Psoriasis – In-Depth Report – NY Times Health

In-Depth From A.D.A.M. Background

An estimated 7.5 million Americans (2.2% of the population) have psoriasis. Psoriasis is a chronic skin disorder in which there are periodic flare-ups of sharply defined red patches, covered by a silvery, flaky surface. The main disease activity leading to psoriasis occurs in the epidermis, the top five layers of the skin.

The process starts in the basal (bottom) layer of the epidermis, where keratinocytes are made. Keratinocytes are immature skin cells that produce keratin, a tough protein that helps form hair, nails, and skin. In normal cell growth, keratinocytes grow and move from the bottom layer to the skin's surface and shed unnoticed. This process takes about a month.

In people with psoriasis, the keratinocytes multiply very rapidly and travel from the basal layer to the surface in about 4 days. The skin cannot shed these cells quickly enough, so they build up, leading to thick, dry patches, or plaques. Silvery, flaky areas of dead skin build up on the surface of the plaques before being shed. The skin layer underneath (dermis), which contains the nerves and blood and lymphatic vessels, becomes red and swollen.

Various forms of psoriasis exist. Some can occur alone or at the same time as other types, or one may follow another. The most common type is called plaque psoriasis, also known as psoriasis vulgaris.

Plaque psoriasis leads to skin patches that start off in small areas, about 1/8 of an inch wide. They usually appear in the same areas on opposite sides of the body.

The patches slowly grow larger and develop thick, dry plaque. If the plaque is scratched or scraped, bleeding spots the sizes of pinheads appear underneath. This is known as the Auspitz sign.

Some patches may become ring-shaped (annular), with a clear center and scaly raised borders that may appear wavy and snake-like.

As the disease progresses, eventually separate patches may join together to form larger areas. In some cases, the patches can become very large and cover wide areas of the back or chest. This is known as geographic plaques because the skin lesions resemble maps.

Plaque psoriasis may persist for long periods of time. More often it flares up periodically, triggered by certain factors such as cold weather, infection, or stress.

Patches most often occur on the:

They may also be seen on the:

Psoriasis of the scalp affects about 50% of patients. In some cases, the psoriasis may cover the scalp with thick plaques that extend down from the hairline to the forehead.

Psoriasis patches rarely affect the face in adulthood. In children, psoriasis is most likely to start in the scalp and spread to other parts of the body. Unlike in adults, it also may occur on the face and ears.

Psoriasis Form

Description of Skin Patches

Comments

Guttate Psoriasis

The patches are teardrop-shaped and appear suddenly, usually over the trunk and often on the arms, legs, or scalp. They often disappear without treatment.

Guttate psoriasis can occur as the initial outbreak of psoriasis, often in children and young adults 1 - 3 weeks after a viral or bacterial (usually streptococcal) respiratory or throat infection. A family history of psoriasis and stressful life events are also highly linked with the start of guttate psoriasis.

Guttate psoriasis can also develop in patients who have already had other forms of psoriasis, most often in people treated with widely-applied topical (rub-on) products containing corticosteroids.

Inverse Psoriasis

Patches usually appear as smooth inflamed areas without a scaly surface. They occur in the folds of the skin, such as under the armpits or breast, or in the groin.

Inverse psoriasis may be especially difficult to treat.

Seborrheic Psoriasis

Patches appear as red scaly areas on the scalp, behind the ears, above the shoulder blades, in the armpits or groin, or in the center of the face.

Seborrheic psoriasis may be especially difficult to treat.

Nail Psoriasis

Tiny white pits are scattered in groups across the nail. Toenails and sometimes fingernails may have yellowish spots. Long ridges may also develop across and down the nail.

The nail bed often separates from the skin of the finger and collections of dead skin can build up underneath the nail.

Over half of patients with psoriasis have abnormal changes in their nails, which may appear before other skin symptoms. In some cases, nail psoriasis is the only symptom.

Generalized Erythrodermic Psoriasis (also called psoriatic exfoliative erythroderma)

This is a rare and severe form of psoriasis, in which the skin surface becomes scaly and red. The disease covers all or nearly all of the body.

About 20% of such cases evolve from psoriasis itself. The condition may also be triggered by certain psoriasis treatments, and other medications such as corticosteroids or synthetic antimalarial drugs.

Pustular Psoriasis

Patches become pus-filled and blister-like. The blisters eventually turn brown and form a scaly crust or peel off.

Pustules usually appear on the hands and feet. When they form on the palms and soles, the condition is called palmar-plantar pustulosis.

Pustular psoriasis may erupt as the first occurrence of psoriasis, or it may evolve from plaque psoriasis.

A number of conditions may trigger pustular psoriasis, including infection, pregnancy, certain drugs, and metal allergies.

Pustular psoriasis can also accompany other forms of psoriasis and can be very severe.

Psoriatic arthritis (PsA) is an inflammatory condition that leads to stiff, tender, and inflamed joints. Estimates on its prevalence among people with psoriasis range from 2 - 42%. AIDS patients and those with severe psoriasis are at higher risk for developing PsA.

