Nephrol Dial Transplant (2004) 19: 1004-1006
Nephrol Dial Transplant Vol. 19 No. 4 © ERA-EDTA 2004; all rights reserved
Teaching Point
(Section Editor: K. Kühn)
Supported by an educational grant from 
Labile hypertension, increased metanephrines and imaging misadventures
Vesna D. Garovic1,
Marie C. Hogan2,
Sharan K. R. Kanakiriya2,
Clive S. Grant3 and
William F. Young, Jr4
1Divisions of Hypertension and Nephrology, 2Division of Nephrology, 3Department of Surgery and 4Division of Endocrinology, Mayo Clinic, Rochester, MN, USA
Correspondence and offprint requests to: Vesna D. Garovic, Divisions of Hypertension and Nephrology, Mayo Clinic, Rochester, MN, USA. Email: Garovic.Vesna{at}Mayo.edu
Keywords: catecholamines; hypertension; paraganglioma; pheochromocytoma
 |
Introduction
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Paragangliomas arise from extra-adrenal chromaffin cells and
represent
15% of adult pheochromocytomas [
1]. Most catecholamine-secreting
paragangliomas are located in the abdomen and pelvis [
2]. [
123I]Metaiodobenzylguanidine
(MIBG) scintigraphy is commonly used to localize these tumours
and, although highly specific (95–100%), it lacks sensitivity
(77–90%) [
3]. We report a case of pelvic paraganglioma
that presented with elevated plasma and urinary metanephrine
levels and [
123I]MIBG scintigraphy suggestive of left adrenal
pheochromocytoma. Magnetic resonance imaging (MRI) of the pelvis
showed a pelvic mass that was surgically resected (histology-proven
paraganglioma), with post-operative normalization of blood pressure
and both urine and plasma metanephrines.
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Case
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This 58-year-old female with a 5-year history of hypertension
was referred to our institution for further evaluation of a
possible pheochromocytoma. One month prior to her visit, she
experienced the onset of episodic blood pressure elevations
associated with headaches, dizziness, sweating and palpitations.
Her physical examination was normal and her blood pressure was
130/80 mmHg on clonidine, 0.1 mg twice a day. Her 24 h urinary
excretion of catecholamines was normal, but the total metanephrine
excretion was 2.9 mg (normal, <1.3). The plasma normetanephrine
concentration was increased at 14.7 nmol/l (normal, <0.9).
Abdominal MRI scan demonstrated asymmetric enlargement of the
left adrenal gland 1 cm in maximum diameter. [
123I]MIBG scintigraphy
demonstrated asymmetric adrenal gland uptake (left > right).
Increased [
123I]MIBG uptake in the pelvis was interpreted as
normal urinary bladder activity (
Figure 1). Initially, left
adrenalectomy was considered, but subsequently we pursued an
evaluation for extra-adrenal catecholamine-secreting tumour
for two reasons. First, most patients with symptomatic sporadic
adrenal pheochromocytomas have tumours much larger than 1 cm
[
4]. Secondly, there can be normal asymmetry in adrenal [
123I]MIBG
uptake. Further testing included an MRI of the pelvis that revealed
a 4 cm vascular mass localized to the right side of the urinary
bladder (
Figure 2), which, in retrospect, correlated with the
area of increased pelvic uptake on [
123I]MIBG scintigraphy.
After the patient had been adequately prepared with
- and ß-adrenergic
blockade, the pelvic tumour was surgically resected (
Figure 3).
Histology confirmed the diagnosis of paraganglioma. Urinary
24 h excretion of total metanephrines and plasma normetanephrine
levels normalized post-operatively. Two years later, she remains
normotensive with normal fractionated plasma metanephrine concentrations
and urinary catecholamine and metanephrine excretion.
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Teaching point
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In a patient with elevated catecholamines or metanephrines,
the use of MIBG scintigraphy for tumour localization can be
misleading due to a normal asymmetry in uptake by the adrenal
glands. In addition, MRI scan of the adrenal glands may be helpful
in further evaluation, as most adrenal pheochromocytomas are
larger than 1 cm. Finally, increased pelvic uptake should be
carefully evaluated, especially in a patient without radiological
evidence of an adrenal tumour, because a pelvic paraganglioma
easily can be misinterpreted as normal accumulation of contrast
in the bladder.
Conflict of interest statement. None declared.
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References
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- Whalen RK, Althausen AF, Daniels GH. Extra-adrenal pheochromocytoma. J Urol 1992; 147: 1–10[ISI][Medline]
- Erickson D, Kudva YC, Ebersold MJ et al. Benign paragangliomas: clinical presentation and treatment outcomes in 236 patients. J Clin Endocrinol Metab 2001; 86: 5210–5216[Abstract/Free Full Text]
- Pacek K, Linehan WM, Eisenhofer G, Walther MM, Goldstein DS. Recent advances in genetics, diagnosis, localization, and treatment of pheochromocytoma. Ann Intern Med 2001; 134: 315–329[Abstract/Free Full Text]
- Kinney MAO, Warner ME, vanHeerden JA et al. Perianesthetic risks and outcomes of pheochromocytoma and paraganglioma resection. Anesthes Analg 2000; 91: 1118–1123[Abstract/Free Full Text]
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