Psoriatic lesions are patches of skin that are covered in a rash called plaques, and psoriatic arthritis (PsA) is a progressive disease that includes psoriatic plaques and arthritis of the joints. You may have one without the other.

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It’s unclear how many people with psoriasis later develop psoriatic arthritis (PsA). One 2022 study estimates the rate to be between 6% and 42%. However, most people with psoriatic lesions do not have psoriatic arthritis, and about 17% of people develop PsA before they have any skin symptoms of psoriasis.

Read on for more information about psoriasis, psoriatic arthritis, and whether you can have one without the other.

Learn more about psoriatic arthritis (PsA).

No, having psoriasis does not mean you will definitely develop PsA. It’s unclear how many people with psoriasis go on to develop psoriatic arthritis.

There are risk factors for developing psoriatic arthritis, including:

  • Psoriasis: Having psoriasis is the single greatest risk factor for developing psoriatic arthritis.
  • Psoriasis of the nails: Having psoriasis that affects your nails is a significant risk factor for developing PsA later.
  • Age: You can develop psoriatic arthritis at any age, but it most often occurs in adults between ages 30 and 55 years.
  • Family history: Having a first-degree relative — parent, sibling, or child — with PsA increases the chances that you may develop PsA.

Psoriasis is an immune-mediated disease with some genetic factors. The cause is not well understood. It’s thought that your immune system is disrupted, causing the T-cells of your immune system to mistakenly attack your skin cells. This leads to a rapid overproduction of skin cells that build up to create the characteristic lesions.

In PsA, there’s a larger genetic factor, and PsA is genetically distinct from psoriasis. You’re 3–5 times more likely to inherit PsA than you are to inherit psoriasis.

With PsA, your immune system attacks not only your skin cells but also joint tissue on both sides of your body. This causes stiffness, pain, and swelling of the joints and the ligaments and tendons that surround them. It can also affect other organs in your body.

Similar to the production of psoriasis skin lesions, T-cells and cytokines (messengers released from immune cells into the blood) produce lesions in your synovial membrane by causing an overproduction of synovial cells. The synovial membrane is the connective tissue lining joints and tendons.

If PsA is left untreated, it can lead to reduced functioning and disability.

PsA can be difficult to diagnose because it has a wide range of symptoms that may be similar to other diseases.

Symptoms can include:

  • joint inflammation of a few joints (oligoarthritis) in an asymmetrical pattern (not the same joint on both sides)
  • inflammation of the smaller joints of the hands and feet
  • swelling of a finger (dactylitis)
  • nail symptoms, including:
    • pitting
    • detached nails (onycholysis)
    • thickening of the skin under your nails (hyperkeratosis)
  • negative blood test for rheumatoid factor (usually rules out rheumatoid arthritis)
  • X-ray evidence of new bone growth near a joint (juxta-articular)

Diagnosing PsA can be challenging, and many cases go undiagnosed. This is partly because there are no universally accepted criteria for PsA. For many years, PsA was considered a form of rheumatoid arthritis. Also, some people develop PsA before they have psoriatic lesions.

In 2006, an international group of rheumatologists created a simple-to-use system for PsA diagnosis based on a large study in several clinics around the world involving people with PsA. The system is called CASPAR (ClASsification criteria for Psoriatic ARthritis), and it provides guidelines for physicians and specialists to diagnose PsA.

It’s important to begin treatment for PsA as soon as you’re diagnosed. Treating PsA early and aggressively can slow joint damage and may be able to prevent it, according to a leading PsA researcher and practitioner.

Your doctor will likely prescribe nonsteroidal anti-inflammatory drugs (NSAIDs) to help with pain and swelling. They may also recommend steroid injections to help relieve your symptoms. These treatments can relieve pain and swelling, but they will not stop joint damage.

Depending on which joints are affected, physical therapy may help stabilize your hands or feet. The therapist may recommend special supportive and assistive medical appliances, such as hand splints, to help your daily functioning if you have hand damage.

Drug therapy usually starts with methotrexate, which is considered the gold standard for initial PsA treatment. It helps clear skin lesions, but it does not stop joint damage.

If you have joint damage or are at risk of it, your doctor may prescribe another disease-modifying antirheumatic drug (DMARD) or one of the newer biologic drugs. The biologics inhibit the production of substances in your blood, such as tumor necrosis factor, that cause inflammation.

Discuss your treatment options with your doctor, especially the serious side effects of methotrexate and other PsA drugs.

Read on to discover more about treatment options for psoriasis.

Is there a cure for psoriasis or PsA?

There’s currently no cure for psoriasis or PsA. Ongoing research is focused on understanding the mechanisms that cause psoriasis and developing targeted treatments based on a better understanding of what causes these conditions.

What are the early signs of PsA?

PsA has many symptoms, but early signs may include:

  • red eyes with blurred vision
  • fingernail or toenail changes like pitting or lifting from the nail bed
  • swelling of an entire finger or toe (not just the joint)
  • pain in the sole of the foot or heel
  • fatigue
  • painful, swollen, or stiff joints

If you notice any of these signs, it’s important to see a doctor, especially if you have more than one of them.

Are there other conditions associated with PsA?

Yes, other autoimmune conditions that may occur more frequently in people with PsA include:

Psoriasis and PsA often occur together, but you may have psoriasis without PsA. Research has also found some people who have PsA either develop it before psoriasis lesions occur or have it without these lesions.

Treatments are available for both conditions.

If you have signs or symptoms of these conditions, it’s important to see a healthcare professional to discuss your treatment options.