[Histonet] Negative IHC Control for Her2

[Lindrud, Scott]

Hi All,

We are having an internal debate regarding Her2 IHC control tissue in our lab.  We run a MTA (multi tissue array) consisting of 0+, 1+, 2+, and 3+ Her2 staining tissue taken from lumpectomy/resection cases.  I'm in the process of searching for more tissue to use in future control blocks and it can be difficult to find tissue that is 0+ and 3+.

I've discussed this with our pathologist in charge of Histology and he says that we don't need to run all 4 of the cores as controls.  He says all we need to run is a positive control and a negative control.  He says the positive control could be a 2+ or 3+ and the negative control could be either a 0+ OR a 1+.

I respectfully disagreed with him and said the negative control is not meant for accessing staining interpretation but to verify the sensitivity and specificity of the actual antibody-antigen reaction.  I said a 1+ is still staining the tissue where there is no staining in a 0+ reaction.  The 1+ is not a negative staining reaction, but a negative interpretation.   The pathologist says I'm wrong.

The CAP in its checklist says "It is also important to assess the specificity of each antibody by a negative tissue control, which must show no staining of tissues known to lack the antigen".    To me, a 1+ Her2 staining reaction shows that that tissue has antigen and should not be used as a negative control.

So, after saying all that, can/should  1+ Her2 breast tissue be used as a negative tissue control?  Seems pretty straight forward to me, but I'm just a Cytotechnologist/Histotech.

Thanks for any input!

Scott

Scott A. Lindrud, MLS(ASCP)CM CTCM
Histopathology Technical Specialist/Cytotechnologist
Rice Memorial Hospital
301 Becker Ave SW
Willmar, MN 56201
WP(320)231-4406
Fax(320)231-4861
scott.lindrud at rice.willmar.mn.us


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