Unusual Findings in Synovial Fluid Analysis: A Review

Synovial fluid analysis is one of the most useful laboratory test in the diagnosis of joint diseases. It allows to determine the degree of synovial inflammation, the presence of pathogenic crystals and microorganisms, and to evaluate the effect of pharmacological treatments as well as the progression of the disease. Synovial fluid therefore represents a precious substrate able to give valuable information from both the clinical and the research points of view.In this educational review we present and discuss some unusual findings, at times associated with rare rheumatic conditions, observed while routine synovial fluid examination is performed. These findings can be highlighted under ordinary or polarized light using simple wet preparations and supravital staining.