Paraneoplastic Cushing syndrome caused by a pancreatic neuroendocrine tumor: A case report

Abstract

Background: Endogenous Cushing syndrome results from uncontrolled overproduction of cortisol. Paraneoplastic Cushing syndrome (PCS) is an uncommon etiology of endogenous hypercortisolism caused generally by bronchial and thymic adrenocorticotropic hormone (ACTH)-producing tumors. Pancreatic neuroendocrine tumors (NETs) have been reported in only few cases. Case Description: We report the case of a 42-year-old female with a history of diabetes mellitus, hypertension, hyperlipidemia, post-surgical hypoparathyroidism and hypothyroidism who presented with rapidly aggravated generalized weakness and severe hypokalemia. High urinary free cortisol and 48-hour low-dose dexamethasone test confirmed the diagnosis of Cushing syndrome. ACTH level was high, thus confirming the ACTH-dependent character of this syndrome. However, pituitary magnetic resonance imaging (MRI) did not detect pituitary lesions. Cortisol level was not suppressed even with high-dose dexamethasone suppression test, thus supporting the diagnosis of ectopic ACTH secretion (EAS). Thoracoabdominopelvic computed tomography was normal. Positron emission tomography with fluorodeoxyglucose (18FDG-PET) revealed a hypermetabolic focus in the pancreatic head. Abdominal MRI was then performed. It detected a small hypervascular mass at the level of pancreatic uncinate process highly suspicious for a pancreatic NET with no evidence of distant metastases. Endoscopic ultrasound-guided biopsy confirmed the diagnosis of functional well-differentiated pancreatic NET as the source of ectopic ACTH. The patient clinical course was complicated by pulmonary embolism and recurrent pulmonary and urinary infections. She passed away three months after the diagnosis of PCS. Conclusions: PCS from pancreatic NETs heavily compromises patients' well-being and survival. Early identification and surgical removal of the tumor in addition to appropriate management of comorbidities could enhance the prognosis.