[Histonet] Histonet Digest, Vol 146, Issue 4 validation suggestions for short cycle processing with conventional equipment

[Steve McClain]

I posted our 7 year experience on this topic previously on histonet.
Remember, this machine (K3000, VIP5) was not designed specifically for this purpose, but it can be made to work admirably.  
IOW Short processing on VIP is unreliable UNLESS you are willing to accept or control certain conditions, 
1) only process well-fixed tissue 
2) take formalin off this processor, making 14 changes beginning in 50%. If you want to keep station 1 formalin and standardize fixation with time X in formalin at temp Y, that may work. I prefer to change the tissues to 50% alcohol at the grossing bench so that all tissues are not only fixed, but rinsed in alcohol and started processing at the growing bench. This simplifies processing to dehydration, clearing and paraffin infiltration.  Simple is reliable and short processing cycles on this machine leave little room for error.
2) Program heat to 50C in all alcohols and xylene. Mixing pressure and vacuum yes yes yes 
4) Keep all solutions fresh, rotate after 200- 400 blocks.
5) Lay blocks out not more than 2 cassettes back to back, max 100 for VIP5.
4 hour is reliable for tissues up to 3mm thickness such as punch biopsy. 
2 hour is reliable for up to 1.5 mm tissue thickness such as core biopsies and shave biopsies of skin.

Method of processor validation for short cycle in machine previously validated in your lab.

To validate create your evaluation form and find a set of cases with sufficient tissue small tissue to divide into 2 equal blocks. This can (and will) be done on clinical cases if you are careful. 
Print duplicate sets of cassettes. 
Mark one half of case 1 yellow and one half blue (tissues will be processed separately, 1 regular and one short cycle and then recombined into 1 final block at embedding).
We held the short processed tissue cassettes in formalin and timed the short cycle to end when the regular program ends.
Then the two blocks are recombined or embedded together so that direct comparisons/measures can be made on one H&E and one on your most common IHC for that tissue. If the H&E and IHC both work, chances are everything else will also.
Modify your regular validation form or Create a form for scoring shrinkage, measured thickness and length, staining reactions, shrinkage, holes and flaws, have your path score.   photo graph yellow and blue tissues under H&E and IHC. 
IF you do observe shrinkage or other undesirable artifact, be certain that your tissues are completely fixed at grossing and repeat.

If they are comparable in the oculars and to the camera, then show your work and voila, there is your validation. 

Steve A. McClain, MD

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