Re: Penfix

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From:Amos Brooks <>
To:by way of Histonet <>
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    We have been performing DAKO's Herceptest since shortly after it came out.
Still many of our clients insist on using alternate fixatives and order the
test. For these clients we still perform the test but have informed them that
alternative fixatives negate the FDA approval of the test, and may impede
    The FDA is trying to ensure that results will be the same for all samples.
The only way to be sure of it is to enforce strict procedures. (If you think
the fixation guidelines are strict, you should see the protocol!)
    This raises many questions about the treatment of the specimens. How do
you regulate the duration of fixation? If you receive 2 blocks from another
lab one fixed for a week in formalin the other fixed for an hour, are both
still FDA approved because they were fixed in formalin. Both will stain
differently than an optimally fixed control. (One is over fixed and the other
is under fixed.) Next, how about xylene substitutes, processing schedules,
types of paraffin. All of this can have an influence on the antigenicity of
the tissue. It is really no wonder that there is only one stain with FDA
approval. (Even H&E is not)
Amos Brooks

by way of Histonet wrote:

> I am curious about the reason for your question Joyce.
> We have been using Penfix as our primary fixative for fatty breast
> biopsies for the last year and a half in order to try to meet the
> unrealistic expectations of our surgeons to have diagnostic results closer
> to twenty four rather than forty eight hours from the date of surgery.
> Even though we tell them that they will get better results if we allow the
> tissue to fix longer, they don't want to hear it and expect more rapid
> results.  We have had success with Penfix and our surgeons seem satisfied
> with the turn around time.
> It has come to our attention through IMPATH labs that DAKO's Hercept Test
> was FDA approved using 10% NB Formalin or Bouins only.  Since there is now
> a concern that Hercept Test results on tissue fixed other than mentioned
> above (Penfix with all the alcohols for example) are suspect, we also need
> to find something else that will allow faster fixation to meet the needs
> of our surgeons and not compromise Hercept Test findings.
> Effective Monday, we stopped using Penfix as our primary fixative for
> breast biospies. We are continuing to use it in our tissue processor.
> Has anyone else been made aware of this issue with DAKO's Hercept Test?
> On Tue, 11 Apr 2000, joyce judge wrote:
> > Does anyone know of any alternatives to "PenFix"
> > Joyce Judge
> > Saints Memorial Medical Center
> >
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