FISH technic for HER2

Hello,
    My mother has breast cancer,and in IHC for
  HER2 it was 2+.Her oncologist said that FISH technic is required.In
  Iran Labs haven`t this technic and we should send the sample to other
  countries.Now I have a block,that is for IHC.I want to know that is it
  sufficient for FISH? or We need to send other specimen such as blood
  sample or bone marrow aspiration.please answe me.
  
  Thanks

[Fernando Roque, MD]

Hi.  The immunohistochemistry (IHC) test gives a definite diagnosis of HER-2 positivity only if the result comes out as strongly positive (3+).  A 2+ result is an equivocal result, and needs to be confirmed by another test - which is FISH (fluorescence in-situ hybridization).  This is a test wherein a fluorescent material is made to attach to the HER-2 genes, causing cells containing these genes to "light up" on microscopic examination.  The tissue block ("paraffin block") used for the IHC testing is sufficient for the FISH test, so no additional blood or tissue specimen needs to be taken again.