Juvenile Idiopathic Arthritis Flashcards
Features
joint pain, swelling and stiffness.
Systemic JIA
This is also knowns as Still’s disease. This is a systemic illness that can occur throughout childhood in boys and girls. 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 factors are typically negative. There will be raised inflammatory markers, with raised 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. It presents with an acutely unwell child with disseminated intravascular coagulation (DIC), anaemia, thrombocytopenia, bleeding and a non-blanching rash. It is life threatening. A key investigation finding is a low ESR.
TOM TIP: Think of Still’s disease (systemic JIA) when a patient presents with a salmon-pink rash, fevers and joint pain. In children that have fevers for more than 5 days, the key non-infective differentials to remember are Kawasaki disease, Still’s disease, rheumatic fever and leukaemia.
Polyarticular jIA
Polyarticular JIA involves idiopathic inflammatory arthritis in 5 joints or more. 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 minimal systemic symptoms, but there can be mild fever, anaemia and reduced growth. Systemic symptoms are mild, unlike systemic onset JIA.
Polyarticular JIA is the equivalent of rheumatoid arthritis in adults. Most children are negative for rheumatoid factor and are described as “seronegative”. When rheumatoid factor is positive they are described as “seropositive”. Seropositive patients tend to be older children and adolescents and the disease pattern is more similar to rheumatoid arthritis in adults.
Oligoarticular JIA
This is also knowns as pauciarticular JIA. It involves 4 joints or less. Usually it only affects a single joint, which is described as a monoarthritis. It tends to affect the larger joints, often the knee or ankle. It occurs more frequently in girls under the age of 6 years.
A classic associated feature with oligoarticular JIA is anterior uveitis. Patients should be referred to an ophthalmologist for management and follow up of uveitis.
Patients tend not to have any systemic symptoms and inflammatory makers will be normal or mildly elevated. Antinuclear antibodies are often positive, however rheumatoid factor is usually negative.
Juvenile Psoriatic Arthritis
Psoriatic arthritis is an seronegative inflammatory arthritis associated with psoriasis, the skin condition. The pattern of joint involvement varies. Patients can have a symmetrical polyarthritis affecting the small joints similar to rheumatoid, or an asymmetrical arthritis affecting the large joints in the lower limb.
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 full finger
Enthesitis, inflammation of the entheses, which are the points of insertion of tendons into bone
Treatment
The management should be coordinated by a specialist in paediatric rheumatology, with a specialist multi-disciplinary team. The aim of treatment is to reduce inflammation within the joints, minimise symptoms and maximise function.
Medical treatment depends on the severity and response, and involves:
NSAIDs, such as ibuprofen
Steroids, either oral, intramuscular or intra-artricular in oligoarthritis
Disease modifying anti-rheumatic drugs (DMARDs), such as methotrexate, sulfasalazine and leflunomide
Biologic therapy, such as the tumour necrosis factor inhibitors etanercept, infliximab and adalimumab
