Internal medicine and rheumatology specialist Siobhan Deshauer, MD, is back for part 2 of "What Your Skin Says About Your Health," where she describes several skin conditions and their associated risks. Watch part 1 here.
Following is a partial transcript of the video (note that errors are possible):
Deshauer: I'm not exaggerating when I say that spotting these signs on your skin could actually save your life or someone you care about. Pattern recognition is key when you're identifying rashes, so I'm going to show you lots of examples so you can start to see the similarities and differences. So let's dive into it.
These two rashes look pretty similar, right? But one primarily affects appearance while the other is a sign of something far more serious that can affect every organ in the body. You're going to see that this is a bit of a theme in this video, similar-looking rashes with different underlying causes.
This patient has lupus and what you're seeing is a classic malar rash. It spreads across the cheeks and nose, often forming a shape similar to a butterfly. This rash is probably the most recognizable sign of lupus, a systemic autoimmune disease that impacts everything from the joints to the kidneys, lungs, and brain.
House, MD: We finally have a case of lupus.
Deshauer: In comparison, this other patient has rosacea, which is a chronic skin condition that causes redness, visible blood vessels, and even bumps that look like acne. People will notice that it gets worse with spicy foods, alcohol, or sunlight. But aside from the cosmetic issues, which can be really distressing for people, it fortunately doesn't seem to have any impact on your overall health. Clearly, it's important to tell these rashes apart and here are some strategies that I use.
Look closely at this area of the face, the nasolabial folds. Interestingly, lupus usually does not affect this area. For simplicity's sake, if you have a rash like this and the rash is present in the nasolabial folds, then it's likely not lupus. The second thing to consider is other symptoms that can flare up with this rash. Because although the rash will often bring people into my office, when I start digging and asking them questions they are often having a lot of other symptoms that are related to all the inflammation caused by lupus.
Check out the lupus classification criteria to get a sense of the wide range of signs and symptoms that we're looking for. If you've got this rash and especially if you've got other symptoms with it, you definitely need to see your doctor. Over the years, some of you guys have emailed me asking if I have a malar rash, and while I love that you're so observant and thinking about it, nope. I just have a lot of freckles.
Next, I want to share with you a simple trick that doctors use to determine whether a rash could be caused by vasculitis, a group of conditions that cause inflammation in blood vessels and can cause irreversible damage to internal organs. Ideally, you would use a glass slide, but you can also just use a regular water glass at home.
See how this rash disappears when you apply pressure and then when you release the pressure it returns? This is called a blanchable rash. Basically, this tells us that there are dilated blood vessels full of blood at the surface of the skin, giving it the red color. When you apply pressure, the blood is pushed out of the blood vessels and the red color disappears. This is actually a good thing because it tells us the blood is where it should be -- inside the blood vessels.
Now, here is the concerning sign. If you apply pressure to the skin, but this time the rash does not disappear, that tells me that the blood has actually leaked out of the blood vessels. This can happen if you have very low platelets or a serious infection. This famously happens in meningococcemia, but I also see this all the time in autoimmune diseases where the immune system attacks and destroys blood vessels. In fact, it was by spotting this type of rash that I made my first-ever diagnosis of vasculitis as a second-year medical resident. I'll never forget it.
I was on call overnight and the emergency physician asked me to see a patient who had gone into kidney failure, but they didn't know why her kidneys had suddenly stopped working. I went through my usual history and physical exam. When I got down to examining her legs, I noticed this small cluster of red dots on her foot that she hadn't noticed. As you might have guessed, the rash was nonblanchable so I was immediately thinking about vasculitis.
I remember ordering the full vasculitis workup that night and in the end, a few days later, she was diagnosed with granulomatosis with polyangiitis, a type of small vessel vasculitis. This gave us the reason for her kidney failure. The same blood vessel destruction that was causing her rash was also happening inside her kidneys. By noticing the rash and diagnosing her as soon as possible, we were then able to suppress her immune system with medications and save her kidneys. It was one of the moments that really solidified for me that I wanted to become a rheumatologist.
OK. Now, these rashes are pretty common and I find people often confuse the two because they both cause red itchy patches on the skin. But they are actually very different conditions and one of them comes with an increased risk of heart disease. To tell the difference, I like to focus on the location and the appearance of the rash.
This is eczema and it tends to affect the flexor surfaces of the body. Think about skin areas that bend like the inner elbow, wrists, and behind the knees, although it can also show up on the neck, face, and hands. In comparison, this is psoriasis and it usually affects the extensor surfaces, so think about skin areas that stretch like the elbows and knees, although psoriasis can also show up on the scalp, palms, and soles of the feet. It's a very general rule: Think about eczema on the inside of the elbow and psoriasis on the outside of the elbow.
When we compare the appearance, eczema tends to be more red and inflamed and intensely itchy. In fact, we often call it the "itch that rashes" because the itchiness usually shows up before the redness. In comparison, psoriasis tends to form thick, silvery-white scales on top of the red plaques. The reason it's so important to differentiate the two is not only because the treatments are different, but because they are associated with different medical conditions.
Watch the video above for more.
Siobhan Deshauer, MD, is an internal medicine and rheumatology specialist in Toronto. Before medicine, she was a violinist, which is why her YouTube channel is called Violin MD.