Richard Cartun replies to Shannon Klassen:

>>Dr. Allen Gown's high molecular weight cytokeratin monoclonal antibody 
(clone 34BetaE12) which is now available through DAKO Corporation (M0630). I 
believe the "903" is the catalog number used by Enzo Diagnostics for this 
antibody.<<

For the working general surgical pathologist, this is probably the most 
frequently useful immunostain out there. It stains the basal cells of 
prostatic glands very strongly. Since the malignant glands of prostatic 
adenocarcinoma lack basal cells, the absence of staining is strong evidence 
that small groups of suspicious glands are in fact malignant. It's a 
blunt-edged weapon in the hands of a duffer, but when used by an experienced 
pathologist it's about as close to "a special stain for cancer" as you're 
going to see. 

An experienced prostate pathologist may use it on 5% of prostate biopsy 
specimens, and call at least half those cases cancer. A less experienced 
pathologist might go 10%, with proportionately fewer calls of cancer. The 
stain is useful enough that it dictates cutting extra slides on every 
prostate biopsy, since recutting often loses the small focus I'm looking for.

Bob Richmond
Samurai Pathologist
Knoxville TN