The patient is a 65-year-old white man with a past medical history
significant for severe coronary artery disease, arrhythmias, hypertension,
hyperlipidemia, anxiety and type 2 diabetes. He was referred to the endocrine
clinic for the evaluation of a right adrenal nodule. The adrenal mass was found
incidentally on an abdominal CT performed as part of an evaluation for
epigastric pain caused by peptic ulcer disease.
Stephanie L. Lee
The patient had an extensive history of CAD with myocardial infarctions
complicated by arrhythmias at the ages of 30 and 57. At the time of his last
MI, nine months prior to presentation, a coronary artery stent was placed. His
family history was negative for early CAD or endocrine disorders. His
medications included: lisinopril 5 mg, isosorbide (Imdur, Schering-Plough) 30
mg, amlodipine (Norvasc, Pfizer) 10 mg, and atenolol 50 mg. He was taking other
medications including diazepam 10 mg, metformin 500 mg, pantoprazole (Protonix,
Wyeth) 40 mg, dutasteride (Avodart, GlaxoSmithKline) 0.5 mg, rosuvastatin
(Crestor, AstraZeneca) 10 mg and aspirin 325 mg daily.
He reported fatigue, occasional lightheadedness when standing and
frequent palpitations over the past few years; he denied headache, sweating,
tremors, weight changes, spells, chest pain or dyspnea on exertion.
His blood pressure was at goal on his antihypertensive regimen.
On physical exam, his BP was 119 mm Hg/70 mm Hg with a pulse of 56 and
he was not orthostatic by heart rate or BP. His weight was 95 kg and BMI 29.4.
His cardiac exam was significant for bradycardia with a II/VI murmur at the
base; he had bilateral trace pretibial edema. Thyroid, pulmonary, abdominal and
neurologic exams were normal.
Twenty-four hour urine collection for catecholamines revealed an
minimally elevated norepinephrine 144 (normal 15-100 mcg/24 hr) with normal
epinephrine 12 (normal 2-24 mcg/24 hr) and dopamine 268 (52-480 mcg/24 hr)
levels. Urine metanephrines were normal with a normetanephrines 446 (normal
44-540 mcg/24 hr) and metanephrines 61 (normal 26-230 UG/24 hr). Plasma
normetanephrine levels were minimally elevated at 164 pg/ml (normal
<148). The patient was not on any medications that would cause false
elevations of catecholamines or metanephrines. The testing was done using high
performance liquid chromatography with tandem mass spectroscopy.
1: Axial CT scan of the abdomen showing a pheochromocytoma. A. The
pheochromocytoma (red arrow) located superior to the right adrenal gland has
high 15 Hounsfield units density on the non-contrast. B. The pheochromocytomas
(blue arrow) markedly enhances after intravenous contrast administration
(Hounsfield units >100).
2: Coronal images of a MRI of a pheochromocytoma. A. The pheochromocytoma
(red arrow) is dark on a T1-weighted image. B. The pheochromocytoma (blue
arrow) is hyperintense (compared to liver) on the T2-weighted image.
3: MIBG scintigraphy scan of a pheochromocytoma. MIBG accumulation (red
arrow) in a right pheochromocytoma is located inferior to the left lobe of the
liver in the posterior view. Right panel: anterior view. Left panel: posterior
Abdominal CT at an outside facility revealed a 1.9 cm x 1.9 cm right
adrenal nodule which measured 15 Hounsfield units on non-contrast CT and avidly
enhanced to greater than 100 Hounsfield units on both the arterial and portal
venous phases (Figure 1). The CT images were unavailable at the time of
presentation and therefore an MRI was done to further evaluate the right
adrenal mass. The scan revealed a T2 hyperintense, T1 hypointense right adrenal
lesion (Figure 2). The patient had a 123-I-Metaiodobenzylguanidine (MIBG) study
to further evaluate his adrenal mass. It showed a single focus of abnormal
uptake inferior to the left lobe of the liver that correlated with the
patients right adrenal nodule and was consistent with a functional
pheochromocytoma (Figure 3).
CT scans have a sensitivity of 93% to 100% of detecting an adrenal
pheochromocytoma but the sensitivity falls to 90% with extra-adrenal
pheochromocytomas. However, its specificity is poor and has been reported to be
as low as 50% in some studies because of adrenal incidentalomas.
This patients adrenal CT scan was suggestive of a pheochromocytoma
including high Hounsfield units density pre-contrast with a >10
Hounsfield units and marked enhancement of the Hounsfield units density with IV
contrast. In addition, a delay in contrast washout of <50% at 10
minutes is typical of a pheochromocytoma. MRI is similar in sensitivity to CT
scans for detecting adrenal pheochromocytomas, however, more sensitive than CT
scans for detecting extra-adrenal tumors. Like CT scan, the specificity has
been reported to be as low as 50%. This patients adrenal MRI scan was
highly suggestive of a pheochromocytoma with a high signal intensity
(hyperintense compared to liver) on T2 weighted images. The 123-I-MIBG is taken
up into the pre-synaptic adrenergic tissue in a manner similar to
norepinephrine. Therefore uptake into the adrenal gland of this agent has a
high 95 to 100% specificity for pheochromocytoma detection but its sensitivity
has been reported to be 77% to 90%. The MIBG is not as sensitive as a CT or MRI
scans and therefore cannot be used to exclude the presence of a
pheochromocytoma. But in this case, the patient was at high risk for surgery
because of his recent MI and with his minimally abnormal biochemical studies,
the functional accumulation of MIBG confirmed the diagnosis of a
pheochromocytoma prior to surgery. Generally, significantly positive
biochemical tests plus confirmation of an adrenal mass with a high T2 signal on
a MRI scan or marked enhancement after IV contrast on a CT scan is sufficient
to go forward with surgery.
The patient was started on an alpha blockade with terazosin (Hytrin,
Abbott) and continued his atenolol and other hypertensive medications. One week
prior to surgery he was started on metyrosine (Demser, Merck) which blocks the
rate limiting enzyme in the biosynthetic pathway of catecholamines to deplete
the pheochromocytoma of catecholamine stores. He underwent a laparoscopic right
adrenalectomy without complications. The pathology revealed a right 2.2 cm
pheochromocytoma with positive staining for NSE, chromogranin and
synaptophysin. Plasma metanephrines and 24 hour urine metanephrines and
catecholamines one month after surgery returned to normal.
Stephanie L. Lee, MD, PhD, is an Associate Chief in the Section of
Endocrinology, Diabetes and Nutrition and an Associate Professor of Medicine at
Boston Medical Center.
Beth Kaplan, MD, is a Fellow in Endocrinology in the Section of
Endocrinology, Diabetes and Nutrition at Boston Medical Center.
For more information:
- Francis IR, Korobkin M. Pheochromocytoma. Radiol Clin North
- Pacak, K, Linehan, WM, Eisenhofer, G, et al. Recent advances in
genetics, diagnosis, localization, and treatment of pheochromocytoma. Ann
Intern Med. 2001;134:314-329.
- Quint LE, Glazer GM, Francis IR, et al. Pheochromocytoma and
paraganglioma: comparison of MR imaging with CT and I-131 MIBG scintagraphy.
- Sawka A, et al. The Economic Implications of Three Biochemical
Screening Algorithms for Pheochromocytoma. J Clin Endo Metab.