Juvenile idiopathic arthritis (JIA) involves idiopathic inflammation affecting the joints in children and adolescents. It is diagnosed when inflammatory arthritis occurs without any other cause and lasts more than 6 weeks in a patient under the age of 16. It has also been known as juvenile chronic arthritis and juvenile rheumatoid arthritis.
The three key features of inflammatory arthritis are joint pain, swelling and stiffness.
There are various subtypes of juvenile idiopathic arthritis, with distinct clinical features. The key subtypes are:
- Systemic JIA
- Polyarticular JIA
- Oligoarticular JIA
- Enthesitis-related arthritis
- Juvenile psoriatic arthritis
Systemic JIA
Systemic JIA is also known as Still’s disease. It is a systemic illness that can occur throughout childhood. It is an idiopathic inflammatory condition. Typical features are:
- Subtle salmon-pink rash
- High swinging fevers
- Enlarged lymph nodes
- Weight loss
- Joint inflammation and pain
- Splenomegaly
- Muscle pain
- Pleuritis and pericarditis
Antinuclear antibodies and rheumatoid factor are typically negative. There will be elevated inflammatory markers, with elevated CRP, ESR, platelets, and serum ferritin.
A key complication is macrophage activation syndrome (MAS), where there is severe activation of the immune system with a massive inflammatory response, which is potentially life-threatening. MAS presents with an acutely unwell child with:
- Disseminated intravascular coagulation (DIC)
- Anaemia
- Thrombocytopenia
- Abnormal bleeding
- Non-blanching rash
- Falling or inappropriately low ESR (a key investigation finding)
TOM TIP: Think of Still’s disease (systemic JIA) when a patient presents with a salmon-pink rash, fevers and joint pain. In children with fevers lasting more than 5 days, the key non-infective differentials to consider are Kawasaki disease, Still’s disease, rheumatic fever and leukaemia.
Polyarticular JIA
Polyarticular JIA involves inflammatory arthritis in 5 or more joints. The inflammatory arthritis tends to be symmetrical and can affect the small joints of the hands and feet, as well as the large joints, such as the hips and knees. There are often minimal systemic symptoms, but there can be mild fever, anaemia and reduced growth.
Polyarticular JIA is similar to rheumatoid arthritis in adults. Most children are negative for rheumatoid factor and are described as “seronegative”. Positive rheumatoid factor is described as “seropositive”. Seropositive patients tend to be older, and the disease pattern is closer to rheumatoid arthritis in adults.
Oligoarticular JIA
Oligoarticular JIA is also known as pauciarticular JIA. It involves 4 joints or fewer. Usually it only affects a single joint, which is described as monoarthritis. It tends to affect the larger joints, often the knee or ankle. It occurs more frequently in girls under 6 years of age.
Anterior uveitis is classically associated with oligoarticular JIA, and patients are referred for ophthalmology screening even if asymptomatic.
Patients tend not to have any systemic symptoms. Inflammatory markers will be normal or only mildly elevated. Antinuclear antibodies are often positive, although rheumatoid factor is usually negative.
Enthesitis-Related Arthritis
Enthesitis-related arthritis is more common in male children over 6 years of age. It is similar to the seronegative spondyloarthropathy conditions that affect adults, including ankylosing spondylitis, psoriatic arthritis, reactive arthritis and inflammatory bowel disease-related arthritis. Patients have inflammatory arthritis in the joints as well as enthesitis.
An enthesis (plural: entheses) is where a tendon, ligament or joint capsule attaches to bone. Enthesitis refers to inflammation of this insertion point. Enthesitis can be caused by traumatic stress, such as repetitive strain during sporting activities, or by an autoimmune inflammatory process. An MRI scan can demonstrate enthesitis but cannot distinguish between enthesitis due to stress and that due to an autoimmune process.
Many patients with enthesitis-related arthritis have the HLA-B27 allele.
It is also associated with anterior uveitis, and all patients should be referred to an ophthalmologist.
Patients with enthesitis have localised tenderness to palpation of the entheses. Commonly affected sites include:
- Achilles tendon insertion at the calcaneus
- Plantar fascia insertion at the calcaneus
- Patellar tendon insertion at the tibial tuberosity
- Quadriceps tendon insertion at the patella
Juvenile Psoriatic Arthritis
Psoriatic arthritis is a seronegative inflammatory arthritis associated with psoriasis, the skin condition. The pattern of joint involvement varies. Patients can have symmetrical polyarthritis affecting the small joints, similar to rheumatoid arthritis, or asymmetrical arthritis affecting the large joints of the lower limbs.
Juvenile psoriatic arthritis is associated with several signs on examination:
- Plaques of psoriasis on the skin
- Pitting of the nails (nail pitting)
- Onycholysis, separation of the nail from the nail bed
- Dactylitis, inflammation of the whole digit (finger or toe)
- Enthesitis, inflammation of the entheses, which are the points of insertion of tendons into bone
Management of Juvenile Idiopathic Arthritis
Management should be coordinated by a paediatric rheumatology specialist, with a multidisciplinary team. Treatment aims to reduce inflammation, minimise symptoms and maximise function.
Medical treatment depends on the severity and response, and involves:
- NSAIDs, such as ibuprofen
- Steroids (oral, intramuscular or intra-articular)
- Disease-modifying antirheumatic drugs (DMARDs), such as methotrexate, sulfasalazine and leflunomide
- Biologic therapy, such as the tumour necrosis factor inhibitors etanercept, infliximab and adalimumab
Last updated July 2026
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