Comparison of serial synovial fluid cytology in rheumatoid arthritis: delineation of subgroups with prognostic implications.

Serial synovial fluid samples were obtained from patients with rheumatoid arthritis and analysed cytologically. Positive correlations in the serial samples between proportions of polymorphs and ragocytes were found. Based upon the serial synovial fluid cytology, distinct subgroups of rheumatoid joints emerged. Comparison of clinical findings in these subgroups showed that the joints with high ragocyte proportion had a significantly poorer outcome. This study therefore identifies two distinct subgroups of rheumatoid joints on the basis of the nature of the cellular reaction within the joint fluid, which usually holds true during subsequent clinical relapse. Identification of these groups may have prognostic significance.