title: Comparative analysis of electron microscopy and immunocytochemistry in the cytologic diagnosis of malignant small round cell tumors.
abstract: OBJECTIVE
  To compare the contributions of electron microscopy (EM) and immunocytochemistry (ICC) as adjuncts in the cytodiagnosis of malignant small round cell tumors (MSRCT).
  
  
  METHODS
  This prospective study included 57 cases with a preliminary aspiration diagnosis of MSRCT. The contributions of EM and ICC in arriving at a specific diagnosis were evaluated.
  
  
  RESULTS
  The 57 cases included 22 cases of Ewing's sarcoma/peripheral neuroectodermal tumor (PNET), 12 neuroblastomas, 8 Wilms' tumors, 6 rhabdomyosarcomas, 5 lymphomas, 2 retinoblastomas and 1 synovial sarcoma. One case remained unclassified. Electron microscopy was crucial to the diagnosis in 38.4% cases as against 39.2% of cases by ICC. The light microscopic diagnosis was confirmed in 42.3% and 53.5% cases by EM and ICC, respectively. EM and ICC were inconclusive for a specific diagnosis in 19.2% and 7.1% of cases, respectively. Technically unsatisfactory preparations in EM and ICC accounted for 5 and 1 cases, respectively. The overall efficiency in making a diagnosis was 80.7% for EM versus 92.8% for ICC. Aberrant expression of antigens led to difficulties in interpretation of ICC, and EM was particularly helpful. The ultrastructural demonstration of neural differentiation in Ewing's sarcoma/PNET tumors helped place tumors in the PNET category.
  
  
  CONCLUSIONS
  While ICC is the ancillary method of choice in the cytologic diagnosis of MSRCT, EM contributes to the diagnosis and improves diagnostic accuracy.
authors.affiliation: Departments of Cytology and Gynecologic Pathology and of Histopathology, Postgraduate Institute of Medical Education and Research, Chandigarh, India.
authors.forename: Urmil
authors.initials: U
authors.lastname: Brahmi
authors.forename: Radhika
authors.initials: R
authors.lastname: Srinivasan
authors.forename: Harbhajan Singh
authors.initials: HS
authors.lastname: Komal
authors.forename: Kusum
authors.initials: K
authors.lastname: Joshi
authors.forename: Subhash Kumari
authors.initials: SK
authors.lastname: Gupta
authors.forename: Arvind
authors.initials: A
authors.lastname: Rajwanshi
mesh_terms: D000328:Adult; D014408:Biomarkers, Tumor / Q000032:analysis; D001707:Biopsy, Needle; D002648:Child; D003581:Cytodiagnosis / Q000379:methods*; D006801:Humans; D007150:Immunohistochemistry / Q000379:methods*; D008297:Male; D008854:Microscopy, Electron / Q000379:methods*; D009369:Neoplasms / Q000737:chemistry / Q000473:pathology*; D011446:Prospective Studies; D015203:Reproducibility of Results
chemical_list: D014408:Biomarkers, Tumor