Re: Paraffin temp for immuno's
From: | Vinnie Della Speranza |
Ross,
since the # of cases with atypical staining is very small, I recommend that
you consider sending duplicate sections from those cases out to a reference lab
for staining with the same markers.
Yes, this is expensive and I don't necessarily endorse doing this all of
the time
HOWEVER,
it the reference lab gets results similar to yours, the pathologists may
develop more confidence in your work.
if the reference labs' slides turn out better, you get on the phone and
find out what they are doing differently, placing you that much further along to
resolving any potential problems in your shop.
Vinnie Della Speranza
Manager for Anatomic Pathology Services
Medical
University of South Carolina
165 Ashley Avenue Suite 309
Charleston,
SC 29425
Ph: 843-792-6353
fax: 843-792-8974
>>> Ross Stapf
<rstapf@adventisthealthcare.com> 10/17/02 12:05PM >>>
Thank
you to those who have replied so far.
The reason for this post is
that in the troubleshooting section of Dabbs' Diagnostic Immunohistochemistry it
mentions that if the control stains positive and a patient who is expected to
stain positive does not stain positive, then one of the possibilities is that
the paraffin is over 56 degrees.
While this is not very common, we do
about 100 immuno's a day and we have 1 or 2 cases like this every month that the
Pathologists have us repeat the stains over and over on with no luck.
While most are content that this is just a freak thing with certain patients,
they are not content in less everything works like they think it should
work.
I know that our main immuno pathologist will eventually see this
comment in this book and I want to get more information prior to getting
pressured from him. Lately perfecting every detail of Immuno quality has
been a big push.
Ross Stapf
Histology Supervisor
Washington
Adventist Hospital
>>> "Vinnie Della Speranza"
<dellav@musc.edu> 10/17/02 11:12AM >>>
Ross,
it is always
dangerous to generalize especially because we use ihc to
stain for a wide
variety of cellular and tissue antigens and something
is always likely to be
the exception however I'm going to risk it.
The rule of thumb is to try
to prevent overheating of tissues during
exposure to processing chemicals.
There are certainly proponents of low
metling point paraffins but we have a
very successful
immunohistochemistry laboratory that routinely utilizes a 58
degrees
metling point paraffin. I do not recommend that you change paraffin
to
resolve your quality issues as I personally don't believe that this
is
likely to make the difference. Lastly I would add that in my opinion,
if
your tissues are well fixed, most if not all antigens will
survive
exposure to 60 degrees. Its interesting to note that we
frequently
expose tissues to very high heat (90-100 degrees C) to achieve
epitope
retrieval which seems to contradict this notion that temperatures
must
be kept as low as possible.
Vinnie Della
Speranza
Manager for Anatomic Pathology Services
Medical University of
South Carolina
165 Ashley Avenue Suite 309
Charleston, SC
29425
Ph: 843-792-6353
fax: 843-792-8974
>>> Ross Stapf
<rstapf@adventisthealthcare.com> 10/16/02 04:04PM >>>
Hi
everyone:
I was reading through Diagnostic Immunohistochemistry by Dabbs
and came
across a comment that paraffin temperatures should not exceed 56
degrees
when doing immuno's on the tissue later.
We have been trying
to standardize our methods for optimal immuno
results. We have the
occasional case where the staining is not as
expected. We are trying to
eliminate as many of these problems as
possible. Is the paraffin temp
really that important? I am beginning
to wonder if this is one of the
reasons for those cases that should, but
just don't stain positive.
We have been using Paraplast and Paraplast xtra for over 10 years
at
60 degrees. If I do experiment with a paraffin with a lower
melting
point, what can I expect? Will my techs have a harder time
cutting the
blocks? Will I need to increase my infiltration
times?
Turn around time is very important, I don't want techs complaining
that
they can't get good routine sections just to possibly fix an
immuno
variable. Also from my research so far the lower melting point
paraffin
is more expensive.
Basically has anybody made a change in
paraffin for this reason, and
was it worth it?
Ross Stapf
Histology
Supervisor
Washington Adventist Hospital
Takoma Park
MD
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