I've been informed from our pathologists that over-fixation of breast tissue (more than 48 hours) will potentially mask Her2 staining. This in turn impacts our FISH staining, as cases for FISH are selected based on Her2 results. The fear then, is that cases which should've reflexed to FISH will not. The over-fixation could result in under-expression of Her2 run cases. Sounds a bit contradictory but that's how I understand it. I do have to agree with you, my concern would be under-fixation vs. over-fixation. But, I guess under-fixation is more readily apparent and easier to address than over-fixation. This will be a new thing for everybody and we're looking at a new mandatory week-end shift because of it (oh joy). Anyway, this is what I've been told and how I understand it, good luck down there in Bama.
Tom Jasper HT (ASCP) BAS
[mailto:email@example.com]On Behalf Of Lott,
Sent: Friday, June 15, 2007 11:37 AM
Subject: [Histonet] Fixation for Her-2/neu -Where's the Beef???
.....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,
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 L. Lott, HTL(ASCP)
Manager, Anatomic Pathology
LabFirst / Trinity Medical Center - formerly
Montclair Baptist Medical Center
800 Montclair Road
Birmingham, AL 35213
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