August • 1997   JOINT FLUID ANALYSIS CONT'D   Joint Fluid in Disease States Degenerative Joint Disease This category of disease is an end-stage of chronic arthritis seen in older animals or conformational osteoarthritis in young dogs. It may be secondary to chronic injury, conformational changes, joint instability, aging of the articular surfaces, chronic metabolic or nutritional disease, or any other cause imposing abnormal stresses on the joint and articular surfaces. The joint fluid is usually only slightly increased in volume with loss of viscosity. The cells counts are slightly elevated with mostly a rnononuclear response including large monocytoid histiocytes, lymphocytes, and desquamated synovial lining cells. Few neutrophils are seen and these are generally normal, intact, and well-segmented or show aging degeneration. Red cells are few in number unless associated with hemorrhage. The background is a granular matrix. Occasionally, cartilaginous basophilic hyaline debris can be seen denoting erosion of the joint surface. Septic Arthropathies These are associated with bacterial infection within the joint. They may result from local injury or hematogenous spread from another site of sepsis, e.g., bacterial endocarditis, periodontal disease, etc. Organism numbers may vary from "not obvious" to "many seen, both free and phagocytized". Toxic changes are often seen in the predominantly neutrophilic cell response. There is a loss of joint matrix granularity associated with the loss of viscosity, and erosive changes may also be noted. Staphylococci, streptococci, E. coli, and other coliforms are the most common isolates in cases of septic joint disease. Lyme Disease Arthropathy Lyme disease is characterized by an acute hemorrhagic inflammatory arthritis. On cytology, the inflammation is predominantly neutrophilic with lesser numbers of scattered mononuclear cells. Synovial fluid from acute Lyme disease tends to be more hemorrhagic. Condensation of joint matrix and erosive changes may also be present in advanced cases. No organisms are seen, and even with special staining, it is difficult to identify the spirochetal cause. In chronic cases, the changes begin to resemble chronic degenerative joint disease, but with more obvious red cell involvement. Immune-Mediated Polyarthritis Immune-mediated arthropathies include rheumatoid arthritis, systemic lupus erythematosus, immune-complex-mediated polyarthritis, viral-and drug- induced arthropathy, and some forms of idiopathic polyarthropathies. These are characterized by a marked neutrophilic response, arising as a result of complement fixation and chemotaxin release from within the joint synovial membrane. The neutrophils observed are generally intact and often actively phagocytic. Much of the joint matrix, immune complexes, cell debris and rarely nuclei (LE cells) are phagocytized by these cells. There is loss of joint matrix granularity as a result of this phagocytic activity, and hence reduced viscosity. Differentiation of these types of arthropathies is made based on the results of the rheumatoid factor, ANA, Lyme titer, and serum protein electrophoresis tests, in addition to negative results on cultures. Corticosteroids and cytotoxic drugs, such as cyclophosphamide and azathioprine, as well as gold salt therapy and non-steroidal anti-inflammatory drugs, have all been used in the treatment of these polyarthridities. Lymphocytic Plasmacytic Synovitis This condition of unknown etiology primarily affects the stifle joints of small to medium sized dogs, leading to joint instability and lameness. The animals are not systemically ill, the synovial cytology is chiefly mononuclear lymphocytes, lymphoplasmacytic cells and islands of hyperplastic synovial cells. Treatment is similar to that of immune-mediated arthropathies. Neoplasia Involving the Joint Primary tumors involving the bones of the joint (osteosarcoma), the synovial membrane (synovial cell sarcoma) or metastatic disease (mast cell tumors, lymphosarcoma) are the most common tumors that may shed cells into the joint space and permit detection by cytologic analysis. In these cases the radiographs of the affected joint and other clinical data will support the diagnosis. In addition to the detection of the tumor cells within the sediment by cytology, these fluids also have increased inflammatory cell numbers and associated hemorrhage. Treatment is directed at the underlying tumor with supportive care for the joint involved. Test Code 6671 Specimen Requirements Fluid in LTT Turnaround Time 24 hours       Please send comments to the webmaster. ©1997-2008 Antech Diagnostics, Inc. Site design and maintenance by amesDesign.