Summary: A 67-year-old white male presented with several days’ history of
abdominal discomfort associated with some nausea and vomiting. The
patient on the day of admission had a syncopal spell while going to the
bathroom. He was brought to the hospital, where ultrasound (US) of the
abdomen showed a right adrenal mass that was further evaluated with a
computed tomography (CT) scan.
Abdominal US revealed a large heterogeneous lesion in the right
suprarenal region that arises from the adrenal gland (Figure 1). A CT
scan of the abdomen revealed a 7-cm heterogeneous right suprarenal mass
with attenuation similar to the liver (Figure 2).
Pheochromocytomas arise from the chromaffin cells of the adrenal
gland. Anatomically on CT each adrenal gland can be seen as alinear or
inverted Y- or V-shaped organ located superior, medial, and anterior to
each kidney. Several imaging modalities can be used to evaluate the
adrenal gland; these include CT, magnetic resonance imaging (MRI),
nuclear medicine, and US.
On CT, pheochromocytomas can be seen as
homogeneous or heterogeneous solid or cystic masses, possibly showing
some calcification. Most pheochromocytomas have attenuation higher than
10 Hounsfield units (HU). Rarely do they contain sufficient
intracellular fat to have an attenuation of < 10 HU, although some
pheochromocytomas may demonstrate very high attenuation due to
hemorrhage.1 The extent of attenuation of the adrenal gland
differentiates adenomas, adrenocorticocarcinomas, pheochromocytomas,and
metastases.2 Boland et al.,3 performed a
meta-analysis of 10 studies to determine an optimal threshold for
differentiating benign lesions from malignant. From this study, a
threshold of 10 HU had 71% sensitivity and 98% specificity for
characterizing adrenal masses.
On MRI, pheochromocytomas are
usually seen as hypointense or isointense relative to the liver on
T1-weighted spin-echo (SE) images, and they are highly intense on
T2-weighted SE images. The cause of this appearance is unknown, but it
likely results from the high water content in cellular homogeneous
tumors or the high water content in necrotic regions.1 Some
investigators have reported that pheochromocytomas can have atypical
signal characteristics on MRI in up to 25% of patients.3
Nuclear imaging is another study used to detect lesions that are not
adequately seen by a CT scan or MRI. Pheochromocytoma shows intense
uptake of metaiodobenzylguanidine (miBG), thus allowing for detection of
small lesions in atypical areas.
Ultrasonography is limited to the differentiation of cystic lesions from solid lesions in the adrenal gland.
Pheochromocytoma incidence could be increasing because of changes in detection methods.4 CT and MRI have resulted in more frequent and incidental detections of adrenal masses.
Pheochromocytoma, in which symptoms are not very specific and
hypertension is present in only half of patients, remains rare; it
occurs in 0.1% to 0.9% of hypertensive individuals.1
has no race predilection, occurs with equal incidence in men and
women,and commonly occurs in adults aged 20 to 40. Its clinical
presentation includes headache, palpitations and diaphoresis that can
lead to an episodic hypertensive crisis due to increased catecholamine
production. Other associated symptoms include pallor, nausea, tremor,
trembling, fatigue, anxiety, pain, and flushing.5
these symptoms are paroxysmal and may be precipitated by abdominal
exertion, such as heavy lifting or performing the Valsalva maneuver.
Some individuals can be asymptomatic, which explains why imaging studies
are useful in diagnosing these tumors. About 10% of pheochromocytomas
are malignant, bilateral, familial, and extra-adrenal. Diagnosis is
usually based on clinical presentation and imaging and biochemical
- Blake MA, Kalra MK, Maher MM, et al. Pheochromocytoma: An imaging chameleon. Radiographics. 2004;24:S87-S99.
DH, Karobkin M, Reittner P, et al. Adrenocortical carcinomas and
adrenal pheochromocytomas: Mass and enhancement loss evaluation at
delayed contrast enhanced CT. Radiology. 2005;234:479-485.
- Mayo-Smith WW, Boland GW, Noto RB, et al. State-of-the-art adrenal imaging. Radiographics. 2001;21:995.
JP, Hammer L, Mazzuco TL, et al. Circumstances of discovery of
phaeochromocytoma: A retrospective study of 41 consecutive patients. Eur J Endocrinol. 2004;150:681-686.
- Lee TH, Slywotzky CM, Lavelle MT, Garcia RA. Best cases from the AFIP: Cystic pheochromocytoma. Radiographics. 2002;22:935-940.