ACTH is produced by which of the following Bronchogenic carcinomas

Answer is B (Small cell carcinoma): Small cell carcinomas are the most common bronchogenic carcinomas associated with paraneoplastic syndrome and ectopic hormone production including ACTH. ACTH may also be uncommonly produced by non small cell variants including adenocarcinoma and squamous carcinomas, but small cell carcinoma is the most common source of ectopic ACTH. 'Small cell carcinoma lung (>50%) is by for the most common cause of ectopic ACTH production followed by Thymic carcinoids (15%), islet cell tumors (10%), bronchial carcinoids (10%), other carcinoids (5%) and pheochromocytomas (2%) - Harrison's 18th/829 Ectopic ACTH Production (Bold) Small cell carcinoma (50) Lung Thymic carcinoids (15%) Islet cell tumors (10%) Bronchial carcinoid (10%) Other carcinoids (5%) Pheochromocytomas (2%)