DOI:10.2214/AJR.05.0370
AJR 2006; 187:492-504
© American Roentgen Ray Society
Extraadrenal Paragangliomas of the Body: Imaging Features
Ki Yeol Lee1,
Yu-Whan Oh1,
Hyung Jun Noh1,
Yu Jin Lee1,
Hwan-Seok Yong1,
Eun-Young Kang1,
Kyeong Ah Kim1 and
Nam Joon Lee1
1 All authors: Department of Radiology, Korea University Anam Hospital, College
of Medicine Korea University; #126-1, 5-Ka, Anam-Dong, Sungbuk-Ku, Seoul
136-705, Korea.
Received March 2, 2005;
accepted after revision April 29, 2005.
Address correspondence to Y.-W. Oh.
Abstract
OBJECTIVE. This article illustrates the anatomic distribution of the
healthy paraganglion system and the imaging and pathologic features of various
extraadrenal paragangliomas occurring in the head and neck, chest, and
abdomen.
CONCLUSION. Although paragangliomas can occur in a variety of
anatomic locations, the majority are seen in relatively predictable regions of
the body. Extraadrenal paragangliomas have nearly identical imaging features,
including a homogeneous or heterogeneous hyperenhancing soft-tissue mass at
CT, multiple areas of signal void interspersed with hyperintense foci
(salt-and-pepper appearance) within tumor mass at MRI, and an intense tumor
blush with enlarged feeding arteries at angiography.
Keywords: body imaging • CT • MRI • oncologic imaging • paraganglioma
Introduction
The term "paraganglioma" is a generic one applied to tumors
arising from paraganglia regardless of location
[1,
2]. The only exception is the
paraganglioma of the adrenal medulla, which is universally known as
pheochromocytoma. By extension, paragangliomas located outside the adrenal
gland have been designated as extraadrenal paragangliomas. Although these
tumors can be found in practically every site in which healthy paraganglia are
known to occur, the majority are commonly seen in specific locations: the
carotid body, jugular foramen, middle ear, aorticopulmonary region, posterior
mediastinum, and abdominal paraaortic region including Zuckerkandl's body.
Several radiologic imaging and nuclear imaging techniques are currently
available to evaluate extraadrenal paragangliomas of the body. Among these
imaging methods, the primary methods of diagnosis are anatomic imaging
techniques, including CT and MRI, and functional imaging techniques with
metaiodobenzylguanidine (MIBG) scintigraphy. Angiography is not currently used
for diagnosis alone, but it is performed preoperatively for surgical planning
and often for preoperative embolization.
In this pictorial essay, we present the anatomic locations of the healthy
paraganglion system and the imaging and pathologic features of various
extraadrenal paragangliomas occurring in the head and neck, chest, and
abdomen.
Anatomy and Physiology
Paraganglia make up a dispersed neuroendocrine system near or in the
autonomic nervous system, which has a roughly symmetric distribution with
extension from the skull base down to the pelvic floor
[1]. The most conspicuous
member of this system is known as the adrenal medulla. Extraadrenal
paraganglia, defined as paraganglia located outside the adrenal gland, can be
divided in two broad groups: paraganglia associated with the parasympathetic
system and those related to the sympathetic system
[2] (Figs.
1A and
1B). The former are located in
the head, neck, and anterior mediastinum and are believed to have a
chemoreceptor function. The latter are predominantly found in the posterior
mediastinum and retroperitoneum along the thoracolumbar paravertebral region,
and they are thought to have a similar function to that of the adrenal
medulla. In addition, small paraganglia are found within viscera such as the
urinary bladder and gallbladder.
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Fig. 1A —Drawings of paraganglion system. Drawings show anatomic
distribution of healthy extraadrenal paraganglia connected with
parasympathetic system (A) and sympathetic system (B). APP =
aorticopulmonary paraganglia, CBP = carotid body paraganglion, JTP =
jugulotympanic paraganglia, VP = vagal paraganglia.
