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Difficulty: EasyNeoplastic Processes

Match each classic paraneoplastic clinical presentation with its most strongly associated primary neoplasm.

  • Severe hyponatremia, low serum osmolality, and inappropriately concentrated urineSmall cell carcinoma of the lung
  • Hypercalcemia, hypophosphatemia, and suppressed intact parathyroid hormoneSquamous cell carcinoma of the lung
  • Erythrocytosis with an elevated hemoglobin and hematocrit in the absence of hypoxiaRenal cell carcinoma
  • Episodic cutaneous flushing, secretory diarrhea, and right-sided valvular heart diseaseNeuroendocrine tumor of the small intestine

Answer

Severe hyponatremia matches with small cell carcinoma of the lung; hypercalcemia matches with squamous cell carcinoma of the lung; erythrocytosis matches with renal cell carcinoma; and episodic flushing/diarrhea matches with neuroendocrine tumor of the small intestine.
Each listed clinical presentation represents a classic paraneoplastic syndrome directly linked to the ectopic hormone or peptide production of its respective primary tumor. Small cell lung cancer causes SIADH (ADH), squamous cell lung cancer causes humoral hypercalcemia (PTHrP), renal cell carcinoma causes erythrocytosis (EPO), and neuroendocrine tumors cause carcinoid syndrome (Serotonin).

Step-by-Step Solution

1
Identify the paraneoplastic syndrome responsible for hyponatremia with inappropriately concentrated urine.
Recognize this as SIADH, which is most classically associated with small cell carcinoma of the lung.
Small cell lung cancer has a strong neuroendocrine differentiation capable of secreting ectopic ADH.
2
Identify the driver of hypercalcemia with suppressed intact parathyroid hormone.
Recognize this as PTHrP-mediated hypercalcemia, which maps to squamous cell carcinoma of the lung.
PTHrP acts at the same receptors as PTH, causing hypercalcemia and hypophosphatemia, but suppresses endogenous PTH.
3
Identify the mechanism of erythrocytosis without hypoxia.
Recognize this as ectopic erythropoietin (EPO) production, most commonly associated with renal cell carcinoma.
The kidneys are the primary source of EPO; malignancies of renal origin can autonomously secrete it.
4
Identify the syndrome characterized by flushing, diarrhea, and right heart lesions.
Recognize carcinoid syndrome, which is caused by vasoactive substances from a neuroendocrine tumor of the small intestine.
Serotonin secretion leads to systemic symptoms when the tumor load (often via liver metastasis) exceeds hepatic breakdown capacity.

Key Concept

Paraneoplastic Syndromes in Oncology
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Topics

Neoplastic Processes

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