Kaitlin: Hello, my name is Kaitlin Walden, and I'll be your moderator for today's episode about inverse psoriasis. I was initially diagnosed with plaque and scalp psoriasis at the age of 6 and have experienced inverse psoriasis myself. With me to talk about this topic is dermatologist Dr. Jeffrey Cohen, who is the Director of the Psoriasis Treatment Program at Yale School of Medicine, where he's also the Director of Safety for the Department of Dermatology, and an Assistant Professor of Dermatology. Dr. Cohen also serves on the editorial board of the Journal of the American Academy of Dermatology, is a senior editor for NPF's Journal of Psoriasis and Psoriatic Arthritis, a counselor of the International Psoriasis Council, and a member of the Medical Board of the National Psoriasis Foundation.

Welcome Dr. Cohen. It's an honor having you here today on Psound Bytes™, which will soon have a new name. We've heard a lot of discussions in recent years about how psoriasis severity is determined and how severity does not always correlate with body surface area, also known as BSA, or the Dermatology Life Quality Index or DLQI. Can you please address what is the reason for this discussion and the change in how psoriasis severity is determined.

Dr. Cohen: Well, first I'd just like to thank you for having me. I'm very happy to be here and it's a real honor to be talking with you today.

Kaitlin: Of course.

Dr. Cohen: This is a very important question. And I think really highlights a change in the way that we're all conceptualizing psoriasis severity. So as you mentioned in the past, we would talk a lot about the body surface area. You know, what percentage of your body has psoriasis lesions on it? And then also looking plainly at things like the Dermatology Life Quality Index. But what we've come to realize and what we're really now trying to advocate for is an understanding that not every place on the body is the same. And so even though, for example, the palms of your hands or the soles of your feet do not account for a very large percentage of your total body, they are extremely important for your day-to-day function, the way you feel, and the things that you're able to do. For example, if you're an auto mechanic and you have psoriasis all over your palms, it's going to be very hard to do your daily life. If you have family obligations and you need to bathe small children, same problem. If you have a lot of athletic activities you enjoy doing and your feet are covered in psoriasis. You may not be able to engage in those activities. Similarly, we talk about sensitive sites like the genitalia, and when that's involved you may have trouble with your intimate relations and other things like that. So we've come to understand that those indicators of psoriasis severity can be really important for people and the move in this is well supported by the International Psoriasis Council, and also the NPF in terms of really trying to understand the burden of disease and capture that better than we can with a plain body surface area percentage.

Kaitlin: Thank you so much. I think that's super insightful considering a lot of us in the psoriasis world have had multiple experiences across many decades with psoriasis and how many different doctors view what is considered appropriate treatments based upon surface area. So, what I'm hearing you say is that appropriate treatment should be identified by a number of different factors, not just BSA. A topical treatment might not be the right choice to start with. Is that correct?

Dr. Cohen: Absolutely. So one of the very important aspects of all these types of discussions is that many times insurance companies will determine whether or not someone is a candidate for a given therapy based on their body surface area and they want that documented in our medical notes to determine whether they want to approve a drug. And so a lot of this has implications in terms of drug approval because now there's been a move, as we mentioned, to think about sensitive sites and other factors beyond body surface area and to characterize people as candidates for systemic therapy. For example, as opposed to just saying they have 4% body surface area or 60% body surface area, we want to say that this is someone who has a need for a systemic treatment, they're a candidate for a systemic treatment. And so we have kind of moved well beyond that BSA era and now we're talking about these candidates for systemic treatment. So along with that, we realized that there may be people for whom they have a relatively small body surface area, but they should still be escalated directly to a systemic therapy. And some examples of common situations in which this is important is for example, if someone has nail changes from psoriasis, we know the topical therapies don't do a whole lot to help with the nails. And so those patients would benefit the most from going directly to a systemic therapy. Similarly, we know that psoriasis on the palms and soles are not often responsive to topical therapies, and many of those patients should go directly to systemic therapies. Scalp is another similar example. And so we are now trying to characterize people again beyond the body surface area and as candidates for systemic therapy and thinking about first line, right away getting people on the most effective treatment, whether it's topical or systemic, depending on the appropriate choice for an individual patient.

Kaitlin: It seems like a very exciting future for all of us with psoriasis and PsA. Which leads us to our topic today, a topic that is near and dear to my heart, a discussion of inverse psoriasis. Inverse psoriasis includes special sites. Can you please define what is inverse psoriasis and what areas are typically affected by this type of psoriasis?

