Why Psoriatic Arthritis Is So Difficult to Diagnose

In 2019, psoriatic arthritis made its prime-time debut on an episode of Keeping Up With the Kardashians, thrusting the chronic disease into the spotlight. Sure, a reality-TV show plotline may not seem to offer the most accurate take, but the depiction of Kim's experience, which was marked by joint pain, psoriatic flare-ups, and major fatigue, was spot-on — after her experience had initially been misdiagnosed for an entire episode. Unfortunately, that's fairly common with this disease, which is often invisible.

"There's no one test that can diagnose or rule out psoriatic arthritis, which is why, at times, it can be difficult to diagnose," says Rebecca Haberman, a rheumatologist at NYU Langone Health. Ahead, what to look for and what you should do if you suspect you have psoriatic arthritis, or PsA.

What Is Psoriatic Arthritis?

Let's start with psoriasis, a chronic, inflammatory skin condition that's usually marked by patches of red, flaky, or otherwise scaly patches of skin called plaques. Psoriasis is an autoimmune disease, which essentially means that your body is attacking itself by mistake. "While the immune system is programmed to fight off foreign invaders such as viruses and bacteria, at times it can attack your own body, which is what happens in these conditions," Haberman says.

Psoriatic arthritis, however, occurs when those skin patches are eventually accompanied by joint pain, swelling, and stiffness, says Haberman, noting that up to 30 percent of patients with psoriasis will develop these symptoms in addition to their skin condition. Though the symptoms themselves aren't mutually exclusive — meaning, if you have PsA, a flare-up in topical psoriasis doesn't always mean joint paint is imminent, or vice versa — they can present together. "Skin psoriasis usually appears before joint pain, but they can occur at the same time, and more rarely, joint pain can appear first," Haberman says.

Though studies on the topic are limited, there are certain locations where plaques on the skin may indicate that someone has or will develop psoriatic arthritis, including the scalp, nails, and lower back, or intergluteal psoriasis, says Ana-Maria Orbai, an assistant professor of medicine and director of the psoriatic arthritis program in the division of rheumatology at Johns Hopkins Medicine. You're more likely to develop PsA if psoriasis runs in your family, and most patients are diagnosed between ages 30 and 50. "There also may be environmental factors, such as certain infections, that can make you more prone to developing psoriatic disease," says Haberman. In rare cases, inflammation in the joints can be permanent.

What Does Psoriatic Arthritis Feel Like?

While it can look a lot like regular psoriasis, anyone with PsA will tell you it often feels very different: The joint pain and stiffness, which can sometimes be debilitating, can affect everything from small movements (like typing or using a pen) to full-body activities (like bending down or walking). This stiffness is often more common in the mornings and tapers off throughout the day, but it can strike at any time. Mild to moderate fatigue is also common.

Other symptoms include swelling and tenderness of the tendons, like the Achilles, or plantar fascia, which runs along the bottom of your foot near your heel, Haberman says. "It can also present with nail changes with pitted, crumbling, or discolored nails," she adds, noting that it’s sometimes confused with run-of-the-mill nail fungus.

Joshua Zeichner, the director of cosmetic and clinical research of dermatology at Mount Sinai Hospital in New York City, mentions another unpleasant symptom: "There may be individual red, swollen toes or fingers, which are commonly referred to as 'sausage digits.'"

As with some other common skin diseases and disorders, psoriasis and PsA can also present differently on darker skin, sometimes making it more difficult to diagnose, says Corey L. Hartman, a board-certified dermatologist in Alabama. "There may be more of a violaceous or purple color, which has led to misdiagnosis in patients with skin of color."

How Is Psoriatic Arthritis Treated?

Currently, there's no cure for psoriatic arthritis, but managing the symptoms is possible, often starting with over-the-counter anti-inflammatories. "Those with very mild arthritis may require treatment only when their joints are painful and may stop therapy when they feel better," says Hartman, who recommends nonsteroidal treatments like ibuprofen or naproxen to treat the pain at first. If that doesn’t effectively manage the pain, or you find yourself taking nonsteroidal treatments often, a rheumatologist may prescribe disease-modifying antirheumatic drugs like sulfasalazine, methotrexate, and cyclosporine, says Hartman. And Haberman points out that your doctor may prescribe injectable medications like Cimzia, Humira, or Simponi. The goal, of course, is to be in remission, which about 30 to 50 percent of patients achieve with medication, according to Orbai.

Though it may sound counterintuitive, Haberman says that one of the best ways to alleviate joint pain is to get moving: Regular exercise helps keep muscles and tendons around the joints strong and can prevent other types of joint pain. Unlike with psoriasis, topical solutions, like creams, or UV treatment won’t help with joint pain. Still, they can be fairly effective at keeping plaque flare-ups at bay. Be sure to consult your doctor before beginning any treatment or regimen.

"Leaving the arthritis untreated can lead to destruction of the joint in psoriatic arthritis," says Orbai. "It can start with erosion and bone formation, but sometimes people reach ankylosis, where the patient loses range of motion and the joints remain in a fixed position, decreasing use."

When Should You See a Doctor?

As soon as possible, says Orbai, especially if you have psoriasis and develop joint pain or stiffness in any part of the body. A study published in 2017 in the journal Arthritis & Rheumatology that looked at more than 400 psoriasis patients over the course of a year found that nearly 14 percent of those patients were diagnosed with PsA within that year, and reported symptoms like joint pain, stiffness, and fatigue. “If someone with psoriasis has [these symptoms], these are signs that you might be developing psoriatic arthritis,” Orbai says. “I would definitely bring it up with [your] doctor.… It can cause damage within six months of diagnosis, so it’s important to treat.” 

Since there's no single test that can determine conclusively if you have (or don't have) psoriatic arthritis, most rheumatologists instead use a combination of family history, blood work, X-rays, CT scans, and MRIs to look at the joints in more detail and make a diagnosis.

Be sure to make note of your symptoms — and take photos in case you're not suffering from any topical flare-ups when you see your doctor. Says Zeichner, "It's treated from the inside out." 

This story is part of Survivor's Guide, a series on navigating the impact of psoriasis through beauty and self-care.

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