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Clinical, Laboratory, and Imaging Clues in the Search for the Lurking Neuroendocrine Tumor (NET)
a Summit Medical Group, Berkeley Heights, New Jersey 07922, USA b Rheumatology Division of the Hospital for Special Surgery, New York, New York 10021, USA c Hypertension Center of New York Presbyterian Hospital-Weill Cornell Medical Center, New York, New York 10021, USA d Radiology and Oncology and Director, Diagnostic Radiology and Body CT, The Russell H. Morgan Department of Radiology and Radiological Science, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21287, USA e Endocrine Oncology and Dean, Medical Faculty, Uppsala University Hospital, Uppsala, Sweden f Summit Medical Group, Oncology Department, Berkeley Heights, New Jersey 07922, USA g New York University School of Medicine, New York, New York 10016, USA h R&D, Bell Laboratories Holmdel (Ret.), Warren, New Jersey 07059 USA
Key Words: carcinoid • imaging • multidetector CT (MDCT) • catecholamines • tumor markers • pheochromocytoma
Address for correspondence: Hendricks H. Whitman III, M.D., Summit Medical Group. One Diamond Hill Road, Berkeley Heights, NJ 07922, USA. Voice: +1-908-769-2521; fax: +1-908-769-2530. e-mail: whitmanh{at}hss.edu
Catecholamine-secreting metastatic carcinoid should be considered in differential diagnosis of malignant pheochromocytoma. Paroxysmal functioning or hormonally silent gastroenteropancreatic neuroendocrine tumors (GEP NETs) require repeat biochemical measurements and sensitive anatomic and functional imaging studies overlapping those for malignant pheochromocytoma. This report presents clinical, laboratory, and radiologic findings in a patient presenting with heart rate variability; vasoactive headaches reactive to ethanol, tyramine and tryptophan; labile blood pressure; diaphoresis; diarrhea; abdominal pain; unexplained pancreatitis; joint pain; and paroxysmal flushing with pallor. GI studies (including endoscopic ultrasound) and multiple imaging modalities (including 2D CT, MRI with gadolinium, [18]FDG PET/CT, [123I]MIBG, and SRS [111In]Octreotide [OctreoScan]) were not diagnostic. 24-h BP, Holter and 30-day cardiac event monitors plus urinary biochemical studies consistently suggested catecholamine-synthesizing NET. NIH plasma metanephrines studies and [6]-[18F]Fluorodopamine PET ruled out malignant pheochromocytoma (pheo). Repeated studies showed persistently abnormal GEP NET biomarkers and urinary catecholamines. Capsule endoscopy revealed suspicious submucosal lesions throughout the small intestine. Dual-phase 64-slice multidetector computed tomography (MDCT) with 3D volumetric reconstruction of the abdomen and pelvis revealed multiple diffuse liver metastases and three extrahepatic lesions consistent with metastatic carcinoid. In combination, intensive biochemical testing repeated over time, dual-phase 64-slice MDCT with 3D image reconstruction and volume-rendering (VR) technique, and advanced radionuclide imaging are required to detect NETs' sporadic or paroxysmal functioning, rule out extra-adrenal pheochromocytoma, and localize and characterize metastatic carcinoid. If pheochromocytoma is ruled out, yet symptoms and biochemical markers for catecholamine excess are present, then carcinoid and other amine-precursor-uptake decarboxylation (APUD) tumors must remain in the differential diagnosis.
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