Pigmented villonodular synovitis. Report of a case with diagnostic synovial fluid cytologic features.

BACKGROUND

The identification of neoplastic cells in synovial fluid is an uncommon occurrence and most often is related to extension of extraarticular tumor into the joint space than to primary neoplasm arising in the joint.

CASE: In this report the cytologic features of synovial fluid obtained from the right knee of an 18-year-old male with biopsy-proven pigmented villonodular synovitis are described and compared with the features of the concurrent surgical specimen.

CONCLUSION

The cytologic features of pigmented villonodular synovitis in synovial fluid include abundant mononuclear histiocytic cells occurring singly and in papillary clusters, hemosiderin within histiocytes and few multinucleated giant cells.