[Histonet] Fixation for Her-2/neu -Where's the Beef???

[Tony Henwood]

Some comments:

Underfixed tissue retrieve poorly (looks like a bomb has hit the
section). Overfixed tissues may require extended antigen retrieval,
though usually not.

It seems that there is no allowance for thickness of tissue nor the
vagaries of tissue constituency. Too thick, then the fixation may be
equated with an underfixed specimen. Too much connective tissue (eg
fibrosis) may impede fixation giving an under-fixed specimen.

Hope you all had a good weekend

Regards

Tony Henwood JP, MSc, BAppSc, GradDipSysAnalys, CT(ASC)
Laboratory Manager & Senior Scientist
The Children's Hospital at Westmead,
Locked Bag 4001, Westmead, 2145, AUSTRALIA.
Tel: 612 9845 3306
Fax: 612 9845 3318




-----Original Message-----
From: histonet-bounces <@t> lists.utsouthwestern.edu
[mailto:histonet-bounces <@t> lists.utsouthwestern.edu] On Behalf Of Jasper,
Thomas G.
Sent: Saturday, 16 June 2007 6:32 AM
To: Lott, Robert
Cc: histonet <@t> lists.utsouthwestern.edu
Subject: RE: [Histonet] Fixation for Her-2/neu -Where's the Beef???


Hey Robert,

I've been informed from our pathologists that over-fixation of breast
tissue (more than 48 hours) will potentially mask Her2 staining.  This
in turn impacts our FISH staining, as cases for FISH are selected based
on Her2 results.  The fear then, is that cases which should've reflexed
to FISH will not.  The over-fixation could result in under-expression of
Her2 run cases.  Sounds a bit contradictory but that's how I understand
it.  I do have to agree with you, my concern would be under-fixation vs.
over-fixation.  But, I guess under-fixation is more readily apparent and
easier to address than over-fixation.  This will be a new thing for
everybody and we're looking at a new mandatory week-end shift because of
it (oh joy).  Anyway, this is what I've been told and how I understand
it, good luck down there in Bama.

Tom Jasper HT (ASCP) BAS
SMDC 
Duluth, MN


-----Original Message-----
From: histonet-bounces <@t> lists.utsouthwestern.edu
[mailto:histonet-bounces <@t> lists.utsouthwestern.edu]On Behalf Of Lott,
Robert
Sent: Friday, June 15, 2007 11:37 AM
To: histonet <@t> lists.utsouthwestern.edu
Subject: [Histonet] Fixation for Her-2/neu -Where's the Beef???


Hello Everyone,

.....been a lot of talk about this already, I'm aware of that.  Now I
want to know if there is any "real" scientific" basis for the new CAP
guideline for Her-2 IHC fixation that states "No less than 6 hrs. and no
more than 48 hrs. in aqueous NFB."  Any documented, peer-reviewed,
published data???

 

My sense is that this guideline really does represent best practice.
Most of us do well to get our breast specimens fixed for 6 hrs. in NBF!!

 

However, is there really some difference in performance of the Her-2 IHC
assay if a breast case is fixed for 48 hrs vs. one fixed for 54 hrs. or
72 hrs. (i.e. weekend/ holiday scenario).  UNDER-fixation would seem to
be so much more of issue than OVER-fixation.

It's this top end that bothers me so much!!!  

 

I am not aware of real data to support this new guideline!  Does anyone
out there know anything different?????

 

Robert

 

Robert L. Lott, HTL(ASCP)

Manager, Anatomic Pathology

LabFirst / Trinity Medical Center - formerly

Montclair Baptist Medical Center

800 Montclair Road

Birmingham, AL   35213

205-592-5388  phone

205-592-5646  fax

robert.lott <@t> triadhospitals.com

 


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