Diagnosis

Polymyalgia rheumatica

Etiology

Cause [eub][6tm][mhw][abq]

• Unknown

• Genetic predisposition --> Familial aggregation, common in Scandinavia, HLA-DR4

• Environmental triggers (cyclical pattern, seasonal variation): mycoplasma pneumonia, parvovirus B19, EBV, vaccine adjuvants

Pathophysiology [abq]

1. Autoimmune activation --> elevated inflammatory markers and cytokines

2. Inflammation of the glenohumeral and hip joints

   • Pain and stiffness in and around the shoulders, neck, and hip girdle

   • Worst in the morning or after rest/inactivity

   • Carpal tunnel syndrome

   • Distal tenosynovitis

3. Closely related to giant cell arteritis (GCA): headache, claudication

   of the muscles of the jaw, and visual loss

   • PMR is 2–3 times more common than giant cell arteritis

   • 15% of patients with PMR develop giant cell arteritis GCA

   • 40-50% of patients with GCA have associated PMR

Complications [abq]

• Premature atherosclerosis resulting from chronic inflammation

• Premature CAD

• Lymphoplasmacytic lymphoma

• Waldenstrom macroglobulinemia

• Inflammatory arthritis

Epidemiology

Incidence per 100.000 [eub][6tm]

Approach

• Blood tests: Hb, WBC, TRC, ESR, CRP, anti-CCP, ANA, ANCA, tuberculosis tests, creatinine, liver function test, Calcium, ALP, TSH, fT4, creatine kinase, vitamin D [6tm][rsa]

• Protein electrophoresis

• Ultrasound of hips and shoulders: subacromial–subdeltoid bursitis, biceps tenosynovitis, glenohumeral joint inflammation and hip synovitis/trochanteritis

• MRI: to rule out differential diagnosis

• PET-CT: systemic inflammatory connective tissue disease

Diagnostic criteria [6tm]

2012 Provisional Classification Criteria for Polymyalgia Rheumatica: A European League Against Rheumatism/American College of Rheumatology Collaborative Initiative

1. Mandatory criteria:

   • Age ≥50 years

   • Bilateral shoulder aching

   • Abnormal CRP and/or erythrocyte sedimentation rate >40mm/h

2. Requires ≥4 points without ultrasound or ≥5points with ultrasound

   • Morning stiffness duration >45 min: 2 points

   • Hip pain or limited range of motion: 1 points

   • Absence of RF and/or ACPA: 2 points

   • Absence of other joint involvement: 1 points

   • At least one shoulder with subdeltoid bursitis and/or bicep tenosynovitis and/or glenohumeral synovitis (either posterior or axillary) and at least one hip with synovitis and/or trochanteric bursitis with/without ultrasound: 0/1 points

   • Both shoulders with subdeltoid bursitis, biceps tenosynovitis or glenohumeral synovitis with/without ultrasound: 0/1 points

Treatment

1. Glucocorticoids: Prednisolone 12.5–25 mg per day and gradually tapered by 2.5 mg per month down to 10 mg per day for a minimum of 12 months [6tm][mhw][abq]

   • Dose based on inflammatory activity, risk of relapse and risk of GC toxicity (diabetes, cardiovascular disease, osteoporosis, infections, cataract and glaucoma)

   • Vitamin D and calcium supplementation

2. Methotrexate 7.5–10 mg/week (if GC toxicity)

3. Azathioprine: 100–150 mg/day (limited evidence)

4. Disease‐modifying antirheumatic drugs (DMARDs): Tocilizumab, Sarilumab, TNF-α inhibitor

Differential diagnoses

Adhesive capsulitis, Amyloidosis, Ankylosing spondylitis, Cancer origo incerta, Depression, Dermatomyositis, Diabetes mellitus, Endocarditis, Fibromyalgia, HIV, Hyperparathyroidism, Hyperthyroidism, Hypoparathyroidism, Hypothyroidism, Leukemia, Lymphoma, Mononucleosis, Multiple myeloma, Obstructive sleep apnea, Osteoarthritis, Osteomalacia, Osteomyelitis, Parkinson's disease, Parvovirus B19, Polymyositis, Prostate cancer, Pseudogout, Psoriatic arthritis, Rheumatoid arthritis, Scleroderma, Septic arthritis, Sjogren syndrome, Spondylosis, Systemic lupus erythematosus, Temporal arteritis, Tuberculosis, Viral hepatitis