[Histonet] IHC neg. controls (Friday rant)

Patti Loykasek ploykasek <@t> phenopath.com
Fri Jun 6 15:01:03 CDT 2008

Can someone rationalize to me the practice of running a negative control for
every  antibody in an IHC workup? For example, six antibodies & six negative
controls??? This makes me crazy. Just had a case, needle biopsy, where this
occurred at an outside institution, and now we don¹t have enough tumor left
to run more IHC & get a diagnosis. It borders on malpractice IMO.

On the AP CAP checklist ANP.2270 Are appropriate negative controls used? The
comment has the following (near the end):

A negative tissue control must be processed for each antibody in a given
run.  Any of the following can serve as a negative tissue control:
1.             Multitissue blocks.  These can provide simultaneous positive
and negative tissue controls, and are considered ³best practice²
2.             The positive control slide or patient test slides, if these
slides contain tissue elements that should not react with the antibody.
3.             A separate negative tissue control slide.

I think it best to asses this negative tissue control on your positive
controls that should contain negative elements. Plus, use known negative
elements on the patient slides. The patient tissue is precious & these
patients have undergone procedures that have associated morbidity. I can¹t
see using up patient tissue for multiple negative controls & Having the
patient have to undergo another procedure!
Ok ­ I¹ll stop now.

Patti Loykasek

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