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Fig. 1B —Drawings of paraganglion system. Drawings show anatomic
distribution of healthy extraadrenal paraganglia connected with
parasympathetic system (A) and sympathetic system (B). APP =
aorticopulmonary paraganglia, CBP = carotid body paraganglion, JTP =
jugulotympanic paraganglia, VP = vagal paraganglia.
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Microscopically, all paraganglia have a similar morphologic appearance
characterized by well-defined cell nests ("Zellballen"). Cell
nests are composed of chief cells (type 1) and encircled by a thin layer of
sustentacular cells (type 2) at the periphery of cell nests. Chief cells have
numerous membrane-bound, electron-dense granules containing catecholamines and
possibly the tryptophanic protein
[3]. Type 2 cells lack
granules, and their processes envelop type 1 cells partially or completely.
Paraganglia are highly vascularized, and their secretory type 1 cells are
intimately related to one or more fenestrated capillaries. Thus, paraganglia
have been suggested as endocrine organs producing catecholamines and proteins
and storing them as cytoplasmic granules until stimulated to release them. In
addition, these secretions may mediate a regulatory effect (paracrine action)
on nearby cells [1].
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Fig. 2 —Gross pathologic specimen obtained at surgery in 23-year-old
man with retroperitoneal paraganglioma. Photograph of resected specimen shows
meaty to light tan appearance of 5.5-cm tumor with slightly bulging surface.
Note multiple feeding vessels within tumor (arrowheads). Scale = 0.5
cm.
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Fig. 3 —Gross pathologic specimen obtained at surgery in 64-year-old
woman with retroperitoneal paraganglioma. Photograph of cut section of
specimen shows marked hemorrhage (arrowheads) within tumor. Scale =
0.5 cm.
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Fig. 4 —Microscopic appearance of carotid body tumor from 30-year-old
woman. Photomicrograph of histologic specimen shows organoid arrangement of
neoplastic chief cells (arrowhead) surrounded by highly vascularized
fibrous septa (arrows). (H and E, x400)
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Pathology
Paraganglioma is a rare neuroendocrine tumor arising from the
neuroectodermally derived paraganglionic cells scattered throughout the body
[4]. The term
"pheochromocytoma" has been used to refer to the paraganglioma of
the adrenal medulla. Paragangliomas have been reported in a variety of
anatomic sites in which healthy paraganglia are known to occur. The gross and
microscopic morphology of paragangliomas is practically the same irrespective
of location. Most tumors are rubbery, firm, and usually well demarcated with
expansile borders, ranging in diameter from only a few centimeters to 20 cm
(Fig. 2). On cross section
these tumors have a meaty to light tan appearance with a slightly bulging
surface. Hemorrhage and cystic degeneration may be extensive in some tumors
[5]
(Fig. 3). Microscopically, the
most typical pattern is an organoid or trabecular arrangement (Zellballen) of
neoplastic chief cells that is separated by highly vascularized fibrous septa
(Fig. 4). The neoplastic cells
contain myriad cytoplasmic granules that appear to be similar to those seen in
healthy paraganglia. Nuclear hyperchromasia and pleomorphism may be quite
prominent, but this is not a reliable feature to diagnose malignancy
[6]. The criteria for malignant
paraganglioma on the basis of histopathology are not well defined, except the
presence of documented metastases. A well-developed vascular network is
present in most paragangliomas, and in some tumors vascular ectasia or an
arborizing pattern may be found. Because of their hypervascular nature, biopsy
of paragangliomas can result in significant bleeding
[7]. The incidence of malignant
paragangliomas, based on extensive local invasion or metastases, varies
according to the series, from a low of 2% to a high of 36%
[8,
9]. The frequent sites of
metastases are regional lymph node, bone, liver, and lung.
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Fig. 5A —30-year-old woman with carotid body tumor. On unenhanced
(A) and contrast-enhanced (B) CT scans, hyperenhancing mass
measuring 1.2 cm in diameter (arrow) is seen in left carotid space,
where tumor is typically located between left internal carotid artery and
external carotid artery.
