A 70 year old male known case of a certain malignancy presents with elevated erythropoietin levels and PCV of 52%. Most likely tumour is –
## **Core Concept**
The question tests the understanding of paraneoplastic syndromes, specifically the association between certain malignancies and the inappropriate production of erythropoietin (EPO), leading to secondary polycythemia. Erythropoietin is a hormone primarily produced by the kidneys that promotes the formation of red blood cells by the bone marrow. Inappropriate production of EPO can lead to an increase in red blood cell mass, which is reflected by an elevated packed cell volume (PCV) or hematocrit.
## **Why the Correct Answer is Right**
The correct answer, **C. Renal cell carcinoma**, is associated with the production of erythropoietin. Renal cell carcinoma, a type of kidney cancer, can lead to the ectopic production of erythropoietin. This results in secondary polycythemia, characterized by an increased production of red blood cells, which in turn causes an elevated PCV. The elevated EPO levels and PCV of 52% in the given patient point towards a diagnosis of renal cell carcinoma.
## **Why Each Wrong Option is Incorrect**
- **Option A: Prostate cancer** - While prostate cancer can cause paraneoplastic syndromes, it is not commonly associated with the production of erythropoietin or secondary polycythemia.
- **Option B: Hepatocellular carcinoma** - Hepatocellular carcinoma can be associated with various paraneoplastic syndromes but is not typically linked with erythropoietin production.
- **Option D: Small cell lung cancer** - This type of cancer can cause a variety of paraneoplastic syndromes, including the syndrome of inappropriate antidiuretic hormone secretion (SIADH), but it is not commonly associated with erythropoietin production.
## **Clinical Pearl / High-Yield Fact**
A key clinical pearl is that renal cell carcinoma can cause secondary polycythemia due to the inappropriate production of erythropoietin. This association is crucial for postgraduate medical students to remember, especially when encountering patients with polycythemia and malignancy.
## **Correct Answer:** **C. Renal cell carcinoma**