Cushing's Syndrome Caused by a Well-Differentiated Ileal Neuroendocrine Carcinoma

We report a very rare case of Cushing's syndrome caused by an ileal adrenocorticotrophin-secreting well-differentiated endocrine carcinoma with liver metastases. A 62-yr-old woman presented with clinical and biological signs suggestive of paraneoplastic Cushing's syndrome Radiological investigations, including magnetic resonance imaging of the pituitary gland, chest and abdominal computerized tomography scan, smalI bowel barium study and pancreatic endoscopic scan, 111 -pentetreotide scintigraphy (octreoscan), esogastroduodenoscopy, and colonoscopy did not detect the source of the ectopic adrenocorticotropic hormone (ACTH) secretior but showed a few liver nodules. Because a 10 mo-long ketoconazole treatment was not effective, a bilateral adrenalectomy was performed in order to control the Cushing's syndrome, and a liver nodule biopsy diagnosed a metastatic neuroendocrine tumor. Subsequently, a second laparotomy disclosed a 1.8 cm ileal neuroendocrine tumor, cosecreting ACTH and serotonin on immunohistochemistry with many liver metastases. ACTH and secretion by intestinal neuroendocrine tumors is rare, and the secretion is a most always clinicailly silent. Cushing's syndrome caused by an intestinal low grade neuroendocrine tumor is even rarer, with only two previous cases reported in the literature. Our observation underlines the difficulty of localizing the source of ectopic ACTI-I secretion in paraneoplastic Cushing's syndrome.