7743 A Case Study of Ectopic Adrenocorticotropic Hormone Secretion from Pancreatic Neuroendocrine Tumor

Abstract Disclosure: K.S. Wei: None. J. Huang: None. Introduction: Pancreatic neuroendocrine tumors (PanNETs) are uncommon cancers that account for less than 2% of pancreatic malignancies. Even rarer are ACTH-producing NETs which may only become symptomatic until after metastasis. This case study examines the distinct presentation and diagnostic complexities associated with ectopic adrenocorticotropic hormone (ACTH) secretion from a PanNET. Clinical Case:A 42 year-old male with hypertension and type 2 diabetes initially presented to the hospital with increased abdominal girth for one month, bilateral lower extremity edema for two weeks, and generalized abdominal pain. He had unremarkable surgical, family, and social histories. Patient was afebrile, normotensive, saturating well on room air, with exam notable for a distended abdomen and 2+ bilateral pitting edema. Admission labs were notable for potassium of 2.4 (ref: 3.5-5.1 mmol/L). MRI abdomen showed hepatomegaly with numerous heterogeneously enhancing masses and an ill-defined pancreatic tail mass with involvement of the spleen. Liver biopsy showed well-differentiated neuroendocrine tumor, grade 2. He was started on octreotide 20mg q4weeks and capecitabine/temozolomide q4weeks. Two months later, the patient was readmitted after presenting with back pain for two days, found to have acute compression fractures of T9-L1 without spinal PET activity. At follow-up visit with endocrinology, he endorsed easy bruising and muscle weakness and had hypertension (161/96 mmHg) with hypokalemia. Random cortisol was 43.7 (ref: 2.5-11.9 mcg/dL). ACTH was 124 (ref: 6-50 pg/mL) despite receiving chemotherapy. 24-hour urine cortisol was 3,049 (ref: 4-50 mcg/24 hrs). He was diagnosed with ectopic Cushing’s disease from ACTH-producing PanNET leading to osteoporosis and fracture of the vertebral bodies. For the ectopic Cushing’s disease, he was started on ketoconazole 200mg BID with plan to start osilodrostat once approved. For the fracture, he is scheduled for Zometa infusion and IR kyphoplasty. Conclusion: This case offers several important clinical insights. In patients with PanNET with Cushingoid exam findings, ACTH-producing PanNET should be high on the differential. Most ACTH NETs are aggressive often with liver metastases, whereby metastatic disease will have already occurred by the time the Cushingoid features develop. The initial severe hypokalemia and hypertension should have prompted investigation for mineralocorticoid excess from hypercortisolism, which may have led to an earlier diagnosis of ectopic ACTH Cushing’s disease, thereby decreasing the possibility of developing vertebral fractures, uncontrolled diabetes and hypertension. Ketoconazole or osilodrostat may be used to treat Cushing’s disease from ACTH NETs. Presentation: 6/1/2024