Dr. Cohen: Yes. So when we talk about inverse psoriasis, we're thinking about things that are sort of opposite to the key characteristics that are often defined in the textbooks. And so if you look at the textbooks, you see that psoriasis comes on the elbows, on the knees. We call these extensor sites of the body. Inverse psoriasis is named inverse because it's the opposite of that, it's the skin folds. So it’s under the arms, in the skin folds of the legs, areas like that, in the skin fold near the gluteal cleft. These are areas that are involved in inverse psoriasis as opposed to the classic plaque psoriasis, for example, which comes mostly on the elbows, on the knees, and on the rest of the body. So that's why we call it that and the Intertriginous sites are folds where inverse psoriasis takes place.

Kaitlin: Thank you so much for going into that. Something that I've experienced actually is inverse psoriasis and when we move on to talking about what it looks like and what areas, and what the typical symptoms are, I'd love to tell you a little bit about my experience and maybe that can help other listeners. I recently had to travel cross country from West Coast to East Coast in August when my father was on hospice care and so I have plaques on my elbows and my knees and my typical locations. And so I was the sole driver with my kiddos. My husband was deployed and so I was on the road driving for probably 12 hours a day over the course of six days. By the time I made it cross country, underneath my arms, near where my bra line would be I had inverse psoriasis. And at first I thought I was having allergic reaction to maybe soaps along the way at the hotels. And then I realized what it was, it was not like my plaque psoriasis at all. It was flat. It was red. It was very itchy and it was painful and it just hurt and to be honest, before inverse psoriasis actually showed itself on my skin, I had pain. And I was thinking maybe it was just from my material of my clothes or whatever it might have been. And so I'd love to get your take on what inverse psoriasis typically looks like, what areas, and what typical symptoms exist.

Dr. Cohen: So you bring up a lot of very important points and a lot of causes for confusion when people present for medical care and try to get a diagnosis with inverse psoriasis. So one important thing that I heard you mention was that you didn't see the typical scale that you see in other areas. And the reason for that is that these skin folds tend to be somewhat moist, right? We sweat a little bit under our arms, for example. And so the typical dry, whitish scale that we see on our psoriasis plaques, on our elbows or knees or elsewhere on the body, that white scale becomes moist, and so it doesn't look white anymore. And so the plaques are what we call in our description, a beefy plaque, which means that basically it's a kind of pink or red area that may have some thickness to it, but usually actually does not show a lot of scale, which often people rely on when they diagnose psoriasis. And so in areas, for example, like inframammary folds, under breasts or in the folds under the arm, there's moisture and so there's not a lot of scale there. And so these pink plaques that arise can be easily confused with lots of other things, including an allergic reaction such as allergic contact dermatitis. Or sometimes people think they're an infection of different types. And so it can be challenging for people who present with that type of psoriasis, particularly who don't have other types of psoriasis to help point someone in the right direction to get the correct diagnosis. In terms of symptoms, there can be a variety, so these are also areas that rub a lot and so the lesions can become fairly irritated and so sometimes people have stinging or pain. Other times, people get the typical itch that you might get with psoriasis elsewhere on the body. But there can be multiple different symptoms going on at the same time. So they may have itch at some point, they may have pain or burning at other points, or feeling irritated, especially as you mentioned these spots are doing a lot of rubbing on clothing and rubbing against other areas of skin. So it’s an area that can get a lot of irritation.

Kaitlin: I appreciate that. And I now know moving forward what it is because at first I really didn't know. I did reach out to a physician. Because it wasn't my normal doctors and they were like, no, I think you're having an allergic reaction to your deodorant and I was like, I don't think so. So I really appreciate this. I think it will help a lot of people, especially in circumstances like myself where you're traveling, you have a lot of new things going on. I'm curious what triggers inverse psoriasis?

Dr. Cohen: The triggers for inverse psoriasis, fairly similar actually to the triggers for psoriasis elsewhere on the body are in large part still being worked out. We know of certain things that can trigger psoriasis for example we know that certain medications can trigger psoriasis. We know that smoking cigarettes increases the likelihood of someone getting psoriasis. We know that sometimes when people feel sick, they have a psoriasis flare, for example. But there are no known specific triggers of inverse psoriasis. Though sometimes people find that they can pick out things themselves, like triggers in their environment or things they may eat, there are not good studies that point to universal triggers for inverse psoriasis, similar to regular psoriasis.

Kaitlin: So going back to what we were just talking about, it could be more difficult to diagnose inverse psoriasis. Are there other diseases that could complicate treatment or that could be confused with inverse psoriasis?

