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Lateral Cervical Swellings
MahmoudSakr
10
10.1 Introduction
A neck swelling should include any mass that
presents in the neck whatever its origin is.
However, for the sake of classication, neck
swellings described in this chapter will not include
masses arising from the thyroid gland, parathyroid glands, salivary glands, pharynx, larynx, or
lymph nodes, as these entities are detailed in separate chapters. Accordingly, diseases of such
organs will be mentioned in this chapter only by
name, so that differential diagnosis is complete.
Swellings of the neck are generally categorized into midline and lateral neck swellings.
“Midline neck swellings” include those few
swellings that clinically present in the neck midline from the sub-mental triangle just below the
chin above to the supra-sternal notch below.
Swellings that do not respect this anatomical
imaginary midline are termed “lateral neck
swellings,” whether presenting in the anterior or
posterior triangle. Midline and lateral neck
swellings may be further classied as solid versus cystic, congenital versus acquired, or according to the anatomical sub-region of presentation.
It should be noted that approximately half of all
neck masses seen in a general hospital are of thyroid origin.
M. Sakr (*)
Department of Surgery, Faculty of Medicine,
Alexandria University, Alexandria, Egypt
10.2 Surgical Anatomy
From a surgical perspective, the neck is usually
divided into two triangles; the “anterior triangle”,
which consists of three and a half triangles and
the “posterior triangle”, which consists of two
triangles.
10.2.1 Anterior Triangle
10.2.1.1 Boundaries
The anterior triangle of the neck is bounded by
the anterior border of the sternocleidomastoid
(SCM) muscle posteriorly, the lower edge of the
body of the mandible superiorly (base), and the
midline of the neck anteriorly [1]. The apex of
the triangle is the supra-sternal notch, and the
oor is made by the investing layer of the deep
cervical fascia. Structures deep to the SCM muscle are considered to be inside the anterior
triangle.
10.2.1.2 Subdivisions
The anterior triangle is subdivided by the digastric muscle and the superior belly of omohyoid
muscle into three-and-half triangles; namely,
digastric (submandibular) triangle, carotid
triangle, muscular triangle, and half of the submental triangle. The midline of the neck extends
from the “symphysis menti” above to the “suprasternal notch” below (Fig.10.1).
© The Author(s), under exclusive license to Springer Nature Switzerland AG 2024
M. Sakr (ed.), Head and Neck and Endocrine Surgery,
https://doi.org/10.1007/978-3-031-64102-2_10
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207
208
Tr
Fig. 10.1 Subdivisions
of the anterior triangle
of the neck (digastric,
carotid, muscular
triangles, and half of the
submental triangle)
SCM muscle
apezius muscle
Omohyoid muscle
M. Sakr
ANTERIOR TRIANGLE
Submental triangle
Digastric triangle
Carotid triangle
Muscular triangle
10.2.1.3 Contents
Contents of the anterior triangle include muscles,
nerves, arteries, veins, and lymph nodes (LNs).
Muscles are divided as to where they lie in relation to the hyoid bone. The supra-hyoid muscles
(digastric, stylohyoid, mylohyoid, and geniohyoid) are located superior to the hyoid bone and
the infra-hyoid muscles (omohyoid, sternohyoid,
sternothyroid, and thyrohyoid) inferior to the
hyoid bone. The common carotid artery (CCA)
bifurcates within the triangle into the external
carotid artery (ECA) and internal carotid artery
(ICA). The internal jugular vein (IJV) can also be
found within this area. The cranial nerves in the
anterior triangle are the facial [VII], glossopha-
ryngeal [IX], vagus [X], accessory [XI], and
hypoglossal [XII] nerves.
10.2.2 Posterior Triangle
10.2.2.1 Boundaries
The posterior triangle of the neck is bounded by
the posterior edge of the SCM muscle anteriorly,
the anterior margin of the trapezius posterolaterally, and the superior aspect of the middlethird of the clavicle inferiorly (base of the
triangle). The apex of the triangle (superior) is
formed by the meeting of the SCM and trapezius
muscles at the superior nuchal line of the occipital bone [2].
10.2.2.2 Subdivisions
The inferior belly of the omohyoid muscle
crosses the lower part of the posterior triangle
obliquely upwards and forwards dividing it into
two subdivisions: (1) a bigger upper part (occipital triangle) and (2) a small lower part (subclavian or supraclavicular triangle) (Fig.10.2).
