title: Ectopic ACTH syndrome caused by bronchial carcinoid tumor indistinguishable from Cushing's disease.
abstract: A 75-year-old woman was admitted to our hospital because of a poor glycemic control. She was found to have Cushingoid feature and dynamic endocrine tests showed elevated plasma ACTH and cortisol levels, lack of their circadian rhythm, non-suppressibility to high-dose dexamethasone, responsiveness to CRH, but not to DDAVP, and suppression to octreotide. Pituitary MRI showed an equivocal small lesion. CT scan of the chest showed two nodular lesions in the right lung (S5, S7), while a mild uptake was noted only in S5 lesion by FDG-PET, but positive uptake was only in S7 lesion by somatostatin receptor scintigraphy (SRS). Inferior petrosal sinus sampling revealed a gradient of plasma ACTH after CRH stimulation, consistent with the diagnosis of Cushing' s disease. She underwent middle and inferior lobectomy of the right lung. The resected tumor in S7 was consistent with the diagnosis of a bronchial carcinoid tumor with positive ACTH immunoreactivity, while that of S5 was cryptococcal granuloma. RT-PCR revealed abundant expressions of POMC and SSTR (-1, -2, -5), but not of CRHR and V1bR. Postoperatively, abnormal endocrine data were normalized along with improvement of hypertension and diabetes. This was a diagnostic challenging case with ectopic ACTH syndrome indistinguishable from Cushing' s disease by various endocrine and imaging tests, among which SRS successfully localized the tumor responsible for ectopic ACTH secretion.
authors.affiliation: Department of Clinical and Molecular Endocrinology, Tokyo Medical and Dental University Graduate School, Tokyo, Japan.
authors.forename: Yuji
authors.initials: Y
authors.lastname: Tani
authors.forename: Toru
authors.initials: T
authors.lastname: Sugiyama
authors.forename: Shinichi
authors.initials: S
authors.lastname: Hirooka
authors.forename: Hajime
authors.initials: H
authors.lastname: Izumiyama
authors.forename: Yukio
authors.initials: Y
authors.lastname: Hirata
mesh_terms: D000182:ACTH Syndrome, Ectopic / Q000175:diagnosis* / Q000209:etiology; D000324:Adrenocorticotropic Hormone / Q000097:blood; D000368:Aged; D001984:Bronchial Neoplasms / Q000150:complications / Q000175:diagnosis* / Q000601:surgery; D002276:Carcinoid Tumor / Q000150:complications / Q000175:diagnosis* / Q000601:surgery; D003346:Corticotropin-Releasing Hormone; D003920:Diabetes Mellitus / Q000628:therapy; D003937:Diagnosis, Differential; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D006854:Hydrocortisone / Q000097:blood; D006973:Hypertension / Q000150:complications / Q000628:therapy; D015282:Octreotide / Q000627:therapeutic use; D047748:Pituitary ACTH Hypersecretion; D049268:Positron-Emission Tomography; D011877:Radionuclide Imaging; D017481:Receptors, Somatostatin; D014057:Tomography, X-Ray Computed
chemical_list: D017481:Receptors, Somatostatin; D019788:Fluorodeoxyglucose F18; D000324:Adrenocorticotropic Hormone; D003346:Corticotropin-Releasing Hormone; D015282:Octreotide; D006854:Hydrocortisone