[Histonet] Extended time in paraffin

godsgalnow <@t> aol.com godsgalnow <@t> aol.com
Fri Feb 23 10:51:05 CST 2007

I vore for option number 2.
-----Original Message-----
From: RohrT <@t> nyackhospital.org
To: Histonet <@t> lists.utsouthwestern.edu
Sent: Fri, 23 Feb 2007 11:14 AM
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 

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 

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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