10.2.2.3 Contents
In the posterior triangle of the neck, the spinal
accessory nerve (SAN), phrenic nerve (C3, 4, 5),
branches of the cervical plexus, and the supraclavicular brachial plexus with its proximal
branches can be found. The apical pleura and
lung extend upwards behind the rst rib, and the
proximal subclavian artery and vein pass anterior
to it. The posterior triangle contains also the deep
cervical group of LNs [2].
Contents of the occipital triangle include the
SAN, third and fourth cervical nerves (C3, 4)
supplying branches to levator scapulae and trapezius muscles, dorsal scapular nerve (C5), four
cutaneous branches of cervical plexus, supercial transverse cervical artery, and occipital
artery.
Contents of the subclavian (supra-clavicular)
triangle include the third part of the subclavian
artery, subclavian vein, terminal part of external
jugular vein (EJV), trunks of the brachial plexus,
supercial transverse cervical, supra-scapular
and dorsal scapular arteries, and LNs.
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e
10 Lateral Cervical Swellings
Fig. 10.2 Subdivisions
of the posterior triangle
of the neck (green
color), occipital triangle
(bigger upper triangle),
and subclavian or
supra-clavicular triangle
(smaller lower triangle)
209
Posterior belly
of digastric muscle
SCM muscle
Superior belly
of omohyoid muscl
Suboccipital triangle
apezius muscle
Table 10.1 Classication of lateral neck swellings by
consistency and location
Anterior triangle Posterior triangle
Solid swellings Solid swellings
1. Lymphadenopathy
2. Thyroid gland nodule
3. Submandibular gland
swellings
4. Parotid swellings (lower
pole of the gland)
5. Swellings of the angle
of the jaw
6. Paragangliomas
(glomus tumors)
7. Schwannoma
8. Ganglioneuroma
9. Sternocleidomastoid
(SCM) tumor
10. Lipoma
Cystic swellings Cystic swellings
1. Pyogenic abscess
2. Cold abscess
3. Thyroid cyst
4. Branchial cyst
5. Plunging ranula
6. Laryngocele
7. Carotid artery
aneurysm
8. Arterio-venous stula
1. Lymphadenopathy
2. Lipoma
3. Cervical rib
1. Pyogenic abscess
2. Cold abscess
3. Retro-pharyngeal
abscess
4. Cystic hygroma
5. Pharyngeal pouch
6. Subclavian
aneurysm
7. Pneumatocele
Subclavian triangle
10.4 Solid Swellings
oftheAnterior Triangle
10.4.1 Lymphadenopathy
Enlargement of cervical LNs is the most common
cervical swelling, whether presenting in a single
or a multiple fashion. In children, cervical LNs
are enlarged mainly due to inammatory causes,
and in adults mainly due to neoplastic causes. In
adults, LNs tend to be more rm and less tender
than those usually found in the neck of children
due to recurrent upper respiratory tract infections. Cervical LN enlargement may represent a
local disease in the neck (Fig.10.3), be a part of
generalized disease as lymphoma, or reect a
metastatic disease from below the clavicles as in
the case of Virchow’s (left supra-clavicular) LNs.
Sonographic features of LNs help much in the
diagnosis of their nature. Being rounded, of irregular contour, lost echogenic hilum, lost central
and scattered peripheral vascularity, and internal
necrosis are all in favor of malignancy.
Elastography index and type of calcication if
Inferior belly
of omohyoid muscle
any are other parameters that might be included
in the sonography report. The advantages of com-
10.3 Classication
puted tomography (CT) scan in the imaging cervical LNs are the detection of extracapsular
Lateral neck swellings are summarized in
Table 10.1 according to their consistency (solid
or cystic), and their anatomical location (anterior
triangle or posterior triangle).
invasion and accurate assessment of their relation
to carotid sheath vessels. Level VII LNs are denitely assessed by CT scan much more accurately
than by US. Fine needle aspiration cytology
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210
Fig. 10.3 A 35-year-old gentleman with enlarged and
matted cervical LNs
(FNAC) is a very important tool in completing
the assessment of the patients presenting with
cervical LNs [3].
10.4.2 Thyroid Swelling
M. Sakr
Fig. 10.4 Right parotid swelling (adenolymphoma) in a
64-year-old gentleman
A thyroid swelling is characteristically mobile
with deglutition and lies in the lower part of the
front of the neck, deep to the SCM and strap
muscles.
10.4.3 Swelling oftheLower Pole
ofParotid Gland
Swellings arising from the lower pole of the
parotid gland may be present on the lateral side
of the neck, below the angle of the mandible
(Fig.10.4). This situation may give rise to diagnostic difculty and should be included in differential diagnosis of a mass in the lateral side of the
neck. A CT scan is helpful in the identication of
the parotid origin of the swelling.
