MON-408 Development of Rapidly Progressive Cushing's Disease Following Pituitary Apoplexy Several Years Prior

Cushing’s disease is characterized by hypersecretion of adrenocorticotropin hormone (ACTH), typically from a pituitary microadenoma, resulting in excess cortisol. It accounts for up to 70% of cases of Cushing’s syndrome and is associated with significant morbidity and increased mortality. We present a case of a patient with a history of pituitary apoplexy of a non-secretory adenoma who developed Cushing’s disease 4 years later. The patient is a 61-year-old woman with a history of hypertension, prediabetes, and renal cell carcinoma status post cryoablation who presented to our multidisciplinary skull-base clinic for management of a right parasagittal meningioma, left anterior clinoid nodule, and pituitary apoplexy that occurred 4 years prior. She had no signs or symptoms of pituitary hormone excess at that time. She also had an incidental 1 cm left adrenal adenoma that was recently seen on CT scan of the abdomen and she had not undergone biochemical evaluation at the time of her presentation to our clinic. As part of her evaluation of the adrenal incidentaloma, she underwent a 1 mg Dexamethasone suppression test with an 8 am cortisol of 71 ug/dL. 24 hour urine cortisol was also significantly elevated at 394 ug/24 hours (reference range <45 ug/24 hours). An ACTH level was measured to determine if the excess cortisol secretion was ACTH-dependent or ACTH-independent. The ACTH level was quite elevated at 166 pg/mL (reference range 0-46 pg/mL). MRI of the pituitary showed multinodular areas of enhancement within the sella and interval growth of tissue within the right cavernous sinus compared to an MRI obtained a year prior. While undergoing evaluation of the cortisol excess, the patient developed progressive proximal muscle weakness, worsening hypertension, easy bruising, mood swings, severe fatigue, and a 14 pound weight loss. The patient’s prediabetes progressed to diabetes with an A1c of 11%. Given the rapid progression of her symptoms, her prior history of carcinoma, her prior history of pituitary apoplexy and no definite pituitary lesion on MRI, the patient underwent inferior petrosal sinus sampling (IPSS) to determine if the source of ACTH was ectopic or from the pituitary. The results from IPSS revealed a pituitary source of excess ACTH secretion. The patient underwent endoscopic transsphenoidal resection of tissue on the right side of the pituitary. Surgical pathology was consistent with a pituitary adenoma with immunostaining positive for ACTH. Following surgical resection, the patient’s hyperglycemia and hypertension significantly improved. This case highlights a very rare presentation of Cushing’s disease following an episode of pituitary apoplexy. To our knowledge there is only one other reported case of a patient who developed Cushing’s disease in the setting of pituitary apoplexy. We will review the key clinical features and approach to diagnosis in patients with this rare presentation.