[Synovial membrane changes in early rheumatoid arthritis. I. Histological studies]

The histological and histochemical findings in synovial membranes of 13 patients with early rheumatoid arthritis (duration not more than 6 months; clinical follow-up at least 2 years) have been compared with 16 late cases of definite RA (ARA criteria). The authors intended to investigate the dynamic evolution of rheumatoid synovitis and to analyze the full-fledged changes with reference to diagnosis and pathogenesis of RA. Although the basic pattern of reaction is the same, the following peculiarities are found in early RA: 1) A band-like mucoid swelling of the synovial adventitia, histochemically with increase of acid glucosaminoglycans; 2) more frequent occurrence of vasculitis; 3) less marked infiltration with lymphocytes and plasma cells; 4) absence of gross fibrin insudation and granulocyte infiltration; 5) absence of diffuse fibrosis and hyalinosis. For diagnostic purposes it is also important that proliferative reactions can be found but are much less marked than in late cases. In conclusion, the early morphological findings do not allow more than the suspicion of RA. The combined mucoid swelling of the ground substance and vasculitis together with further signs of proliferation and exsudation are most important. With reference to the pathogenesis of RA, the authors insist on the frequent vasculitic changes and the early occurrence of immuno-competent cells which are the cytological condition of immunological reactions.