Polymyalgia rheumatica vs Giant cell arteritis and polymyositis
How to tell Polymyalgia rheumatica and Giant cell arteritis and polymyositis apart when a board question makes them look alike.
PMR is proximal pain/stiffness with normal CK; GCA is cranial ischemic vasculitis; polymyositis is true weakness with high CK.
Side by side
Polymyalgia rheumatica causes aching and stiffness of shoulders and hips in older adults, elevated ESR/CRP, normal CK, and rapid response to low-dose steroids.
Giant cell arteritis adds headache, jaw claudication, vision risk, temporal artery tenderness; polymyositis causes true proximal weakness and elevated CK.
PMR is an inflammatory periarticular syndrome in older adults, closely associated with GCA.
GCA is granulomatous large-vessel vasculitis; polymyositis is inflammatory muscle fiber injury.
High ESR/CRP with normal CK and proximal pain/stiffness support PMR.
Temporal artery symptoms support GCA; high CK and objective weakness support polymyositis.
The trap
Pain can sound like weakness, so CK and objective strength testing separate PMR from polymyositis while headache/vision symptoms flag GCA.
The repair move
For older patients with proximal symptoms, separate pain-stiffness from true weakness and screen for GCA danger symptoms.
Try a free question
CoreA 72-year-old woman has 3 months of bilateral shoulder and hip girdle pain and stiffness, worst in the morning lasting >1 hour. She cannot lift her arms above her head or rise from a chair. Strength testing is limited by pain but appears normal. Labs: ESR 84 mm/hr, CRP 32 mg/L, CK normal. Symptoms improve dramatically within 48 hours of starting prednisone 15 mg daily. Which diagnosis is most likely?
Show answer and explanation
Answer: A. Polymyalgia rheumatica. Polymyalgia rheumatica presents in patients >50 with bilateral shoulder/hip girdle pain and stiffness, prolonged morning stiffness, very elevated ESR/CRP, normal CK, and dramatic response to low-dose prednisone (10-20 mg daily).
Why the other choices are tempting
- B. Polymyositis has true muscle weakness with markedly elevated CK and endomysial inflammation on biopsy.
- C. Giant cell arteritis adds cranial features (temporal headache, jaw claudication, visual symptoms) and requires high-dose steroids.
- D. RA has small joint synovitis with anti-CCP/RF positivity and erosions.
- E. Hypothyroidism would show elevated TSH and lacks the dramatic steroid response.
Flashcards
Tap a card to flip it.
What CK pattern supports PMR?
Normal CK supports polymyalgia rheumatica rather than myositis.
What symptom makes GCA urgent?
Vision symptoms or jaw claudication make giant cell arteritis urgent.
Quick answers
What is the fastest way to tell Polymyalgia rheumatica from Giant cell arteritis and polymyositis?
PMR is proximal pain/stiffness with normal CK; GCA is cranial ischemic vasculitis; polymyositis is true weakness with high CK.
What is the key clue for Polymyalgia rheumatica?
Polymyalgia rheumatica causes aching and stiffness of shoulders and hips in older adults, elevated ESR/CRP, normal CK, and rapid response to low-dose steroids.
What is the key clue for Giant cell arteritis and polymyositis?
Giant cell arteritis adds headache, jaw claudication, vision risk, temporal artery tenderness; polymyositis causes true proximal weakness and elevated CK.
What is the common trap with Polymyalgia rheumatica vs Giant cell arteritis and polymyositis?
Pain can sound like weakness, so CK and objective strength testing separate PMR from polymyositis while headache/vision symptoms flag GCA.