[Histonet] Re: Ohh the pain (replacing formalin)

From:"Johnson, Teri"

Douglas, if it is your Pathology group pushing you to go to non-formalin
fixative, I'm quite surprised. Pathologists are accustomed to making
diagnoses based on formalin-based artifacts. In a lab I worked in (in a
galaxy far, far away) we did the "Folger's crystals replacement"
experiment, replacing all the GI and prostate biopsy formalin fixative
with zinc formalin. I thought the pathologists were going to have a
major meltdown. The nucleoli were more prominent in all the cells, and
that freaked them out. We effectively changed what the cellular
structure looked like (even mild cellular changes can be a
diagnostically significant).

Disregarding the FDA issue and interlaboratory issues already raised
(quite valid points!), if you change what fixative you are using, the
cells will look different. And while that is not an insurmountable issue
for pathologists, it does take getting used to.

One possible substitute is glyoxal. Anatech provides this commercially
in a fixative called "Prefer". It is supposed to provide formalin-like
morphology with heightened immunoreactivity. Remember - ALL your
immunohistochemistry staining will have to be redone. ALL OF IT. It is
optimised  using formalin, and changing the fixative changes the
structure of the proteins. Some immunos may work better, some may not
work as well, some may no longer require antigen retrieval, some may
require a different retrieval method.

Do you get any consultation material (outside blocks) from other
institutions for second opinion? If so, and you need to do staining of
any kind (H&E, special stains, and IHC), you will need to optimise your
staining of that material back to formalin. Your non-formalin controls
will be useless.

I'm not saying this is an impossible task. It will be difficult and seem
impossible until it's all worked out. It takes a tremendous amount of
effort and energy to make the switch, and above all, the pathologists
should have a major stake in how their samples will be fixed, processed,
and stained. Their reputation depends on it. Their patient's diagnosis
also depends on it.

If you want to turn your attention to making formalin safer, there are
ways of doing that. That's fodder for another post altogether.

Good luck!

Teri Johnson, HT(ASCP)QIHC
Managing Director Histology Facility
Stowers Institute for Medical Research
1000 E. 50th St.
Kansas City, MO 64110

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