Confusable diagnoses · PANCE / PANRE

Polymyalgia Rheumatica vs Fibromyalgia

Written & clinically reviewed by Ryan Busch, PA-C · Updated August 2026 · Report an error

Polymyalgia Rheumatica and Fibromyalgia are easy to mix up on the boards. Here's a side-by-side comparison — presentation, workup, imaging, and first-line treatment — drawn from our full outlines.

Polymyalgia Rheumatica vs Fibromyalgia at a glance

  • Polymyalgia Rheumatica: Inflammatory syndrome of shoulder and hip girdle stiffness in adults over 50; dramatic response to low-dose steroids.
  • Fibromyalgia: Centralized pain syndrome with widespread tenderness, fatigue, and sleep and cognitive disturbance; normal labs and imaging.

Try two board-style questions on Polymyalgia Rheumatica vs Fibromyalgia

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Question 1MusculoskeletalEasy
A 72-year-old woman presents with 6 weeks of bilateral aching and stiffness in her shoulders, neck, and hips, worst in the morning and lasting more than an hour. She has difficulty getting out of bed and lifting her arms to comb her hair. She reports fatigue and a 6 lb weight loss but no muscle weakness on formal testing. ESR is 92 mm/hr and CRP is markedly elevated. Creatine kinase is normal. Which is the most likely diagnosis?
  • APolymyalgia rheumatica
  • BRheumatoid arthritis
  • CInflammatory polymyositis
  • DFibromyalgia syndrome
Reveal answer & full explanation
Correct answer: A — Polymyalgia rheumatica
  • APolymyalgia rheumatica✓
  • BRheumatoid arthritis
  • CInflammatory polymyositis
  • DFibromyalgia syndrome

Why Polymyalgia rheumatica is correct

  • Polymyalgia rheumatica (PMR) classically affects adults over age 50 and presents with bilateral shoulder and pelvic girdle aching and stiffness, prolonged morning stiffness (lasting more than an hour), constitutional symptoms, and markedly elevated ESR and CRP.
  • Formal muscle testing shows no true weakness in PMR — pain limits effort — and creatine kinase (CK) is normal, distinguishing PMR from polymyositis.
  • PMR responds dramatically to low-dose prednisone (15–20 mg/day), and the rapid response is itself supportive of the diagnosis.

Why the others are wrong

  • Inflammatory polymyositis — produces true proximal muscle weakness on formal testing and an elevated creatine kinase; both are absent here.
  • Fibromyalgia syndrome — has normal inflammatory markers and widespread tender points without elevated ESR or CRP.
  • Rheumatoid arthritis — typically involves small joints (metacarpophalangeal (MCP), proximal interphalangeal (PIP), wrist) symmetrically with synovitis, rather than the bilateral shoulder and pelvic girdle pattern seen here.
Question 2MusculoskeletalMedium
A 45-year-old woman presents with 6 months of widespread musculoskeletal pain that is bilateral and both above and below the waist, along with marked fatigue, non-restorative sleep, and difficulty concentrating. Examination reveals diffuse soft-tissue tenderness without synovitis, and 16 of 18 tender points are positive. CBC, comprehensive metabolic panel, TSH, ANA, and ESR are all within normal limits. Which intervention is the most appropriate initial therapy?
  • AAerobic exercise
  • BOral duloxetine
  • CTender point injections
  • DTizanidine at bedtime
Reveal answer & full explanation
Correct answer: A — Aerobic exercise
  • AAerobic exercise✓
  • BOral duloxetine
  • CTender point injections
  • DTizanidine at bedtime

Why Aerobic exercise is correct

  • This patient meets criteria for fibromyalgia: chronic (>3 months) widespread pain in all quadrants with fatigue, non-restorative sleep, cognitive symptoms (fibro fog), and 16 of 18 tender points positive
  • Normal inflammatory and metabolic workup (CBC, CMP, TSH, ANA, ESR) excludes inflammatory and endocrine mimics
  • The cornerstone of initial management is non-pharmacologic and patient-centered: education, graded aerobic exercise (strongest and most consistent evidence for improving pain, function, and global well-being), and cognitive behavioral therapy to address sleep, mood, and pain coping
  • EULAR and U.S. guidelines recommend these as first-line before drug therapy

