A 58-year-old man with clear cell renal cell carcinoma is found on routine testing to have a hemoglobin of 18.5 g/dL with a hematocrit of 55%. Serum erythropoietin level is elevated. Which paraneoplastic mechanism accounts for this finding?
- A Tumor secretion of intact erythropoietin by the neoplastic cells ✓
- B Cross-reactivity of tumor antigens with erythroid growth factor receptors
- C Compression of the renal parenchyma causing reactive EPO release from normal kidney
- D Ectopic secretion of androgenic steroids stimulating marrow erythropoiesis
Correct answer: A. Tumor secretion of intact erythropoietin by the neoplastic cells
Explanation
Polycythemia occurs in approximately 3 to 10% of renal cell carcinomas because the tumor cells themselves produce erythropoietin, one of the classic products of renal neoplasia. The same phenomenon can be seen with hepatocellular carcinoma, hemangioblastoma, and pheochromocytoma. Reactive EPO release from compressed normal kidney is not the accepted mechanism, and parathyroid hormone-related peptide causes hypercalcemia, not erythrocytosis, eliminating options C and D.
Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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