6419 Cushing’s Syndrome due to Metastatic Pancreatic Neuroendocrine Neoplasm With Incidental Pituitary Microadenoma

Abstract Disclosure: A. Ibrahim: None. L. Esper: None. R. Jain: None. N. El Asmar: None. Introduction: Pancreatic neuroendocrine neoplasms (PNENs) are rare with a reported incidence of 1-2/100,000. While the majority are non-functional, insulinomas and gastrinomas are the most common functional PNENs. Our case of ACTH-producing PNENs is extremely rare. Case presentation: A previously healthy 47-year-old female was hospitalized for worsening dyspnea. Her symptoms included rapid weight gain, skin hyperpigmentation, and lower extremity edema. Her exam was notable for elevated blood pressure of 181/120 mmHg, moon facies, purple abdominal striae, and proximal myopathy. Her lab analysis showed a cortisol level of 42 mcg/dL (6.2-19.4), ACTH of 254 pg/ml (7.2-63), DHEA sulfate of 171 mcg/dl (41-243), HbA1C 7%, K of 3 mmol/l and 24H urine cortisol >2100 mcg/24hrs. A post low-dose DST cortisol level was 42.7 mcg/dl. CT chest demonstrated an ill-defined hypodense lesion in the region of the pancreatic head. MRI abdomen revealed a 3 x 2.3 x 2.3 cm mass in the pancreatic head and many small enhancing lesions within the right lobe of the liver. Adrenal glands appeared normal. Subsequent PET CT scan with GA 68 DOTOTATE showed increased uptake in the pancreatic head mass and in the right hepatic lobe. Her pituitary MRI revealed a right pituitary gland 6 mm hypointense lesion, possibly a microadenoma. A high dose DST resulted in a cortisol level of 80 mcg/dl mostly consistent with ectopic ACTH secretion. EUS-guided biopsy of the pancreatic mass showed a well-differentiated neuroendocrine tumor that stained positive for ACTH, chromogranin, synaptophysin, and CD56. Treatment with Ketoconazole 600mg q6h and Octreotide 50mg q6h was started 3 days before surgery to control acute hypercortisolism as she developed acute psychosis. The patient subsequently underwent a Whipple procedure with successful resection of the pancreatic mass. Post-op, her ACTH levels dropped to 19 pg/ml with a cortisol level of 6 mcg/dl. Final pathology showed a well-differentiated grade 3 neuroendocrine tumor with a KI-67 labeling index greater than 20%. After surgery, the patient received a short course of stress dose hydrocortisone which was tapered off over the following 2 months. The patient is being followed for planning further intervention given the aggressive grade of the tumor and hepatic metastases. Conclusion: Ectopic ACTH-producing PNENs are rare. An accurate and timely diagnosis, while challenging, is key. Patients usually present with rapidly progressing symptoms that could cause life-threatening complications such as thrombosis and sepsis. We demonstrated the importance of utilizing a multidisciplinary team approach and starting cortisol-lowering medications early given the complexity of the disease, requiring rapid intervention and lifelong follow-up. Presentation: 6/3/2024