On a recent workshop a speaker of NordiQC gave information on their sampled
knowledge on this subject.
He said, that the receptor-results are most influenced by underfixation.
Especially in the comparison of small needle-biopsies to the
large-mamma-surgical specimen he said, that there is no difference in the
IHC after a minimum fixation of 6 hours. - I think, that is the usual
problem with the rush-biopsies, that show differences in the margins and the
center; and afterwards to the big speciman.
Overfixation should'nt be a problem up to some weeks. And in the clinical
histolab the usually used markers all work well with a fixation duration of
5-6 days. So no worries about too long fixation.
Some markers like lambda or kappa react sensitive on underfixation and give
either false positive or false negative results.
If somebody is interested in this organisation for Quality Control in IHC:
http://www.nordiqc.org
Gudrun Lang
Biomed. Analytikerin
Histolabor
Akh Linz
Krankenhausstr. 9
4020 Linz
+43(0)732/7806-6754
-----Ursprüngliche Nachricht-----
Von: histonet-bounces@lists.utsouthwestern.edu
[mailto:histonet-bounces@lists.utsouthwestern.edu] Im Auftrag von Lott,
Robert
Gesendet: Freitag, 15. Juni 2007 18:37
An: histonet@lists.utsouthwestern.edu
Betreff: [Histonet] Fixation for Her-2/neu -Where's the Beef???
Hello Everyone,
.....been a lot of talk about this already, I'm aware of that. Now I
want to know if there is any "real" scientific" basis for the new CAP
guideline for Her-2 IHC fixation that states "No less than 6 hrs. and no
more than 48 hrs. in aqueous NFB." Any documented, peer-reviewed,
published data???
My sense is that this guideline really does represent best practice.
Most of us do well to get our breast specimens fixed for 6 hrs. in NBF!!
However, is there really some difference in performance of the Her-2 IHC
assay if a breast case is fixed for 48 hrs vs. one fixed for 54 hrs. or
72 hrs. (i.e. weekend/ holiday scenario). UNDER-fixation would seem to
be so much more of issue than OVER-fixation.
It's this top end that bothers me so much!!!
I am not aware of real data to support this new guideline! Does anyone
out there know anything different?????
Robert
Robert L. Lott, HTL(ASCP)
Manager, Anatomic Pathology
LabFirst / Trinity Medical Center - formerly
Montclair Baptist Medical Center
800 Montclair Road
Birmingham, AL 35213
205-592-5388 phone
205-592-5646 fax
robert.lott@triadhospitals.com
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