Small Cell Lung Cancer
Also written as SCLC.
Small cell lung cancer is the classic paraneoplastic source of ectopic ACTH, causing Cushing syndrome.
What our notes say
- Small cell lung cancer is the classic paraneoplastic source of ectopic ACTH, causing Cushing syndrome. (Chemical Pathology: Endocrine Cases, Pituitary & Thyroid Q&A)
- Small cell lung cancer is aggressive and metastatic at diagnosis. - Lung Transplantation: For end-stage lung disease. (Endocrine & Renal Pathology — Must Know Notes)
- | Small cell lung cancer (SCLC) ≈ 15% | Central; very strong smoking link; neuroendocrine origin; very rapid growth and early metastasis; paraneoplastic syndromes (ectopic ACTH, SIADH, Lambert–Eaton); chemotherapy-sensitive | (Lung Cancer)
- | Etoposide | Topoisomerase II inhibitor | With a platinum drug in small cell lung cancer | Low blood counts, hair loss | (Lung Cancer)
- Central masses with the syndrome of inappropriate antidiuretic hormone secretion point to small-cell lung cancer, a neuroendocrine tumour linked to smoking that spreads early. (Respiratory Medicine Question Bank: 15 Clinical MCQs)
- A 55-year-old man with small cell lung cancer develops proximal muscle weakness that improves transiently after brief exercise. (Master Bone & Soft Tissue Pathology: CAT 2 MCQs & Answers)
Study material on Small Cell Lung Cancer
- Lung Cancer
- Respiratory System Pathology 1A
- Ovarian & Colorectal Cancer: Risks, Pathogenesis, Staging
- Genetic Disorders Pathology Crash Course: Exam Revision Notes
- Molecular Basis of Cancer: Cell Cycle, Apoptosis & Angiogenesis
- Respiratory System Pathology 1A — Practice Questions
- Respiratory System Pathology 1A — Practice Questions
- Chemical Pathology
- Respiratory System Pathology 1A — Practice Questions
- Respiratory System Pathology 1A — Practice Questions
- Respiratory System Pathology 1A — Practice Questions
Practice questions on Small Cell Lung Cancer
A patient with small cell lung cancer develops hyponatremia with concentrated urine. The ectopic hormone responsible is
- PTHrP
- GnRH
- ADH
- ACTH
Answer: C. ADH secreted ectopically causes water retention and dilutional hyponatremia with inappropriately concentrated urine (SIADH). ---
A patient with Small Cell Lung Cancer (SCLC) has anti-VGCC antibodies, weakness that improves with repeated use. What is the diagnosis?
- Myasthenia gravis
- Polymyositis
- Guillain-Barré syndrome
- Lambert-Eaton Myasthenic Syndrome
Answer: D. LEMS is characterized by anti-VGCC antibodies that impair presynaptic ACh release. Strength paradoxically improves with repeated stimulation — the opposite of Myasthenia Gravis. ---
A 65-year-old man with small-cell lung cancer develops hyponatraemia (Na⁺ 118 mmol/L), urine osmolality 520 mOsm/kg and euvolaemia. Which ectopic hormone production BEST explains this?
- PTHrP
- ADH → SIADH
- Ectopic ACTH
- Erythropoietin
Answer: B. SIADH from ectopic ADH secretion is the classic paraneoplastic syndrome of SCLC, giving euvolaemic hyponatraemia with high urine osmolality and low serum osmolality. PTHrP causes hypercalcaemia; ectopic ACTH causes Cushing's features. ---
A patient with small cell lung cancer develops hyponatremia with concentrated urine. The ectopic hormone responsible is ---
- PTHrP
- GnRH
- ADH
- ACTH
Answer: C.