What paraneoplastic syndrome is associated with small cell lung carcinoma?

• A. Hypercalcemia
• B. SIADH and Cushing's syndrome
• C. Polycythemia
• D. Gigantism

Answer: (B)

Small cell lung carcinoma (SCLC) is associated with specific paraneoplastic syndromes due to the secretion of various hormones and hormone-like substances by the tumor cells. One of the most prominent paraneoplastic syndromes associated with SCLC is the syndrome of inappropriate antidiuretic hormone secretion (SIADH), which leads to hyponatremia and water retention.

In addition to SIADH, small cell lung carcinoma can also cause Cushing's syndrome through ectopic production of adrenocorticotropic hormone (ACTH). The increased levels of ACTH result in elevated cortisol levels, leading to the clinical manifestations of Cushing's syndrome such as weight gain, hypertension, and abnormal glucose metabolism.

While hypercalcemia, polycythemia, and gigantism may be seen in association with other cancers or medical conditions, they are not characteristic of small cell lung carcinoma. Hypercalcemia is often linked to malignancy in cases such as squamous cell lung carcinoma, while polycythemia is more associated with conditions that stimulate erythropoiesis, and gigantism is related to excess growth hormone often from pituitary adenomas. Thus, the correct association for small cell lung carcinoma is with SIADH and Cushing