[Diagnostic spectrum of synovitis].

This review will suggest an algorithm for standardised histopathological diagnosis of synovial biopsies and synovectomy specimens. In principal, changes of the synovial membrane can be inflammatory or non-inflammatory. To the latter group belong some benign tumors, such as tenosynovial giant cell tumor, lipoma or synovial chondromatosis. Rare non-inflammatory changes are the group of storage diseases. Inflammatory synovial diseases can be differentiated into crystal-induced arthropathy, such as gout and pseudogout, granulomatous diseases, such as tuberculosis, sarcoidosis and foreign body reactions and into the large group of non-granulomatous synovitis. This last group is by far the most common and often causes difficulties in assigning the histopathological findings to a definite diagnosis. Therefore, the synovitis score should be applied in these cases as a diagnostic means, leading to the diagnosis of low-grade synovitis (which is associated with degenerative and posttraumatic arthropathies) or high-grade synovitis (associated with rheumatic diseases), the sensitivity and specificity being 60.5% and 95.5%, respectively. In detritus synovitis the synovitis score is not applicable.