Polymyalgia Rheumatica (PMR)
The most likely diagnosis is B. Polymyalgia rheumatica. This patient presents with the classic triad of PMR: bilateral shoulder and pelvic girdle pain worse in the morning, constitutional symptoms (fever and weight loss), and a markedly elevated ESR in a patient presumably over 50 years old 1.
Clinical Reasoning
The clinical presentation is textbook for PMR:
- Bilateral shoulder and buttock (pelvic girdle) pain with morning predominance is the hallmark symptom 1
- Constitutional symptoms including fever and 2 kg weight loss are common features 1
- Triple-digit ESR is characteristic, though not absolutely required for diagnosis 2
- Normal physical examination is typical—PMR causes pain and stiffness but not objective weakness or joint deformity 1
Why Not the Other Options?
Polymyositis (A) would show:
- Objective muscle weakness on examination (not just pain)
- Elevated creatine kinase
- Difficulty with tasks requiring proximal muscle strength (climbing stairs, rising from chair)
- The physical exam would NOT be normal
Rheumatoid arthritis (C) would demonstrate:
- Symmetric small joint involvement (hands, wrists, feet)
- Joint swelling and tenderness on examination
- Morning stiffness but in peripheral joints
- Physical exam would show synovitis
Multiple myeloma (D) could present with:
- Bone pain (but typically axial, not girdle distribution)
- Anemia would be prominent
- Would require additional findings like hypercalcemia, renal dysfunction, or lytic lesions
- Less likely to cause the specific bilateral girdle pain pattern
Hypothyroidism (E) causes:
- Generalized fatigue and weight gain (not loss)
- Diffuse myalgias without the specific girdle distribution
- Bradycardia, not fever
- Would not cause triple-digit ESR
Key Diagnostic Features of PMR
The diagnosis is primarily clinical 1:
- Age >50 years (average 70-75 years) 1
- Bilateral pain in shoulder AND pelvic girdles
- Morning stiffness
- Elevated inflammatory markers (ESR/CRP)
- Rapid, dramatic response to low-dose glucocorticoids (15-20 mg prednisone daily) 1
Important caveat: While this patient has a markedly elevated ESR, 7-22% of PMR patients can have normal or only slightly elevated ESR 3, 4. These atypical cases are more common in younger patients and men, with less frequent constitutional symptoms 4. However, this patient's triple-digit ESR makes the diagnosis even more straightforward.
Clinical Pitfalls to Avoid
- Don't dismiss PMR if ESR is normal—up to 20% of cases have ESR <40 mm/hr 4. Check CRP, which is often elevated even when ESR is normal 3
- Screen for giant cell arteritis (GCA)—PMR and GCA overlap in many patients 2, 1. Ask about headache, jaw claudication, and visual symptoms
- Expect rapid response to steroids—if symptoms don't dramatically improve within days of starting prednisone, reconsider the diagnosis 1, 5
- Don't confuse disease relapse with other shoulder pathology—shoulder pain in PMR patients can be from osteoarthritis, rotator cuff disease, or adhesive capsulitis rather than PMR relapse 2
The answer is B. Polymyalgia rheumatica.