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Chapter 7: ALK Analysis in Cytology
Because IHC is broadly available, the number of pathology laboratories using IHC as a first means of ALK testing may increase and limit FISH analysis to equivocal or positive findings on IHC, provided that standardized assays and appropriate external quality-control programs are in place both for histologic and cytologic specimens.
RT-PCR A
RT-PCR may be used to analyze cytologic specimens (Betz 2013, Mitiushkina 2013). As discussed in chapter 6, RT-PCR may be adequate for confirming the results of ALK IHC or FISH, but is less appropriate for primary screening for ALK rearrangement.
Conclusion
Cytologic preparations, including conventional slides and cell blocks can be used as a useful alternative to biopsy specimens for predictive ALK analysis.
B
C
Figure 4. ALK IHC of an ALK-positive pulmonary adenocarcinoma (x 200), with testing done with the 5A4 antibody (Novocastra) on a slide with previously Papanicolaou-stained tissue (4A) and corresponding cell block sections stained with the 5A4 antibody (4B), and the D5F3 antibody (Ventana Medical Systems, Inc.) (4D).