Rheumatoid factor-negative polyarthritis is a term used to describe a group of poorly defined heterogenous conditions that incorporates forms of rheumatoid factor-negative polyarthritis and forms of oligoarticular arthritis that become extensive in less than 6 months after onset. Rheumatoid factor-negative polyarthritis represents around 15-20% of cases of juvenile idiopathic arthritis (JIA). Prevalence has been estimated at between 1 and 13 in 22,200 children, with an annual incidence of 1-26 in 700,000 children. Females are affected more often than males. The joint manifestations are bilateral, nearly symmetrical and affect both the large and small joints. Biological signs of inflammatory disease are frequent. Rheumatoid factor tests are always negative but antinuclear antibodies may be present. The aetiology is difficult to determine as a result of the heterogeneity. The diagnostic criteria for the disease were established in 2001 at the last international meeting in Edmonton. Rheumatoid factor-negative polyarthritis is defined as the presence of arthritis affecting five or more joints at disease onset. Exclusion criteria are the presence of systemic arthritis or psoriasis in the patient, or a family history of psoriasis in one of the parents or a first-degree relative, HLA B27-positivity in males with onset of arthritis after 6 years of age, and detection of rheumatoid factor IgM in two test samples taken three months apart. Other exclusion criteria include: the presence of ankylosing spondylarthritis, enthesitis and arthritis, sacroiliitis with an inflammatory enteropathy or acute anterior uveitis in the patient, or a family history of one of these conditions in a parent or first-degree relative. The differential diagnosis should include other forms of polyarthritis (associated with inflammatory or haemato-oncologic diseases). Patients should be managed in a multidisciplinary manner, incorporating expertise in paediatric rheumatology, physiotherapy, psychologyand infantile orthopaedic care. Treatment is based on the association nonsteroidal anti-inflammatory agents (NSAIDS), disease-modifying antirheumatic drugs (methotrexate as a first-line treatment and tumour necrosis factor (TNF)-alpha as a second-line treatment) and rehabilitation. Corticotherapy is used at low doses and as rarely as possible. Intraarticular injection of delayed-action corticoids (triamcinolone hexacetonide) may be recommended in case of persistent arthritis. The prognosis is difficult to determine due to the heterogeneity of the condition but it appears the percentage of remission is low.
Last update: January 2007