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Fig. 5B —30-year-old woman with carotid body tumor. On unenhanced
(A) and contrast-enhanced (B) CT scans, hyperenhancing mass
measuring 1.2 cm in diameter (arrow) is seen in left carotid space,
where tumor is typically located between left internal carotid artery and
external carotid artery.
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Clinical Manifestations
Extraadrenal paragangliomas can occur in individuals at any age, although
most arise in the fourth or fifth decades of life. There appears to be a
roughly equal sex predilection, except for glomus jugulotympanicum and vagal
paragangliomas that have a striking predilection for women.
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Fig. 6A —35-year-old man with carotid body tumor. Coronal T1-weighted
image shows tumor (arrow) of isointensity at left common carotid
bifurcation. Note multiple flow voids (arrowheads) within tumor.
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Fig. 6B —35-year-old man with carotid body tumor. Axial T2-weighted
image shows heterogeneous high signal intensity of tumor (arrow) in
left carotid space. Salt-and-pepper appearance is noted in tumor.
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Fig. 6D —35-year-old man with carotid body tumor. Lateral angiogram of
left common carotid artery shows splaying of internal carotid artery and
external carotid artery by hypervascular mass (arrow).
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Paragangliomas that are hormonally active with excess catecholamine
secretion are called functioning paragangliomas. These functioning tumors are
rare in the head and neck region but occur frequently in the thorax and
abdomen [9]. The most common
clinical presentations related to catecholamine hypersecretion include
headache, palpitations, and sweating
[10]. The cardiovascular
effects, particularly a sudden heart attack, cerebral hemorrhage, or malignant
hypertension, can be life threatening. For those patients with nonfunctioning
extraadrenal paragangliomas, the classic clinical manifestation is an
insidiously enlarging palpable mass or pain related to the local growth of a
tumor mass. In addition, approximately 10% of paragangliomas are clinically
silent and detected incidentally at imaging study during evaluation of
patients with unrelated symptoms
[11,
12].
Although most paragangliomas are solitary and arise sporadically, they can
be multicentric, and familial occurrence is well recognized. The incidence of
multicentricity for this tumor is approximately 10% of the total cases
[13]. Familial paragangliomas
constitute approximately 10% of cases, and 35-50% of cases of familial
paragangliomas have multicentric tumors
[13,
14]. Thus, a careful family
history is required, and relatives of a familial case should be screened for
paraganglioma. In general, the mode of transmission is known as an
autosomal-dominant pattern with incomplete penetrance
[15]. These familial tumors
are commonly associated with these conditions: multiple endocrine neoplasia
(MEN IIA and IIB) and neuroectodermal syndromes (tuberous sclerosis,
neurofibromatosis, and von Hippel-Lindau disease). Paragangliomas may also
occur as part of Carney's triad, which consists of gastric leiomyosarcoma,
pulmonary chondroma, and extraadrenal paraganglioma
[16].
Paragangliomas of the Head and Neck
Paragangliomas of the head and neck are closely aligned with the
distribution of the parasympathetic nervous system, and they most commonly
arise at the carotid body, followed by lesions within the jugular foramen or
middle ear and along the course of the vagus nerve, especially from the
inferior vagal ganglion [17].
In addition, these tumors are found in other less common sites including the
orbit, nasal cavity, nasopharynx, thyroid gland, larynx, pineal gland, and
cheek [18].
Carotid body and aorticopulmonary paraganglia have been shown to have a
chemoreceptor role in reflex changes in respiratory and cardiovascular
function in response to alterations in the composition of arterial blood
[19]. The physiologic function
of other paraganglia in the head and neck region remains unknown, but they
have a nearly identical histologic appearance, which suggests a similar
function in chemoreception.
Carotid Body Paragangliomas
The carotid body, the largest compact collection of paraganglia in the head
and neck, is located on the medial aspect of the carotid bifurcation on each
side of the neck. The carotid body tumor, which originates from these
paraganglionic cells, is the most common paraganglioma of the head and neck.
