Ectopic ACTH syndrome from a neuroendocrine tumor of the pancreas

Abstract

Background: Ectopic ACTH syndrome is a potentially fatal clinical entity that Results in excess cortisol production. Rarely, these syndromes originate from tumors in the pancreas. We discuss a case report of a patient with pancreatic ectopic ACTH syndrome who ultimately required surgical treatment of her disease. Methods: A 70 year-old female presented with rapid onset of insomnia, anxiety, weight loss, and proximal muscle weakness over 6 months. A thorough laboratory work up revealed ACTH-dependent hypercortisolism, with an ACTH level of 284. Imaging studies showed a negative pituitary MRI, and inferior petrosal sinus sampling was consistent with ectopic ACTH tumor. A CT of the chest, abdomen and pelvis performed at an outside hospital did not identify any potential culprit lesions. A DOTATE scan was unable to be completed initially due to insurance limitations. The patient was therefore initiated on medical therapy with Ketoconazole, pending further imaging. Following three days on medical therapy, the patient presented to our emergency department with malaise, hypotension, and hypoxia. She was admitted to the medical ICU and intubated for respiratory failure. A CT scan done to rule out a pulmonary embolism (PE) found no evidence of PE but a diagnosis of multifocal pneumonia. A review of her prior CT scan at the outside hospital revealed a lesion in the distal pancreas, suspected to be the source of ACTH producing tumor. She underwent endoscopic ultrasound with biopsy. Pathology Results were suspicious for neuroendocrine tumor with faint staining of ACTH. Therefore, the decision was made to perform an open distal pancreatectomy and splenectomy. The procedure was done without any complications. This led to an immediate decrease in the patient’s ACTH level to 18, as well as an improvement in her clinical status. She did well post operatively and was discharged to home on post op day 9. Final pathology revealed a well-differentiated neuroendocrine tumor at 3.4 cm, with clean margins and no evidence of metastasis to the lymph nodes. Conclusion: We report on the clinical management of a pancreatic ACTH producing tumor. It is important to note that on first evaluation at the outside hospital, this mass was not identified as the source of the ACTH syndrome. This is likely due to the uncommon diagnosis of a pancreatic ACTH producing tumor. It is, therefore, important to consider pancreatic neuroendocrine tumor, as well as other uncommon locations as part of the differential diagnosis when evaluating patients with ectopic ACTH syndrome. Figure legend: CT abdomen reveals a solid mass in the pancreas (arrow) enhancing on arterial phase of CT.