“For patients where the diagnosis between eczema and psoriasis isn’t clear, tape strips could be used instead of a biopsy,” says Emma Guttman-Yassky, MD, PhD, lead author and director of the Center of Excellence in Eczema and director of the Laboratory of Inflammatory Skin Diseases at the Icahn School of Medicine at Mount Sinai. A biopsy is a procedure in which a piece of skin is removed so that it can be examined under a microscope. Biopsies are the gold standard for identifying inflammatory skin diseases, but they have their drawbacks, says Dr. Guttman-Yassky. “This procedure is painful, it takes time to heal, and it can leave a scar,” she says. Tape strips, which look like a smaller version of Scotch tape, offer a new avenue for diagnosis. “The process of collecting the samples takes about five minutes. It doesn’t break the skin, and it leaves no scarring — it can create a slight irritation that goes away within 30 minutes to a few hours,” Guttman-Yassky says. Correctly distinguishing between eczema and psoriasis is important for a number of reasons. “The treatments for eczema and psoriasis are very different, and so having an add-on tool to be able to help us diagnose would be very helpful. Making the right diagnosis from the outset can save a patient from a few months of unsuccessful treatment, and it could save thousands of dollars in unnecessary healthcare costs,” Guttman-Yassky says. RELATED: Is That Rash Psoriasis, or Is It Something Else?
Tape Strips Are Quick and Painless
The study enrolled a total of 60 participants, who were then divided into three groups: 20 adults with moderate to severe eczema, 20 with moderate to severe psoriasis, and 20 healthy individuals. Twenty tape strips were collected from each individual by applying the strips to both the lesions and unaffected skin to collect cell samples for analysis. Investigators used a method called molecular profiling to identify biomarkers (biological markers) unique to each disease. They found that a single biomarker, the enzyme nitride oxide synthase 2, differentiates between the diseases with 100 percent accuracy. “Even in biopsies that’s not possible — it takes two biomarkers,” says Guttman-Yassky. Tape strips might be most useful to primary care doctors and allergists, who may not recognize subtle differences between the two conditions. “Dermatologists spend years and years training and studying the skin, and so we’re usually able to know whether something is eczema or psoriasis based on the health history and clinical presentation. It’s actually very rare that we do a biopsy to diagnose these conditions,” says Shilpi Khetarpal, MD, a dermatologist at the Cleveland Clinic in Ohio. RELATED: Why You Shouldn’t Skip Your Dermatology Appointments During COVID-19
Eczema vs. Psoriasis
About 30 percent of people in the United States are affected by eczema, mostly children and adolescents, according to the National Institute of Allergy and Infectious Diseases. Psoriasis is present in only about 2 to 3 percent of the population and is mostly found in adults, according to the National Psoriasis Foundation. Eczema and psoriasis have a number of key differences: The Itch “There are two arms of the immune system, and when we look at different skin conditions, we tend to group them into what we call a T helper 1 (Th1) response or a Th2,” says Dr. Khetarpal. Eczema is considered a Th2 response: It’s a hypersensitivity in which your skin is essentially reacting to factors in its environment like fragrances, certain materials, or allergens. “Because it’s a hypersensitivity, these patients tend to present with a lot of itching. In our younger patients, the itching can wake them up in the middle of the night — it’s incredibly uncomfortable,” she says. “Psoriasis is an autoimmune disease, and it’s a Th1 response, and it’s basically an overproduction of skin cells,” says Khetarpal. Because these skin cells are just rapidly multiplying, psoriasis is typically not that itchy, or at least not to the same degree as eczema, she adds. Infection In psoriasis, skin rarely becomes infected, says Khetarpal. “In eczema, because people are itching and breaking the skin barrier, it’s common to see the skin superficially infected,” she says. Nail Changes In psoriasis, it’s very common to see nail changes, says Khetarpal. Common signs can include tiny dents in the nails; white, yellow, or brown discoloration; crumbling nails; or separation of the nail from the finger or toe, according to the American Academy of Dermatology. “In eczema, usually the nails are completely normal unless there’s eczema around the cuticle,” Khetarpal says. Family History People with psoriasis often have a family history of psoriasis or psoriatic arthritis, whereas in eczema, you might see people in the family who have hay fever or asthma, says Khetarpal. Age of Onset Eczema usually affects young children, who may outgrow it, says Khetarpal. “We typically see psoriasis beginning in the teens — the average age is 15 to 30 years old, and so later in life compared to eczema,” she says. Location on the Body Both eczema and psoriasis can show up anywhere on the body, but they have more typical areas, says Khetarpal. Eczema often appears on the insides of the elbows or behind the knees in children, and on the hands of adults, she says. In psoriasis, the most commonly affected areas are the scalp, elbows, front of the knees, buttocks, lower back, palms, and soles of the feet. Koebner Phenomenon This is a term that basically means that a flare or new lesions can occur when the skin is injured, says Khetarpal. “A sunburn or a vaccine or any kind of trauma can cause psoriasis to appear in that area, which doesn’t happen in eczema,” she says. RELATED: A Guide to Living With Psoriasis During the COVID-19 Pandemic: Help, Resources, and Making a Personal Checklist
What to Do if You Think You Have Eczema or Psoriasis
If you suspect that you have either eczema or psoriasis, it’s safe to try over-the-counter medications to see if that helps, says Khetarpal. “In cases where the symptoms are really bothersome, make an appointment with your doctor or dermatologist,” she says. “This can be done by either a virtual or in-person visit. We can ask screening questions about symptoms and medical history, look at the skin, and make a diagnosis and treatment recommendation that will work fairly quickly.”
