Medicine – Causes of an Acute Polyarthritis

Acute polyarthritis refers to the relatively sudden development of inflammatory symptoms affecting several joints. It may result from autoimmune disease, infection, crystal deposition, systemic inflammatory disorders, or less commonly other multisystem conditions. The pattern of joint involvement, associated systemic symptoms, age of the patient, and laboratory findings help distinguish the underlying cause. Conditions marked with an asterisk are among the more common causes.

1. Rheumatoid Arthritis*

Rheumatoid arthritis (RA) is a common cause of inflammatory polyarthritis. Although RA more often develops gradually, some patients can present with a relatively acute onset of symmetrical pain, swelling, and morning stiffness, particularly involving the MCP, PIP, wrist, and MTP joints. Persistent synovitis and serological findings such as rheumatoid factor or anti-CCP antibodies help support the diagnosis.

2. Generalised Osteoarthritis*

Generalised osteoarthritis can produce pain and stiffness in multiple joints, particularly in older adults. Although osteoarthritis is usually chronic and non-inflammatory, symptoms can sometimes worsen abruptly, especially when several joints become symptomatic at the same time. Typical sites include the knees, hips, spine, DIP joints, PIP joints, and first carpometacarpal joints of the thumbs.

3. Seronegative Spondyloarthritides*

The seronegative spondyloarthritides can present with acute peripheral polyarthritis or oligoarthritis. This group includes ankylosing spondylitis, psoriatic arthritis, reactive arthritis, and enteropathic arthritis. Joint involvement is often asymmetrical and predominantly affects the lower limbs, although the exact pattern varies. Enthesitis, sacroiliitis, uveitis, psoriasis, or bowel disease may provide additional diagnostic clues.

4. Viral Infections*

Several viral infections can cause an acute polyarthritis, often as part of a systemic viral illness. The joint symptoms may be transient and can closely resemble an autoimmune inflammatory arthritis.

Rubella may cause arthralgia or polyarthritis, particularly in adults. Mumps can occasionally be associated with joint inflammation. Parvovirus B19 is a particularly important cause because it may produce an acute symmetrical small-joint polyarthritis resembling rheumatoid arthritis. Coxsackie viruses may also cause musculoskeletal symptoms. Hepatitis B and hepatitis C can produce inflammatory polyarthritis as part of their extrahepatic manifestations.

5. Reactive Arthritis

Reactive arthritis, formerly called Reiter’s syndrome, develops after an infection elsewhere in the body, particularly a gastrointestinal or genitourinary infection. It typically causes an asymmetrical inflammatory arthritis of the lower limbs, although several joints may be involved. Conjunctivitis, urethritis, enthesitis, and mucocutaneous lesions may accompany the arthritis.

6. Gonococcal Arthritis

Disseminated gonococcal infection caused by Neisseria gonorrhoeae can produce migratory polyarthralgia or polyarthritis. Patients may also develop tenosynovitis and pustular skin lesions. In some cases, the illness progresses to a more localised purulent monoarthritis. Recognition is important because antimicrobial treatment is required.

7. Adult- and Childhood-Onset Still’s Disease

Still’s disease can occur in both children and adults and may present with acute inflammatory polyarthritis. It is typically associated with high spiking fever, an evanescent salmon-pink rash, and systemic inflammation. Arthritis may appear after the constitutional symptoms have already begun.

8. Rheumatic Fever

Acute rheumatic fever can cause a characteristic migratory polyarthritis, particularly affecting large joints such as the knees, ankles, elbows, and wrists. The arthritis is usually very painful but transient, with inflammation resolving in one joint as another becomes affected. Other features may include carditis, chorea, erythema marginatum, and subcutaneous nodules.

9. Systemic Lupus Erythematosus

Systemic lupus erythematosus (SLE) commonly causes inflammatory polyarthralgia or polyarthritis. The arthritis is usually non-erosive and often affects the small joints of the hands and wrists. Associated manifestations such as rash, photosensitivity, oral ulcers, serositis, renal disease, or haematological abnormalities may help establish the diagnosis.

10. Gout

Although gout usually presents as an acute monoarthritis, particularly of the first MTP joint, approximately a minority of patients may develop polyarticular gout, especially in longstanding or severe disease. Multiple joints can become acutely inflamed, sometimes making the presentation difficult to distinguish from septic or autoimmune arthritis. Synovial fluid examination reveals needle-shaped, negatively birefringent monosodium urate crystals.

11. Pyrophosphate Arthropathy

Calcium pyrophosphate deposition disease (CPPD or pseudogout) can also cause an acute polyarthritis, although large-joint monoarthritis or oligoarthritis is more typical. The knees, wrists, and other large joints are frequently involved. Joint aspiration demonstrates weakly positively birefringent calcium pyrophosphate crystals, and radiographs may show chondrocalcinosis.

12. Acute Sarcoidosis

Acute sarcoidosis can present with polyarthritis, particularly involving the ankles. A classic acute presentation is Löfgren syndrome, which consists of bilateral hilar lymphadenopathy, erythema nodosum, and acute arthritis or periarthritis. This form of sarcoidosis often has a relatively favourable prognosis.

Key Clinical Approach

Common causes of acute polyarthritis include rheumatoid arthritis, seronegative spondyloarthritis, and viral infection. Important alternatives include reactive arthritis, gonococcal infection, Still’s disease, rheumatic fever, SLE, crystal arthropathies, and acute sarcoidosis. The diagnosis is guided by the distribution of affected joints, duration of symptoms, systemic manifestations, infection history, serology, inflammatory markers, and synovial fluid analysis when appropriate.