In a case of suspected liver metastasis from a colon primary with multiple hepatic lesions, which IHC profile would be expected?

• A. CA19-9-, CEA+
• B. CK7+, CK20-
• C. CD34-, PAX8+
• D. Claudin18.2+, CK20-

Answer: (A)

Understanding how immunohistochemistry reveals the tissue of origin is key here. Colorectal adenocarcinoma that has spread to the liver typically shows a profile with CEA expression, reflecting its intestinal origin, while CA19-9 tends to be less reliable for colon cancer and is more often elevated in pancreaticobiliary tumors.

So, a pattern with CEA positivity and CA19-9 negativity fits a colon primary metastasis best. The other profiles would suggest different origins (for example, CK7+/CK20− is less typical for colorectal cancer, PAX8 positivity points toward renal or Müllerian tumors, and CK20 negativity would argue against a colorectal source).