Commonest cause of Cushing syndrome is:

MC cause of Cushing's syndrome is iatrogenic exogenous administration of steroids MC endogenous cause of Cushing's syndrome is bilateral adrenal hyperplasia secondary to hypersecretion of ACTH from pituitary or from an ectopic non-pituitary source. Cause of Cushing's Syndrome Endogenous Exogenous ADRENAL HYPERPLASIA Pituitary ACTH overproduction: Microadenoma>Marcoadenoma Ectopic ACTH overproduction: Small cell carcinoma lung Thymus carcinoid Carcinoma pancreas Bronchial adenoma Iatrogenic exogenous administration of steroids (MC cause) ADRENAL NEOPLASIA Adenoma Cacrinoma