Aetiology and Pathology

Abstract

Rheumatoid arthritis can be defined as a chronic inflammation of many synovial structures which is not explained by the presence of bacteria, crystals, bony or cartilage irregularities or other stimuli that might be present. It is an unexplained chronic widespread synovitis. There is a general belief, increasingly supported by immunogenetic evidence, that rheumatoid arthritis differs both in its cause and its mechanism from other forms of inflammatory arthritis, such as psoriatic arthritis and Reiter’s syndrome which also present with unexplained synovitis. The hallmarks of the rheumatoid process are a wide-spread symmetrical involvement, bone erosions, serum rheumatoid factor and subcutaneous nodules. Not all patients have all four features. This probably indicates that rheumatoid arthritis is not one disease but a number of different, closely related diseases. Nevertheless at the present time it is practical to consider these under a single disease heading.