Juvenile idiopathic arthritis

What it is

Juvenile idiopathic arthritis, formerly called juvenile rheumatoid arthritis, is a broad term for childhood rheumatic diseases that begin before the age of 16 and are characterized by joint inflammation that lasts more than 6 weeks. It is classified into various types by the pattern of joint involvement, the presence of extra-articular manifestations such as uveitis, rash, nail changes, lymphadenopathy and hepatosplenomegaly, the laboratory findings, and the prognosis. The types are oligoarthritis, polyarthritis that is RF-negative or RF-positive, systemic arthritis, psoriatic arthritis, enthesitis related arthritis and undifferentiated arthritis.

How it presents

The arthritis lasts at least 6 weeks. Its symmetry is given differently: one source calls the arthritis symmetric, while another calls the most common form, oligoarticular JIA, asymmetric, and both are kept here. Oligoarticular disease is the form with few joints and polyarticular the form with many; the cut is put at up to four joints in one place, at fewer than 4 in another, and at fewer than 5 against 5 or more in a third. Oligoarticular JIA is the most common type, is asymmetric, and most often takes the knee joint; it makes about 60% of cases against 30% for polyarthritis and 10% for systemic disease, and it takes large joints while the other two take small and large joints.

Systemic juvenile idiopathic arthritis is also called Still disease. Its peak age of onset is 2-4 years, and it presents with intermittent fever, a transient salmon-pink rash that appears with the fever episodes and may disappear when the fever subsides, generalized lymphadenopathy, hepatomegaly or splenomegaly, serositis as pleuritis, pericarditis or peritonitis, and arthritis with synovitis of the knees, ankle and small joints of the hand. Still disease accounts for 10 to 20% of cases and is defined as arthritis associated with daily temperature spikes to 39.4 C for at least 2 weeks, with or without a rash.