title: Pigmented villonodular synovitis. Report of a case with diagnostic synovial fluid cytologic features.
abstract: 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.
  
  
  METHODS
  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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Department of Pathology and Laboratory Medicine, Albany Medical Center, New York 12208, USA.
authors.forename: D C
authors.initials: DC
authors.lastname: Chhieng
authors.forename: A
authors.initials: A
authors.lastname: Boguniewicz
authors.forename: B J
authors.initials: BJ
authors.lastname: McKenna
mesh_terms: D000293:Adolescent; D002467:Cell Nucleus / Q000473:pathology; D004396:Coloring Agents; D015726:Giant Cells / Q000473:pathology; D006485:Hemosiderin / Q000032:analysis; D006644:Histiocytes / Q000473:pathology; D006801:Humans; D008297:Male; D013582:Synovial Fluid / Q000166:cytology*; D013586:Synovitis, Pigmented Villonodular / Q000473:pathology*
chemical_list: D004396:Coloring Agents; D006485:Hemosiderin