[Histonet] mishap with Carnoy's fixative

Robert Richmond rsrichmond <@t> gmail.com
Fri Dec 25 22:40:26 CST 2009

I recently had a mishap with Carnoy's fixative that bears retelling on Histonet.

I was preparing a colon cancer resection specimen - in a pathology
service I've just started doing some work for - and needed a
disclosing fixative for the mesenteric lymph nodes. What they had was
Carnoy's fixative (6 parts alcohol, 3 parts chloroform, 1 part glacial
acetic acid - I checked the MSDS and the chloroform was actually

This was one of those labs that isn't allowed to have extra specimen
containers on hand (a rather common problem in my experience - I think
it's Good Management), so I was offered a plastic mammographic
specimen container that happened to be lying around. I cut up the
mesenteries into small pieces - no obviously positive lymph nodes -
and left them in the Carnoy's fixative in the specimen container.

The next day the plastic container had dissolved into a gooey mess
that was intimately mixed with the fatty mesentery. It took two of us
an hour to pick the stuff out. The lymph nodes were easy to find,
though how the blocks will cut I don't know.

The goo was somewhat soluble in xylene, so we used that. With
inadequate ventilation, I stood there in a cramped position breathing
in chloroform and xylene while I retrieved the lymph nodes.

Chloroform has serious toxic problems and has no place in a hospital
histology lab. If you have to use Carnoy's fixative, be very careful
what you put it in.

Bob Richmond
Samurai Pathologist
Knoxville TN

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