<prompt> Commonest cause of Cushing syndrome is:Adrenal adenomaCarcinomaHyperplasiaAtrophy  <response>: MC cause of Cushings syndrome is iatrogenic exogenous administration of steroids MC endogenous cause of Cushings syndrome is bilateral adrenal hyperplasia secondary to hypersecretion of ACTH from pituitary or from an ectopic non-pituitary source. Cause of Cushings Syndrome Endogenous Exogenous ADRENAL HYPERPLASIA Pituitary ACTH overproduction: MicroadenomaMarcoadenoma Ectopic ACTH overproduction: Small cell carcinoma lung Thymus carcinoid Carcinoma pancreas Bronchial adenoma Iatrogenic exogenous administration of steroids MC cause ADRENAL NEOPLASIA Adenoma Cacrinoma 