Malignant Knee Joint Effusion—A New Dimension of Laboratory Diagnostics

Abstract

Joint effusions are most frequently caused by osteoarthritis, trauma, an infection process or an autoimmune disease. The development of joint effusion due to a tumor process is rare but should be taken into consideration in the diagnostics. Joint effusions are examined mostly by means of microbiology to rule out or confirm pyogenic synovitis. These standard processes may take up to several days. The article presented here describes a unique case of a 74-year-old female diagnosed with a generalized malignant process according to a cytological-energy analysis and an immunocytochemical examination of a malignant joint effusion caused by femoral condyle metastasis. Other widely-used imaging methods such as X-ray, full-body CT scan and also laboratory examinations confirmed the malignancy and the origin. A cytological-energy analysis and an immunocytochemical examination can expedite the diagnostic process, can outline the processes happening in the joint and can indicate further examinations and subsequent therapy. The use of these laboratory methods appears to be a helpful diagnostic option to obtain additional information about a joint effusion, including the information about an ongoing malignant process. In our case report, they helped to confirm the typing of the tumor within three days, without the need for a metastasis biopsy. In appropriate cases, synovial fluid can play a role in tumor diagnostics.

Reactive synovitis of the knee joint after COVID‐19 vaccination: The first ultrastructural analysis of synovial fluid

“…In addition, the normal level of uric acid indicated that there were no gout alterations. A cytological‐energy analysis of the SF can also be used in the diagnostic process, for typing the tumor and for accelerating the start of treatment 6 . There are also case reports in the literature of reactive arthritis developing during or after COVID‐19 infection 12–14 …”

“…The aerobic metabolism in the SF is determined by the coefficient of energy balance (KEB). In the first SF sample area the aerobic metabolism with KEB = 34.1 reliably excluded the purulent type of inflammation induced by extracellular bacteria 5,6 . The analysis of the second SF sample manifested a decrease in the cell count (360/1 μL) and a significant decrease in neutrophils (percentage of neutrophils = 6.0%; percentage of lymphocytes = 71.0%; percentage of monocytes = 23.0%) (Figure 3).…”

“…The persisting aerobic metabolism in the SF sample area (KEB = 33.5) again excluded a significant inflammatory reaction in this site. 5 , 6 …”

“…In the first SF sample area the aerobic metabolism with KEB = 34.1 reliably excluded the purulent type of inflammation induced by extracellular bacteria. 5,6 The analysis of the second SF sample manifested a decrease in the cell count (360/1 μL) and a significant decrease in neutrophils (percentage of neutrophils = 6.0%; percentage of lymphocytes = 71.0%; percentage of monocytes = 23.0%) (Figure 3). The persisting aerobic metabolism in the SF sample area (KEB = 33.5) again excluded a significant inflammatory reaction in this site.…”

“…The persisting aerobic metabolism in the SF sample area (KEB = 33.5) again excluded a significant inflammatory reaction in this site. 5,6 An evaluation of these findings led us to the conclusion that there had been significant reactive changes in the knee joint, followed by regression.…”