Efficacious Primary Pasireotide Therapy in a Case of a Large Invasive Adrenocorticotropin-secreting Pituitary Tumor.

A 41-year-old woman presented with a headache, diplopia, weight gain, moon face, and central obesity. Her plasma adrenocorticotropin (ACTH) level was 25.5 pmol/L (116 pg/mL) (normal range, 1.6-13.9 pmol/L [7.2-63.3 pg/mL]), serum cortisol level was 397.3 nmol/L (14.4 µg/dL) (normal range, 195.1-540.7 nmol/L [7.1-19.6 µg/dL]), and urinary free cortisol was 413.9 nmol/day (150.3 µg/day) (normal range, <221.5 mmol/day [<80.3 µg/day]). ACTH-dependent hypercortisolism was present, with cortisol suppression using a high-dose dexamethasone suppression test. Cushing disease was diagnosed and a contrast-enhanced magnetic resonance imaging scan demonstrated a 36-mm pituitary tumor with right cavernous sinus invasion. Before surgery, 20 mg pasireotide long-acting-release was initiated, and her symptoms rapidly improved. After 1 month, obvious tumor shrinkage was observed, ACTH and cortisol levels decreased, and diplopia resolved; therefore, we continued medical therapy. After 11 months, her ACTH and cortisol levels normalized, and most of the tumor had disappeared. The clinical course in this case suggests that pasireotide may be useful for preoperative treatment and primary medical therapy, at least in some patients with Cushing disease caused by a large tumor predicted to have difficulty achieving remission by surgery.