Several autoimmune diseases can cause joint pain and other symptoms that mimic rheumatoid arthritis (RA). These diseases most commonly include lupus, systemic scleroderma, and polymyalgia rheumatic.
Lupus vs. Rheumatoid Arthritis
A complex autoimmune disease, lupus can cause a wide range of symptoms that vary in severity, making it challenging to diagnose. Many people refer to lupus by its full medical name, systemic lupus erythematosus (SLE).
How is it similar to RA? One of the most common symptoms of lupus is pain and swelling in the hands, knees, and other joints. People often report fatigue, fever, and a general feeling of being unwell.
How is it different? A person with lupus may find it painful to take a deep breath. He or she may have sensitivity to light, hair loss, mouth sores, and/or a skin rash, particularly over the face. Digestive difficulties and neurological problems, such as headaches and tingling, are also possible.
Systemic Sclerosis vs. Rheumatoid Arthritis
Systemic sclerosis, sometimes called scleroderma, is a rare and complicated autoimmune condition. It produces a build-up of collagen in the body that can cause a wide variety of symptoms.
How is it similar to RA? The wrists, fingers, feet, and other joints can become painful, swollen, and stiff. People with systemic sclerosis can experience fatigue and weight loss.
How is it different? Scleroderma typically causes skin changes. (In Greek, sclero means hard and derma means skin.) For example, the skin may appear thickened and patchy or shiny and tight. Systemic scleroderma can also affect internal organs, resulting in breathing and/or digestive tract problems.
Polymyalgia Rheumatica vs. Rheumatoid Arthritis
This autoimmune disease is challenging to diagnose for two reasons. First, its symptoms overlap with many other inflammatory and autoimmune conditions. Second, it can cause a variety of symptoms, and an individual may experience just a few symptoms that are not considered typical to the disease.
How is it similar to RA? Polymyalgia rheumatica joint pain is often symmetrical (e.g. affecting both the right and left shoulders)1 and most noticeable after getting out of bed in the morning. In one study, researchers found inflammation of joints’ lining—a condition called synovitis, a classic sign of RA—in 23% of polymyalgia rheumatica cases.2
People with polymyalgia rheumatica also may feel like they have the flu, have a fever, feel weak, or experience weight loss.
How is it different? Polymyalgia rheumatica usually affects the shoulders, neck, or hips first, whereas RA usually affects hands, feet, or knees first. People with polymyalgia rheumatica typically also experience muscle pain: myalgia means muscle pain, and polymyalgia means muscle pain in multiple locations.
At least 10% of people with polymyalgia rheumatica also have a related disorder called giant cell arteritis.4 This condition has the potential to cause headaches, scalp pain and tenderness, vision problems, jaw pain, dizziness, and decreased coordination.