[Differential diagnosis of synovitis]. / Differenzialdiagnostik der Synovialitis.

The synovial membrane is a site where many diseases with different etiologies can become manifest. Tumors and storage diseases are some of the rare conditions, whereas crystal deposition diseases, acute bacterial infections and in particular chronic uncharacteristic synovitis are frequently encountered. The latter present a diagnostic problem, because they can barely be assigned to concrete diagnoses. This report will give an overview of the differential diagnosis of joint diseases and will focus on the so-called synovitis score as a tool for the systematic evaluation of chronic uncharacteristic synovitis, providing a possibility to differentiate between degenerative and rheumatic synovitis with a specificity of 60.5% and a sensitivity of 95.5%.

Antigenicity testing by immunohistochemistry after tissue oxidation.

AIMS: Archived tissue blocks preserve the antigenicity of samples for a long time under normal storage conditions, whereas tissue sections may show a diminished immunoreactivity over time. Little is known about the processes responsible for antigenicity loss and how tissue sections should be conserved for extended storage. Oxidation and drying are presumed mechanisms of antigenicity loss. To prove this, degradation of immunoreactivity was provoked by chemical oxidation, photo-oxidation and artificial drying. METHODS: First, paraffin sections of an oestrogen receptor (ER) positive breast carcinoma were subjected for variable time periods to H2O2, ultraviolet A (UVA) irradiation and dry heat (56 degrees C) prior to ER immunohistochemistry. Second, using heat and UVA irradiation several other antigens (ER, PR, HER-2neu, p53, p63, p16, PSA, CK5/6, CK7, CK20, SMA, Fli-1, c-kit, CD20 and EGFR) were tested, using internal control tissue microarray sections. RESULTS: While H2O2 had no effect on the ER-staining intensity, extended drying showed a detectable decrease in staining after 10 days, and UVA irradiation induced a decrease after 3 days. Entire antigenicity loss was not observed. Except for HER-2neu, PSA and Fli-1, all antigens showed some diminution in antigenicity, but no entire antigenicity loss, after heating and UVA irradiation. CONCLUSIONS: This study confirms that photo-oxidation and drying have an influence on immunohistochemistry outcome, and protocols for testing the stability of specific antigens are provided.

Receptor activator of nuclear factor kappaB ligand is expressed in resident and inflammatory cells in aseptic and septic prosthesis loosening.

OBJECTIVE: The pathogenesis of periprosthetic bone loss in aseptic and septic prosthesis loosening is unclear. There is considerable evidence that macrophages and osteoclasts play a key role in focal bone erosion and osteolysis around the prosthesis. RANKL (receptor activator of nuclear factor kappaB ligand) was shown to be a potent osteoclastogenic factor, and to be involved in bone destruction of myeloma and rheumatoid arthritis patients. Osteoprotegerin (OPG) is the natural RANKL inhibitor and may prevent periprosthetic bone loss. METHODS: The presence and distribution of RANKL, its receptor RANK and OPG in the periprosthetic interface of septically (n = 5) and aseptically (n = 6) loosened prostheses was examined by immunohistochemistry and immunoblotting. Additionally, the immunophenotype of the inflammatory infiltrate was determined [CD3, CD68, Ki-67, tartrate-resistant acid posphatase (TRAP)]. RESULTS: Aseptic and septic cases revealed a different histopathologic pattern. However, in all cases RANKL and RANK could be demonstrated in macrophages and giant cells. In addition, RANKL detected by immunoblot analysis proved to have the same molecular weight as a recombinant RANKL used as a control (31 kD and approximately 48 kD). OPG was detected in aseptic loosening, where macrophages showed a strong staining, but multinucleated giant cells were only weakly stained. A weak OPG staining was also observed in septic loosening. CONCLUSION: The pathogenesis of bone loss in septic loosening remains unclear, because the septic membrane bears few macrophages and giant cells, and half of them express OPG. In aseptic loosening, macrophages might not be stimulated by RANKL as a result of OPG expression. But multinucleated giant cells may be activated, as they hardly express OPG. They might be responsible for periprosthetic bone loss in aseptic loosening as a result of their RANKL and RANK expression.