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Conditions That Can Look Like PsA But Aren’t

Medically Reviewed by Michael W. Smith, MD on July 12, 2021

Psoriatic arthritis (PsA) is a type of arthritis that affects some people with psoriasis. It can cause your joints to become stiff, painful, swollen, or warm to touch. You might notice symptoms in your spine, hands, feet, or lower back, but PsA can affect any part of your body.

Signs of PsA also may be signs of other diseases. If you think your pain is related to PsA, visit your doctor. They’ll be able to tell if your symptoms are caused by this or another condition.

Rheumatoid Arthritis

Rheumatoid arthritis (RA) is an inflammatory disorder that happens when your immune system attacks your body’s tissue. It can affect your joints, skin, eyes, lungs, blood vessels, and heart.

The symptoms of RA include tender, swollen, warm, and stiff joints. These signs are usually more intense in the morning or after you haven’t moved for a while. You may also feel fatigued, have a fever, or lose your appetite.

Joint pain usually starts in your fingers, hands, toes, and feet. As RA progresses, it may affect your wrists, knees, ankles, shoulders, hips, or elbows.

On the surface, RA and PsA seem very similar. But your doctor will be able to identify which condition you have based on key differences in the specific joints affected, the symmetry of the condition, the presence of autoantibodies, and other biological features.

Osteoarthritis

This condition affects millions of people worldwide, making it the most common type of arthritis. Osteoarthritis (OA) happens when the cartilage that protects the ends of your bones wears down. It can damage any joint, but it usually targets your hand, hip, knee, and spine joints.

Symptoms of OA typically develop slowly and get worse over time. You might notice pain, stiffness, tenderness, or a grating sensation in your joints. Loss of flexibility, bone spurs (which are extra bits of bone that create lumps), or swelling are also common side effects of this condition.

PsA is an inflammatory arthritis, and signs of inflammation show up in the blood, typically. Experts can normally tell the two apart. But sometimes, similar symptoms can make it more difficult. OA sometimes comes with joint inflammation, and both conditions involve bone spurs, which makes them look similar at first. Since treatment for each condition is very different, a correct diagnosis is important.

Gout

This condition is a common and complex form of arthritis. Gout causes sudden pain attacks, swelling, redness, and tenderness in your joints. It often affects your big toes but could cause symptoms in more than one joint.

Gout symptoms may come and go. They can include intense joint pain, lingering discomfort, redness, inflammation, joint warmth, tenderness, and limited range of motion. Gout side effects usually occur suddenly and at night.

Gout and PsA are both linked to uric acid, which is a substance that forms when your body breaks down purines. People with both conditions have more uric acid in their bodies. Due to this, people with PsA are about 5 times more likely to have gout than those without it.

Lupus

Lupus is a chronic autoimmune disease that could cause inflammation and pain in any part of your body. It most commonly affects your skin, joints, and internal organs like your kidneys and heart.

The symptoms of lupus include fatigue, joint pain, or a butterfly-shaped rash. But the early signs can vary for each person.

Lupus is not a form of arthritis, but arthritis is one of the most common symptoms. However, it’s rare that arthritis would be the only sign that someone has this condition. Usually, people with lupus will also have other symptoms as well.

Fibromyalgia

This disorder causes musculoskeletal pain, fatigue, and issues with sleep, memory, and mood. Doctors believe that fibromyalgia worsens pain sensations by influencing the way your spinal cord and brain process painful and nonpainful signals.

Symptoms of this condition usually arise after a certain event, like a physical trauma, infection, surgery, or intense psychological stress. But cases could also develop over time without a single trigger. Primary symptoms include widespread and dull pain, fatigue due to sleep disorders or poor sleep, and cognitive troubles that affect how well you focus.

One study showed that people with PsA were more likely to have fibromyalgia than those without the condition. They concluded that fibromyalgia pain and fatigue were more frequent in those with PsA. Due to this, experts believe that doctors should check people with PsA for fibromyalgia before they start treatment, since the two conditions commonly occur together.

Ankylosing Spondylitis

Ankylosing spondylitis (AS) is an inflammatory disease that can cause the small bones in your spine to fuse over time. This causes your spine to become less flexible and may lead to a hunched-forward posture.

Symptoms of this condition usually begin in early adulthood. They may include pain and stiffness in your lower back and hips, neck pain, and fatigue.

PsA and AS are both forms of arthritis that have similar symptoms. But the main difference is that AS usually affects your back and hip joints, while PsA tends to also cause pain in your hand and foot joints.

Plantar Fasciitis

This condition happens when the plantar fascia, the tissue that runs across the bottom of your foot and connects your heel bone to your toes, becomes inflamed. It’s one of the most common causes of heel pain and can cause intense pain, especially in the morning, after standing awhile, or after getting up after sitting for a long time.

Plantar fasciitis tends to be more common in runners, people who are overweight, or those who wear shoes without good support. People with PsA are more likely to get plantar fasciitis, too.

With this condition, you might notice stabbing pain in the bottom of your foot near your heel.

PsA and plantar fasciitis can seem similar in that foot pain is common in both. But in most cases with PsA, you’ll also notice joint pain or inflammation in other areas of your body.

Lyme Disease

This condition happens when you become infected with bacteria from an infected blacklegged tick. If you don’t treat Lyme disease, infection can spread to your heart, nervous system, or joints.

The symptoms of Lyme disease include headache, fever, fatigue, and a skin rash called erythema migrans.

Late-stage, untreated infections could cause arthritis, especially in your knees. But beginning-stage Lyme disease resembles a mild flu, not PsA.

Show Sources

SOURCES:

Mayo Clinic: “Psoriatic Arthritis,” “Rheumatoid Arthritis,” “Osteoarthritis,” “Gout,” “Fibromyalgia,” “Ankylosing Spondylitis,” “Plantar Fasciitis.”

RMD Open: “What makes psoriatic and rheumatoid arthritis so different.”

Rheumatology (Oxford): “Differentiation between osteoarthritis and psoriatic arthritis: implications for pathogenesis and treatment in the biologic therapy era.”

Johns Hopkins Medicine: “Psoriatic Arthritis and Osteoarthritis.”

Arthritis Foundation: “Psoriasis and Psoriatic Arthritis May Increase Gout Risk,” “Lyme Disease.”

Medscape: “Gout Risk High in Those with Psoriasis, Psoriatic Arthritis.”

Lupus Foundation of America: “What is Lupus?” “How Lupus Differs from Arthritis.”

Arthritis: “High Frequency of Fibromyalgia in Patients with Psoriatic Arthritis: A Pilot Study.”

CDC: “Lyme Disease.”

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