[Histonet] Histonet Digest, Vol 170, Issue 13 histology hacks

[Steve McClain]

I purchased the book and applaud the effort because there is some decent information.  However, the term hack is a poor choice for histology and many of the fixes or secrets described are because some hack failed to do her/his job at an earlier step in the process. (Definition of hack. transitive verb. 1 a : to cut or sever with repeated irregular or unskillful blows. b : to cut or shape by or as if by crude or ruthless strokes. As a noun it is used to mean a mediocre performer or worker; tiresome drudge.)

Some methods, while useful in some settings, have important cons not listed, cons which may be counterproductive. For example using Mercurochrome or Eosin to mark tissue may preclude further testing with fluorescent endpoints, such as FISH.  Plus if you really want to use Eosin to mark the dermis, it is far easier to add used Eosin to one alcohol in the tissue processor. That gives a visible indicator of carryover, indicating need to change or rotate solutions.

Other methods seem (to me) like workarounds or Band-Aids for Labs w poor grossing, poor processing or poor reagents or poor technique or poor method choices, eg, 2.14 describes a situation where an incompetent grosser truly hacks or crudely cuts into unfixed tissue yielding too thick a slice. The real solution is to fix the tissue before slicing. Poor fixation results in poor processing and poor sectioning and poor staining reactions.

For another example, Cassette sponges offer few advantages, while folding lens paper allows the grossers to see through the paper and know all pieces are inside before closing the cassette lid.  The tissue does not stick to it, and small flakes can be scraped from the lens paper at embedding. Last during folding, the forceps can be cleaned at grossing and during unfolding, forceps may be cleaned w the paper after embedding.  Sponges also result in greater solution carryover.

Several colloquial naming conventions, eg, chamber saver 2.16 for underprocessed tissue may be memorable to some readers, yet seem  are odd to me.

This 2.16 method is an especially useful technique which may also be done to extend paraffin time, whenever poor sectioning due to poor processing is encountered at the microtome.
Variation 1 Place the block back into the proper sized mold and return to the heated side of the embedding center for an hour to extend processing (reprocessing). Then remove the old paraffin from the mold w a plastic pipette,  then re-embed, replacing the paraffin w new.
Variation 2 for outside blocks we routinely replace an unknown paraffin from another lab by melting in a mold, and ‘reprocess’ in our (blue ribbon) paraffin for 1 hr in a mold in the embedding center then re-embed.

Good first effort, yet this book could be improved by a good editor, by more collaborators, by illustrations, and the addition of variations or other uses as described above for 2.16.
The font size and format will cause many readers to suffer because of the small font.

Steve
Steve A. McClain, MD