Why the others are wrong

  • Oral duloxetine — an SNRI that is FDA-approved for fibromyalgia and a reasonable add-on if symptoms persist despite non-pharmacologic measures, but it is not the initial step; pregabalin and milnacipran fill the same second-line role
  • Tender point injections — local anesthetic injection targets focal myofascial trigger points and has no established role in diffuse fibromyalgia; it does not address deconditioning, sleep, or central sensitization, and repeated injections are not recommended
  • Tizanidine at bedtime — a central alpha-2 agonist borrowed for muscle spasm and sleep, but it lacks guideline support in fibromyalgia and adds sedation, hypotension, and hepatotoxicity risk
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Side-by-side comparison

FeaturePolymyalgia RheumaticaFibromyalgia
At a glanceInflammatory syndrome of shoulder and hip girdle stiffness in adults over 50; dramatic response to low-dose steroids.Centralized pain syndrome with widespread tenderness, fatigue, and sleep and cognitive disturbance; normal labs and imaging.
Classic presentationSubacute onset of bilateral shoulder and hip girdle aching and stiffness; Morning stiffness >45 minutes (often hours); Difficulty rising from a chair or lifting arms above the head; Constitutional symptoms in 30-50%: fatigue, low-grade fever, anorexia, weight loss; No true muscle weakness once pain is controlled; Restricted active…Diffuse musculoskeletal pain >3 months in multiple body regions, often migratory; Profound fatigue, especially morning fatigue and after exertion; Nonrestorative sleep, frequent awakenings; Cognitive symptoms — word-finding difficulty, decreased concentration ('fibro fog'); Headache, paresthesias, dizziness; GI symptoms (IBS overlap),…
Workup / key labs2012 EULAR/ACR provisional criteria: age ≥50, bilateral shoulder pain, abnormal CRP or ESR, plus weighted morning stiffness, hip involvement, absence of other joint pain, and absence of RF/anti-CCP.; ESR — characteristically >40 mm/h (often >50-100); CRP elevated and may be more sensitive; CBC — normochromic normocytic anemia,…2016 revised fibromyalgia criteria (Wolfe et al.): widespread pain index (WPI) and symptom severity scale (SSS) — pain in 4 of 5 body regions for ≥3 months with WPI ≥7 and SSS ≥5 (or WPI 4-6 and SSS ≥9); the diagnosis is valid irrespective of other diagnoses, so coexisting RA, SLE, or OA does not exclude it.; Goal is to exclude…
ImagingShoulder ultrasound or MRI — subacromial-subdeltoid bursitis, biceps tenosynovitis, glenohumeral synovitis (supportive but not required); Temporal artery ultrasound or biopsy if GCA features develop; PET-CT in atypical cases — can show large-vessel uptakeGenerally NOT indicated — incidental findings on MRI commonly mislead; Image only if focal red-flag findings emerge (true weakness, focal joint signs, neurologic deficits)
First-line treatmentPrednisone 12.5-25 mg/day — dramatic improvement within 48-72 hours is both therapeutic and diagnostic; Slow taper over 1-2 years guided by symptoms and inflammatory markers (EULAR/ACR 2015: taper to 10 mg/day within 4-8 weeks, then by 1 mg every 4 weeks until discontinuation while remission is maintained); Bone-protective therapy:…Patient education — emphasize that pain is real, reflects altered central pain processing, and is not destructive or progressive; Aerobic exercise — graded, low-impact (walking, swimming, cycling); cornerstone of treatment; Sleep hygiene and treatment of sleep disorders (OSA, restless legs); Cognitive behavioral therapy and…

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Full outlines

Polymyalgia Rheumatica (PMR) Fibromyalgia All 514 diagnoses

Educational use only. This outline is a study aid for PA students and is not medical advice or a substitute for clinical judgment. FirstPassPA is an independent study tool and is not affiliated with, endorsed by, or sponsored by NCCPA or PAEA. PANCE® and PANRE® are registered trademarks of the National Commission on Certification of Physician Assistants; End of Rotation™ is a program of the Physician Assistant Education Association.