title: Imaging in covert ectopic ACTH secretion: a CT pictorial review.
abstract: The syndrome of ectopic adrenocorticotrophin secretion (EAS) is rare and is due to excess adrenocorticotrophin (ACTH) production from a nonpituitary tumour. These tumours can be covert, where the tumours are not readily apparent, and very small making them challenging to image. It is clinically and biochemically difficult to distinguish between covert EAS and Cushing's disease. The first-line investigation in locating the source of ACTH production is computed tomography (CT). The aim of this pictorial review is to illustrate the likely covert sites and related imaging findings. We review the CT appearances of tumours resulting in covert EAS and the associated literature. The most common tumours were bronchial carcinoid tumours, which appear as small, well-defined, round or ovoid pulmonary lesions. Rarer causes included thymic carcinoids, gastrointestinal carcinoids and pancreatic neuroendocrine tumours. Awareness of the imaging characteristics will aid identification of the source of ACTH production and allow potentially curative surgical resection.
authors.affiliation: Department of Academic Radiology, Dominion House, St Bartholomew's Hospital, West Smithfield, London, EC1A 7BE, UK, paul.sookur@bartsandthelondon.nhs.uk
authors.forename: Paul A
authors.initials: PA
authors.lastname: Sookur
authors.forename: Anju
authors.initials: A
authors.lastname: Sahdev
authors.forename: Andrea G
authors.initials: AG
authors.lastname: Rockall
authors.forename: Andrea M
authors.initials: AM
authors.lastname: Isidori
authors.forename: John P
authors.initials: JP
authors.lastname: Monson
authors.forename: Ashley B
authors.initials: AB
authors.lastname: Grossman
authors.forename: Rodney H
authors.initials: RH
authors.lastname: Reznek
mesh_terms: D000324:Adrenocorticotropic Hormone / Q000378:metabolism*; D002276:Carcinoid Tumor / Q000175:diagnosis / Q000000981:diagnostic imaging; D003937:Diagnosis, Differential; D003952:Diagnostic Imaging / Q000379:methods*; D006801:Humans; D009490:Neurosecretory Systems; D015282:Octreotide / Q000031:analogs & derivatives; D047748:Pituitary ACTH Hypersecretion / Q000175:diagnosis / Q000000981:diagnostic imaging; D010900:Pituitary Diseases / Q000175:diagnosis / Q000000981:diagnostic imaging; D014057:Tomography, X-Ray Computed / Q000379:methods*
chemical_list: C094279:indium-111-octreotide; D000324:Adrenocorticotropic Hormone; D015282:Octreotide