[Juvenil idiopathic arthritis. Part 1: diagnosis, pathogenesis and clinical manifestations].

Juvenile idiopathic arthritis is not a single disease and constitutes an heterogeneous group of illnesses or inflammatory disorders. This new nomenclature encompasses different disease categories, each of which has different presentation, clinical signs, symptoms, and outcome. The cause of the disease is still unknown but both environmental and genetic factors seem to be related to its pathogenesis. Is the most common chronic rheumatic disease in children and an important cause of short-term and long-term disability. In this article, clinical manifestation, new classification and approach to diagnosis are reviewed.