About 80% of PsA patients have psoriasis in the nails. Arthritic and skin flare-ups tend to occur at the same time. It is not clear whether psoriatic arthritis is a unique disease or a variation of psoriasis, although evidence suggests they are both caused by the same immune system problem.

PsA is often divided into five forms. The forms differ according to the location and severity of the affected joint:

People who start to smoke after developing psoriasis may delay the onset of psoriatic arthritis. However, research has also linked smoking to an increased risk of psoriasis, and because smoking causes serious health problems, it should not be considered as a way to delay this type of psoriasis.

The precise causes of psoriasis are unknown. It is generally believed to be caused by damage to factors in the immune system, enzymes, and other materials that control skin cell division. This prompts an abnormal immune response, which causes rapid production of immature skin cells and inflammation.

The Normal Immune System Response. The inflammatory process is the result of the body's immune response, which fights infection and heals wounds and injuries:

The Infection Fighters. The primary infection-fighting units are two types of white blood cells: lymphocytes and leukocytes.

Lymphocytes are a type of white blood cell designed to recognize foreign substances (antigens) and launch an offensive or defensive action against them. Lymphocytes include two subtypes known as T cells and B cells:

A type of T cell called a helper T cell stimulates B cells and other white blood cells to attack a foreign substance. In psoriasis, however, the helper T cell appears to direct the B cells to produce autoantibodies ("self" antibodies), which attack skin cells. In psoriatic arthritis, cells in the joints also come under attack.

In psoriasis, helper T cells also release or stimulate the production of powerful immune factors called cytokines. In small amounts, cytokines are very important for healing. However, the high level of these cytokines that occurs in psoriasis can cause serious damage, including inflammation and injury during the psoriasis disease process.

A combination of genes is involved with increasing a person's susceptibility to the conditions leading to psoriasis. However, researchers are still unsure as to exactly how the disease is inherited.

HLA Molecules. The processes leading to all autoimmune diseases involve the human leukocyte antigens (HLA), a group of protein markers found on cells. Most immune disorders are associated with problems in how the body reacts to these different protein markers or antigens. However, other genetic and environmental factors are required to actually trigger the disease.

Four key genes (named PSOR 1 - 4) seem to be involved with psoriasis. Certain variations or changes in these genes may increase the risk of psoriasis. These same variations linked to psoriasis and psoriatic arthritis are also associated with four autoimmune diseases: type 1 diabetes, Grave's disease, celiac disease, and rheumatoid arthritis, suggesting that all of these diseases have the same genetic basis.

The presence of a recently identified variation in a group of genes known as LCE can protect against the development of psoriasis.

Weather, stress, injury, infection, and medications, while not direct causes, are often important in triggering the disease process that initiates and worsens psoriasis.

Weather. Cold, dry weather is a common trigger of psoriasis flare-ups. Hot, damp, sunny weather helps relieve the problem in most patients. However, some people have photosensitive psoriasis, which actually improves in winter and worsens in summer when skin is exposed to sunlight.

Stress and Strong Emotions. Stress, unexpressed anger, and emotional disorders, including depression and anxiety, are strongly associated with psoriasis flare-ups. Research has suggested that stress can trigger specific immune factors associated with psoriasis flares.

Infection. Infections caused by viruses or bacteria can trigger some cases of psoriasis. For example:

Skin Injuries and the Koebner Response. The Koebner response is a delayed response to skin injuries, in which psoriasis develops later at the site of the injury. In some cases, even mild abrasions can cause an eruption, which may be why psoriasis tends to frequently occur on the elbows or knees. However, psoriasis can develop in areas that have not been injured.

Medications. Drugs that can trigger the disease, worsen symptoms, or cause a flare-up include:

Severe flare-ups may occur in people with psoriasis who stop taking their steroid pills by mouth, or who discontinue the use of very strong steroid ointments that cover wide skin areas. The flare-ups may be of various psoriatic forms, including guttate, pustular, and erythrodermic psoriasis. Because these drugs are also used to treat psoriasis, this rebound effect is of particular concern.

Medications that cause rashes (a side effect of many drugs) can trigger psoriasis as part of the Koebner response.

Risk factors for psoriasis include:

A microscopic examination of tissue taken from the affected skin patch is needed to make a definitive diagnosis of psoriasis and to distinguish it from other skin disorders. Usually in psoriasis, the examination will show a large number of dry skin cells, but without many signs of inflammation or infection. Specific changes in the nails are often strong signs of psoriasis.

The severity of psoriasis ranges from one or two flaky inflamed patches to widespread pustular psoriasis that, in rare cases, can be life threatening. To help determine the best treatment for a patient, doctors usually classify the disease as mild to severe. The classification depends on how much of the skin is affected:

The palm of the hand equals 1% of the body.

The severity of the disease is also measured by its effect on a person's quality of life.

The National Psoriasis Foundation has proposed a new classification method. The group suggests a two-tiered system that classifies patients as needing either local or body-wide (systemic) treatment.

In general, severe or widespread psoriasis is harder to treat. However, some forms of psoriasis can be very resistant to treatment, even though they are not categorized as severe. They include:

Many creams, ointments, lotions, and pills are available to treat psoriasis. Some patients require only over-the-counter treatment, or even no treatment.

