A tumor that expresses carcinoembryonic antigen (CEA) and CA 19-9 is most consistent with a malignancy arising from which tissue?

• A Germ cell tissue (testicular tumor)
• B Gastrointestinal tract or pancreaticobiliary epithelium ✓
• C Thyroid C cells (parafollicular cells)
• D Liver parenchymal cells (hepatocytes)

Explanation

CEA (carcinoembryonic antigen) is an oncofetal adhesion molecule elevated in colorectal, gastric, pancreatic, and lung adenocarcinomas, used for monitoring recurrence rather than screening. CA 19-9 (sialyl-Lewis antigen) is most sensitive for pancreatic carcinoma and cholangiocarcinoma. Together, co-expression strongly suggests GI/pancreaticobiliary origin. AFP is the hepatocyte/germ cell marker. Calcitonin and CEA are markers of medullary thyroid carcinoma (not CA 19-9).

Reference: Robbins & Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.