Matthew,

In cases like this, we run the combination of Cytokeratin 7 and cytokeratin
20.
If CK20 is positive, that would be a strong indicator that the primary is
colonic.
CK20 is strongly expressed by colonic enterocytes, the degree of expression
becoming increasingly restricted to surface cells higher up the bowel. CK20
expression may be found in the ampulla of vater, but not higher up the
common bile duct, with no expression in the biliary tree. CK20 may also be
positive in Merkel cell tumours, transitional cell tumours and a percentage
of ovarian tumours.
CK7 is strongly expressed by biliary epithelium, not at all by normal
hepatocytes and delineates the biliary tree beautifully. CK7 expression may
be found in damaged or developing hepatocytes and is a terrific marker for
Mallory bodies. The expression of CK7 is strong in small bowel but
diminishes lower down the GI tract to the point that in colon, very little
expression is found.
However, some caution should be used in interpretation of IHC expression
patterns. One should always bear in mind, that tumours may express "whatever
their little hearts desire"!

Regards,

Bryan

Bryan R. Hewlett
Technical Specialist
Anatomical Pathology
Hamilton Regional Laboratory Medicine Program
Ontario, Canada

----- Original Message -----
From: 
To: 
Sent: Monday, June 17, 2002 3:21 PM
Subject: Antibodies


>
>
> Does anyone know how I can differentiate colonic epithelial cells from
biliary
> epithelial cells. I have a neoplasm occuring in the colon and liver.  I am
> trying to decide if it is  the same tumor or two different ones.  Are
there any
> antibodies out their to use  with immunohistochemistry.
>
>
> Thanks,
>
> Matthew Starost
> MD Anderson Cancer Center
>
>
>
>
>
>