[Possibilities and limits of the morphological diagnosis of rheumatoid arthritis]

For the morphological diagnostics of rheumatoid arthritis only the judgment of the synovial membrane is of practical importance. Based on the experience gleaned on more than 2,000 synovectomy preparations the following evidence concerning the possibilities and the limits of the morphological diagnostics and the judgment of activity can be enunciated. 1. A certain histological diagnosis of the rheumatoid arthritis is possible only when rheumatoid granulomas or their equivalents are proved. 2. A probability diagnosis results from a definite combination of symptoms of proliferative and exsudative reactions of the synovial membrane. Especially the absence of proliferative signs decreases the degree of probability of the diagnostic evidence. 3. Seropositive and seronegative cases do not reveal any differences in histological respect. The possibility of the class-specific determination of rheumatoid factors by means of an immunofluorescence test and the fact the seronegative cases showed IgM and IgM rheumatoid factors, when this test was used, demands an examination of this evidence. 4. As to the synovial membranes of large joints in the same membrane so distinctive local differences of the findings may exist that thus the value of the needle biopsy is restricted. Only positive findings may be evaluated diagnostically. 5. Apart from a diagnosis the histological findings of the synovial membrane also allow a judgment of the local activity. The basis activity and the actual activity are differentiated. The basis activity is regarded as an expression of the immunological activity, the actual activity as an expression of the inflammatory activity. There are no unambiguous relations to the total clinical activity. Differences in the behaviour of the activity between seropositive and seronegative cases are not to be proved. A revision of this evidence under the aspect of the class-specific proof of the rheumatoid factor is necessary.