title: A pitfall in diagnosing Cushing's disease: ectopic ACTH-producing pituitary adenoma in the sphenoid sinus.
abstract: OBJECTIVE
  To show a rare case of Cushing's disease and possible cause of failed transsphenoidal surgery.
  
  
  METHODS
  We report on a 50-year-old woman suffering from ACTH-dependent Cushing's syndrome. Endocrinological work-up including low-dose/high-dose dexamethasone test (Liddle-test) and CRH test were clearly compatible with pituitary origin. Although an MRI showed no pituitary tumor, CRH-stimulated petrosal sinus sampling revealed a significant central-peripheral gradient in ACTH concentrations, rendering Cushing's disease very likely. The patient underwent transsphenoidal surgery with negative exploration of the pituitary gland. After intraoperative re-evaluation of the preoperative MRI, a "polyp" at the bottom of the sphenoid sinus was identified. The intraoperative microscopic aspect as well as instantaneous sections and cytology of a biopsy confirmed an adenoma, which was then removed. Histological analysis demonstrated an ACTH-producing pituitary adenoma adjacent to respiratory mucous membrane consisting of ciliated epithelium with submucous connective tissue. Postoperatively, ACTH concentrations were decreased and intermittent hydrocortisone substitution treatment was initiated. At the 3-month follow up, Cushing's stigmata were found to be alleviated and the hydrocortisone dosage could be reduced.
  
  
  CONCLUSIONS
  Ectopic pituitary adenoma tissue causing Cushing's disease is extremely rare but a potential cause for surgical failure or re-evaluation.
authors.affiliation: Department of Neurosurgery, Bereich Hypophysenchirurgie, Neurochirurgische Klinik, University Medical Center Hamburg-Eppendorf (UKE), Martinistraße 52, 20246, Hamburg, Germany, flitsch@uke.de.
authors.forename: J
authors.initials: J
authors.lastname: Flitsch
authors.forename: S M
authors.initials: SM
authors.lastname: Schmid
authors.forename: C
authors.initials: C
authors.lastname: Bernreuther
authors.forename: B
authors.initials: B
authors.lastname: Winterberg
authors.forename: M M
authors.initials: MM
authors.lastname: Ritter
authors.forename: H
authors.initials: H
authors.lastname: Lehnert
authors.forename: T
authors.initials: T
authors.lastname: Burkhardt
mesh_terms: D000182:ACTH Syndrome, Ectopic / Q000175:diagnosis*; D049913:ACTH-Secreting Pituitary Adenoma / Q000150:complications / Q000175:diagnosis* / Q000601:surgery; D000236:Adenoma / Q000150:complications / Q000175:diagnosis* / Q000601:surgery; D001706:Biopsy; D002828:Choristoma / Q000175:diagnosis* / Q000473:pathology / Q000601:surgery; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D008279:Magnetic Resonance Imaging; D008875:Middle Aged; D010255:Paranasal Sinus Neoplasms / Q000175:diagnosis* / Q000473:pathology / Q000601:surgery; D017591:Petrosal Sinus Sampling; D047748:Pituitary ACTH Hypersecretion / Q000175:diagnosis* / Q000209:etiology / Q000601:surgery; D011237:Predictive Value of Tests; D013101:Sphenoid Sinus / Q000473:pathology / Q000601:surgery