10.4.4 Paragangliomas
10.4.4.1 Denition/Synonyms
Paragangliomas are “tumors that are derived
from neuroendocrine tissues in the paraganglia of
nerves” and are known to occur in the cervical,
thoracic, and abdominal para-vertebral spaces.
They may also occur in the adrenal medulla
where they are known as “pheochromocytomas.”
Tumors that are thought to be derived from parasympathetic system are nonsecretor and nonfunctional tumors, whereas those which are thought
to be derived from the sympathetic system are
generally secretor and functional ones [4].
Synonyms include chemodectoma, carotid body
tumor, and glomus cell tumor.
10.4.4.2 Site ofOrigin
Approximately, 85% of paragangliomas develop
in the abdomen, only 12% develop in the chest,
and 3% in the head and neck region. At imaging,
four sites of origin of head and neck paragangliomas may be distinguished and include carotid
body tumor (CBT), glomus vagale, glomus jugulare, and their fourth partner—glomus tympanicum [5].
Carotid paraganglioma (carotid body tumor—
CBT) is the most common and usually presents as
a painless lateral neck mass, but larger tumors may
cause cranial nerve palsies, usually of the vagus
nerve and hypoglossal nerve. Globus tympanicum
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10 Lateral Cervical Swellings
211
and glomus jugulare, also known as “jugulo-tympanic paraganglioma,” both commonly present as
a middle ear mass resulting in tinnitus (80%) and
hearing loss (60%). The cranial nerves of the jugular foramen may be compressed, resulting in dysphagia or ipsilateral weakness of the upper
trapezius and SCM muscles (from compression of
the SAN) [6]. Vagal Paragangliomas (glomus vagale) are the least common of the head and neck
paragangliomas. They usually present as a painless lateral neck mass but may result in dysphagia
and hoarseness [7].
10.4.4.3 Carotid Body Tumor (CBT)
Natural History
Carotid body tumor (CBT) is a rare “nonchromafn paraganglioma arising from the chemoreceptor cells of the carotid body (3-6 mm)
found at the postero-medial side of the carotid
bifurcation (carotid bulb)”. It responds to higher
CO2, lower O2, and acidity resulting in increased
blood pressure, heart rate, and depth and rate of
respiration. CBT shows a greater tendency to
splay the ICA and ECA and is usually benign but
can become quite large and locally malignant,
with regional metastases occurring in 20% of
cases and distant metastases rarely [8]. Carotid
body tumors have a high incidence at high altitudes (e.g., Peru, Colorado and Mexico) [9].
Chronic hypoxia leads to carotid body hyperplasia. Approximately, 10% of patients have a positive family history (autosomal dominant) [10].
Epidemiology
Carotid body tumors (CBTs) are very rare neoplasms with a prevalence of 1–2 per 100,000
population [11], constituting <0.5% of all body
tumors [12]. Although rare, CBTs represent
about 50–60% of head and neck paragangliomas
[13]. Approximately, 5% of CBTs are bilateral
and 5–10% is malignant [13], but these rates are
much higher in patients with inherited disease
[14–16].
Any age can be affected by CBTs including
children, but the average presentation is in the
fth decade [17]. There is no gender predilection
for CBTs; men and women are equally affected
except at high altitudes above 2000 m where
females appear to predominate with a female-tomale ratio of 8.3:1 [5, 17].
Etiology/Genetics
The exact cause of CBTs is not known [12, 17].
An increased incidence of CBTs in populations
living at high altitudes (>5000 ft above sea
level), and in patients with chronic obstructive
pulmonary disease (COPD) and cyanotic heart
disease suggest a role of chronic hypoxia [5, 12,
17–22].
Approximately, 75% of paragangliomas are
sporadic; the remaining 25% are hereditary, and
have an increased likelihood of being multiple
and developing at an earlier age [12]. The familial form is transmitted in an autosomal dominant
pattern [17]. Mutations of the genes for the succunate dehydrogenase have been identied as
causing familial head and neck paragangliomas.
Paragangliomas may also occur in MEN types
2A and 2B.
Pathology
Grossly, paragangliomas appear as wellcircumscribed polypoid masses that have a rm
to rubbery consistency and may have a pseudocapsule. They are highly vascular tumors and
may have a deep red color. The actual size of the
tumor may vary greatly. Some authors have
reported tumors as large as 10cm [18].