The average age at diagnosis is usually the fifth decade of life, and the sex
incidence is known to be nearly equal. The typical clinical presentation of a
carotid body tumor is a painless, slowly growing lateral neck mass.
On CT scans, the carotid body tumor manifests as a well-defined soft-tissue
mass within the carotid space of the infrahyoid neck (FigS.
5A and
5B). Splaying of the internal
and external carotid arteries is a distinctive imaging feature on CT, MRI, and
angiography, which is highly suggestive of a carotid body tumor
[20]. Paragangliomas including
carotid body tumors typically show homogeneous and intense enhancement after
IV administration of contrast material because of their hypervascularity.
However, large tumors are frequently inhomogeneous, with areas of both
necrosis and hemorrhage. Approximately 8% of carotid body tumors extend into
the suprahyoid neck and present clinically as a parapharyngeal space mass
[21]. On MRI, they typically
have a low to intermediate signal intensity on T1-weighted MR images and high
signal intensity on T2-weighted MR images (Figs.
6A,
6B,
6C, and
6D). The most characteristic
MR finding of paragangliomas is the presence of multiple serpentine and
punctate areas of signal void within the tumor matrix. These areas of signal
void are believed to be caused by high-velocity flow of the intratumoral
vessels [22]. The adjacent
high- and low-intensity regions of the tumor have been described as having a
"salt-and-pepper" appearance
[22]. The salt component
representing high-signal regions is because of slow flow or hemorrhage, and
the pepper component corresponds to the multiple signal voids of tumor vessels
on both T1- and T2-weighted images. The common angiographic features of
paragangliomas include marked hypervascularity, multiple enlarged feeding
arteries, dense tumor blush, and rapidly draining veins
[23]
(Fig. 6D). Angiography is no
longer performed only for diagnosis, but it is indicated for palliative or
preoperative embolization and for outlining the vascular supply before
surgical resection [17,
22].
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Fig. 7A —31-year-old woman with glomus jugulare tumor.
Contrast-enhanced axial CT scan shows left jugular foramen mass
(arrow) with irregular margins and lytic changes of surrounding
temporal bone.
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Fig. 7B —31-year-old woman with glomus jugulare tumor. Axial CT scans
obtained 5 mm (B) and 10 mm (C) cranial to A show
well-enhanced tumor mass (arrowhead) extending through jugular
foramen into posterior cranial fossa.
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Fig. 7C —31-year-old woman with glomus jugulare tumor. Axial CT scans
obtained 5 mm (B) and 10 mm (C) cranial to A show
well-enhanced tumor mass (arrowhead) extending through jugular
foramen into posterior cranial fossa.
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Fig. 8A —51-year-old woman with glomus tympanicum tumor. Axial
(A) and coronal (B) thin-section CT scans of temporal bone (bone
window) show 5-mm soft-tissue mass (arrow) filling hypotympanum of
left middle ear cavity.
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Fig. 8B —51-year-old woman with glomus tympanicum tumor. Axial
(A) and coronal (B) thin-section CT scans of temporal bone (bone
window) show 5-mm soft-tissue mass (arrow) filling hypotympanum of
left middle ear cavity.
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Glomus Jugulare Tumors
Paraganglia cells are distributed in the jugular fossa along the tympanic
branch (Jacobson's nerve) of the glossopharyngeal nerve and the auricular
branch (Arnold's nerve) of the vagus nerve. Paragangliomas arising in the
jugular foramen from Jacobson's nerve or Arnold's nerve are termed
"glomus jugulare tumors." Both glomus jugulare and glomus
tympanicum tumors are three times more common in women than in men, usually
presenting in middle age (fifth and sixth decades of life). Patients may
present with pulsatile tinnitus, hearing loss, or vertigo. A variety of
symptoms related to adjacent cranial nerves (glossopharyngeal, vagus, and
spinal accessory) involvement is seen late in the clinical course of these
lesions.
