy. Medical light sources use particular wavelengths of light. Sunlamps and tanning booths are usually not acceptable as substitutes for medical light sources.
- Ultraviolet B (UV-B) light therapy is usually combined with one or more topical treatments and is extremely effective for treating moderate to severe plaque psoriasis. UV-B is light with wavelengths of 290-320 nanometers (nm), shorter than the range of visible light (visible light ranges from 400-700 nm). The major drawbacks of this therapy are the time commitment required for treatments and the accessibility of UV-B equipment. With long-term use, there is a risk of skin cancer, just as there is from natural sunlight.
- PUVA is the therapy that combines a psoralen drug (taken by mouth) with ultraviolet A (UV-A) light therapy (UV-A is light with wavelengths of 320-400 nm). Psoralen drugs make the skin more sensitive to light and the sun. More than 85% of patients report relief of disease symptoms with 20-30 treatments. Therapy is usually given two to three times per week on an outpatient basis, with maintenance treatments every two to four weeks until remission. Adverse effects of PUVA therapy include nausea, itching, and burning. Long-term complications include increased risks of sensitivity to the sun, sunburn, skin cancer, and cataracts. Protective glasses must be worn during and after treatment to prevent cataracts. PUVA therapy is not used for children younger than 12 years of age.
Medical Treatment – Systemic Agents (Drugs Taken Within the Body)
These drugs are often started for psoriasis after both topical treatment and phototherapy have failed. These agents are potent drugs given by mouth or injection and block inflammation which can slow the growth of skin cells in psoriasis. Examples include methotrexate (Rheumatrex, Trexall), adalimumab (Humira), and infliximab (Remicade). Systemic agents may also be considered for psoriatic arthritis. People whose disease is disabling because of physical, psychological, social, or economic reasons may also be considered for systemic treatment.
What Is the Long-Term Prognosis in Patients With Psoriasis?
Overall, the prognosis for most patients with psoriasis is good. While it is not curable, it is controllable. Many newer medications have led to excellent results."
There have been a few studies showing a possible association of psoriasis and other medical conditions, including obesity and heart disease. Psoriasis research is heavily funded and holds great promise for the future. Just the last five to 10 years have brought great strides in the treatment of the disease with medications aimed at treating the overactive immune system that causes the skin inflammation of psoriasis. Ongoing research is needed to decipher the precise underlying cause of this disease.
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