Even so. Remember that with the negative control you are trying to characterize any background or "suspicious" reaction as just background noise.
Again, the positive control, no matter how many slides or cases, could be just one because with it you want to demonstrate that the procedure worked.
I realize that in cases with many chips or needle prostate biopsies, there are too many slides to deal with.
This is decision that is not yours to make. Ask you pathologist or medical director, present him/her with the problem and explain that IF there were to be just 1 negative, any reaction in one section had to be interpreted on both structural and reactivity characteristics.
IF s/he accepts that argument, that is his/her decision.
René J.
godsgalnow@aol.com wrote:
But what if all of the blocks are prostate core biopsies?
Roxanne
-----Original Message-----
From: Amos Brooks
To: histonet@lists.utsouthwestern.edu
Sent: Sat, 15 Sep 2007 11:16 pm
Subject: [Histonet] Re: negative controls
Hypothetically:
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,
Amos
Message: 1
Date: Fri, 14 Sep 2007 15:35:48 -0400
From: godsgalnow@aol.com
Subject: [Histonet] negative controls
To: histonet@lists.utsouthwestern.edu
Message-ID: <8C9C51D962FF31B-284-1FE4@webmail-md17.sysops.aol.com>
Content-Type: text/plain; charset="us-ascii"
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??
Roxanne
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