<prompt> The most common cause of Cushings syndrome is:Pituitary adenomaAdrenal adenomaEctopic ACTHIatrogenic steroids  <response>: d. Iatrogenic steroidsRef: Nelsons 20e p 2227-2729, Ghai 8e p 525The most common cause of Cushings syndrome is prolonged exogenous administration of glucocorticoid hormones, especially at the high doses used to treat lymphoproliferative disorders. 