Just a thought - could it be endogenous biotin? Do you do antigen retrieval
for this stain? Even on my breast panels, I see cytoplasmic staining if I
don't treat with biotin blockers. I think it is because we do a pretty hefty
retrieval. It appears granular. It looks like positive staining. Liver is
supposed to have much more biotin than breast? 
Marg


-----Original Message-----
From: Patti Loykasek [mailto:ploykasek@phenopath.com]
Sent: Friday, March 23, 2001 8:20 AM
To: histonet
Subject: Re: Unusual staining pattern with TTF


on 3/22/01 3:51 PM, Tom Wells at tomers@home.com wrote:

> We recently came across a case that stained strongly positive with Dako
TTF,
> but, instead of the usual nuclear staining the staining was cytoplasmic
and
> granular.  Has anyone else seen this staining pattern?  We have performed
> numerous TTF stains before and since and have not come across this before.
> Thanks. Tom
> 
> Tom Wells, BSc, ART
> Supervisor, Immunohistochemistry Laboratory
> Lions Gate Hospital
> North Vancouver, BC
> Canada
> 
> 
We have seen this type of granular, cytoplasmic staining with TTF in liver
tissue. Other techs I have talked with have observed this staining pattern,
too. Is the tissue in question liver? I would be interested to know if it is
something else, and add it to my list of artifacts.

Patti Loykasek, HTL, IHC sp
Phenopath Laboratories
Seattle, WA