Early thin-section CT findings of glomus jugulare tumors are irregular
demineralization of the cortical outline and enlargement of the jugular
foramen. As the tumor enlarges, the moth-eaten pattern of erosion of the
jugular foramen, tympanic cavity involvement, and extensive destruction of
surrounding complex bone structures can be shown
[24] (Figs.
7A,
7B, and
7C). When a large glomus
jugulare tumor extends into the middle ear, the term "glomus
jugulotympanicum" is used
[25]. Further extension of
tumor beyond the temporal bone may involve intracranial space or infratemporal
fossa [24,
25] (Figs.
7A,
7B, and
7C). MRI is superior to CT in
showing the location and extent of these tumors. The internal jugular vein and
internal carotid artery are also better evaluated on MR images
[22]. When the patient is
considered a candidate for extensive skull base surgery, it is essential to
know precisely whether the great vessels are involved with the tumor or
not.
Glomus Tympanic Paragangliomas
The glomus tympanicum tumor is another subtype of paraganglioma occurring
in the inferior temporal bone. This tumor is defined as a paraganglioma that
arises in the middle ear from paraganglia along Jacobson's nerve near the
cochlear promontory. Patients typically present with pulsatile tinnitus or
conduction deafness. Early on, these tumors appear as a small soft-tissue
nodule classically located at the cochlear promontory and confined to the
middle ear on thin-section CT
[26] (Figs.
8A and
8B). Larger tumors fill the
tympanic cavity but typically do not cause ossicular destruction, although
encasement is frequent in these tumors
[27]. They may extend
posteriorly into the mastoid and anteriorly into the eustachian canal and
nasopharynx. Although MRI may be helpful in defining the extension of a large
tumor, most small tumors can be reliably evaluated on thin-section CT alone
[28].
Vagal Paragangliomas
Vagal paraganglioma may arise anywhere along the course of the vagus nerve
and its branches, but most commonly arise at the ganglion nodosum (inferior
ganglion) of the vagus nerve. This ganglion is the inferior one of the two
vagal ganglia and located just below the skull base. Vagal paragangliomas have
a predilection for women in the fifth and sixth decades of life. On physical
examination, the vagal paraganglioma usually presents as an asymptomatic
lateral neck mass located behind the angle of the mandible. Symptoms of vagal
nerve dysfunction such as dysphagia, hoarseness, or vocal cord paralysis
appear late in the course of the disease. These tumors are usually confined to
the parapharyngeal space, but large tumors may extend higher up through the
jugular foramen into the posterior fossa or extend down toward the carotid
bifurcation. However, in contrast to carotid body tumors, vagal paragangliomas
rarely fill the crotch of the carotid bifurcation
[29]. CT and MRI findings of
the vagal paraganglioma are similar to those of the carotid body tumor: a
well-defined ovoid parapharyngeal mass with intense contrast enhancement and
possibly a salt-and-pepper appearance (Figs.
9A,
9B,
9C, and
9D). However, vagal
paragangliomas, unlike the carotid body tumors, tend to displace both the
external carotid artery and internal carotid artery anteromedially and
commonly extend into the suprahyoid neck
[30,
31].
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Fig. 9D —37-year-old woman with vagal paraganglioma.
Gadolinium-enhanced coronal T1-weighted MR image shows enhancing tumor
extending from skull base down to level of common carotid bifurcation. Note
multiple flow voids (arrowheads) within tumor.
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Fig. 12A —23-year-old man with retroperitoneal paraganglioma arising
from organs of Zuckerkandl. Contrast-enhanced CT scan shows inhomogeneously
enhancing soft-tissue mass (arrow) located in right paraaortic area.
Note focal area of low attenuation (arrowhead) within tumor.
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Fig. 12B —23-year-old man with retroperitoneal paraganglioma arising
from organs of Zuckerkandl. Metaiodobenzylguanidine (MIBG) scintigram shows
focal area of intense radiotracer uptake (arrow) in mid abdomen.
