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Probability diagnosis


Viral polyarthritis (e.g. hepatitis, parvovirus)

Serious disorders not to be missed


  • rheumatic fever

  • endocarditis

  • tuberculosis

  • brucellosis

  • pyogenic (septic) arthritis: gonococcus, Staphylococcus, Kingella kingae

  • HIV arthropathy

  • dengue fever


  • bronchogenic carcinoma

  • leukaemia/lymphoma

  • secondary malignancy


  • rheumatoid arthritis (RA)

  • connective tissue disorders: SLE, scleroderma, polymyositis and dermatomyositis, other

Pitfalls (often missed)

Spondyloarthropathies (e.g. psoriasis)

Fibromyalgia syndrome

Polymyalgia rheumatica

Crystal deposition:

  • gout

  • pyrophosphate (pseudogout)


Dengue fever

Lyme disease

Ross River virus

Avascular necrosis


  • other vasculitides (e.g. polyarteritis nodosa)

  • haemochromatosis

  • sarcoidosis

  • Whipple disease

  • hyperparathyroidism

  • familial Mediterranean fever

  • amyloidosis

  • pigmented villonodular synovitis

Masquerades checklist


Diabetes (?arthropathy)

Drugs: uncommon but some implemented

Thyroid disorder

Spinal dysfunction (spondyloarthropathies)

Is the patient trying to tell me something?

Always a consideration with pain.

Psychogenic factors aggravate chronic arthritic conditions.

Key history

There is such a multitude of causes of arthralgia that a skilful history to cover many angles is required. Note the pattern of joint involvement (monoarticular or polyarticular), immediate and more recent history, family history and drug use.

   Enquire whether the joint pain is acute or insidious and confined to specific joints or fleeting as in rheumatic fever.

Key examination

A systematic examination of the affected joint or joints should look for signs of inflammation, deformity, swelling and limitation of movement.

   Searching for associated systemic disease such as connective tissue disorders and infection demands examination of the chest, heart and abdomen.

Key investigations

  • FBE

  • EBR & CRP

  • Uric acid

  • Urine analysis

  • Joint X-rays

  • Synovial fluid analysis and culture

  • RA factor

  • Autoantibodies (ANA, dsDNA, ENA), anti-CCP antibody (for RA)

  • Other tests according to findings of tests for infection (e.g. specific serology, blood culture)

Diagnostic tips

  • The commonest cause of arthritis is osteoarthritis (OA).

  • Other causes of monoarthritis include crystal deposition disease, sepsis, trauma and spondyloarthritis.

  • The pain of inflammatory disease is worse at rest and improved by activity.

  • There should be no systemic manifestations with OA.

  • With polyarthritis (usually PIPs) and rash consider viral arthritis or a drug reaction.

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