title: Ectopic ACTH syndrome caused by desmopressin-responsive thymic neuroendocrine tumor.
abstract: A 32-year-old Chinese woman with rapid weight gain and progressive edema was found to have typical Cushingoid features. Her endocrine data were consistent with a diagnosis of ACTH-dependent Cushing's syndrome. To differentiate ectopic ACTH syndrome (EAS) from Cushing's disease (CD), various dynamic endocrine and imaging tests were performed. Her ACTH response was negative to corticotropin-releasing hormone (CRH) and positive to desmopressin. Magnetic resonance imaging of the pituitary showed no mass lesion. Computed tomography scan of the chest revealed a large mass (21 × 15 mm) in the anterior mediastinum, where positron emission tomography showed accumulation of [(18)F] fluorodeoxyglucose. Selective venous sampling showed marked step-up in ACTH level in the internal thoracic vein but not in the cavernous sinus after CRH stimulation. These data are compatible with the diagnosis of EAS. The resected tumor was pathologically consistent with thymic neuroendocrine tumor (NET) positive for ACTH by immunohistochemistry and abundant V1b receptor gene expression by RT-PCR. Postoperatively, her circulating ACTH/cortisol levels became normalized, and responded to stimulation with CRH but not with desmopressin. Her Cushingoid appearance gradually disappeared, and she was free from recurrence 5 years after surgery. This is a rare case of desmopressin-responsive EAS caused by thymic NET with predominant V1b gene expression, which was successfully localized by imaging modalities combined with selective venous sampling.
authors.affiliation: Division of Endocrinology and Diabetology, Ohme Municipal General Hospital, Ohme 198-0042, Japan.
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Sekiguchi
authors.forename: Yuki
authors.initials: Y
authors.lastname: Miyamoto
authors.forename: Ichiro
authors.initials: I
authors.lastname: Kasahara
authors.forename: Yoshihito
authors.initials: Y
authors.lastname: Hara
authors.forename: Yuji
authors.initials: Y
authors.lastname: Tani
authors.forename: Masaru
authors.initials: M
authors.lastname: Doi
authors.forename: Yukio
authors.initials: Y
authors.lastname: Hirata
mesh_terms: D000182:ACTH Syndrome, Ectopic / Q000175:diagnosis / Q000209:etiology*; D000324:Adrenocorticotropic Hormone / Q000032:analysis / Q000097:blood; D000328:Adult; D003346:Corticotropin-Releasing Hormone / Q000494:pharmacology; D003894:Deamino Arginine Vasopressin / Q000494:pharmacology*; D003937:Diagnosis, Differential; D005260:Female; D019788:Fluorodeoxyglucose F18; D015870:Gene Expression; D006801:Humans; D006854:Hydrocortisone / Q000097:blood; D018358:Neuroendocrine Tumors / Q000150:complications* / Q000175:diagnosis / Q000601:surgery; D047748:Pituitary ACTH Hypersecretion; D049268:Positron-Emission Tomography; D017483:Receptors, Vasopressin / Q000235:genetics; D013953:Thymus Neoplasms / Q000150:complications* / Q000175:diagnosis / Q000601:surgery; D014057:Tomography, X-Ray Computed
chemical_list: D017483:Receptors, Vasopressin; D019788:Fluorodeoxyglucose F18; D000324:Adrenocorticotropic Hormone; D003346:Corticotropin-Releasing Hormone; D003894:Deamino Arginine Vasopressin; D006854:Hydrocortisone