This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Respiration, Subject name: Pathology
Which type of paraneoplastic syndrome is most commonly associated with lung carcinoma? 
Select and explain. 
A. SIADH, B. Gynaecomastia, C. Acanthosis nigricans, D. Hypocalcaemia
A: SIADH
Answer: A: SIADH 
Explanation: Ans. is 'a' i.e., SIADH * Among the given options, SIADH is the most common paraneoplastic syndrome associated with lung carcinoma as Small cell carcinoma is the most common type of lung cancer associated with ectopic hormone production and paraneoplastic syndrome and ADH (Causing SIADH), ACTH (Causing cushingsyndrome) production are predominantly associated small cell carcinoma whereas those that produce hypercalcemia (due to PTH) are mostly squamous cell tumors. Gynaecomastia (due to gonadotropin) isassociated with large cell carcinoma.* Other paraneoplastic syndromes are Lambert eaton syndrome, Acanthosis nigricons and hypertrophic pulmonary oseoarthropathy (clubbing & periosteal reaction).