ARTHRITIS IN PATIENTS WITH OSTEOID OSTEOMA - DIAGNOSTIC-VALUE AND PATHOPHYSIOLOGIC IMPLICATIONS

Two cases of arthritis in patients with osteoid osteoma are reported. An immunofluorescence study of the synovial membrane was performed in one patient. The pathologic characteristics of this form of synovitis are described. Two types have been distinguished on the basis of the severity of the inflammatory reaction and the presence of lymphoplasmocytic follicles suggestive of rheumatoid arthritis. In the light of histological findings, the pathophysiologic hypotheses put forward are discussed. The issue is not only the mechanism of the joint manifestations but also the genesis of the osteoid osteoma.