The most common cause of Cushing&;s syndrome is:: (A) Pituitary adenoma, (B) Adrenal adenoma, (C) Ectopic ACTH, (D) Iatrogenic steroids
Answer is D. The most common cause of Cushing&;s syndrome is Iatrogenic administration of steroids for a variety of reasons." REF: Harrison book of internal medicine 21ST EDITION