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Fig. 13A —64-year-old woman with retroperitoneal paraganglioma.
Unenhanced (A) and enhanced (B) CT scans show 4.5-cm mass
(arrow) with heterogeneous enhancement in left paraaortic area. Note
large cystic component with fluid-fluid level (arrowhead) within
tumor mass. High attenuation of dependent fluid in cystic portion is
suggestive of intratumoral hemorrhage.
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Fig. 13B —64-year-old woman with retroperitoneal paraganglioma.
Unenhanced (A) and enhanced (B) CT scans show 4.5-cm mass
(arrow) with heterogeneous enhancement in left paraaortic area. Note
large cystic component with fluid-fluid level (arrowhead) within
tumor mass. High attenuation of dependent fluid in cystic portion is
suggestive of intratumoral hemorrhage.
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Paragangliomas of the Chest
Thoracic paragangliomas, which constitute only 1-2% of all paragangliomas
including adrenal pheochromocytomas, are found mostly in mediastinal
compartments [32]. Much less
common locations include the lung, heart, esophagus, and trachea. Mediastinal
paragangliomas can be divided into two main groups on the basis of anatomic
location and innervation: those located in the anterior mediastinum arise from
parasympathetic paraganglia, and those located in the posterior mediastinum
arise from the sympathetic chain along the paravertebral sulci
[33]. Because the former
usually arise from the aortic body chemoreceptors located in the
aorticopulmonary window, they are termed aorticopulmonary paragangliomas or
aortic body tumors [34]. The
aorticopulmonary paragangliomas usually present with an asymptomatic mass
discovered incidentally on chest radiographs, and they occur in persons older
than 40 years. In contrast with aorticopulmonary paragangliomas, the posterior
mediastinal paragangliomas occur in younger adults (mean, 29 years), and
approximately half of patients present with symptoms related to functional
activity of the tumor
[35].
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Fig. 14A —67-year-old man with duodenal gangliocytic paraganglioma.
Unenhanced (A) and contrast-enhanced (B) CT scans show
intraluminal soft-tissue mass (arrow) with hyperenhancement in second
part of duodenum.
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Fig. 14B —67-year-old man with duodenal gangliocytic paraganglioma.
Unenhanced (A) and contrast-enhanced (B) CT scans show
intraluminal soft-tissue mass (arrow) with hyperenhancement in second
part of duodenum.
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Irrespective of locations, imaging features of intrathoracic paragangliomas
are virtually identical. On CT, these tumors appear as well-enhancing masses
located in characteristic sites, either the aorticopulmonary window or the
posterior mediastinum [33]
(Figs. 10A,
10B,
11A,
11B, and
11C). Although extremely rare,
paragangliomas can occur within the pericardial sac or heart
[36]. Some tumors have
extensive hemorrhage or cystic degeneration, which results in large areas of
low attenuation at CT (Figs.
11A,
11B, and
11C). Angiography usually
shows marked hypervascularity, multiple feeding vessels, and a homogeneous
capillary blush. To reduce perioperative bleeding, embolization before surgery
should be considered if surgical excision of a bulky tumor at a difficult
location is planned [37].
Mediastinal paragangliomas show homogeneous or heterogeneous intermediate
signal intensity similar to that of liver on T1-weighted MR images. On
T2-weighted images, increased signal intensity greater than liver parenchyma
but less intense than subcutaneous fat is observed
[36,
38].
Paragangliomas of the Abdomen
Extraadrenal paragangliomas of the abdomen arise predominantly from
paraganglia located in the retroperitoneum. These paraganglia are
symmetrically distributed along the abdominal aorta and are closely related to
the sympathetic nervous system. They are known to play a role in the
production and secretion of catecholamines causing rapid physiologic changes,
and they probably represent lesser homologues of the adrenal medulla
[1]. Of the paraganglionic
tissues adjacent to the abdominal aorta, the most prominent collection is seen
near the origin of the inferior mesenteric artery, which is known as the
organs of Zuckerkandl [11,
39]. Retroperitoneal
paragangliomas affect mainly adults in the fourth or fifth decade of life,
with no sex predilection. These tumors are functional in more than half of
cases, and patients commonly present with symptoms related to excess secretion
of catecholamine, such as palpitations, headache, sweating, and hypertension
[40].
