<prompt> All of the following are ACTH independent Cushing syndrome except :Pituitary adenomaAdrenal hyperplasiaAdrenocoical carcinomaMcCune Albright Syndrome  <response>: ACTH dependent Cushing syndrome is caused by : ACTH producing pituitary adenoma Ectopic ACTH Bronchial or pancreatic carcinoid Small cell cancer of lung Medullary carcinoma of thyroids Pheochromocytoma ACTH Independent Cushing syndrome is caused by : Adrenocoical adenoma carcinoma Primary pigmented nodular adrenal disease Adrenal hyperplasia McCune Albright Syndrome PetrosalPeripheral ACTH ratio 2 indicates the presence of a pituitary adenoma-secreting ACTH. NOTE: Overall the most common cause of Cushings syndrome is Iatrogenic steroids but if asked regarding ACTH dependent cause then answer should be given as Pituitary adenoma. 