<prompt> ACTH is produced by which of the following Bronchogenic carcinomasAdenocarcinomaSmall cell carcinomaSquamous cell carcinomaBranchoalveolar carcinoma  <response>: 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 - Harrisons 18th829 Ectopic ACTH Production Bold Small cell carcinoma 50 Lung Thymic carcinoids 15 Islet cell tumors 10 Bronchial carcinoid 10 Other carcinoids 5 Pheochromocytomas 2 