Although paragangliomas can occur anywhere in the paraaortic region, these
tumors are frequently found in the infrarenal area near the origin of the
inferior mesenteric artery, where the organs of Zuckerkandl are located
[11] (Figs.
12A and
12B). On contrast-enhanced CT
scans, these tumors appear as paraaortic soft-tissue masses with either
homogeneous enhancement or central areas of low attenuation (Figs.
12A,
12B,
13A, and
13B). Smaller tumors are more
likely to be homogeneous in attenuation and sharply marginated as compared
with larger ones [41].
Punctate calcification or focal areas of high attenuation caused by acute
hemorrhage may be seen in some tumors
[41]. These tumors are usually
hypointense or isointense compared with the liver parenchyma on T1-weighted MR
images and are markedly hyperintense on T2-weighted MR images
[42,
43]. Because of superior
tissue characterization and absence of radiation hazard, MRI is recommended as
the technique of first choice in evaluating patients with suspected
paragangliomas [42]. CT and
MRI, unlike MIBG scintigraphy, are not useful in differentiating functioning
from nonfunctioning paragangliomas. MIBG, either labeled with 123I
or 131I, is a norepinephrine analogue that follows the same
pathways as norepinephrine and is therefore avidly taken up in many
pheochromocytomas and extraadrenal paragangliomas
[44]
(Fig. 12B). MIBG scintigraphy
provides useful functional information and can be used for the detection of
multiple primary tumors, tumors outside the usual locations, or metastases
[42,
43]. MIBG scanning offers very
good specificity (95-100%) but suffers from relatively imperfect sensitivity
(85%) [45]. Because the
false-negative rate with MIBG scintigraphy is reportedly approaching 10-15%,
additional CT or MRI is recommended if, despite a high index of suspicion for
paraganglioma, a causative tumor is not found with scintigraphy
[11,
45].
Other less common locations of abdominal paragangliomas include the
gallbladder, urinary bladder, prostate, spermatic cord, uterus, and duodenum.
Among these locations, the duodenum can be a primary site for a very unusual
paraganglioma, which is referred to as a gangliocytic paraganglioma (GP). GP
has unique histologic features consisting of three cell components:
epithelioid cell nests, spindle cells, and scattered ganglionlike cells
[46]. This tumor, typically
found in the second portion of the duodenum, is either sessile or
pedunculated. Duodenal GP usually occurs in middle-age patients (mean age, 54
years) and has a slight male predominance
[47]. These tumors clinically
present with abdominal pain, gastrointestinal bleeding, or obstruction, or
they are found incidentally at endoscopy. The imaging features of duodenal GP
include an intramural or extrinsic soft-tissue mass or a pedunculated
intraluminal mass arising from the duodenum on sonographic, CT, and MR images
(Figs. 14A,
14B,
14C, and
14D). After the administration
of IV contrast material, this tumor enhances homogeneously on CT and MR images
[48].
In conclusion, extraadrenal paragangliomas can be found in practically
every site in which healthy paraganglia are known to occur, but the majority
are seen in relatively predictable regions of the body: the carotid body,
jugular foramen, middle ear, aorticopulmonary region, posterior mediastinum,
and abdominal paraaortic region including Zuckerkandl's body. Although these
tumors occur in a variety of anatomic locations, they have nearly identical
imaging features, including a homogeneous or heterogeneous hyperenhancing
soft-tissue mass at CT, multiple areas of signal void interspersed with
hyperintense foci (salt-and-pepper appearance) within tumor mass at MRI, and
an intense tumor blush with enlarged feeding arteries at angiography.
Therefore, when hypervascular masses are seen in specific locations of the
body, the possibility of paragangliomas should always be considered.
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Abstract
Introduction
