11 Diseases That Mimic Rheumatoid Arthritis
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.