Differentiating Polymyalgia rheumatica from other diseases

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Ahmed Elsaiey, MBBCH [2]

Overview

Polymyalgia rheumatica (PMR) must be differentiated from other conditions such as late onset rheumatoid arthritis, polymyositis, dermatomyositis, fibromyalgia, and remitting seronegative symmetrical synovitis with pitting edema.

Differentiating Polymyalgia Rheumatica from other Diseases

Polymyalgia rheumatica (PMR) must be differentiated from other conditions such as late onset rheumatoid arthritis, polymyositis, dermatomyositis, fibromyalgia, and remitting seronegative symmetrical synovitis with pitting edema.

Differentiating polymyalgia rheumatica on the basis of fatigue and chronic pain

Disease	Differentiating signs and symptoms	Diagnostic findings
Polymyalgia rheumatica	Older at onset Generalized stiffness	Elevated ESR or CRP Response to corticosteroids
Fibromyalgia	Symptoms have been present at a similar level for at least 3 months. Chronic musculoskeletal pain with multiple tender points Stiffness, numbness, and fatigue Headaches Sleep disorder	All lab tests are normal
Rheumatoid arthritis	Multiple joint swelling Morning stiffness Rheumatoid nodules	Positive RF or anti-cyclic citrullinated protein (CCP) antibody Elevated ESR or CRP
SLE	Maculopapular rash Multi-system involvement	Positive anti-Smith antibodies
Chronic fatigue syndrome	Fatigue plus 4 of the following symptoms: Short-term memory loss Sore throat Tender lymph nodes in the neck or armpit Muscle pain Joint pain without swelling or redness Headaches Insomnia Malaise	Diagnosis of exclusions Symptoms must present for more than 6 months
Spondyloarthritis	Axial skeletal pain and stiffness Restricted spinal motion	Elevated ESR or CRP Negative RF Bamboo spine on x-ray
Osteoarthritis	Localized joint pain Restricted to affect joints Older at onset	Degenerative joint changes on x-ray
Hypothyroidism	Systemic symptoms such as weight gain, constipation, dry skin Muscular aching Prominent fatigue	Elevated TSH Low free T4
Polymyositis and dermatomyositis	Pelvic and shoulder girdle muscle weakness Rash	Muscle biopsy confirms the diagnosis Elevated CPK enzyme
Neuropathy	Numbness and tingling Paresthesia	Abnormal EMG

Differentiating polymyalgia rheumatica from other causes of inflammatory myopathy

Organ system	Disease	Symptoms												History	Physical Examination	Diagnosis
		Age of onset	Muscle weakness	Fever	Myalgia	Contractures	Gait abnormality	Neuropathy	Atrophy	Stiffness	Myoglobinuria	Other features	Laboratory Findings			Creatine Kinase	Muscle Biopsy	Electromyogram
Inflammatory/ Rheumatologic	Polymyalgia Rheumatica	50s	Diffuse	+	+	−	−	−	−	+	−	Weight loss	History of joints stiffness, worse in the morning	Restricted shoulder motion	↑↑ ESR ↑↑ CRP	Normal	Normal	Normal
	Dermatomyositis	40s−50s Can affect children	Proximal	+	+	−	−	−	−	+	−	Rash Dyspnea Weight loss Cough	Viral infections Cancer	Heliotrope rash on face and hands Telangiectasia Erythema Mechanic's hands Gottron's sign ( violaceous scaly eruption )	↑↑ ESR ↑↑ CRP	↑↑	Perimysial mononuclear infiltrate	Myopathic
	Polymyositis	> 18 years	Proximal	+	+	−	−	−	−	+	−	Similar to dermatomyositis without mucous and skin involvement	N/A	N/A	↑↑ ESR ↑↑ CRP	↑↑	Endomysial mononuclear infiltrate Patchy necrosis
	Inclusion body myositis	50s	Proximal & distal	−	−	−	−	−	−	−	−	Dysphagia Asymmetric weakness	Retrovirus (most common)	N/A	Antibodies to cytoplasmic 5'−nucleotidase	↑↑	Inflammatory cells Invading muscle cells Vacuolar degeneration Inclusions or plaques	Neurogenic
	Fibromyalgia	40−50s	Generalized	−	−	−	−	+	−	−	−	Anxiety or depression features Fatigue Sleep disturbance Numbness Muscle spasms	History of depression	Tenderness in the soft tissue anatomical location	Normal	Normal	Normal	Normal
Organ system	Disease	Age of onset	Muscle weakness	Fever	Myalgia	Contractures	Gait abnormality	Neuropathy	Atrophy	Stiffness	Myoglobinuria	Other features	History	Physical Examination	Laboratory Findings	Creatine Kinase	Muscle Biopsy	Electromyogram