2023 Volume 72 Issue 1 Pages 83-89
Joint fluid is tested to identify the cause of joint effusions, and crystal classification is particularly useful for the diagnosis of crystal-induced arthritis. However, quality control and educational activities on joint fluid analysis are not sufficiently widespread, and the reasons are attributed to the small number of requests for analysis and unstable preservation. In this study, we examined the possibility of long-term preservation of crystals in specimens with calcium pyrophosphate crystals (CPPD crystals) or sodium urate crystals (MSU crystals) in joint fluid, using 10% neutral buffered formalin-fixed or anhydrous ethanol-fixed cell block specimens. CPPD crystals were significantly well preserved by 10% neutral buffered formalin fixation. In contrast, MSU crystals were significantly well preserved by anhydrous ethanol fixation. The crystals detected by polarized light microscopy also showed characteristic birefringence for CPPD and MSU crystals. In the online microscopy training using cell block specimens, the survey results showed that more than 70% of the participants responded ‘good’. These results suggest that the use of cell block specimens prepared by anhydrous ethanol fixation enables long-term preservation of both CPPD and MSU crystals and can be useful for education in joint fluid analysis.