Dr. Cohen: There are, and the diagnosis of inverse psoriasis, especially for someone who does not have psoriasis elsewhere, can sometimes be pretty challenging. And it can be a little bit confusing to figure out exactly what you're looking at, because there are other things that can present in a fairly similar fashion in the folds. I would say the two most common confusions and things that people get mixed up with are number one allergic contact dermatitis. So for example having an allergy to your deodorant, or soap or detergent, or a fabric or a dye in a fabric, or something like that. And the second one actually is fungal infections because fungal infections also like areas that are kind of moist in skin folds. So it can be pretty common for someone to be told that their inverse psoriasis is actually a fungal infection. And many times we'll see people who have tried to use antifungal treatments that are not particularly effective 'cause again it's inverse psoriasis and not a fungal infection. But that's, I would say probably the number one most commonly confused entity is fungal infection and we see that very often.

Kaitlin: Thank you for that. I think that will help a lot of people who are going to see different doctors who are experiencing inverse psoriasis for the first time. So something I've learned recently is that scalp and inverse psoriasis are risk factors for the development of psoriatic arthritis. Can you explain why having a certain type of psoriasis places you at a higher risk for PsA?

Dr. Cohen: The one type of psoriasis actually that we know the most about in terms of correlation with risk for psoriatic arthritis is nail psoriasis and we think that that has to do with the proximity of the nail unit, how close the nail unit is to the joint in the finger. When we think about other forms of psoriasis like scalp psoriasis or inverse psoriasis, and why they correlate with psoriatic arthritis risk, we don't know 100%. We imagine that maybe there's a higher burden of inflammation in the body when people have these special subtypes of psoriasis. In other words, your inflammation in general, which is what we think links psoriasis to its other comorbidities like psoriatic arthritis, may be higher if you have inverse psoriasis then if you have plaque psoriasis for example. There may also be an element of coexistence between multiple. So there are lots of people who have both inverse psoriasis and plaque psoriasis, or scalp psoriasis and plaque psoriasis, and it may be that some of those people, in addition to having the inverse psoriasis or scalp psoriasis, also have lots of psoriasis on other parts of the body, and that may partially also account for some of that association that we see. But we are hoping to learn more and understand more about the progression from psoriasis to psoriatic arthritis and importantly, we want to understand if there are ways to predict who might have that. And also, if there are things we can do early on to prevent that from happening in the right people. So these are all areas of active research and investigation and hopefully when we do this same podcast in a few years, we'll have more concrete Information to share.

Kaitlin: I hope so too. It sounds like science is moving in a really wonderful direction for the whole community of psoriasis and PSA. Something that we touched on earlier, evidence-based care or treatment. Given the complexities of treating this type of psoriasis and the impact on quality of life, what medications do you typically start with if inverse psoriasis affects, for example, armpits, under the breasts, behind the ears, what does that look like?

Dr. Cohen: Generally, when we start, for most people we might try a topical treatment first before going on to a systemic treatment like a biologic or a pill. And topical treatments for inverse psoriasis tend to be fairly similar in their pattern to those for regular psoriasis. So, for example, many people will first start with a topical steroid. One important difference between what we do with inverse psoriasis and psoriasis on other parts of the body is that the steroid that you're going to use in a skin fold often not going to be quite as strong as you would use for example on the elbow or the knee. So people may have gotten betamethasone, or clobetasol or halobetasol. These are some pretty strong steroids for their elbows and knees. Those might be too strong and are generally not what we reach for, for the underarms, for example. And so in underarms we may use slightly weaker ones like hydrocortisone or desonide. We also often use non-steroid topical medications in these sites and examples of those include tacrolimus or pimecrolimus. Some of our newer psoriasis topicals are very good at treating inverse psoriasis locally. So things like Zoryve® or VTAMA® can be very helpful for that. Often times people do require more than just their topical treatments. And so that tends to take a fairly similar pattern and cadence to what we see for general psoriasis in other parts of the body. And so we may move to a pill next, something like Otezla® or  Sotyktu®. And then if those don't work, some patients do require injectable biologics in order to control inverse psoriasis. And again even though it may not be a high body surface area, as we often think about for biologics, it can be a very impactful part of the body that's involved. And so the inability to function with your hands, function with your feet, engage in the normal types of relationships you want to engage in. Those are very important factors that even though there's not a large body surface area, they may have an impact on life that would warrant the use of something like a biologic if the other treatments like topicals or orals are either inappropriate or ineffective.

Kaitlin: I'm hearing a lot of talk about quality of life which brings me to another subject about medications that might differ if we're treating inverse psoriasis in the genital area. What does that look like? What's involved?

