Psoriasis is a persistent skin disorder in which there are red, thickened areas with silvery scales, most often on the scalp, elbows, knees, and lower back. Some cases of psoriasis are so mild that people don’t know they have it. Severe psoriasis may cover large areas of the body. As dermatologists, we can help even the most severe cases.

Psoriasis is not contagious and cannot be passed from one person to another, but it is most likely to occur in members of the same family. In the United States, two out of every hundred people have psoriasis (four to five million people). There are approximately 150,000 new cases diagnosed each year.

What causes psoriasis?

The cause is unknown. However, recent discoveries point to an abnormality in the functioning of special white blood cells (T-cells) that trigger inflammation and the immune response in the skin. Because of the inflammation, the skin grows too rapidly. Normally, the skin replaces itself in about 30 days; but in psoriasis, the process speeds up and replaces the skin in three to four days, and the signs of psoriasis develop.

People often notice new spots 10 to 14 days after the skin is cut, scratched, rubbed, or severely sunburned (the Koebner phenomenon). Psoriasis can also be activated by infections, such as strep throat, and by certain medicines (beta blockers, lithium, etc.) Flare-ups sometimes occur in the winter as a result of dry skin and lack of sunlight.

Types of Psoriasis

Psoriasis comes in many forms. Each differs in severity, duration, location, shape, and pattern of the scales. The most common form, called plaque psoriasis, begins with little red bumps. Gradually, these become larger, and scales form. While the top scales flake off easily and often, scales below the surface stick together. These small red areas can enlarge.

• Scalp, elbows, knees, legs, arms, genitals, nails, palms, and soles are the areas most commonly affected by psoriasis. It will often appear in the same place on both sides of the body.

• Scalp psoriasis may be mistaken for dandruff.

• Nails with psoriasis frequently have tiny pits in them. Nails may loosen, thicken, or crumble and are difficult to treat.

• Inverse psoriasis occurs in the armpits, under the breasts, and in skin folds around the groin, buttocks, and genitals.

• Guttate psoriasis usually affects children and young adults. It often starts after a sore throat with many small, red, scaly spots appearing on the skin. It frequently clears up by itself in weeks or a few months.

• Up to 30% of people with psoriasis may have symptoms of arthritis, and 5% to 10% may have some functional disability from arthritis of various joints. In some people, the arthritis is worse when the skin is very involved. Sometimes, the arthritis improves when the condition of the patient’s skin improves.

How is psoriasis diagnosed?

Many times, as dermatologists, we can diagnose psoriasis by examining the skin, nails, and scalp. If the diagnosis is in doubt, a small skin biopsy may be helpful.

How is psoriasis treated?

The goal is to reduce inflammation and to control shedding of the skin. Moisturizing creams and lotions loosen scales and help control itching. Special diets have not been successful in treating psoriasis except in isolated cases.

Treatment is based on a patient’s health, age, lifestyle, and the severity of the psoriasis. Different types of treatments and several visits may be needed.

We may prescribe medications to apply on the skin containing cortisone compounds, synthetic vitamin D analogues, retinoids (vitamin A derivatives), tar, or anthralin. These may be used in combination with natural sunlight or ultraviolet light. The more severe forms of psoriasis may require oral or injectable medications with or without light treatment.

Sunlight exposure helps the majority of people with psoriasis, but it must be used cautiously. Ultraviolet light therapy may be given in a dermatologist’s office, a psoriasis center, or a hospital.

Types of Treatment

Steroids (cortisone) — Cortisone is a medication that reduces inflammation. Cortisone creams, ointments, and lotions may clear the skin temporarily and control the condition in many patients. Weaker preparations should be used on more sensitive areas of the body such as the genitals and face. Stronger preparations will usually be needed to control lesions on the scalp, elbows, knees, palms, soles, and parts of the torso. Dressings may sometimes be applied to enhance the effectiveness of the medication. These must be used cautiously and with your dermatologist’s instruction. Side effects of the stronger cortisone preparations include thinning of the skin, dilated blood vessels, bruising, and skin-color changes. Stopping these medications suddenly may result in a flare-up of the disease. After many months of treatment, the psoriasis may become resistant to the steroid preparations.

We may suggest an injection of cortisone in difficult-to-treat spots. These injections must be used in very small amounts to avoid side effects.

Scalp Treatment — The treatment for psoriasis of the scalp depends on the seriousness of the disease, hair length, and the patient’s lifestyle. A variety of non-prescription and prescription shampoos, oils, solutions, foams, and sprays are available. Most contain coal tar or cortisone. Salicylic acid and lactic acid preparations may be used to remove the scale. The patient must take care to avoid harsh shampooing and scratching the scalp.

