Juvenile idiopathic arthritis (pauciarticular onset)

oligoarticular juvenile idiopathic arthritis (pauciarticular juvenile idiopathic arthritis)

The term pauciarticular onset refers to involvement of four or less joints. Medium sized joints are usually affected - the knees, ankles, elbows and wrists.

About 5% of children with this form of arthritis have IgA deficiency.

Oligoarticular JIA (Oligo-JIA) is the most common subset of JIA (50-60% of JIA)

• majority of patients are girls with peak age if onset between 1 and 3 years
• it is further divided into
  • persistent - no more than four joints affected during the course of the disease
  • extended - after the initial 6-month period, the total number of affected joints exceeds four (1,2)

Rheumatoid factor is negative but the ANA is positive in around 70%-80% of the patients. In ANA positive patients

• the risk of uveitis is higher
• uveitis (rather than arthritis) is the main disability factor (1)

Patients usually complains of arthritis in 4 or fewer joints during the first 6 months of disease

• at onset
  • symptoms could be sudden or insidious.
  • 50% have monoarthritis
    • most often of the knee (3)
  • morning stiffness may be present (if untreated may become prominent with limpimg)
• affected joints
  • are swollen and often warm (usually not very painful or tender).
  • predominantly involves lower-extremity joints, such as the knee and ankle joint (hip is rarely affected) (1,2)
• uveitis
  • almost always bilateral
  • may be present at diagnosis or later in the disease course
  • chronic anterior uveitis of JIA is often asymptomatic and rarely have symptoms such as erythema, pain, or change in vision
    • develops in 30% of all patients with oligoarticular JIA (3)
  • most respond to topical steroids

Children may modify their behaviour in order to avoid aggravating the affected joints. This will result in disuse atrophy or joint contractures over time e.g - a child with right wrist arthritis will stop using his dominant hand and switch to use the non dominant left hand (2)

Approximately half of patients with oligoarticular JIA have a persistent oligoarticular course, with four or fewer joints involved and a high likelihood of medication-free remission (3).

Early involvement of the wrist or ankle and an elevated erythrocyte sedimentation rate are associated with an increased risk of extended oligoarticular JIA (3).

Reference:

• (1) Barut K, Adrovic A, Şahin S, Kasapçopur Ö. Juvenile Idiopathic Arthritis. Balkan Medical Journal. 2017;34(2):90-101.
• (2) Kahn P.Juvenile idiopathic arthritis - an update on pharmacotherapy. Bull NYU Hosp Jt Dis. 2011;69(3):264-76.
• (3) Sandborg CI et al. Juvenile Idiopathic Arthritis. NEJM 2025;393:162-174.