Dr. Cohen: So obviously having psoriasis in the genital area is something that can be really disruptive to people. It can be uncomfortable when they're wearing their clothing, going around doing their normal thing, and then of course that would have an impact on your ability to be potentially intimate with your partner, and for a lot of people that takes a huge toll on their mental health, on their quality of life, and can be a really big deal. And so a lot of times we move pretty quick to give people systemic treatment for psoriasis on the genital areas so that we can get things clear and keep things clear. Many of the treatments that we use for psoriasis in other areas, for example the interleukin-23 inhibitors, like Skyrizi® or Tremfya®, work very well for this, as do some of our interleukin-17 inhibitors like Taltz® or the most recently approved one, Bimzelx®. These all have very good efficacy and some even have some dedicated trials that look at treating inverse psoriasis or genital psoriasis.

Kaitlin: I appreciate that. I think this is an incredibly important topic. I know that the conversation with doctors in discussing genital psoriasis can be incredibly embarrassing to bring up with a dermatologist, a doctor. Do you have any recommendations for patients and doctors when discussing this sensitive issue?

Dr. Cohen: I agree completely. And you know, it really shouldn't be taken lightly how embarrassing some of this can be for people, and sometimes people actually don't know what's going on. They realize they may have symptoms in an area, or they may see some redness in an area, but they may not realize that is connected to their psoriasis. They may not realize that because it looks different under the arm, for example, than it would on their knee, that these are still related and the same. So I think it's important for both patients with psoriatic disease and physicians treating patients with psoriatic disease to feel comfortable and open the door to these discussions. And I think on the physician side, it is important to ask. I will often directly ask my patients, do you have any concerns about your underarms, your skin folds, your genitalia, what have you. Because oftentimes someone who did not mention it, never brought it up, will say “actually I am worried about that”. Or “I do have something there” and I always offer, I don't make them say more. I say “why don't we take a look” and just check. And people often feel, I think, relieved that they don't have to bring it up and that you ask about it. However, on the patient side, speaking I think for all physicians, I can say that we want to know if something's going on there and you should never feel embarrassed or feel like someone doesn't want to hear about it or look at it. This is our job. This is why we're here. We're all trying to work together to take the best care of you. And so if you feel that you need to be an advocate for yourself and say, “hey, you know something's going on in my underarms or something's going on in my genital area”, we're there to hear it and we want patients to all feel comfortable bringing that up to us if it's an issue. But I think first and foremost, it is important for physicians to take the first step and ask, inquire and check when needed so that this important issue is identified and taken care of quickly because as we have spoken about, it can have a huge impact on patient’s quality of life and their overall well-being.

Kaitlin: That is such an empowering response. To be honest, I  think a lot of people we suffer in silence when we have skin conditions and I really appreciate you bringing that to light, both from the patient perspective and the physicians perspective so that we can all work together and get the best outcome. So on to another topic, which is combinations of medications. What kind of possible combination of medications could be used to treat inverse psoriasis?

Dr. Cohen: Combination therapy is often very important in inverse psoriasis and in all of these types of psoriasis that tend to be somewhat difficult to treat. And so to put that in context, an example when combination treatment is often necessary is someone may have both plaque and inverse psoriasis, and they may be put on a biologic that does a great job of clearing away their plaque psoriasis, but they may still have some troublesome, stubborn, bothersome residual inverse psoriasis, and so in those cases we often do think about combining treatments. What can we add to your biologic to help deal with this bit of inverse psoriasis that's left behind. So often times the first thing we try to combine biologics with is a topical medicine. And so there are some people who are on a biologic. It does a great job. It does most of what they need to do, but there are small areas where they get flares every now and again and maybe they use a topical steroid as needed. Or maybe they use a topical calcineurin inhibitor like tacrolimus as needed, or one of our newer psoriasis medications like VTAMA® or Zoryve® as needed on areas that flare up. And often times the areas that flare up for people are the inverse sites, cause those sites tend to be slightly more challenging to treat and to keep under control. Sometimes to be honest though, it's not enough. A topical on top of the biologic doesn't always do the job. And so sometimes we have to add another systemic medication and for some people that might look like adding methotrexate once a week to give a little bit of extra efficacy or adding something like Soriatane (Acitretin) which is a medicine we've had for a very long time that can help, particularly when there are stubborn areas on the palms and soles, or sometimes in sites that are considered inverse psoriasis, that can be helpful. And then there are people who are on a biologic at the same time as something like Otezla® or Sotyktu®. This can also be effective in trying to capture those areas that are resistant to the initial biologic treatment. Even if those areas are not a huge amount of the body, it can still be very impactful and it may warrant the addition of for example Otezla® to your biologic, and that can generally be done safely, as long as you're an appropriate candidate and your dermatologist is observing you and making sure. Rarely someone might be on two biologics at one time, but that's a generally pretty uncommon situation.

