RE: [Histonet] guidelines
Dorothy et al,
One reason for the new Her2 guidelines from CAP is that there has been a
discrepancy in results when samples are not adequately fixed in formalin
and/or alcohol fixed. If the sample is not adequately cross linked by
formalin fixation before it is processed, alcohols can damage or destroy the
Her2 protein making it unavailable for detection. Your best bet is to fix
the sample for 24 hrs. in formalin, then it will be protected from
processing and can be retrieved but at least it is still there. I know, who
has time to fix for 24hrs., well an approach to that could be that you take
a piece of the sample and process it quickly for the H&E, while leaving
another piece to fix for 24hrs., by the time the H&E is read and Her2
ordered your sample will be properly fixed, will withstand paraffin
processing, then you do the IHC on the fixed piece. Requiring a minimum of
6 hrs fixation in formalin is how CAP is starting to address this problem.
I expect that I am opening up a can of worms here but I think this is what
this is about. Studies have been done in labs using alcohol fixatives
and/or inadequate formalin fixation that show a drop in up to 30% of
positive Her2 cases. That should be telling.
[mailto:email@example.com] On Behalf Of Webb,
Sent: Monday, January 15, 2007 9:00 AM
Subject: [Histonet] guidelines
With the new Her2 guidelines from CAP, how is everyone planning on
handling not using alcoholic fixation of fatty breast tissue? We have
been using Davidson's on mastectomy and lumpectomy specimens (not needle
bx.s) and I have a dedicated processor with the first two stations of an
alcoholic formalin fixative. My pathologists want these breast
specimens to not be placed in these type of fixatives in lieu of the new
regs and I am already seeing underprocessed fatty breast tissue. Does
anyone have a longer processing time for their breast (fatty) specimens
they would be willing to share with me?
Also, does anyone have a dedicated pneumatic tube system for your OR
directly to histology for small specimens? Our facility is looking into
this and I would appreciate any feedback!!
Thanks ahead of time for any help in this area..I love this valuable
access to my fellow histology lab workers!!
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