Histological classification of synovitis

A simple system of synovitis classification is proposed based on histomorphological evaluation of 400 random specimens of synovial tissue. It discriminates between two types of diagnosis: 1) one with a high degree of information, being called C-synovitis (synovitis with a characteristic or diagnostic histomorphological pattern), where the clinical diagnosis can be predicted on the basis of the histomorphological pattern, 2) a second type of diagnosis with a lower degree of information, being called NC-synovitis (synovitis with non-characteristic or non-diagnostic morphological findings in the synovial membrane). We subdivided NC-synovitis into 4 subgroups and determined the RA-probability of each subgroup in order to permit clinical use of the proposed histomorphological classification. In addition, by using immunoperoxidase staining methods for immunoglobulins the subgroups were shown to have different quantities of extravasally deposited immunoglobulins in the synovial membrane. The subgroup with the highest RA-probability also turned out to have the highest amount of extravasally deposited immunoglobulins.