title: [18F]fluoro-2-deoxy-D-glucose ([18F]FDG) positron emission tomography imaging of thymic carcinoid tumor presenting with recurrent Cushing's syndrome.
abstract: We report a case of a young woman with Cushing's syndrome (CS), in whom although endocrine investigations and negative pituitary imaging were suggestive of ectopic ACTH secretion, the results of inferior petrosal sinus (IPS) sampling after coricotropin-releasing hormone (CRH) stimulation were suggestive of pituitary ACTH hypersecretion. (111)In-labelled octreotide and high-resolution computer tomography (CT) revealed a lesion possibly responsible for the ACTH source in the thymus. Thymectomy confirmed concomitant ectopic CRH and probable ACTH production by a thymic neuroendocrine carcinoma. After an 8-year remission period the patient developed a clinical and biochemical relapse. A high-resolution computed tomography (CT) scan of the thorax showed a 2-cm nodule in the thymic bed, which was positive on a [(18)F]fluoro-2-deoxy-D-glucose ([(18)F]FDG) positron emission tomography (PET) scan. However, a repeated thymectomy did not result in remission. A repeat [(18)F]FDG PET study showed persistent disease in the thymic bed and also uptake in the adrenals. The patient underwent bilateral adrenalectomy, which resulted in clinical remission. A further [(18)F]FDG PET scan 8 months later showed no progression of the thymic tumor and confirmed complete excision of the adrenals. This is a rare case of concomitant CRH and ACTH secretion from a thymic carcinoid tumor; the case illustrates the usefulness of functional imaging with [(18)F]FDG PET in the diagnosis, management and follow-up of neuroendocrine tumors.
authors.affiliation: Department of Endocrinology, Middlesex Hospital, London, UK.
authors.forename: Athina
authors.initials: A
authors.lastname: Markou
authors.forename: Patrick
authors.initials: P
authors.lastname: Manning
authors.forename: Banu
authors.initials: B
authors.lastname: Kaya
authors.forename: Sam N
authors.initials: SN
authors.lastname: Datta
authors.forename: Jamshed B
authors.initials: JB
authors.lastname: Bomanji
authors.forename: Gerard S
authors.initials: GS
authors.lastname: Conway
mesh_terms: D000315:Adrenalectomy; D000324:Adrenocorticotropic Hormone / Q000378:metabolism; D000328:Adult; D002276:Carcinoid Tumor / Q000000981:diagnostic imaging* / Q000378:metabolism / Q000601:surgery; D003346:Corticotropin-Releasing Hormone; D003480:Cushing Syndrome / Q000150:complications*; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D009384:Paraneoplastic Endocrine Syndromes; D049268:Positron-Emission Tomography; D012008:Recurrence; D013934:Thymectomy; D013953:Thymus Neoplasms / Q000000981:diagnostic imaging* / Q000378:metabolism / Q000601:surgery
chemical_list: D019788:Fluorodeoxyglucose F18; D000324:Adrenocorticotropic Hormone; D003346:Corticotropin-Releasing Hormone