Ectopic Cushings syndrome caused by a well differentiated ACTH-secreting neuroendocrine carcinoma of the ileum
Joerg Singer1,6, Christian A Koch2, Michael Bartels3, Thomas Aigner4, Thomas Lincke5, Mathias Fasshauer1 & Ralf Paschke1
Cushings syndrome can be caused by adrenocorticotropic hormone-secreting solid tumors. We report a rare case of an ileal endocrine carcinoma that produced ACTH and induced hypercortisolism. A now 47-year-old male patient presented at the age of 41 with perspiration, weight gain, tremor and general fatigue. Diabetes mellitus and hypercortisolism was diagnosed by laboratory testing. Further examinations revealed ectopic Cushings syndrome. The search for the location of the primary tumor proved to be difficult. The patient underwent subtotal thyroidectomy and surgical removal of a pituitary lesion. After resection of an ACTH producing tumor of the mesentery, temporary remission of Cushings syndrome ensued. This lesion was later found to be a metastasis. At the age of 45 the primary tumor was detected in the ileum by Ga-68 DOTATOC PET scan and explorative laparotomy. After surgical removal of this well differentiated neuroendocrine carcinoma the patient significantly improved clinically. He experienced remission of his diabetes mellitus, an increase in muscular strength as well as better blood pressure with 2 of 4 anti-hypertensive medications discontinued. Follow-up laboratory testing confirmed remission of hypercortisolism and diabetes mellitus. A 1 mg dexamethasone suppression test 18 months after surgery and a Ga-68 DOTATOC PET showed normal results. Ectopic ACTH secretion within the small bowel is very rare. This case accentuates the difficulty in locating the source of ectopic ACTH secretion. In addition to standard diagnostic procedures like CT or MRI scan it suggests using SSTR imaging, small bowel barium study, tubus endoscopy or video endoscopy for preoperative localization if the small bowel is suspected as tumor source.