A common cause of Cushing syndrome is:

Answer is B (Pituitary adenoma): Cushing's Syndrome Endogenous Cushing's Syndrome Most common cause of endogenous Cushing's syndrome is an ACTH secreting pituitary adenoma (Cushing's disease) Exogenous Cushing's Syndrome The most common cause of exogenous Cushing's syndrome is iatrogenic administration of steroids. ACTH producing pituitary adenoma are the most common cause of endogenous Cushing syndrome.