Tom,
  Rich Cartun had asked me a long time ago if we had ever seen TTF-1
positivity on hepatocytes.  At the time, I think our answer was no, but more
recently we have seen a couple examples of that.  Then we did a limited
study and found TTF-1 showing a granular, cytoplasmic positivity on
hepatocytes with a pretty high degree of regularity.  We even had a few
cases of metastatic hepatocellular carcinoma that also showed the same
artifact.  The staining pattern looks just like HepPar1.  I know that Rich
Cartun had also seen this same TTF-1 "artifact", in fact, he presented an
abstract on it at the recent USCAP meeting.
    I would be curious to know if your case is marking as a hepatocellular
carcinoma?  Keep us informed.

Best of luck,

Phyllis Davie
PhenoPath Laboratories--Seattle, WA
pdavie@phenopath.com



> From: Tom Wells <tomers@home.com>
> Date: Fri, 23 Mar 2001 15:58:00 -0800
> To: "'histonet'" <histonet@pathology.swmed.edu>
> Subject: Re:unusual staining pattern with TTF
> 
> The Tissue was a solitary nodule found on an elderly man's arm. It  looked
> malignant. I don't think that it was endogenous biotin because the negative
> controls were negative.  I also don't think that it was contamination in the
> primary, because we did other tissues with that antibody and they all worked
> out fine. We do antigen retrieval for TTF, but, we also do it for many other
> ab's and they were all OK. Thanks Tom.
> 
> Tom Wells, BSc, ART
> Supervisor, Immunohistochemistry Laboratory
> Lions Gate Hospital
> North Vancouver, BC
> Canada
> 
>