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.