Microscopically, tumor cells are polygonal to
oval in shape, arranged in distinctive cell balls
called “Zellballen” (Type I cells), which are separated by bro-vascular stroma and surrounded by
sustentacular (supporting) cells (Type II cells)
(Fig.10.5). The tumor cells (paraganglioma cells)
are predominantly chief cells with round, hyperchromatic nuclei, a dispersed chromatin, and
abundant granular cytoplasm, which may range
from eosinophilic to basophilic in color [18].
Clinical Presentation
Symptoms
Carotid body tumors must be considered in the
evaluation of all lateral neck masses [23]. The
patient usually presents with a painless, slowly
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212
Fig. 10.5 Carotid body tumor. The tumor cells form
nests known as zellballen (type I cells) within a brovascular stroma. H&E stain
growing lump in the anterior triangle of the lateral side of the neck [12, 20, 23], neck pain, neck
asymmetry, enlarging neck mass, hoarseness, or
dysphagia [5, 12, 17].
Symptoms are generally due to local involvement of nerves and vessels [12, 23], hoarseness
with laryngeal or vagus nerve involvement, dysphagia with glossopharyngeal and hypoglossal
nerves involvement [20, 23], and Horner’s syndrome with invasion or compression of the cervical sympathetic chain [23]. CBT may also cause
symptoms such as hypertension, tachycardia,
headache, and palpitations [23, 24], and rarely,
attacks of transient cerebral ischemia (giddiness,
fainting, transient paralysis, or paresis) due to
compression of the carotid artery by the tumor
[23]. It has an association with adrenal pheochromocytoma [9].
Functional tumors (1–3% of cases) [5] can
secrete histamine, serotonin, adrenaline, and
nor- adrenaline [7, 12]. Symptoms of inappropriate catecholamine secretion (four to ve
times the normal) include labile (paroxysmal)
blood pressure, headaches, cardiac arrhythmias, weight loss, and unusual ushing or
sweating [7, 12, 17, 20]. Any recent history of
uncontrolled hypertension or tachycardia suggests a functional, catecholamine- producing
tumor [17].
M. Sakr
Clinical Examination
On physical examination, CT is usually a solitary, non-tender, rubbery mass found in the upper
part of the anterior triangle of the neck at the
common carotid artery (CCA) bifurcation, level
with the hyoid bone, deep to the cervical fascia,
and beneath the anterior edge of the SCM muscle
(Fig.10.6) [9]. The size of the tumor is variable
from 2 to 10cm. As it becomes larger it extends
upwards. It is shaped rather like a “potato” and
that is why it is termed “Potato Tumor.” It has a
smooth surface, but sometimes is bosselated,
with an indistinct edge and normal overlying skin
and normal temperature.
The tumor has a rm/rubbery consistency, is
dull to percussion, and does not uctuate. It is
xed to the carotid vessels and shows transmitted
pulsations (i.e., not pulsatile by itself) [23]. It
might sometimes show expansile pulsations from
a soft very vascular tumor, and such tumors are
also compressible, and hence rells in steps synchronous with carotid pulse. However, sometimes it is not pulsating at all. A bruit may be
present and the mass may decrease in size with
carotid compression. The CCA can be felt below
it and the ECA may pass over its supercial surface (palpable pulsations). About 30% of cases
present with a pharyngeal mass pushing the tonsil medially and anteriorly. Thus, a biopsy of a
pharyngeal swelling must never be taken from
within the mouth. It can be moved horizontally
with ease but has very little vertical mobility
(Fontaine sign) [7, 9, 12, 17, 23]. Local LNs are
not enlarged.
Careful neurological examination may reveal
decits of cranial nerves VII, IX, X, XI, or XII
[23] as cranial nerve involvement has been estimated to develop in approximately 20% of cases
[20]. Thorough evaluation for primary tumor of
the thyroid, oropharynx, and nasopharynx is
essential, since metastases to a cervical LN are a
much more frequent cause of a neck mass than
paraganglioma [23].
Investigations/Work-Up
Whenever a CBT is suspected, biopsy is contraindicated [12, 20, 23] as it may lead to profuse
bleeding and/or cranial nerve injuries [25].
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10 Lateral Cervical Swellings
Fig. 10.6 Carotid body
tumor in the anterior
triangle of the neck at
the level of hyoid bone
beneath the anterior
edge of the sternocleidomastoid (SCM)
muscle. The external
carotid artery (ECA)
may cross the surface of
the tumor
Carotid body
tumor
SCM muscle
Careful FNAC with a very narrow-gauge needle
has been described in the literature, though usually with inconclusive results [12]. The diagnostic work-up of CBT may involve one or more of
the following: Duplex US, computed tomography (CT) scan, magnetic resonance imaging
(MRI), magnetic resonance arteriography
(MRA), carotid arteriography, and serum and urinary catecholamine level assessment [20].
