[Histonet] Cytology (Special stains & IHC)

[Beth Cox]

Hi Karen,

The best resource for Cyto questions would probably be a recent edition 
of the Carson Histotechnology book.  The Fourth edition has some info on 
special stains for Cyto, but the new Fifth edition is expanded on that 
topic and has more info on IHCs for Cyto (Chapter 17).

For _special stains_, you would definitely want them fixed in 95% 
alcohol.  The only exception to that would be fat stains which would of 
course require air-dried slides.  It would likely be advantageous to use 
charged slides, but that is not required. Remember when special staining 
Cyto slides fixed in 95% alcohol, that the deparaffinization steps at 
the beginning of the procedure must be skipped.  You are normally okay 
with using regular FFPE controls with your Cytospins or ThinPrep special 
stains.

Doing _IHCs_ on Cytology preps (Cytospin or ThinPrep) gets a little 
trickier. _IF_ you are going to do them, you would want them to be 95% 
alcohol fixed and on charged slides.  However, you would be required to 
do a validation for Cytology for any/all antibodies you were going to 
run.  (Your CAP or CLIA inspector will eat you alive if you don't!).  
Alcohol fixed specimens will require a new optimization since the 
pretreatments will be different than those for FFPE.   Many antibodies, 
particularly nuclear ones, may be difficult or impossible to stain on 
the intact cells in a Cyto prep.

Also, you would not be able to use FFPE controls for Cyto IHC since they 
are 'fixed and processed differently" than the Cyto slide and therefor 
don't properly control the process.  AND, alcohol fixed smears begin to 
lose their antigenicity in about 24 hours, so they must be stained the 
same day the slides are made, so having a control bank of alcohol fixed 
slides isn't feasible.

Doing IHC on Cyto smears using FFPE protocols and FFPE controls is very 
likely to give you false negative results.  Unless you are doing large 
volume Cyto, it is very strongly recommended that you do your IHCs for 
Cyto on the FFPE cell block.

Beth Cox, HTL/SCT(ASCP)QIHC

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Message: 5
Date: Wed, 5 Aug 2020 15:34:28 +0000
From: "Heckford, Karen - SMMC-SF"<Karen.Heckford at DignityHealth.org>
To:"histonet at lists.utsouthwestern.edu"
	<histonet at lists.utsouthwestern.edu>
Subject: [Histonet] Cytology
Message-ID:<903be99abb344593a73079761d76299b at PHX-EXCH-013.chw.edu>
Content-Type: text/plain; charset="us-ascii"

Good Morning,
I rarely do Special stains or IHC's on Cytology cytospins or thin prep type slides.    Should these slides be charged, air dried or fixed in 95% alcohol before doing Special stains or IHC's on them?

Is there a good book or some sort of publication on cytology procedures regarding the above mentioned.   I have tried and look it up and it seems all over the place on what to do.

Any help would be greatly appreciated,

Karen Heckford HT ASCP CE
Lead Histology Technician
St. Mary's Medical Center
450 Stanyan St.
San Francisco, Ca. 94117
415-668-1000 ext. 6167
karen.heckford at dignityhealth.org<mailto:karen.heckford at dignityhealth.org>