JUVENILE CHRONIC ARTHRITIS
synovitis - JUVENILE
Juvenile chronic arthritis is a general term for non-infective chronic
inflammatory joint disease in children, much of which is clinically and aetiologically
distinct from adult disease. There are several different types. Classification is
constantly changing and the term juvenile idiopathic arthritis has also been suggested.
This is likely to need changing again when causes are established, which may be fairly
soon! Growth retardation and bony ankylosis are important features of childhood arthritis.
Hypoplasia of the jaw leads to a typical facial pattern. Synovitis may also lead to
excessive epiphyseal growth with limb length inequality.
Subclassification of Chronic
synovitis - JUVENILE
1. A systemic illness with a fleeting migratory erythematous macular
rash, splenomegaly, serositis, fever and joint pain (Still's Disease). Synovitis may only
be a minor feature. This syndrome has similarities to lupus and adult rheumatoid but no
specific autoantibodies are recognised. The distribution of lesions suggests that it is
mediated by small immune complexes, but the nature of the antigen is unknown.
2. A widespread (polyarticular) synovitis, without systemic features.
This may be chronic and destructive. Some older children have a positive rheumatoid factor
and overlap with adult rheumatoid arthritis. Uveitis may occur.
3. A chronic synovitis of few joints (pauciarticular), commoner in
girls and associated with antinuclear antibodies and chronic uveitis. Eye damage is
insidious and often silent. Synechiae may develop, with secondary glaucoma. Ophthalmic
screening is essential. Joint disease often settles, but overgrowth of epiphyses is a
characteristic of involved joints in this group and leads to limb length discrepancy. A
subgroup develop more widespread joint disease later (extended pauciarticular).
Antinuclear antibodies in this syndrome include specific antibodies to the oncoprotein DEK
which appears to be involved in the control of leucocyte proliferation.
4. A chronic synovitis of one or a few joints, usually including a
knee, in HLA-B27 positive children who may go on to develop Spondylitis in adult life.
Most are adolescent boys. Acute anterior uveitis is associated.
5. Synovitis associated with psoriasis which is similar to the adult
patterns but which tends to lead to widespread ankylosis of both spine and peripheral
joints in older children.
6. The combination of allergic purpura and joint synovitis was
described by Schönlein and the association with abdominal pain by Henoch.
Henoch-Shönlein purpura is almost certainly a post-infective immune complex vasculitis.
The mechanism remains unclear but may involve a disturbance of interactions involving IgA
and complement. Microvascular damage in other organs occurs, the major problem being renal
damage (20-30%). 10-15% of renal cases go on to renal failure.
The three forms of juvenile idiopathic arthritis seen most
characteristically in young children; systemic, polyarticular and pauciarticular, appear
to be aetiologically distinct from adult syndromes. What is not clear is whether they
overlap or whether they are discrete. All three syndromes show varying associations with
MHC Class I and Class II allotypes, changing with age, some of which are shared between
Treatment of juvenile chronic arthritis tends to be by analogy with
adult disease. Methotrexate is widely used to suppress synovitis. The efficacy of other
slow acting agentsis in doubt.