Re: [Histonet] Re: negative controls

>From the CAP checklist.....
In general, a separate negative reagent control should be run for each block of patient tissue being immunostained; however, for cases in which there is simultaneous staining of multiple blocks from the same specimen with the same antibody (e.g., cytokeratin staining of multiple axillary sentinel lymph nodes), performing a single negative control on one of the blocks may be sufficient provided that all such blocks are fixed and processed identically.? This exception does not apply to stains on different types of tissues or those using different antigen retrieval protocols or antibody detection systems.? The laboratory director must determine which cases will have only one negative reagent control, and this must be specified in the department's procedure manual

We interpret this to mean, since all of the blocks that we run IHC on are from the same specimen, the prostate, and they are getting the same IHC? antibody, PIN-4, we run one negative per patient and one positive per batch and one positive control used as a neagtive as well.


-----Original Message-----
From: Amos Brooks 
Sent: Mon, 17 Sep 2007 12:40 pm
Subject: Re: [Histonet] Re: negative controls


?? Is there any possibility that the multiple cores are from different parts of the prostate that may have metastasises from other places like kidney & liver?
?? Ultimately you can do this how you like. It is just important to know the limitations of your testing and be aware that this can bite you in the a$$ later on.

Just my $0.02

On 9/17/07,  wrote:

But what if all of the blocks are prostate core biopsies?

-----Original Message-----
From: Amos Brooks 

Sent: Sat, 15 Sep 2007 11:16 pm
Subject: [Histonet] Re: negative controls

     Let's say an endometriosis case has several parts as they commonly do.
A) Uterus bx (obviously), B) Ovary, C) Lg Colon bx, D) Kidney E) Liver Bx.
So an IHC is ordered on the case and randomly part A is chosen as a
representative negative control. Have you ever noticed how much endogenous
biotin is in kidney & liver? Since there is not a negative control on it
there is no real way of knowing that the labeling that one would see there
is not real.
     Honestly having a negative on each block is best, if not for eash test
being run (a tall order for sure!). Before polymer detection became popular
I once used kidney as a positive control for CD10. It labels the brush
boarder of the proximal convuluded tubule really nicely. Problem is that
this is also a great place to find endogenous biotin! This really sold me on
the use of negative controls. Thanks Mary!

Have a nice day,

Message: 1
Date: Fri, 14 Sep 2007 15:35:48 -0400
Subject: [Histonet] negative controls
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How many non-CAP labs out there are doing negative controls on every block
that you do an antibody on?

If you have a case that goes A-J and they are all 1 block each and you do an
AE1/AE3 on blocks B,C,F,& J, will you do a negative on every block or just
one for the entire case?

This has been an ongoing debate with us.? We typincally only do 1 negative
control for the case and given the above example, it might be on block A.?
We ususally cut an extra on every block we cut and when the IHC is requested
we just go and pull it and for the negative, we just grab whatever slide is
left to run the negative on.? What is everyone else doing??

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