Arthritis is a painful and debilitating disease that is associated with significant joint stiffness and pain. There are several different subtypes of arthritis, which include degenerative arthritis, inflammatory or autoimmune arthritis, infectious arthritis and metabolic arthritis.
One of the most common subtypes of inflammatory arthritis is rheumatoid arthritis, which is so prevalent that studies estimate that it affects up to one percent of the world’s population. However, it can often be difficult to diagnose as it can mimic other diseases.
Consequently, rheumatoid arthritis can be often misdiagnosed as a different disease, or vice versa. These are the top diseases that rheumatoid arthritis mimics and can be misdiagnosed as:
- Lupus. Another type of arthritis, lupus, is an autoimmune disease that affects different parts of the body such as the joints, skin, blood vessels, and internal organs. Hence, the symptoms of lupus very closely mimic those of rheumatoid arthritis. However, unlike patients with lupus, patients with rheumatoid arthritis have erosive, deforming arthritis with more intense symptoms.
- Lyme disease. A common infectious disease that is borne by ticks, Lyme disease is characterized by fever, stiffness, body ache and fatigue. However, in the early phases of Lyme disease, patients can feel symptoms that are suggestive of rheumatoid arthritis including joint and muscle pain. Patients with advance Lyme disease will develop monoarticular inflammatory arthritis, which refers to one swollen joint in the lower extremity. This differs from rheumatoid arthritis as most patients with rheumatoid arthritis have involvement of the same joint on both sides of the body.
- Gout. Another type of arthritis, gout develops due to high levels of uric acid in the blood. If gout is left untreated, it can cause erosive, deforming arthritis, which mimics the pathology of rheumatoid arthritis. Patients with gout will often display tissue deposits around joints called trophi, which resemble rheumatoid nodules and can therefore be confused with rheumatoid arthritis.
- Pseudogout. This disease is characterized by acute attacks of synovitis (inflammation of the synovial membrane, which lines joints) and mimics gout. However, patients with pseudogout can display a wide array of clinical manifestations, some of which are rheumatoid arthritis-like. Hence, these two diseases can sometimes be confused.
- Ankylosing spondylitis. Another type of arthritis, ankylosing spondlytis, affects the joints of the spine. Additionally, patients often experience inflammatory back pain. The pain is generally worse in the morning and improves as the day goes on. Physicians may confuse symptoms of rheumatoid arthritis for those of ankylosing spondylitis.
- Reiter’s syndrome. A subtype of arthritis, Reiter’s syndrome, develops due to an infection in the body. It can take weeks or months after the infection for Reiter’s syndrome to appear. Patients with Reiter’s syndrome have involvement of a few large joints, usually on one side of the body. Patients with Reiter’s syndrome experience inflammation and swelling in joints, and thus can be confused with rheumatoid arthritis. However, Reiter’s syndrome, unlike rheumatoid arthritis, generally goes away in a few months.
- Scleroderma. Symptoms of scleroderma can mimic those of rheumatoid arthritis. When a physician suspects scleroderma, they will order several tests. However, some of the tests, such as measurement of creatine kinase measurements, erythrocyte sedimentation rate, and C-reactive protein, are commonly elevated across several autoimmune or inflammatory disease. Thus, physicians can misdiagnose patients with scleroderma with rheumatoid arthritis or vice versa.
- Vasculitis. Vasculitis is a disease that is characterized by inflammation of blood vessels. Diagnosing vasculitis can take a long time to make, and is often just made by observing the patient for a long period of time. Often, systemic vasculitis can cause the development of polyarthritis and some subtypes of vasculitis can actually be positive for rheumatoid factor (which is suggestive of rheumatoid arthritis). Therefore, physicians may confuse these diseases with each other.
- Osteoarthritis. Generally, the symptoms of osteoarthritis differ from those of rheumatoid arthritis as patients with osteoarthritis lack signs and symptoms of systemic inflammation, tend to be older adults and have joint involvement that differs from that of rheumatoid arthritis. However, erosive osteoarthritis can look inflammatory when examined, and thus can be confused wi rheumatoid arthritis. However, these patients are generally not rheumatoid factor positive.
- Sjogren's syndrome. An autoimmune disease, Sjogren's syndrome can mimic rheumatoid arthritis in its clinical manifestation and test results. Patients with Sjogren's syndrome can experience pain, stiffness and swelling of joints. Furthermore, up to 60-70% of patients with primary Sjogren's syndrome are positive for rheumatoid factor, further confusing the results.
- Sarcoidosis. Patients with sarcoidosis can develop synovitis in several joints. Furthermore, patients may be positive for rheumatoid factor. Therefore, sarcoidosis can be confused for rheumatoid arthritis. However, other characteristics that are unique to sarcoidosis can help establish a definite diagnosis.
- Fibromyalgia. Patients with fibromyalgia develop discomfort or pain and stiffness in joints, mimicking characteristics of rheumatoid arthritis. However, these are several other characteristics such as lack of synovitis, the lack of pain when moving, and test results that can help distinguish fibromyalgia.