The metastatic glands are moderately differentiated. The possibilities for a primary tumor include GI tract, pancreatobiliary and lung. CDX2 is a marker for gastrointestinal differentiation and was positive. The CK7- and CK20+ immunoprofile favors a lower GI origin and less likely a pancreatobiliary origin (which would be CK7+ and CK20-). Of note, but not shown TTF-1 was negative, thus, a lung adenocarcinoma is less likely.
Colon : Adenocarcinoma, Conventional Type