Scaly Skin? Psoriasis Facts

Last Editorial Review: 1/31/2005

Psoriasis can't be cured, but it can be treated successfully.

By Daniel DeNoon
WebMD Feature

Reviewed By Charlotte Grayson

Psoriasis is more common than most people think. It affects as many as two in every 100 people. Most cases are mild. Many are severe. It can't be cured -- but it can be treated.

The Problem

Typically, psoriasis appears as a patch of raised, reddish skin with a thick white scale on top. This is plaque psoriasis, which makes up some 80% of cases. It can appear on any part of the body, causing intense itching and burning. The most common sites are the knees, elbows, scalp, trunk, and nails. Psoriasis on the hands, feet, or genitals can be particularly uncomfortable.

Other, less common forms of psoriasis appear as:

"Generally, psoriasis of the skin is very easy to recognize," says Jeffrey Weinberg, MD, director of clinical research at St. Luke's-Roosevelt Hospital Center in New York. "But if it is not typical, it will usually take a doctor to diagnose it."

Most people get psoriasis between the ages of 15 and 35, but it can strike at any age. You can't catch psoriasis from another person -- but you can inherit it. Cells of the immune system cause the disease. They send out inappropriate chemical messages that make the skin grow too fast.

The Solution

Treatments for psoriasis focus on slowing the immune responses that cause the disease.

Weinberg tells WebMD that psoriasis treatment has three levels:

  • Topical treatments (ointments) are used for mild cases.
  • Ultraviolet or UV light treatments are used when creams fail.
  • Systemic treatments (oral medications) are used for more severe cases.

Topical treatments are spread over areas of skin affected by psoriasis. They come as creams, ointments, sprays, gels, lotions, tapes, and foams.

"The mainstay of psoriasis treatment is topical corticosteroids," Weinberg tells WebMD. "These can be used depending on the location or the severity of disease. We start with the mild ones and move to stronger ones as needed."

Topical corticosteroids often are used in combination with a topical form of vitamin D marketed as Dovonex.

Another commonly used topical treatment is Tazorac. This is a topical retinoid, similar to the Retin-A used to treat acne. Weinberg says Tazorac is most helpful for psoriasis on the palms and soles.

Finally, there are new topical medicines that inhibit the chemical messengers sent to the skin by immune cells. These drugs currently are approved only for eczema. However, dermatologists sometimes prescribe them for psoriasis.

"I've found some of these eczema drugs to be helpful: Elidel cream and Protopic ointment," Weinberg says. "These can be helpful in sensitive areas like the face or the folds of the groin. They may not be helpful on the body so much because they may not penetrate thick plaque."

Another useful treatment for psoriasis is light therapy or phototherapy. Ultraviolet or UV light is thought to rid the skin of the immune cells that trigger psoriasis. There are several ways to deliver this light to the skin:

  • Via broadband UV light B
  • Via narrowband UV light B
  • Via PUVA -- psoralen plus ultraviolet light A, also known as photochemotherapy. The treatment uses a drug called psoralen that makes the skin more sensitive to UV A light. Psoralen can be taken by pill or applied to the skin as a liquid or ointment.

"Narrowband UV B is relatively new -- it's more effective than the traditional broadband UV B and very safe," Weinberg says. "I've started to use it a lot. PUVA is the most effective, but it increases one's risk of skin cancer."

A new kind of laser -- the excimer laser -- delivers a highly focused UV B.

"This isn't a cutting or burning laser -- it just delivers the right wavelength of UV B," Weinberg notes. "It can treat just the areas of psoriasis and not the rest of the skin."

Traditional systemic treatments for psoriasis affect the whole body. The idea is to calm down the immune system. It helps psoriasis -- but also makes a person more vulnerable to infections and even cancer. They have other toxicities as well. The drugs are saved for moderate or severe psoriasis that doesn't respond to other types of treatment.

The traditional mainstay of systemic psoriasis treatment is a drug called methotrexate. Another commonly used immune-suppressing drug is Neoral (known generically as cyclosporine).

A more recent systemic treatment is Soriatane. It's a retinoid compound similar to Accutane, the acne drug. Weinberg notes that Soriatane is less effective but safer than methotrexate or Neoral.

Newer systemic treatments also slow the immune system, but they have specific targets within the immune system. They are called biologic drugs. Weinberg says there are four major biologic drugs with promise for psoriasis:

  • Amaveve targets the T cells involved in psoriasis. As of August 2003, it's the only systemic biologic agent approved specifically for psoriasis treatment. It's given intravenously or by intramuscular injection.
  • Enbrel is approved for a form of arthritis caused by psoriasis called psoriatic arthritis. "The phase III clinical trial data (for using Enbrel to treat psoriasis) is very promising," Weinberg says. "It's given twice weekly by skin injection that can be done at home."
  • Remicade is also approved for rheumatoid arthritis and Crohn's disease. It's given by intravenous infusion every several weeks. "It's effective but can have serious side effects," Weinberg says.
  • Raptiva is currently under FDA consideration for treatment of psoriasis. It's given in once-weekly injections. "Studies show it's safe and effective," Weinberg says.

"One issue with these biologics is their high cost: $15,000 to $30,000 a year," Weinberg says. "And we don't have long-term data with any of them. That means we can't define the exact risk of serious infection or malignancy until they have been used for many, many years. It's not that we think it will happen -- it's just that we can't yet rule it out."

Note: Weinberg is a member of the speakers bureau for Amgen and Genentech, which manufacture biologic psoriasis treatments.

Published August 2003.

SOURCES: Jeffrey Weinberg, MD, director of clinical research, St. Luke's-Roosevelt Hospital Center, New York. National Psoriasis Foundation. The American Academy of Dermatology.

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