A 55-year-old male with hepatocellular carcinoma has serum AFP of 850 ng/mL. AFP is elevated because it is:
- A A fetal oncoprotein re-expressed due to tumour dedifferentiation toward fetal hepatocyte phenotype ✓
- B A mutant form of albumin produced by malignant hepatocytes
- C A cleavage product of albumin in the setting of hepatic synthetic failure
- D Produced by infiltrating inflammatory cells in tumour stroma
Correct answer: A. A fetal oncoprotein re-expressed due to tumour dedifferentiation toward fetal hepatocyte phenotype
Explanation
AFP (alpha-fetoprotein) is the major serum protein of the fetal liver and yolk sac, normally suppressed after birth. In HCC, tumour cells undergo de-differentiation reverting to a fetal gene expression programme, re-expressing AFP. The oncofetal protein AFP is also elevated in yolk sac tumours and hepatoblastoma. AFP is not a mutant albumin nor a cleavage product. Inflammatory stromal cells do not produce AFP. AFP levels >400 ng/mL in the appropriate clinical context (cirrhosis, hepatic mass) are virtually diagnostic of HCC without biopsy.
Reference: Harper's Illustrated Biochemistry, 32nd ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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