Somatostatin-Receptor Scintigraphy Identifies a Cardiac Pheochromocytoma
A17-year-old woman had paroxysmal hypertension. Very high levels of urinary catecholamines suggested a diagnosis of pheochromocytoma (urinary norepinephrine 27 600 nmol/24 hours, normal <485 nmol/24 hours; urinary normetanephrine 37 607 nmol/24 hours, normal <2000 nmol/24 hours), but no adrenal tumor was found on the abdominal CT scan. Metaiodobenzylguanidine (MIBG) whole-body scintigraphy was performed, and no abnormal uptake was observed. To locate the tumor, 111In-labeled pentetreotide somatostatin-receptor scintigraphy was performed. An intense focal uptake was seen in the thoracic area (Figure 1⇓). An intravenous injection of 99mTc microspheres was used to label the lungs. The subsequent double-isotope tomoscintigraphy located the tumor beside the right lung in the inferior mediastinum (Figure 1⇓).
ECG-gated MRI and transesophageal echocardiography gave further information about the anatomic extent of the tumor. The pheochromocytoma was located adjacent to the right atrium (Figure 2⇓).
The patient underwent surgical removal of the tumor and had an uneventful recovery, except for an atrial fibrillation that was resolved after a few weeks. This case emphasizes the value of pentetreotide scintigraphy to localize pheochromocytomas when MIBG scan and abdominal CT scan are negative.
The editor of Images in Cardiovascular Medicine is Hugh A. McAllister, Jr, MD, Chief, Department of Pathology, St Luke’s Episcopal Hospital and Texas Heart Institute, and Clinical Professor of Pathology, University of Texas Medical School and Baylor College of Medicine.
Circulation encourages readers to submit cardiovascular images to Dr Hugh A. McAllister, Jr, St Luke’s Episcopal Hospital and Texas Heart Institute, 6720 Bertner Ave, MC1-267, Houston, TX 77030.
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