Key features of polymyalgia rheumatica mimics
| Disease | Features |
|---|---|
| Inflammatory diseases | |
| Rheumatoid arthritis | Symmetrical joint involvement, autoantibody-positive, may see erosions on imaging in advanced disease |
| Spondyloarthritis | Low back involvement, sacroiliac joint tenderness, sacroiliitis on imaging |
| RS3PE (remitting seronegative symmetrical synovitis with pitting edema) | Peripheral edema, extensor synovitis on imaging, may be paraneoplastic |
| Crystalline arthropathy | Usually involvement of medium to large joints, intermittent symptoms, characteristic radiography and ultrasonographic findings, synovial fluid analysis positive for crystals |
| Autoimmune myositis | Muscle weakness and tenderness, elevated muscle enzymes |
| Other connective tissue diseases | Multiorgan involvement, specific autoantibodies may be positive, hypocomplementemia |
| Noninflammatory diseases | |
| Osteoarthritis | Pain exacerbated with use, normal inflammatory markers, degenerative changes on imaging |
| Fibromyalgia | Fatigue, chronic pain with more generalized involvement |
| Spinal spondylosis and stenosis | Numbness, paresthesias, muscle weakness, normal inflammatory markers |
| Parkinson disease | Muscle stiffness primary complaint, other symptoms typical of Parkinson disease including tremor and rigidity |
| Infection | Fever, heart murmur, leukocytosis, positive blood cultures |
| Malignancy and paraneoplastic syndromes | Weight loss, diffuse symptoms usually not limited to shoulder or pelvic girdle, lack of response to low-dose glucocorticoid therapy |
| Drug-induced myopathy (eg, statin, glucocorticoid, colchicine) | Lack of systemic symptoms, muscle weakness and tenderness, improvement with discontinuation of drug, elevated muscle enzymes, positive anti-HMG-CoA reductase antibody |
| Thyroid and parathyroid disease | Systemic symptoms typical of endocrinopathy; abnormal thyroid markers; abnormal calcium, phosphorus, or parathyroid levels |