Eosinofilia sinovial

Synovial fluid eosinophilia is defined as the presence of eosinophils, irrespective of quantity, in the synovial fluid and is a rare finding that is probably underestimated. The pathogenesis of this entity remains incompletely understood. Secondary and idiopathic forms have been described. Idiopathic forms are those not associated with systemic or rheumatic inflammatory disease or associated with chronic non-inflammatory rheumatic diseases. Idiopathic forms can be divided into pure or pseudoallergic forms when they occur in patients with an atopic background and/or intensely positive dermographism. Both forms are usually monoarthritis of the large joints with a substantial component of joint effusion but few inflammatory signs. Synovial fluid usually contains between 2,000 and 10,000 leukocytes/mm3, with a variable percentage of eosinophils. Although a major form (>10% eosinophils) and a minor form (<10% eosinophils) have been distinguished, both seem to have the same significance in terms of clinical manifestations and prognosis. Peripheral eosinophilia (>600 eosinophils/mm3) is a rare association and is not usually severe. Symptoms resolve within a few days without specific therapy and recurrences occur in approximately half of patients. Non-steroidal anti-inflammatory drugs are usually sufficient to control symptoms. Synovial fluid eosinophilia has not been associated with the development of new joint deformities nor has it been described as a chronic form of arthritis.