A 55-year-old man presents to his primary care physician with a 6-month history of progressive proximal muscle weakness, easy bruising, and worsening hypertension despite being on three antihypertensive medications. On examination, he has central obesity with supraclavicular fullness and purple striae on his abdomen. Laboratory studies show serum potassium of 3.1 mEq/L, fasting glucose of 128 mg/dL, and morning cortisol of 24 µg/dL. ACTH level is 65 pg/mL. A low-dose dexamethasone suppression test (1 mg overnight) results in a cortisol level of 18 µg/dL. A subsequent high-dose dexamethasone suppression test (8 mg overnight) shows suppression of cortisol to 8 µg/dL. Which of the following is the most likely diagnosis?

1. A)Ectopic ACTH secretion from small cell lung cancer
2. B)ACTH-secreting pituitary adenoma (Cushing disease)GABARITO
3. C)Adrenocorticotropic hormone-independent adrenal adenoma
4. D)Ectopic corticotropin-releasing hormone secretion from bronchial carcinoid
5. E)Pseudo-Cushing syndrome from major depressive disorder