Juvenile Idiopathic Arthritis

Excerpt

Juvenile idiopathic arthritis (JIA) is a heterogeneous group of idiopathic inflammatory arthritis affecting children younger than 16 years of age and lasting six weeks or longer. The terminology of chronic arthritis in children has evolved from juvenile chronic arthritis (JCA) and juvenile rheumatoid arthritis (JRA) to JIA since 1995. According to the consensus conference of the International League of Associations for Rheumatology (ILAR) in 2001, there are seven JIA categories: a) oligoarthritis; b) rheumatoid factor (RF) positive polyarthritis; c) RF negative polyarthritis; d) systemic arthritis; e) psoriatic arthritis; f) enthesitis-related arthritis; g) undifferentiated arthritis. These subtypes have distinct phenotypes, genetic predispositions, pathophysiology, laboratory findings, disease course, and prognosis. Although chronic arthritis is mandatory for all subtypes, the extraarticular and the systemic manifestations characterized every specific subtype. Recently, a new preliminary data-driven classification for JIA is proposed and being formally validated by the Pediatric Rheumatology International Trial Organization (PRINTO).