Polyarticular arthritis

Differential Diagnosis

Disease	Symptoms	Signs	Investigations	Distinguishing Features
Rheumatoid arthritis	pain, swelling, stiffness more than 6 weeks	swelling/tenderness, especially wrists, MCP, MTP	RF positive in 70%	symmetric
Psoriatic arthritis	pain, swelling, tenderness in joints and tendon/ligament attachment points	tenderness at tendon attachments, dactylitis	not helpful	may have sacroiliitis, spondylitis, plantar fascitis, DIP arthritis, nail pitting, onycholysis, and personal or family history of psoriasis
Systemic lupus erythematosus	multisystem involvement (rash, pleurisy, etc.) and photosensitivity	often more tender than swollen	ANA positive, ENA may be positive, cytopenias common	nonerosive
Remitting seronegative symmetrical synovitis with pitting edema	acute onset symmetric hand and foot swelling /stiffness	pitting edema of hands and feet	RF negative	good response to low-dose steroids
Polyarticular gout	preceding history of episodic monoarticular arthritis for years	any joint can be affected, tophi often present	increased uric acid, with urate crystals in joint	risk factors for gout