Many patients with psoriasis, however, do not respond to over-the-counter remedies and lifestyle changes, and require aggressive treatments. In some cases, such treatments need to be lifelong.

In general, there are three treatment options for patients with psoriasis:

Individual needs vary widely, and treatment selection must be carefully discussed with the doctor.

Giving treatment in a stepwise order can help provide quick symptom relief and long-term maintenance. It involves three main steps:

Choices for transitional or maintenance treatments depend on the severity of the condition.

In severe chronic cases, the doctor may recommend rotational therapy. This approach alternates treatments. The goal is to prevent severe side effects or the build-up of resistance from long-term use of a single medicine. An example of a rotational schedule may be the following:

Doctors increasingly use combinations of pills, creams, ointments, and phototherapy instead of single medications. Combinations of oral treatments are particularly useful, because the doses of each drug can be reduced. This lowers the risk of severe side effects. Thousands of combinations are possible, and patients should discuss with their doctors the best treatment for their individual needs.

Topical medications are those applied only to the surface of the body. They come in the following forms:

In general, topical treatments are the first line for mild-to-moderate psoriasis, but they may also be used, alone or in combination, with more powerful treatments for moderate-to-severe cases. Topical medicines rarely clear up symptoms completely, however.

Topical corticosteroids are the mainstay of psoriasis treatment in the United States. These drugs work for most patients because they:

Corticosteroids are available in a wide range of strengths, and are generally given as follows:

Topical steroids are often rated by how strong or potent they are:

In the past, topical steroids were used twice a day. For some patients, certain drugs may work just as well if taken once a day. Both high-potency steroids, and possibly medium-strength steroids, such as triamcinolone (Aureocort, Tri-Adcortyl), may be as beneficial as a once-daily treatment.

However, corticosteroids used alone are not enough for most patients. Combining topical steroids with other topical drugs (see below) is often needed. Many patients also need oral medicines.

Side Effects. The more powerful the corticosteroid, the more effective it is. But more powerful steroid drugs also have a higher risk for severe side effects, which may include:

Loss of Effectiveness. In most cases, patients become tolerant to the effects of the drugs, and the drugs no longer work as well as they should. Some experts recommend using intermittent therapy (also called weekend or pulse therapy). This type of treatment involves applying a high-potency topical medication for 3 full days each week.

A topical form of vitamin D3, calcipotriene (Dovonex) is proving to be both safe and effective. It is now available in a foam preparation, which makes using it even easier. Several other topical vitamin D3-related drugs that are showing promise include maxacalcitol (Oxarol), tacalcitol, and calcitriol (Silkis).

Calcipotriene appears to:

It works just as well as moderate topical corticosteroids, short-term anthralin, and coal tar in improving mild-to-moderate plaque psoriasis. But unlike with steroids, patients do not develop thinning of the skin or tolerance to the drug.

Using the drug in combination with other topical and body-wide treatments may improve its effectiveness. Calcipotriene doesn't work as well as the highest potency corticosteroids, but combining both medications is proving to be more effective than taking either one alone. Taclonex, an ointment containing both calcipotriol and betamethasone, is available for the treatment of adults with psoriasis. Studies show the combination works better than either drug alone.

Combining vitamin D ointments with systemic medicines, notably methotrexate, acitretin, or cyclosporine, increases its effectiveness. Because combining medications allows patients to use lower doses of both medications, it reduces side effects.

Studies also report success in some patients who use vitamin D ointments in combination with phototherapy treatment.

Side Effects. Calcipotriene may cause the following side effects:

Calcipotriene appears to cause greater skin irritation than potent corticosteroids. Diluting the drug with petrolatum or applying topical corticosteroids to sensitive areas may prevent this problem.

Coal tar preparations have been used to treat psoriasis for about 100 years, although their use has declined with the introduction of topical vitamin D3-related medicines. Crude coal tar stops the action of enzymes that contribute to psoriasis, and helps prevent new cell production. Tar is often used in combination with other drugs and with ultraviolet B (UVB) phototherapy.

Side Effects. Preparations have the following drawbacks:

Anthralin (Dritho-Scalp, Drithocreme, Micanol) slows skin cell reproduction and can produce remissions that last for months. It is recommended only for chronic or inactive psoriasis, not for acute or inflamed eruptions. People with kidney problems should use anthralin with caution.

As with tar, anthralin's use has also declined since the introduction of the topical vitamin D-related medicines, but newer formulations, such as Micanol, have made its use more tolerable. Micanol (Psoriatec) is an anthralin formulated in microcapsules, which dissolve and allow the drug to be delivered directly to the target skin areas. It is particularly useful for scalp psoriasis, and it is less likely than other formulations to stain.

Side Effects. Anthralin may cause the following side effects:

Patients should not use anthralin on the face. Fair-skinned people should generally avoid it. Triethanolamine (CuraStain) is a chemical that can neutralize anthralin and help reduce irritation from short-contact anthralin treatment. It should be applied 1 or 2 minutes before washing off the anthralin. It is then reapplied after drying the skin.

Go here to read the rest:
Psoriasis - In-Depth Report - NY Times Health