Journal of Clinical Endocrinology & Metabolism, doi:10.1210/jc.2005-1989
The Journal of Clinical Endocrinology & Metabolism Vol. 91, No. 9 3271-3272
Copyright © 2006 by The Endocrine Society
IMAGE IN ENDOCRINOLOGY: Localization of an Occult Adrenocorticotropin-Secreting Carcinoid Tumor with Somatostatin Receptor Scintigraphy Using Single-Photon Emission Computed Tomography/Computed Tomographic Image Scanning
C. Waintrop,
F. Tenenbaum,
J. Coulot,
O. Vignaux,
C. Blanchet,
P. Legmann,
B. Richard and
X. Bertagna
Endocrinology (C.W., C.B., X.B.), Nuclear Medicine (C.W., F.T., J.C., B.R.), and Radiology (O.V., P.L.) Departments, Hôpital Cochin, 75014, Paris, France
Address all correspondence and requests for reprints to: Dr. Florence Tenenbaum, Service de Médecine Nucléaire, Hôpital Cochin, 27 rue du Faubourg Saint-Jacques, 75679 Paris cedex 14, France. E-mail: florence.tenenbaum{at}cch.ap-hop-paris.fr.
A 32-yr-old man was referred for evaluation of ACTH-dependent Cushing’s syndrome. Evidence for ectopic ACTH secretion included normal pituitary magnetic resonance imaging and lack of a central to peripheral gradient on bilateral inferior petrosal sinus sampling. The initial chest computed tomographic (CT) scan was interpreted as normal. The patient underwent somatostatin receptor scintigraphy (SRS) on a dual-head 
-camera (Millenium VG Hawkeye; General Electric Medical Systems, Milwaukee, WI), in which single-photon emission computed tomography (SPECT) and CT are recorded during the same examination, allowing the two images to be fused (SRS/SPECT/CT). A low-intensity uptake that was seen on SPECT acquisition only was located in the left posterior mediastinal area (Fig. 1
). A second chest CT scan, centered on the cardiac area and with cardiac gating, clearly revealed an image compatible with a neuroendocrine tumor in the same position as seen in the SRS (Fig. 2). A left inferior lobectomy was performed, and a typical 2-cm carcinoid tumor with strong immunostaining for ACTH was resected. This scintigraphic approach may lead to promising progress in a condition where small neuroendocrine tumors are often difficult to localize. Since the initial reports (1), SRS has been proposed for the diagnosis of occult tumors with ectopic ACTH secretion. Although diagnostic performance of SRS in small series of patients with neuroendocrine neoplasms have reported contradictory results (2, 3), some clinical investigators have reported patients whose tumors were detected only by SRS (4, 5). Chest CT scan should be the first imaging approach in search of a source of ectopic ACTH secretion; yet no imaging technique with a possible result should be neglected in the diagnosis of these rare tumors, SRS/SPECT/CT should be systematically proposed in occult ectopic ACTH secretion.
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FIG. 1. SRS/SPECT/CT: A, posterior static view with no visible abnormality spot; B–D, the fusion image (D) was obtained by combining CT (B) and SPECT (C) acquisitions, showing faint abnormality (arrow) in the left posterior mediastinal area, in close proximity to the heart.
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FIG. 2. Cardiac CT scan with cardiac gating, axial (left) and small axis (right). A small round hypodense image (arrows) is seen compatible with a neuroendocrine tumor on the left posterior side of the heart and correlating with the findings shown in Fig. 1 .
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Footnotes
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First Published Online May 16, 2006
Abbreviations: CT, Computed tomographic; SPECT, single-photon emission computed tomography; SRS, somatostatin receptor scintigraphy.
Received September 7, 2005.
Accepted May 5, 2006.
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References
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