Introduction: Arthritis in Reiter's syndrome (RS) is a reactive synovitis associated with a localized infection of the urogenital or gastrointestinal tract with a genetic predisposition. The pathogenetic mechanisms for synovitis in RS are still unknown. Our aim was to examine some of the pathogenetic mechanisms in Reiter's syndrome looking for morphologic changes, immunoprotein deposits and microorganism antigens in synovial biopsies and to determine whether synovial biopsy is useful in diagnosis of RS.
Material and methods: Thirty patients with urogenital form of RS were examined within a four-year period. Table 1 illustrates laboratory findings in our patients. We performed synovial biopsies looking for histopathological changes, deposits of immunoproteins and microorganism antigens. Analysis of synovial biopsy specimens was performed using light and immunofluorescence microscopy and fluorescein-labelled monoclonal antibodies to Chlamydia trachomatis.
Results: Histopathological examination of synovial membrane revealed marked proliferation of the synovial lining cells (SLC) with less or more abundant papillary projections, hypertrophic and edematous tissue with marked vascularisation in 28 (93.3%) cases. Fibrinoid necrosis foci were seen on the surface of synovial tissue. Chronic inflammatory cells (CIC) were diffusely distributed. Edema of the vessel walls, swollen endothelial cells, fibrinoid necrosis in vessel walls as well as multilaminated basement membranes were observed. All histopathologic changes are presented in Table 2. Immunofluorescent techniques in 12 out of 30 (40%) synovial membranes showed immunoglobulin deposits: IgG and IgA deposits were found in vessel walls in 7 cases each and IgM in 10 biopsy specimens. C3 was present perivascularly or within the vessel wall in 4 (13.3%) cases. Sections treated using fluorescein-conjugated antibody revealed Chlamydia in the synovial tissue in 2 patients.
Conclusion: Biopsy specimens with previously described changes in patients with suspected Reiter's syndrome can be useful to confirm the diagnosis. According to our experience, multiple biopsies of abnormal synovia are recommended in these patients.