The conundrum of juvenile psoriatic arthritis.

Juvenile psoriatic arthritis (JPsA) has provided paediatric rheumatologists with a controversial topic for many years. The principal area of contention centres on the discordance between its treatment as a single diagnostic category in current classification schemes and the demonstration of its heterogeneous nature. A further point of debate is the distinctiveness of JPsA as an entity. Owing to these uncertainties, the concept of JPsA has evolved over the years and there have been several changes in its definition and diagnostic criteria. Recently, strong evidence has been provided that the spectrum of JPsA include at least two distinct subgroups, one that has the same characteristics as early-onset ANA-positive JIA, and another that is part of the spectrum of spondyloarthropathies and resembles the forms of psoriatic arthritis in adults that belong to the same disease family. These findings call for a revision of the classification of childhood arthritis, that refutes the assumptions that children with JPsA constitute a single homogeneous population and that JPsA should be considered an individual disease entity.