title: Fine-needle aspiration cytology of hemangiopericytoma: A report of five cases.
abstract: BACKGROUND
  Hemangiopericytoma (HPC) is a relatively rare neoplasm, accounting for approximately 2.5% of all soft tissue tumors. Its histopathology has been well documented but to the authors' knowledge reports regarding its fine-needle aspiration (FNA) cytology rarely are encountered. In the current study the authors report the cytologic findings in FNA specimens from nine confirmed cases of HPC and attempt to correlate the cytologic features with the biologic outcomes.
  
  
  METHODS
  FNA was performed with or without radiologic guidance. Corresponding sections of tissue were reviewed in conjunction with the cytologic preparations.
  
  
  RESULTS
  Nine FNAs were performed in 5 patients (3 men and 2 women) with an age range of 38-77 years (mean, 56 years). Two lesions were primary soft tissue lesions arising in the lower extremities; seven were recurrent or metastatic lesions from bone (one lesion), kidney (one lesion), pelvic fossa (one lesion), lower extremities (two lesions), trunk (one lesion), and breast (one lesion). All aspirates were cellular and were comprised of single and tightly packed clusters of oval to spindle-shaped cells aggregated around branched capillaries. Basement membrane material was observed in 6 cases (67%). The nuclei were uniform and oval, with finely granular chromatin and inconspicuous nucleoli in all cases except one. No mitotic figures or areas of necrosis were identified. A correct diagnosis of HPC was made on one primary lesion and all recurrent or metastatic lesions.
  
  
  CONCLUSIONS
  HPCs show a spindle cell pattern in cytologic preparations and must be distinguished from more common spindle cell lesions. The presence of branched capillaries and abundant basement membrane material supports a diagnosis of HPC. Immunohistochemistry and electron microscopy performed on FNA samples may be helpful in the differential diagnosis. FNA is a useful and accurate tool with which to confirm recurrent or metastatic HPC; however, prediction of the biologic behavior of HPC based on cytologic features is not feasible. Cancer (Cancer Cytopathol)
authors.affiliation: Department of Pathology, New York University Medical Center, New York, New York 10016, USA.
authors.forename: D
authors.initials: D
authors.lastname: Chhieng
authors.forename: J M
authors.initials: JM
authors.lastname: Cohen
authors.forename: J
authors.initials: J
authors.lastname: Waisman
authors.forename: G
authors.initials: G
authors.lastname: Fernandez
authors.forename: J
authors.initials: J
authors.lastname: Cangiarella
mesh_terms: D000328:Adult; D000368:Aged; D018952:Antigens, CD34 / Q000032:analysis; D001707:Biopsy, Needle; D005260:Female; D006393:Hemangiopericytoma / Q000737:chemistry / Q000473:pathology* / Q000648:ultrastructure; D006801:Humans; D007124:Immunoenzyme Techniques; D008297:Male; D008854:Microscopy, Electron; D008875:Middle Aged; D009362:Neoplasm Metastasis; D012983:Soft Tissue Neoplasms / Q000737:chemistry / Q000473:pathology* / Q000648:ultrastructure; D014746:Vimentin / Q000032:analysis
chemical_list: D018952:Antigens, CD34; D014746:Vimentin