idiopathic

Definition

Definition

Joint effusion / pain / swelling in two or more joints

- > 6 weeks

- patient > 16 years

Variations

- number of joints affected: oligoarticular (<5)  v polyarticular (5 or more)

- rheumatoid factor positive or negative

- systematic symptoms (rash / fever / lympadenopathy / organomegaly)

Epidemiology

1:10,000

Familial clusters

HLA-gene associations