[Histonet] Extended time in paraffin

Lester Raff LRaff <@t> lab.uropartners.com
Fri Feb 23 10:33:52 CST 2007

We were  not happy with our results (fragments were drying out) when
tissue sat in formalin in our VIP processor over the weekend, so now we
run our weekend cases (all small biopsies) on Friday afternoon, and then
follow your option #2.  It works well for us.

Lester J. Raff, MD
Medical Director
UroPartners, LLC Laboratory

2225 Enterprise Dr. Suite 2511

Westchester, IL 60154

ph:  708-486-0076
fax: 708-486-0080
-----Original Message-----
From: histonet-bounces <@t> lists.utsouthwestern.edu
[mailto:histonet-bounces <@t> lists.utsouthwestern.edu] On Behalf Of Theresa
Sent: Friday, February 23, 2007 10:15 AM
To: Histonet <@t> lists.utsouthwestern.edu
Subject: [Histonet] Extended time in paraffin

I have a problem with processing breast tissue over a weekend. Breast
tissue is run in a separate processor from our Sugical and endo
specimens. We do not have weekend staff. We usually run a two day delay
with the processing starting Sunday night and both processors ending
early Monday AM. 

The current guidelines suggest this delay of breast tissue sitting in
formalin could result in over fixed breast tissue.  The pathologists
want to end the cycle on Saturday but we have no staff here to remove
and/or embed the tissue. The pathologists themselves would have to
remove the cassettes from the paraffin!

The questions are what can they do with these cassettes? Again, the
tissue is breast tissue, mainly cores or target blocks or tumor that may
need IHC and/or FISH on diagnosis

1.  Can they just leave the cassettes on the processor in warm paraffin
(60 degrees) from Saturday until Monday?
2.  Can they remove them from the paraffin and let them harden at room
temperature and then be heated, melted and properly embedded on Monday?
3.  Can they put the cassettes in a container of warm paraffin "to
cover" and then let the whole container solidify and on Monday Histo
melts the container, removes the cassettes and embeds?

 I have only found two clear commentaries.
 Sheehan and Hrapchak who say extended time in paraffin will cause
shrinkage and hardening. There is also a reference in Carson, saying
tissue should remain in paraffin the shortest time necessary for good
infiltration as prolonged heat causes shrinkage and hardening. 

Can any of you offer me any further references and/or assistance or your
own methods/experiences? 

Thank you so much for your time and assistance
Theresa Rohr
Nyack Hospital, NY
rohrt <@t> nyackhospital.org

Theresa Rohr, BA, HT(ASCP)
Section Head, Histology
Nyack Hospital
160 North Midland Avenue
Nyack, New York 10960
phone 845-348-2276
fax 845-348-8430

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