title: Fine needle aspiration biopsy of a small round cell tumor exhibiting both neural and myogenic differentiation. A case report.
abstract: BACKGROUND
  Divergent differentiation may not be detected in the limited material available in a fine needle aspiration biopsy (FNAB).
  
  
  METHODS
  A small round cell malignancy showed neural features ultrastructurally on FNAB, in keeping with primitive neuroectodermal tumor, but desmin and actin positivity on surgical biopsy, suggesting rhabdomyosarcoma.
  
  
  CONCLUSIONS
  Accurate classification of small round cell tumors by FNAB is more likely to occur when both electron microscopy and immunocytochemistry are employed since these tumors may express divergent differentiation.
authors.affiliation: Department of Pathology, University of Manitoba, Winnipeg, Canada.
authors.forename: E
authors.initials: E
authors.lastname: Ravinsky
authors.forename: J R
authors.initials: JR
authors.lastname: Safneck
authors.forename: G
authors.initials: G
authors.lastname: Quinonez
authors.forename: H M
authors.initials: HM
authors.lastname: Yazdi
mesh_terms: D000328:Adult; D001707:Biopsy, Needle; D018288:Carcinoma, Small Cell / Q000175:diagnosis / Q000473:pathology*; D002454:Cell Differentiation; D006258:Head and Neck Neoplasms / Q000175:diagnosis / Q000473:pathology*; D006801:Humans; D007124:Immunoenzyme Techniques; D008297:Male; D008854:Microscopy, Electron; D008870:Microtubules / Q000473:pathology / Q000648:ultrastructure; D017599:Neuroectodermal Tumors / Q000175:diagnosis / Q000473:pathology*; D012208:Rhabdomyosarcoma / Q000175:diagnosis / Q000473:pathology*