title: Destaining of Diff-Quik stained cytologic smears is not necessary for the detection of anaplastic lymphoma kinase gene rearrangement in lung adenocarcinoma by fluorescencein situhybridization.
abstract: BACKGROUND
  Anaplastic lymphoma kinase (ALK) gene rearrangement analysis by fluorescencein situhybridization (FISH) is one of the standard molecular tests for targeted therapy of lung adenocarcinoma. However, insufficient cell block cellularity may impede molecular testing. A recent study showed that Diff-Quik (DQ) stained cytology smear is suitable forALKby FISH.
  
  
  OBJECTIVE
  The aim of our study was to observe the impact of destaining intervals on the quality of FISH signals and determine if DQ smears without destaining would allow FISH analysis.
  
  
  METHODS
  Thirty-five DQ smears from 27 cases of lung adenocarcinoma were analyzed forALKgene rearrangement by FISH. Twenty three DQ smears were destained for different intervals, including 30 s (13 cases), 1 min (6 cases), or 2 min (4 cases). Twelve DQ smears were not subjected to destaining. For further validation, FISH signals in 8 smears and 6 cell blocks were compared with the paired destained DQ smears. The signal quality was semi-quantified and analyzed with Chi-squared test.
  
  
  RESULTS
  Of the total 27 selected cases, three (11%) were positive forALKgene rearrangement, whereas 24 (89%) were negative. FISH signal was satisfactory in all DQ smears. There was no significant difference in the quality of signal among smears with different destaining intervals (P= 0.55) or between smears with and without destaining (P= 0.41). DQ smears without destaining showed identical FISH results and similar or better signals as compared with paired destained smears and cell blocks in all cases.
  
  
  CONCLUSIONS
  Duration of destaining intervals does not impact the quality of FISH signal on DQ smears. Destaining of DQ smears is not necessary forALKby FISH.
authors.affiliation: Department of Pathology, State University of New York (SUNY) Upstate Medical University, Syracuse, New York, USA.
authors.forename: Weisheng
authors.initials: W
authors.lastname: Xu
authors.affiliation: Department of Pathology, State University of New York (SUNY) Upstate Medical University, Syracuse, New York, USA.
authors.forename: Kamal K
authors.initials: KK
authors.lastname: Khurana
authors.affiliation: Department of Pathology, State University of New York (SUNY) Upstate Medical University, Syracuse, New York, USA.
authors.forename: Jamie
authors.initials: J
authors.lastname: Tull
authors.affiliation: Department of Pathology, State University of New York (SUNY) Upstate Medical University, Syracuse, New York, USA.
authors.forename: Charlene
authors.initials: C
authors.lastname: Maciak
authors.affiliation: Department of Pathology, State University of New York (SUNY) Upstate Medical University, Syracuse, New York, USA.
authors.forename: Shengle
authors.initials: S
authors.lastname: Zhang
keywords: Anaplastic lymphoma kinase (ALK); Diff-Quik (DQ); cytology smear; fluorescence in situ hybridization (FISH); lung adenocarcinoma