Which of the following is not part of the IHC panel for primary pancreatic adenocarcinoma?

• A. CA 19-9, CK7, CK20
• B. CK7, CK20, GATA3
• C. CA 19-9, CK7
• D. GATA3

Answer: (D)

In immunohistochemistry for pancreatic ductal adenocarcinoma, the panel relies on markers that reflect pancreatic lineage and help distinguish it from metastases. CK7 is commonly positive in pancreatic cancer, CK20 can be variable, and CA 19-9 is a marker frequently associated with pancreatic origin and can be detected in tissue as well as in serum. GATA3, on the other hand, is a transcription factor tied to other lineages—most notably breast and urothelial carcinomas—and is not used to identify pancreatic origin. Including GATA3 in a primary pancreatic IHC panel would not support confirming pancreatic adenocarcinoma, so it’s not part of the typical panel.