A 55-year-old man with a renal cell carcinoma develops erythrocytosis. Ectopic production of which cytokine by the tumor is responsible?

• A Thrombopoietin
• B Erythropoietin (EPO) ✓
• C G-CSF
• D IL-6

Explanation

Clear cell renal cell carcinoma frequently harbors VHL gene loss, which leads to HIF-1α stabilization; HIF-1α drives transcription of EPO, causing ectopic erythropoietin secretion and paraneoplastic polycythemia. This is distinct from primary polycythemia vera (JAK2 mutation). Thrombopoietin and G-CSF cause paraneoplastic thrombocytosis and leukocytosis, respectively, not erythrocytosis. IL-6 is implicated in Castleman disease-associated erythrocytosis but is not the primary mechanism in RCC.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.