Mark Lebwohl, MD: Let’s go further. Erin, I’ll ask you this question. What are the clinical manifestations of plaque psoriasis? Can you discuss the progressive nature of the disease and the risk for developing other diseases, other comorbidities?
Erin Boh, MD, PhD, FAAD: Psoriasis is a chronic inflammatory immune-mediated process. What we would expect are red scaling plaques. Classically we see them in the elbows and knees. You’ll see scalp involvement in some patients. You’ll see genital. But the classic distribution all of us are familiar with is elbows and knees. Lower back is another common area. And we want to keep in mind that they have a characteristic look, barely sharply demarcated. Actually, as James suggested, they do tend to come back in the same location. We’ll have patients who classically get the same areas of involvement over and over.
What I like to do is look to see what areas are affected, and then I like to then describe in terms of, is it a very little amount? We separate them into mild, moderate, and severe. But I do like to include severe categories: genital, scalp, nail psoriasis. Those are very difficult to treat, and it puts us in a different category.
Mark Lebwohl, MD: Palm and soles.
Erin Boh, MD, PhD, FAAD: And palms and soles, absolutely. Usually psoriasis is a disease that starts in adolescents, but we have a lot of children who do have severe psoriasis. But I do think it starts at a young age. I like to tell people it’s 2 modes of appearance. One around adolescence, 17, 20 years old; then it pops back up in the early 60s. Again, the progression is you start sometimes with mild disease and over time—as our external triggers come into play, other comorbidities are forming—we see a more severe progression or more extensive progression of disease.
I do think we see this march from mild to moderate psoriasis in younger people. As you get older— again, those comorbidities are in part responsible from the pathogenesis of psoriasis—we’ll see other comorbidities tending to make the psoriasis become more and more severe. Especially in regard to psoriasis; most of us see that, in terms of arthritis. Most of us see that arthritis tends to be more problematic with people who had severe disease, recalcitrant disease, or disease presenting in childhood or young adulthood.
I watch for that—patients with severe disease. I’m going to be on the lookout for arthritis developing a little later, maybe 5, 10 years after psoriasis. I like to prepare for that with whatever we choose for treating the disease. And it does tend to get a little more progressive and extend over time, and we start to see comorbidities come into play, which contribute to severity of the disease.
Mark Lebwohl, MD: OK. Any other comments? Leon or James?
Leon Kircik, MD: One thing Erin brought up about the arthritis, they did a study and about 87% of the patients who did not have a psoriatic arthritis diagnosis actually had aches and pains and discomfort. It’s very interesting. As we mentioned, those patients will develop—well, we don’t know how many of them, but eventually some of them will develop psoriatic arthritis. In Europe they are doing studies now looking at those joints with the sonogram and ultrasound, trying to find out, which is very interesting. We don’t have it here yet at this clinic, and they’re able to see the joint damage. Because as you know, the disease progression in psoriatic arthritis is crucial. It can be prevented early on with the appropriate treatment so we can prevent disability.
Erin Boh, MD, PhD, FAAD: Leon, you mentioned that, and it’s a good point. Patients don’t out-and-out say, “I have joint pains. I have arthritis.” They have aches in their skin, or they have fatigue, and then they don’t realize how many arthritic complaints they had until they get on therapy and it goes away. We think of it as arthritis, but patients with psoriasis routinely don’t say, “Oh, this is arthritis.”
Leon Kircik, MD: Actually, most of them don’t even know that 1 relates to another, right?
Erin Boh, MD, PhD, FAAD: Exactly.
Leon Kircik, MD: When I ask them about their joints they say, “Doc, I’m here for my skin. What’s wrong with you? Why are you asking me about the joints?”
James Song, MD, FAAD: Yeah. What’s interesting is, we’re taught that the more severe your skin psoriasis is, the higher the risk of a psoriatic arthritis. That’s certainly true. But just in the real world, when we talk to our rheumatology colleagues, the majority of their arthritis patients who have pretty limited skin psoriasis. When you look at the data, you know up to 50% of arthritis patients will have mild to moderate psoriasis. We just need to remember that even though their plaques might be limited, they’re still at a higher risk for psoriatic arthritis.
And the other thing—I just wanted to switch gears really quick—is pediatric psoriasis. I’m not a pediatric dermatologist, but I have recognized that sometimes the plaque in pediatric patients could look different. They may not be as dark. They may be much lighter pink, much finer scale. Sometimes it’s like, is this psoriasis or is it eczema? I didn’t think they could coexist. But yes, they can coexist. In our pediatric patients that seems to be more common. I just wanted to point that out.
Mark Lebwohl, MD: Fortunately—getting back to arthritis—we don’t have blood tests to tell us if the patient has psoriatic arthritis. The joints, especially early on, will look normal. And the patient goes to a rheumatologist and gets an x-ray and they say, “The x-ray is normal.” So they say, “I don’t have it.”
But in fact, if they have morning stiffness that lasts 30 minutes after they wake up and they’ve got psoriasis, they’re already headed to that diagnosis. They’ve got several of the criteria for that diagnosis. When we have a serologic marker, a blood test, it will expand the population of patients we use. Things like bone marrow edema on MRI, when that’s been looked at, is dramatically increased in psoriasis patients compared with the general public. We hear a number of 10% to 30%. When we have sensitive methods of diagnosing, it will likely do more.
Transcript Edited for Clarity