[Diagnosis of peripheral joint involvement in children].

The diagnosis is assessed by a meticulous anamnesis, the research of associated clinical signs and the duration of the follow-up. If the clinical onset is recent (< 15 days), bacterial osteo-arthritis is to be treated in emergency; traumatic causes are easily advocated; reactive arthritis is infrequent. If the articular disease has been persistent or recurrent for 15 days to 3 months, and because of the urgency of the treatment, it should be unacceptable not to recognize a leukaemia or a metastatic neuroblastoma; the same is true for bacterial origins and some of the vascular alterations of growth cartilage. Reactive arthritis, frequently due to a digestive infection, has also to be considered. The localised articular lesions of traumatic or malformative origin, may be diagnosed by magnetic resonance imaging and arthroscopy. When the duration of the articular disease exceeds 3 months, the diagnosis of juvenile chronic arthritis, spondylarthropathy and connectivitis (disseminated lupus, panarteritis, dermatomyositis) or of some rare systemic diseases (Behçet, sarcoidosis, periodic disease) has to be considered. The non somatic and/or psychogenic causes must be accepted only if any organic disease has been excluded. The diagnosis of the so-called "growth pains" remains too often a medical error.