[Histonet] IHC Question...

[Bauer, Karen]

Hi to all. 
 
I recently stained a lymph node case and it has brought up an interesting question that I can't explain to our Pathologist.  I'm hoping that someone out there can give me some suggestions.  First of all, a little background...
 
The lymph node was processed, by accident, on a "fast run" on our VIP Tissue Tek.  The processing run was complete in about 3 and a half hours.  (We thought there were just small biopsies on the run, but the lymph node cassette was probably thrown in the wrong basket by mistake.)  Anyway, the lymph node tissue didn't turn out all that bad, but the fatty tissue did not process adequately (no surprise there!!).  Since the lymph node tissue cut fairly well, the block was not run back and re-processed.  H&E's were turned in and stains were ordered.  
 
Here's my problem:  The CD3 and CD20 stained well and the lymph node tissue and controls looked as they should, but the LCA on the patient tissue did not stain at all.  We put the patient tissue on a control slide, so the control and tissue are stained the same all the way through the run.  The LCA control looked beautiful, but the lymph node tissue had no staining.  How can you have positive staining for CD3 and CD20, but no staining for LCA on a lymph node?  
 
Since we use a tonsil for our control, we re-ran the LCA with the tonsil control, a different lymph node case and then the same lymph node case that we were staining.  Again, the control looked great, but the lymph node did not stain again.  The different lymph node case that was also run turned out just fine, so we knew it was tissue specific.  We thought maybe this lack of staining was due to the insufficient processing, but then why did the CD3 and CD20 turn out so well?  Shouldn't they have no staining also?
 
I'm perplexed and was wondering if anyone else out there has had this happen to them.
 
As always, thank you.
 
Karen Bauer HT(ASCP)
Histology Supervisor
Luther Hospital
Eau Claire, WI
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