Rheumatic symptoms, such as limping or limb pain, are common in children, yet childhood arthritis and other rheumatic diseases are rare. Diagnosis and treatment of these conditions therefore require a high level of clinical awareness and careful assessment. Laboratory investigations are rarely pathognomonic and are used instead to help differential diagnosis, to detect complications, and to monitor disease activity. Drug treatment depends on a sound knowledge of the variable nature and prognosis of the conditions and a clear understanding of the pharmacology, risks, and benefits of anti-inflammatory and antirheumatic drugs in children.

Persistent swelling of joints characterises a heterogeneous group of diseases termed juvenile chronic arthritis, formerly known as Still's disease. This group of diseases is, for the most part, genetically and clinically distinct from rheumatoid arthritis in adults. About one child in every 1000 has juvenile chronic arthritis, amounting to over 12000 affected children in Britain. Each year one new case would be expected in every 10000 children.