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Understanding Psoriasis

Posted Aug 24 2008 1:49pm
MABEL JONG: Hello, everyone. I'm Mabel Jong. Welcome to our webcast. The word "psoriasis" is derived from the Greek word for "itch," but this chronic skin disease isn't something that can be just scratched away. Research suggests that psoriasis is actually a disorder of the immune system.

Joining us to discuss our current understanding of psoriasis are Dr. Ken Gordon, director of the Psoriasis Treatment Center at Northwestern University, and Dr. Mark Lebwohl, professor and chairman of the department of dermatology at the Mount Sinai School of Medicine. Gentlemen, thanks for being with us today.


MABEL JONG: Let's start with the basics. What is psoriasis, Dr. Lebwohl?

MARK LEBWOHL, MD: Well, psoriasis is an inherited disorder of the skin in which an abnormality of the immune system triggers release of substances that cause the cells of the skin to multiply too quickly, so that ordinarily cells of the skin, of the superficial area of the skin, make themselves over about every 28 days, but in psoriasis that is active, that same portion of the skin may be made over every two to four days, and that comes up as thick, scaly, red plaques.

MABEL JONG: Dr. Gordon, are there some parts of the body that are more susceptible to this than others?

KENNETH GORDON, MD: Typically traumatic areas are more susceptible, so elbows and knees, the lower part of the back. But the important thing to remember is, psoriasis can happen anywhere on the body. Anywhere there's skin you can have psoriasis.

MABEL JONG: Let's go over the different types of psoriasis. Are there many different types?

MARK LEBWOHL, MD: Classically, there are four types, and the four types are plaque psoriasis, which is the most common type, and it's characterized by large, red, scaly patches that, as you've already heard, affect the elbows and knees, but can affect any part of the body, and there are patients who are covered, 80 to 100% of their body surface, with plaques in severe cases. That accounts for the majority of patients with psoriasis.

Probably somewhere on the order of 10 percent of patients will have something called guttate psoriasis, which are simply smaller, red, scaly lesions, the size of 1 or 2 centimeters , covering large areas of the body, and the typical scenario where that happens is after strep throat patients will develop a lot of little spots all over. That's the second most common type.

The two most dangerous types are called erythrodermic psoriasis and pustular psoriasis. Erythrodermic psoriasis patients' entire skin surface turns bright red and scaly, and they lose all of the protective functions of their skin. They literally can't control body temperature. They lose nutrients through their skin, they lose fluid through their skin. They're susceptible to infection. The skin barrier against infection is lost, and that is a life-threatening form of psoriasis. Patients have actually died from that form of psoriasis.

The other form that I mentioned, pustular psoriasis, occurs in two variants. One of them is generalized pustular psoriasis, in which, again, patients lose all of those protective functions of the skin, and this becomes a life-threatening instance where patients can die from their psoriasis.

MABEL JONG: In very, very severe cases?

MARK LEBWOHL, MD: Very severe. And there is a localized form which, while it is not life-threatening, is just as debilitating, and that's localized pustular psoriasis of the palms and soles. Patients simply can't use their hands or feet. They can't walk, they can't handle anything with their hands, because it is a painful form of psoriasis. So that's pustular psoriasis.

Fortunately, the latter two forms are rare. They're most commonly triggered by systemic steroids, or withdrawal of systemic steroids.

MABEL JONG: If someone has a very chronic case of psoriasis, are other parts of the body affected by it, Dr. Lebwohl?

MARK LEBWOHL, MD: The one particular part of the body that can routinely be affected in patients with psoriasis are the joints. It turns out that roughly 7 percent, or a little less than one out of ten patients who have psoriasis, will have significant psoriatic arthritis, meaning inflammation of the joints. And there are several different forms of that, and it can range in severity from fairly mild to quite severe and debilitating.

MABEL JONG: Who gets psoriasis? How common is it, Dr. Lebwohl?

MARK LEBWOHL, MD: It affects a little over 2.5 percent of the population, and it can affect anyone. While I said it was inherited, ordinarily, about a third of patients will have a family history of the disease. So two-thirds of patients actually don't know of someone else in the family that has the disease. Nevertheless, it can affect anyone, and it can actually start at any age. There have been patients who were born with psoriasis. There are patients who develop psoriasis for the first time after the age of 100. An average age would be somewhere around 30 years old. But, again, it can affect any age. MABEL JONG: Is it safe to say that it isn't contagious?

KENNETH GORDON, MD: It is not contagious at all.

MABEL JONG: What is going wrong when psoriasis happens or develops in someone? Is it something to do with the immune system and how it operates?

KENNETH GORDON, MD: The scenario of what happens when psoriasis develops, a patient who is genetically predisposed to developing the disease will have some kind of immune challenge. That challenge will cause these cells, the lymphocytes, to respond and go to the skin and release cytokines, which induce the skin cells to change. The problem is, we don't know exactly what causes those lymphocytes to behave in that manner, and that's why we don't fully understand the etiology. But what we do know is that those lymphocytes that are causing those problems are necessary for the disease, and the elimination of their activity can help to treat the disease.

MABEL JONG: How does this disease affect patients?

KENNETH GORDON, MD: I think one thing to remember is, though psoriasis manifests itself on the skin primarily, the effects of psoriasis are very far-ranging in patients' health and the way patients view themselves. I think if you look at the patients with psoriasis, they view their disease as as disabling as diabetes or congestive heart failure. The important thing to remember is that people have a very visible disease on their skin. They're sometimes not allowed in their swimming pool because of the myth that psoriasis is contagious. People who have very limited disease, only limited to the palms or soles, might be very debilitating because of pain on walking or holding a pencil. So I think when you think about psoriasis, patients will go a long way to try to get treatment because of the both mental and physical disabling properties of the disease.

MABEL JONG: So quite a severe psychological toll can be exacted, as well?

KENNETH GORDON, MD: There are surveys that show that the psychological toll of psoriasis is the equivalent of depression, which is about as severe as you can get.

MABEL JONG: You've worked with this disease for a long time. What hope is there out there for patients who have it now?

MARK LEBWOHL, MD: I would say if you looked over the past 20 or 30 years at drugs that have been introduced for a variety of dermatologic conditions, an enormous proportion have been introduced for psoriasis. A lot of that is due to the patient advocacy groups, like the National Psoriasis Foundation, that have been pushing that. In addition, on the forefront, coming out in the future, you will find a number of drugs approved for psoriasis that I think are both safer and as effective or more effective than many of the treatments we use today.

MABEL JONG: Dr. Mark Lebwohl, Dr. Ken Gordon, thanks for being with us today. And thank you for watching our webcast. I'm Mabel Jong.

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