A 38-year-old woman comes to the clinic because of progressive weight gain, easy bruising, proximal muscle weakness, and irregular menses. Physical examination shows moon facies, abdominal violaceous striae, and a dorsocervical fat pad. Screening confirms hypercortisolism. ACTH is elevated, and high dose dexamethasone suppresses cortisol production. Which of the following is the most likely diagnosis?

1. A)Primary adrenal insufficiency
2. B)Ectopic ACTH secretion from small cell carcinoma
3. C)ACTH secreting pituitary adenomaGABARITO
4. D)Adrenal adenoma
5. E)Exogenous glucocorticoid use