Vasculitis in rheumatoid arthritis.

The inflammatory process characteristic of rheumatoid arthritis is typically targeted to the synovial membrane. In a subset of patients, rheumatoid disease is complicated by an inflammatory destruction of blood vessels, rheumatoid vasculitis. Rheumatoid vasculitis has been understood to be the result of severe disease extending beyond the joint, possibly caused by immune complex deposition. In an alternative pathogenetic model, it is hypothesized that rheumatoid vasculitis represents a distinct dimension of rheumatoid disease. This model implies that rheumatoid arthritis patients can be separated into two groups: individuals with synovial disease and individuals with synovial plus extra-articular disease. The model is supported by immunogenetic analysis describing an accumulation of vasculitis patients with rheumatoid arthritis among HLA-DRB1*0401 homozygotes. The clinical experience that different types of extra-articular diseases cluster in some patients and the lack of correlation between the activity of synovial and extra-articular disease provide further support for this model.