Kaitlin: Thank you for that. Moving on to something we touched a little bit on before which is kind of the development and significant treatment developments that are happening right now. What would you say is the most significant treatment development for inverse psoriasis?

Dr. Cohen: I think the most important developments for inverse psoriasis are the same as the most important developments for psoriasis in general, and I see those happening in three areas. The first area is we are continuing to see more and more effective biologics reach the market that work in slightly different ways in terms of mechanism. For example, bimekizumab or Bimzelx® was just approved and that blocks both Interleukin-17A and F which is different from the interleukin-17 inhibitors that blocked A for example that we've been using for a while. And so I think that's one area that's very exciting and there is a pipeline of biologics that are coming out that will continue to add options for patients because every new biologic that's one more person who may respond to that drug that didn't respond to other drugs. One more choice for someone whose medication stops working. One more option to try to treat psoriasis for people. So that's always good. Number two is there are more oral medications coming onto the market and these hold certain advantages for people. For example, some people don't do well with needles. Some people would prefer to take a pill each day or twice a day, as opposed to having to give themselves injections and having more oral medications on the market just adds more options for those people and gives us more choices when we're treating psoriasis. And then I would say in the third zone, it's topical treatments. We've seen over the last several years VTAMA® and Zoryve® be approved and that's really exciting, particularly for inverse psoriasis, because there are patients who may be able to manage their inverse psoriasis using those types of non-steroid treatments which are safe long term and safe for skin folds which, for example, some of our stronger topical steroids might not be. Those topical medications can add a new treatment option that can be really helpful for people. And so with more topical medications coming in the pipeline and more development on that side, that just adds more options for people who either want to use those alone or want to use those as add-ons with biologics or other systemic treatments to try to get their skin as clear as possible.

Kaitlin: It sounds like it's a very exciting time for medications being released and just new and promising direction when it comes to treatment. So with that, what do you think

Dr. Cohen: Absolutely.

Kaitlin: the inverse psoriasis future looks like as far as treatment goes and developments?

Dr. Cohen: My hope and my anticipation is that over time we will continue to have more options that are more and more effective to try to treat inverse psoriasis. As we get more data, not just clinical trial data, but also larger scale real world data with our biologics, we may get a sense of which particular biologics or which particular agents are the best for inverse psoriasis specifically, and that may help us select the best treatment up front for someone who has inverse psoriasis, either in combination with other forms of psoriasis or on its own. And so I think that some of that data will be helpful in helping us pick the best medicine for each individual patient. And then I think as we think about whether the biologics may be used or other strategies may be used to prevent the onset of psoriatic arthritis or other comorbidities that could be a big helpful treatment advance for psoriasis in general and specifically for inverse psoriasis, because as we discussed the risk of psoriatic arthritis is higher in those with inverse psoriasis as compared to those with plaque psoriasis.

Kaitlin: As someone who has suffered with inverse psoriasis myself, you give me a lot of hope and I want to thank you so much for this conversation and the interesting look at inverse psoriasis. I am so grateful to have you here with us today. Do you have any final comments? Anything else you would like to share for our listeners?

Dr. Cohen: Well, it's been an absolute pleasure being here and I would say the thing I would like to leave people with is just an understanding that inverse psoriasis is important and it's impactful. And even if your dermatologist doesn't ask about it, we know that it is. And so for all the patients listening, I really want you to each feel empowered to mention this if it's a problem and to let us all know how it's going so that we're able to help you manage the problem, pick the right treatment and make sure that we have effective treatment, not just for plaque psoriasis or other forms of psoriasis, but also for inverse psoriasis, which as we mentioned may not be talked about as much as some of the other forms. And for the dermatologist listening, thank you for continuing to work on this as a community and thank you for continuing to pay attention to patient’s concerns about inverse psoriasis and continue to ask people and try to learn more about how this is impacting them so that we can do the best job treating each patient holistically and managing all aspects of their psoriatic disease.

Kaitlin: Thank you again Dr Cohen for being here today to discuss inverse psoriasis, which is something we don't often speak about. And I'm very excited for the future. If you have inverse psoriasis, as Dr Cohen mentioned, have that conversation with your dermatologist or healthcare provider to help find the right treatment plan for you. If you would like more information about genital psoriasis, visit our resource library to download the latest genital psoriasis guide at psoriasis.org/resources-library. If you know someone who could benefit from information provided by Dr Cohen, please share this episode link. Thank you for listening. Join us for our next episode about what lies underneath the skin also known as related conditions and hear our new name.