This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Cushing Syndrome, Subject name: Medicine
[{'content': 'A patient presents with hemoptysis and Cushingoid features with a lack of dexamethasone suppression. What could be the likely reason? \nSelect and explain. \nA. Adrenal Hyperplasia, B. Adrenal Adenoma, C. Bronchial Adenoma, D. Bronchial Carcinoid', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Ectopic ACTH production is predominantly caused by Occult carcinoid tumors, most frequently in the lung, but also in thymus or pancreas. About 25% of patients with Pulmonary Carcinoid tumors are asymptomatic at the time of discovery. In symptomatic patients of pulmonary carcinoids, the most common clinical findings are those associated with bronchial obstruction, such as persistent cough, hemoptysis, and recurrent or obstructive pneumonitis. Wheezing, chest pain, and dyspnea also maybe noted. Although uncommon, various endocrine or neuroendocrine syndromes can be initial clinical manifestations of either typical or atypical pulmonary carcinoid tumors. Only advanced small cell lung cancer can cause ectopic ACTH production.', 'role': 'assistant'}]