[Histonet] Re: HER2 fixation time

Rene J Buesa rjbuesa <@t> yahoo.com
Thu Jan 24 10:46:40 CST 2008

Not if you set the instrument to start EXACTLY when you want. You will have the tissues in melted paraffin more time, or you can extend the dehydration times. You can do a lot of things all preventing longer fixation in NBF. Modern TP are very flexible instruments and I have no data that reflects any deleterious effects for the tissues' reactive qualities or sectioning characteristics after being in melted paraffin for long periods of time. 
  René J.

ancillarypath <@t> mac.com wrote:
  I agree with Rich, and it's good to hear that some colleagues have 
started their own mode of cross-validation.

If you choose to deviate from the upper fixation limit of 48 hours, 
you will ONLY be at default if you do not have evidence (with 
documentation) that raising the upper fixation limits to 72 or 96 
hours has no detrimental effects on the results. The CAP will 
eventually increase the upper limit to 72 (or hopefully 96) hours once 
there is solid evidence that is ok to do so.

Rene's suggestion to put the instrument on delay is not a valid 
solution. As long as the tissue is sitting in formalin in the 
instrument while it's on delay, it's still being fixed. This issue was 
discussed at the ASCO/CAP meeting.


Hadi Yaziji, M.D., Medical Director
Vitro Molecular Laboratories,
President, Ancillary Pathways
7000 SW 62nd Avenue, Suite Penthouse-C
Miami, FL 33143
Tel 305.740.4440
Fax 786.513.0175

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Message: 18
Date: Thu, 24 Jan 2008 09:57:05 -0500
From: "Richard Cartun" 
Subject: Re: [Histonet] HER2neu Fixation times
To: "Ramona Turner" ,

Message-ID: <479860F2020000770000A527 <@t> gwmail4.harthosp.org>
Content-Type: text/plain; charset=US-ASCII

Personally, I would not initiate any drastic changes at this point. 
Keep in mind that these are guidelines; however, you must validate 
your testing if you are going to follow other fixation guidelines. I 
think everyone knowledgeable with this issue knows that the problem is 
with underfixation, not overfixation. I recently pulled tumor out of 
formalin after 8 months of fixation and the IHC was still "3+" and the 
FISH showed beautiful amplification (ratio of 10.0). I hope that once 
the scientific evidence is evaluated, these guidelines will be 
changed. Major expense is being incurred here unnecessarily. How is 
your concordance between IHC and FISH for the detection of HER2? If 
it's not broken, don't try to fix it. Our "ad-hoc" committee on IHC 
standardization is meeting in Santa Barbara on Sunday and I hope this 
issue will be discussed.


Richard W. Cartun, Ph.D.
Director, Immunopathology & Histology
Assistant Director, Anatomic Pathology
Hartford Hospital
80 Seymour Street
Hartford, CT 06102
(860) 545-1596
(860) 545-0174 Fax

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