11 Diseases That Mimic Rheumatoid Arthritis

How Are They Distinguished?

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Rheumatoid arthritis is complicated. Most people with rheumatoid arthritis will tell you that some time passed before they were given a definitive diagnosis. Even if their doctor suspected rheumatoid arthritis early on, there is no single test or piece of evidence that confirms the diagnosis. Findings from a patient's physical examination, medical history, laboratory tests, and imaging studies must all be considered.

Not only are there few disease-specific features associated with rheumatoid arthritis, patients present with various manifestations of the disease. In most rheumatoid arthritis patients, the onset of symptoms occurs gradually and is well-established before even being recognized. The polyarthritis aspect typically involves the small joints of the hands and feet before moving to larger joints. But there are other ways rheumatoid arthritis presents itself which are less common: palindromic (short bouts of recurrent pain and stiffness, affecting one or more joints, later becoming persistent);  polymyalgic (often an elderly patient with primary complaint of stiffness, often shoulders or hips); systemic (non-articular manifestations, such as fever, malaise, weight loss); persistent monoarthritis (arthritis in a single large joint that persists). 

Early rheumatoid arthritis can differ from what we think of as typical rheumatoid arthritis.

Many patients have normal inflammatory markers when they first consult a doctor about their initial symptoms. Many have normal x-rays. What can be even more confusing to the diagnostician, and therefore to the patient, is that there are several other conditions characterized by polyarthritis which has characteristics typically associated with rheumatoid arthritis.

Because those conditions mimic rheumatoid arthritis, they must be considered, then excluded, before the diagnosis of rheumatoid arthritis can be confidently established. Here are some of the conditions that mimic rheumatoid arthritis:

Post-viral arthritis - Acute and chronic viral infections can result in a polyarthritis that looks just like rheumatoid arthritis clinically. Acute viral infections, such as parvovirus B19, usually can be distinguished by exposure history, rash, and the fact that symptoms last a specific duration of time. It is important for the diagnostician to exclude chronic hepatitis infection or human immunodeficiency virus, especially if treatment with immunosuppressants is being considered.

Seronegative spondyloarthritis - Psoriatic arthritis can be difficult to distinguish from rheumatoid arthritis, especially if no rash exists. Involvement of the sacroiliac joints or the distal interphalangeal joints of the hands can narrow the diagnosis to psoriatic arthritis. The other seronegative spondyloarthropathies (reactive arthritis, ankylosing spondylitis, inflammatory bowel disease–associated arthropathy) can also mimic rheumatoid arthritis.

"Asymmetrical joint involvement, the absence of small-joint disease, sausage-like appearance of digits, and involvement of the lumbosacral spine all favor the seronegative arthropathies", according to the Cleveland Clinic.

Lupus - Systemic lupus erythematosus can be associated with joint involvement that mimics rheumatoid arthritis, but lupus differs by rarely being an erosive disease. With lupus, deformities can develop that resemble those related to rheumatoid arthritis -- the difference being it is due to tendon and ligament laxity with lupus, not joint destruction.

Scleroderma - A complete blood count, comprehensive chemistry panel, and serologic studies (e.g., antinuclear, anticentromere, and antitopoisomerase antibodies) are typically ordered when a patient is suspected of having scleroderma. Creatine kinase measurements, erythrocyte sedimentation rate, and C-reactive protein measurements may also be helpful as the diagnosis is formulated. "Elevated results suggest myositis, vasculitis, malignancy, or overlap of systemic sclerosis with another autoimmune disease", according to the AAFP.

Vasculitis - Polymyalgia rheumatica (PMR) and giant cell arteritis (GCA) can occur with symmetrical polyarthritis. Most often, a detailed medical history from these patients can help distinguish PMR or GCA (e.g., headache, along with shoulder and hip pain). In some cases, diagnosis may depend on observation of the disease over time. In other words, serious complications can develop over time that point to a vasculitide. Systemic vasculitis can also manifest with polyarthritis. Wegener's granulomatosis can be rheumatoid factor positive.

Osteoarthritis - The absence of signs and symptoms of systemic inflammation, onset in older adulthood, and the pattern of joint involvement (asymmetric) are often enough to distinguish osteoarthritis from rheumatoid arthritis. "Erosive osteoarthritis can have an inflammatory appearance on examination, but it tends to involve the PIP joints primarily, is not associated with proliferative synovitis, is not RF (rheumatoid factor) positive, and has a distinct radiographic appearance", reports the Cleveland Clinic.

Gout - Acute gout usually is associated with asymmetric monoarticular or oligoarticular inflammation and arthritis, lasting 3 to 10 days. But, gout attacks can become more frequent, last longer, and may not resolve, leading to chronic gouty arthropathy. Gouty arthropathy can cause erosions and joint destruction. It is distinguished from rheumatoid arthritis by the absence of joint space narrowing and absence of periarticular osteopenia, according to the Cleveland Clinic.

Pseudogout - CPPD crystal deposition disease is linked to  an array of clinical manifestations. It can be asymptomatic, gout-like (pseudogout), rheumatoid arthritis–like, or osteoarthritis-like. Pseudogout is distinguished by acute attacks of synovitis that mimic gout. Synovial fluid analysis is used for the differential diagnosis.

Sjogren's Syndrome - Sjogren's syndrome is an autoimmune, inflammatory disease. It can occur as a primary condition with no other rheumatic disease or as a secondary condition along with another rheumatic condition. Primary Sjogren's syndrome can mimic rheumatoid arthritis. Approximately 60 to 70 percent of primary Sjogren's patients are positive for rheumatoid factor. There also typically is pain, stiffness, and mild swelling of the joints. Specialized testing can help distinguish between Sjogren's syndrome and rheumatoid arthritis.

Sarcoidosis - Sarcoidosis can manifest with synovitis in several joints and may be rheumatoid factor positive. But, other characteristics help distinguish it from rheumatoid arthritis. In some cases, a tissue biopsy may be required to establish the diagnosis.

Fibromyalgia - Fibromyalgia can be characterized by diffuse symmetrical arthralgias and stiffness at rest, but the absence of synovitis, the lack of pain on motion, and normal laboratory and imaging studies favor the diagnosis of fibromyalgia, distinguishing it from rheumatoid arthritis, according to the Cleveland Clinic.

The Bottom Line

There are conditions that mimic rheumatoid arthritis, especially early in the course of the disease. The primary common characteristic is polyarthritis. A patient's medical history, observation of symptoms and disease manifestations over time, and additional diagnostic testing help distinguish the conditions from rheumatoid arthritis.


Gout and Pseudogout. Feyrouz Al-Ashkar. Cleveland Clinic. Accessed June 18, 2014.

Rheumatoid Arthritis. William S. Wilke. Cleveland Clinic. Accessed June 18, 2014.

Systemic Sclerosis/Scleroderma: A Treatable Multisystem Disease. Monique Hinchcliff, M.D. and John Varga, M.D. American Family Physician. October 15, 2008.

Diagnosis of Early Rheumatoid Arthritis: What the Non-Specialist Needs to Know. E Suresh, M.D. MRCP. Journal of the Royal Society of Medicine. September 2004.

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