title: Subclassification of non-small cell lung cancer by cytologic sampling: a logical approach with selective use of immunocytochemistry.
abstract: OBJECTIVE
  To determine the diagnostic accuracy of cytomorphology for subclassifying non-small cell lung cancer into adenocarcinoma (AC) and squamous cell carcinoma (SqC), and the utility of immunocytochemistry (ICC) for poorly differentiated cases.
  
  
  METHODS
  Preoperative cytologic diagnoses of SqC, AC, or non-small cell carcinoma (NSCC) were compared with surgical resection diagnoses. NSCC cases with adequate cell block material were stained with CK7, CK5/6, TTF-1 and p63 antibodies and subclassified as SqC, AC, or equivocal.
  
  
  RESULTS
  123 of 140 (88%) preoperative cytologic specimens had a malignant diagnosis, including 36 SqC, 72 AC, 6 adenosquamous carcinomas (ASC), and 9 large cell carcinomas (LCC). Accurate cytologic diagnoses were rendered in 18 (50%) SqC and 49 (68%) AC; 26 of 54 cases with a diagnosis of NSCC had adequate cell block material for ICC. TTF-1 and p63 accurately classified 8 of 9 (89%) SqC and 8 of 8 (100%) AC. One SqC, 2 ASC and 3 LCC had equivocal staining, while 1 ASC and 3 LCC stained as AC.
  
  
  CONCLUSIONS
  The majority of SqC and AC (56%) can be classified by cytomorphology alone. TTF-1 and p63 ICC on cell blocks can provide accurate subclassification for NSCC in the vast majority of cases.
authors: Department of Pathology and Laboratory Medicine, Tulane University School of Medicine, New Orleans, LA, USA. hkimbrel@tulane.edu
authors: Hillary Z
authors: HZ
authors: Kimbrell
authors: Karen S
authors: KS
authors: Gustafson
authors: Min
authors: M
authors: Huang
authors: Hormoz
authors: H
authors: Ehya
mesh_terms: D002289:Carcinoma, Non-Small-Cell Lung / Q000145:classification* / Q000175:diagnosis; D003581:Cytodiagnosis / Q000379:methods*; D006801:Humans; D007150:Immunohistochemistry; D008175:Lung Neoplasms / Q000145:classification* / Q000175:diagnosis; D012189:Retrospective Studies