One-half of each synovial specimen was used for histopathological analysis. The tissue specimens were fixed with 10% formalin in 0.01 mol/l phosphate buffer, pH 7.2, and embedded in paraffin wax. They were stained with hematoxylin and eosin for examination by light microscopy. Histopathological parameters of synovitis were evaluated in accordance with established criteria [14 (link)], with modifications involving the degree of proliferation of synovial cells, typical palisading of synovial cells in the intimal lining layers, non-foreign-body-type giant cells in the lining regions, lymphoid and plasma cell infiltration, neovascularization, mesenchymoid transformation, and fibrinoid necrosis in synovium. Of these features, the degree of proliferation of synovial cells was scored as follows: fewer than three layers (0), three to four layers (1), five to six layers (2), or more than six layers (3). Lymphoid cell infiltration was scored as follows: none to diffuse infiltration (0), lymphoid cell aggregates (1), lymphoid follicles (2), or lymphoid follicles with germinal center formation (3). The other features were evaluated using a quantitative grading system consisting of a 4-point scale: none (0), mild (1), moderate (2), or severe (3). The maximum score with this system was 24. The results of scoring of each histopathological feature are presented as the highest score among all the specimens for the patient. The remaining half of the synovial specimen showing the highest score in the feature 'proliferation of synovial cells' was used as multilayered lining tissue for LCM. Nearly normal synovial tissues from the same patient that had no inflammatory lesions and received a score of 0 for all of the histopathological features were used as 'normal-like lining tissue' for LCM.
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