Aggressive Pancreatic ACTH-Secreting Neuroendocrine Tumor as a Rare Cause of Rapid-Onset Cushing's Syndrome

ABSTRACT: Ectopic adrenocorticotropic hormone (ACTH) secretion is an uncommon cause of Cushing syndrome, with pancreatic neuroendocrine tumors (pACTHomas) being exceptionally rare. We report the case of a 31-year-old woman who presented with rapidly progressive Cushingoid features including facial rounding, acne, bruising, proximal muscle weakness, menstrual irregularity, and weight gain over six weeks. Laboratory tests showed severe hyperglycemia and hypokalemia, along with markedly elevated cortisol and ACTH. Imaging demonstrated a pancreatic mass consistent with a neuroendocrine tumor. Her clinical course was complicated by atrial fibrillation, stroke, and worsening metabolic disturbances. This case illustrates the aggressive nature of pACTHomas and the considerable challenges they present in both diagnosis and management. Keywords: Ectopic ACTH syndrome; Pancreatic neuroendocrine tumor; Cushing’s syndrome; Refractory hypokalemia.