Anthralin — This is a medication that works well on tough-to-treat, thick patches of psoriasis. It can cause irritation and temporary staining of the skin and clothes. Newer preparations and methods of treatment have lessened these side effects.

Vitamin D — Synthetic vitamin D analogue (calcipotriene) is useful for individuals with localized psoriasis and can be used with other treatments. Limited amounts should be used to avoid side effects. Ordinary vitamin D, as one would buy in a drug store or health food store, is of no value in treating psoriasis.

Retinoids — Prescription vitamin A-related gels, creams (tazarotene), and oral medications (isotrentinoin, acitretin) may be used alone or in combination with topical steroids for treatment of localized psoriasis. Women who are or may become pregnant should not use topical or oral retinoids.

Coal Tar — For more than l00 years, coal tar has been used to treat psoriasis. Today’s products are greatly improved and less messy. Stronger prescriptions can be made specifically to treat difficult areas.

Light Therapy — Sunlight and ultraviolet light slow the rapid growth of skin cells. Although ultraviolet light or sunlight can cause skin wrinkling, eye damage, and skin cancer, light treatment is safe and effective under a doctor’s care. People with psoriasis all over their bodies may require treatment in a medically approved center equipped with light boxes for full-body exposure. Psoriasis patients who live in warm climates may be directed to carefully sunbathe. Talk to one of us before self-treating your psoriasis with natural sunlight.

Ultraviolet light B (UVB) — This treatment involves exposing the skin to a wavelength of ultraviolet light called UVB. It may be used alone or in combination with topical or systemic treatments. UVB is administered with a light box that surrounds the patient or with a light panel in front of which the patient stands. It takes about 24 treatments over a two-month period for clearing to occur. A new type of UVB treatment called “narrow-band” UVB may be used if patients do not respond to broadband UVB. Although UVB is very safe and effective, it does have possible side effects that include burns, freckling, and skin aging. Risks of skin cancer appear to be no greater than those caused by sun exposure.

PUVA — When psoriasis has not responded to other treatments or is widespread, PUVA is effective in approximately 85% of cases. Patients are given a drug called psoralen, which may be taken orally or applied to the psoriasis, and are then exposed to a carefully measured amount of a special form of ultraviolet (UV) light. The treatment name comes from “psoralen + UVA,” the two factors involved. It takes approximately 25 treatments, over a two-month or three-month period, before clearing occurs. About 30 to 40 treatments a year are usually required to keep the psoriasis under control. Because psoralen remains in the lens of the eye, patients must wear UVA-blocking eyeglasses when exposed to sunlight from the time the psoralen is taken until sunset that day. PUVA treatments over a long period increase the risk of skin aging, freckling, and skin cancer. A trained dermatology staff member must monitor PUVA treatment very carefully.

Methotrexate — This is an oral anti-cancer drug that can produce dramatic clearing of psoriasis when other treatments have failed. Because it can cause side effects, particularly liver disease, regular blood tests are performed. Chest X-rays and occasional liver biopsies may be required. Other side effects include upset stomach, nausea, and dizziness. Methotrexate should not be used by pregnant women or by men and women who are trying to conceive a child. Conception should be avoided for at least 12 weeks after stopping methotrexate. Alcoholic beverages should not be consumed if using methotrexate.

Retinoids — Prescription, oral vitamin A-related drugs may be prescribed alone or in combination with ultraviolet light for severe cases of psoriasis. Side effects include dryness of the skin, lips, and eyes; elevation of fat levels in the blood (cholesterol and triglycerides); and formation of tiny bone spurs. Oral retinoids should not be used by pregnant women or women who intend to become pregnant during or within three years of discontinuation of therapy, as birth defects may result. Close monitoring is required together with regular blood tests.

Cyclosporine — This is an immunosuppressant drug used to prevent rejection of transplanted organs (liver and kidneys). It is used for treatment of widespread psoriasis when other methods have failed. Because of potential effects on the kidneys and blood pressure, close medical monitoring is required together with regular blood tests.

Biologic Agents

Alefacept — This is a biologic agent that works by blocking the overactivation of T-cells. Alefacept is for moderate-to-severe, chronic plaque psoriasis and is administered through an injection.

Etancercept — This is a biologic agent that blocks tumor necrosis factor-alpha (TNF-a), thereby interfering with a key cytokine that contributes to the development of psoriasis. It has been used for psoriatic arthritis and also benefits cutaneous psoriasis.

Other Biologic Agents

Infliximab and Adalimumab — These also blocks tumor necrosis factor-alpha (TNF-a) and have been under investigation for the treatment of psoriasis. They are approved for other indications.

Efalizumab — This is another biological agent studied for psoriasis. It blocks activation of T-cells and the movement or “trafficking” of T-cells into inflamed skin, thus improving psoriasis.