[Histonet] Cell block processing

[Joe W. Walker, Jr.]

Hi Terri,

At one time we did the same thing but have changed our approach in light of the FDA's and CAP's view point on ASRs.  The potential problem is that IHCs are all validated/tested by the manufacturer on FFPE tissue.  By introducing methanol/ethanol as the first step in fixation, you potentially have altered the initial fixation steps.  I've attended several meetings on this topic and have been advised to stop performing IHC on methanol/ethanol fixed specimens unless we validated that this fixation step doesn't alter the expression of the target antigen in the tissue.  Formalin fixation after an alcohol fixation doesn't change/reverse any alterations to the antigen in the tissue.

We utilize an IBF tissue fixative but have also validated this fixative with our antibody panels that we offer.  The IBF does contain a small amount of alcohol and the fixative is slightly different than 10% buffered formalin.

I agree that CytoLyt is excellent at lysing red blood cells but would just caution you on using the specimen for IHC without a disclaimer within your report or validating your IHCs on these specimens to ensure they work as expected.  Keep in mind that most control tissue is FFPE and using it to compare if the IHC worked in a first fixed alcohol specimen is not an apples to apples comparison.

Cheers,

Joe W. Walker, Jr. MS, SCT(ASCP)
Anatomical Pathology Manager
joewalker at rrmc.org, www.rrmc.org

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From: Terri Braud via Histonet <histonet at lists.utsouthwestern.edu>
Sent: Monday, October 28, 2019 10:14 AM
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Subject: Re: [Histonet] Cell block processing

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We collect our FNAs in CytoLyt.  We also use it to wash all our non-gyn fluids, but then we fix the cell block "pellet" in formalin.
We have had no problems with immunos, and are able to lyse the RBCs to provide a nice, clear specimen.
Hope this helps.

Terri L. Braud, HT(ASCP)
Anatomic Pathology Supervisor
Laboratory
Holy Redeemer Hospital
1648 Huntingdon Pike
Meadowbrook, PA 19046
ph: 215-938-3689
fax: 215-938-3874
Care, Comfort, and Heal



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