Mid-gut ACTH-secreting neuroendocrine tumor unmasked with (18)F-dihydroxyphenylalanine-positron emission tomography.

Détails

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Etat: Public
Version: Final published version
ID Serval
serval:BIB_3B86A9A9F5B2
Type
Article: article d'un périodique ou d'un magazine.
Collection
Publications
Institution
Titre
Mid-gut ACTH-secreting neuroendocrine tumor unmasked with (18)F-dihydroxyphenylalanine-positron emission tomography.
Périodique
Endocrinology, Diabetes and Metabolism Case Reports
Auteur(s)
Ducry J., Gomez F., Prior J.O., Boubaker A., Matter M., Monti M., Pu Y., Pitteloud N., Portmann L.
ISSN
2052-0573 (Electronic)
ISSN-L
2052-0573
Statut éditorial
Publié
Date de publication
2015
Peer-reviewed
Oui
Volume
2015
Pages
140104
Langue
anglais
Notes
Publication types: Journal Article
Résumé
Ectopic ACTH Cushing's syndrome (EAS) is often caused by neuroendocrine tumors (NETs) of lungs, pancreas, thymus, and other less frequent locations. Localizing the source of ACTH can be challenging. A 64-year-old man presented with rapidly progressing fatigue, muscular weakness, and dyspnea. He was in poor condition and showed facial redness, proximal amyotrophy, and bruises. Laboratory disclosed hypokalemia, metabolic alkalosis, and markedly elevated ACTH and cortisol levels. Pituitary was normal on magnetic resonance imaging (MRI), and bilateral inferior petrosal sinus blood sampling with corticotropin-releasing hormone stimulation showed no significant central-to-periphery gradient of ACTH. Head and neck, thoracic and abdominal computerized tomography (CT), MRI, somatostatin receptor scintigraphy (SSRS), and (18)F-deoxyglucose-positron emission tomography (FDG-PET) failed to identify the primary tumor. (18)F-dihydroxyphenylalanine (F-DOPA)-PET/CT unveiled a 20-mm nodule in the jejunum and a metastatic lymph node. Segmental jejunum resection showed two adjacent NETs, measuring 2.0 and 0.5 cm with a peritoneal metastasis. The largest tumor expressed ACTH in 30% of cells. Following surgery, after a transient adrenal insufficiency, ACTH and cortisol levels returned to normal values and remain normal over a follow-up of 26 months. Small mid-gut NETs are difficult to localize on CT or MRI, and require metabolic imaging. Owing to low mitotic activity, NETs are generally poor candidates for FDG-PET, whereas SSRS shows poor sensitivity in EAS due to intrinsically low tumor concentration of type-2 somatostatin receptors (SST2) or to receptor down regulation by excess cortisol. However, F-DOPA-PET, which is related to amine precursor uptake by NETs, has been reported to have high positive predictive value for occult EAS despite low sensitivity, and constitutes a useful alternative to more conventional methods of tumor localization.
LEARNING POINTS: Uncontrolled high cortisol levels in EAS can be lethal if untreated.Surgical excision is the keystone of NETs treatment, thus tumor localization is crucial.Most cases of EAS are caused by NETs, which are located mainly in the lungs. However, small gut NETs are elusive to conventional imaging and require metabolic imaging for detection.FDG-PET, based on tumor high metabolic rate, may not detect NETs that have low mitotic activity. SSRS may also fail, due to absent or low concentration of SST2, which may be down regulated by excess cortisol.F-DOPA-PET, based on amine-precursor uptake, can be a useful method to localize the occult source of ACTH in EAS when other methods have failed.
Pubmed
Open Access
Oui
Création de la notice
17/06/2015 15:17
Dernière modification de la notice
20/08/2019 14:31
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