[Histonet] IHC controls for Cytology

Kirbis Srebotnik Irena IKirbis <@t> onko-i.si
Thu Dec 15 03:32:14 CST 2005

I agree with Glen, that control slide should be processed in the same manner as the test slide and this should be a basic rule especially for cytology samples. It's not an easy job to adopt, introduce and organize immuno for cytology samples giving consistent, interpretable and reliable results but it can be done and it is worth to do it.
in average for last 10 yrs, we have 3000 immuno reactions per year, 40-60% are QA/QC reactions (positive, negative controls, testings for new markers...) 
majority of reactions were performed on cytospins prepared from FNAB and effusions, we use home made cell medium for this purpose which allows short term storage of this samples, this cell suspensions can be also used for other diagnostic methods - flow cytometry immunophenotyping,immunocytochemistry, DNA measurements...
control slides are prepared in the same way as diagnostic samples from highly cellular diagnostic FNAB samples, effusions, cell cultures, FNAB of resected tumors. 
immunocytochemistry is done on:
- Papanicolaou stained cytospin without destaining - cytoplasmic antigens, not for nuclear and membrane antigens (very convenient for long term storage of positive controls)
 - cytospins immediately fixed and stored in methanol (up to 1 month) for all antigens including Ki67, TTF, ER, CD's (not possible to prepare positive controls for long term storage for all antigens!)
best regards
Irena Srebotnik Kirbis, MSc
Institute of Oncology
Dept. of Cytopathology
Zaloska 2
1000 Ljubljana
phone +386 15879 705
fax +38615879400

-----Original Message-----
From: histonet-bounces <@t> lists.utsouthwestern.edu [mailto:histonet-bounces <@t> lists.utsouthwestern.edu]On Behalf Of Dawson, Glen
Sent: Wednesday, December 14, 2005 7:26 PM
To: histonet <@t> lists.utsouthwestern.edu
Subject: RE: [Histonet] IHC controls for Cytology

FFPE tissue sections are not appropriate controls for smears.  Kemlo is
correct, the control tissue/slide must be processed/stained exactly like the
test slide in order for it to be valid.  I do IHC on smears/PAPs
occasionally when absolutely nothing else is available, but I am sure to
tell the ordering pathologist that I do not have an appropriate control to

I routinely do a rapid melanoma procedure on smears so I have a bank of
known positive melanoma smears in my freezer, but that is the only one.  

It is unrealistic to believe that an IHC lab could have appropriate controls
for any situaion that may come up, but I can also see how a pathologist
needs to use whatever is available in an emergency situation.  I believe
that many of them will gleen what they can from these smears but not put
them in their report since an appropriate control is not available.  Then,
as with so many other situations, the IHC lab takes one for the team when it
comes time to bill.

Interesting thread,

Glen Dawson
IHC Manager
Milwaukee, WI

-----Original Message-----
From: Rogerson Kemlo (ELHT) Pathology
[mailto:Kemlo.Rogerson <@t> elht.nhs.uk]
Sent: Wednesday, December 14, 2005 9:14 AM
To: Orr, Rebecca; histonet <@t> lists.utsouthwestern.edu
Subject: RE: [Histonet] IHC controls for Cytology

Aren't controls supposed to be treated exactly the same as the test? So
unless you treat them exactly the same you will never know if you have a
false negative and I'm not bright enough to know if you could have false
positives too.

Hi everyone,

We have very recently begun to destain pap stained smears as  well as
unstained  cytology smears,  and run IHC.

Because my Docs are happy with the results, I anticipate receiving more
of these types of smears to run.

I only  have FFPE tissue in stock to use as control, so I give them the
slides with the disclaimer that the control has been treated differently
than the smear.

This seems to be acceptable as long as they can detect some positive
stained cells (TTF, PanCk, WT-1  Mart-1 for example). But if the smear
is negative, how can I be sure it's a true negative?  My antibodies
aren't really titered for  smears....

I would appreciate some comments from anyone who is running a
standardized protocol for smears. Do you have a set of smears you can
use as controls?  I have access to our molecular lab and there is
potential to make my own cell cultured controls,  what do you think?


Many thanks,



Becky Orr CLA,HT(ASCP)

IHC Lead 

Evanston Northwestern Healthcare



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