[Histonet] guidelines

Barry Madigan barry_m <@t> ozemail.com.au
Tue Jan 16 16:11:24 CST 2007

Been on the fixation bandwagon for years ever since the word turn around
times became fashionable with management.
I certainly notice the effects of lack of adequate fixation and processing
on Immunohistochemistry.

Barry Madigan
QHPS Central
Royal Brisbane Hospital

-----Original Message-----
From: histonet-bounces <@t> lists.utsouthwestern.edu
[mailto:histonet-bounces <@t> lists.utsouthwestern.edu] On Behalf Of Patsy Ruegg
Sent: Tuesday, 16 January 2007 3:00 AM
To: 'Webb, Dorothy L'; Histonet <@t> lists.utsouthwestern.edu
Subject: 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.

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