What happens if you try to do a frozen section on tissue that's already been fixed in formalin (assume the formalin has penetrated thoroughly)? Are you able to cut the tissue? Does it freeze well? Can you read it?
Frozen section on formalin fixed tissue?
- Thread starter batboy
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I assume that you mean cutting formalin fixed tissue in a cryostat? If so, it looks and cuts like **** -- or at least it did the one time I tried. To find out, I did an excision of a small SCC on the forearm and read out the frozen section. We then thawed the tissue, placed it in a bottle, and cut it again two days later. Did not cut well, did not stain well, architecture all screwed up. Perhaps it was user error, I don't know.
I'll seen this twice. Once was a section of a fixed uterus that actually turned out ok. Another was a skin that was accidently immersed in a jar of formalin and then pulled out, dried off, and sent for frozen. Multiple levels would not stick to the slide and washed off in the staining baths.
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I've done it a time or three on autopsy specimens -- formalin fixed but, obviously, unprocessed. As I recall, each time was to try an Oil Red O on tissue. Actually had good pretty good results (architecturally & with the stain), but it seriously helps to use charged or coated slides (I -believe- all of ours were? Maybe just all the ones available by the cryostats. It's been a few years.) and dry the tissue well prior to embedding/freezing. I did it with brain and kidney at least, and possibly liver, but my memory fails. I can imagine skin being extra difficult.
Mind you, all I did was get the tissue on the slide, then gave it to the magic histotechs for staining. Both places I was at for any length doing surg path had at least one near omniscient histotech, who I would bounce questions like this off of with rude regularity.
Mind you, all I did was get the tissue on the slide, then gave it to the magic histotechs for staining. Both places I was at for any length doing surg path had at least one near omniscient histotech, who I would bounce questions like this off of with rude regularity.
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The only times I have ever tried it it wouldn't stick to the slide.
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A good trick for making it stick better to the slide (which was the main problem) is to expose the slide to heat for a while. Of coarse this will not help with getting fast results, but lets say you are grossing something and you wanna know if it is tumor or not. It worked pretty well for me on several occasions. Another thing, is to try the metachromatic stain of DQ. Just add several drops to the slide, leave it for a while and try gently to get rid of the remaining dye. This will minimize exposing the slide (with the not-well-sticking tissue) to multiple soulution, Of coarse the stain will be crapy but it might give you a helpful answer.
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Did it twice, the main reason being our PA telling me that it is absolutely_impossible to do. It worked fine both times.
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I think it depends on how long the tissue has been fixing in formalin.
I was able to do a frozen on a POC that was placed in formalin less than 5 min, but I was not able to get the tissue to stick for some GI biopsies that have been in formalin for many days (was trying to help out a researcher).
In order to do a frozen, I think the tissue has to retain some of its moisture. I remember not being able to freeze an ENT biopsy because it had been sitting on a piece of gauze in the OR. They were waiting to have a batch before they brought it over, & it had gotten too dry in the meantime.
If someone brings over a specimen in formalin, I usually tell the surgeon that we can't freeze it. Either they can send another specimen, or they can just wait for the permanent section. Just let them know that histology will be better w/ permanents, & you can tell them the result the next day.
----- Antony
I was able to do a frozen on a POC that was placed in formalin less than 5 min, but I was not able to get the tissue to stick for some GI biopsies that have been in formalin for many days (was trying to help out a researcher).
In order to do a frozen, I think the tissue has to retain some of its moisture. I remember not being able to freeze an ENT biopsy because it had been sitting on a piece of gauze in the OR. They were waiting to have a batch before they brought it over, & it had gotten too dry in the meantime.
If someone brings over a specimen in formalin, I usually tell the surgeon that we can't freeze it. Either they can send another specimen, or they can just wait for the permanent section. Just let them know that histology will be better w/ permanents, & you can tell them the result the next day.
----- Antony
I did this once on a weekend while on call. An ORL resident called and said he was concerned a node excised from the neck may be lymphoma. This was after the fact and the specimen had been placed in formalin. For my own interest I cut a frozen. The quality wasn't perfect but it was good enough to recognize the tumor was epithelial. Of course, I told him he would have to wait for the signed out permanents and told him i'd put it in the front of the stack.
D
deleted314957
And SUGGEST to him that it may be worthwhile to submit his nodes FRESH, particularly if he is concerned about lymphoma. Just another shining example why our clinical colleagues need more path exposure.
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what actually happens is the formalin is part water...thus the tissue contains more water than it had when not fixed...freeze and ice crystals form..and you get crappy sections...as well as the firmness of the tissue from the formalin....as well as the tissue not adhering to slides, whcih we tried to cope with by using coated slides.
in my prior positions if physicians wanted frozens on tissues put in formalin more than hour before receipt in our lab..we said NO and NO exceptions.
If they popped it in by mistake, took it out, and got it down to us right away..we would try...but never for small biopsies( needles...)too late even if down to us in 10 minutes...it penetrates that quickly
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Yes, you can do this and your slides should look quite similar to fresh (ie non-snap frozen) tissue.
