*1.6. Oligoarticular JIA*

Oligoarticular juvenile idiopathic arthritis, formerly referred to as pauciarthritis or juvenile rheumatoid arthritis with pauciarticular onset, is defined by the inflammatory involvement of one or less of five joints [2].

It is the most common subgroup in juvenile arthritis, accounting for about 50% of all cases. The oligoarticular JIA comprises two categories: the persistent form in which the number of inflamed joints remains the same throughout the disease, and the extensive form in which the number of active joints is five or cumulatively more, after the first 6 months onset [2,16].

A particular case is that of oligoarthritis as a more homogeneous entity observed only in childhood, with early onset and an association of positive antinuclear antibodies (ANA) [26], young age, and female gender, complicated with iridocyclitis [19,27–29].