Carotid arteriography is the gold standard for
diagnosis. It shows the high vascular mass with
tumor blush causing splaying of carotid arteries
(lyre sign) (Fig. 10.7). It also demonstrates a
tumor circulation, cross-circulation if present,
and determines tumor extent. MRI is also useful
to determine tumor extent [22]. Currently, MRI is
performed in combination with a dynamic
contrast- enhanced MRA, which helps to diagnose or rule out additional head and neck paragangliomas [22]. Although not specic, some
CBTs are demonstrated (show uptake) by with
Meta-iodobenzyl Guanidine (
125
I-MIBG) and
octreoscan scintigraphy, and this can be useful
for assessing multiple lesions [9].
Dierential Diagnosis
The differential diagnosis of a CBT presenting
with a non-tender, lateral neck mass includes
lymphadenopathies, branchial cleft cysts, salivary
gland tumors, neurogenic tumors, and aneurysms
of the carotid artery [12, 17, 22]. In addition, other
neuroendocrine tumors such as medullary carcinoma of the thyroid and neuroendocrine carci-
213
External
carotid artery
Fig. 10.7 Angiography showing a carotid body tumor
(CBT) with separation of the internal carotid artery (ICA)
and external carotid artery (ECA) (arrows)
noma should also be included in the differential
diagnosis. A hyalinizing trabecular adenoma of
the thyroid gland should also be considered but
typically does not display neuroendocrine features on immunohistochemistry (IHC) [18].
Surgical Treatment
Metastases are exceptionally rare and the disease
is rarely fatal. Thus, the mere presence of a CBT
does not justify an attempt at removal. Provided
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214
M. Sakr
that the patient has good general health, the indications for excision of a CBT are (1) age
<50 years, (2) small- or medium-sized tumors,
(3) those extending into the palate or pharynx
interfering with swallowing, speaking or breathing, and (4) aggressive tumors (rapid growth).
Surgical removal is considered the treatment
of choice. Shambling classication [26] is used
to assess the difculty of surgical resection: class
I lesions consist of tumors easily isolated and dissected from the carotid vessels, class II lesions
are more adherent to the adventitial layer and
partially encircle the vessel at bifurcation, and
class III lesions are more densely adherent to the
carotid vessels, and completely encircle the
carotid bifurcation [20]. As described, types II
and III tumors are more likely to require carotid
resection [27].
The use of “shunts” during resection of CBTs
is controversial. Patetsios et al. (2002) believe
that familiarity with the use of intraluminal vascular shunts is critical since the vessel wall is easily damaged during sub-adventitial dissection
[23]. In their series, a temporary in-lying carotid
shunt was used routinely whenever vascular
reconstruction was required [23].
Ferreira etal. (2013), reported four cases of
CBTs resected using an “ultrasound dissector”
[28]. They reported that this technique improves
the safety of excision, decreases the technical difculties, lowers blood loss, and shortens the
operation time [28].
Preoperative Embolization
The routine use of preoperative embolization is
controversial because of the potential neurological complications associated with the accidental
reux of particulate matter into the ophthalmic or
cerebral circulation [13]. It has been used in an
attempt at decreasing tumor vascularity and
reducing intraoperative bleeding and transfusion
requirements [29]. Cobb etal. (2020) indicated
that preoperative tumor embolization provides no
benet in patients undergoing CBT resection,
nding no signicant differences in mortality,
cranial nerve injury, and blood loss between
patients who underwent embolization and those
who did not [30]. In contrast, a systematic review
of literature and meta-analysis by Texakalidis
etal. (2019) indicated that intraoperative blood
loss was signicantly lower and operative time
shorter in patients who underwent preoperative
embolization. Moreover, the investigators found
the length of stay to be similar between the two
groups [31]. In general, the apparent benet of
embolization should be weighed against the risk
of stroke. Its current use seems to be limited to
tumors greater than 5cm in diameter [20].
Intraoperative Details
The incision chosen is usually based on tumor
size and extent. Different types of cervical incisions have been described. A horizontal incision
in the mid-neck affords excellent exposure both
superiorly and inferiorly and typically provides
excellent cosmesis. Some surgeons prefer an
endarterectomy approach using a transverse cervical incision along the anterior border of the
SCM muscle. For larger tumors, many incisions
have been described, including preauricular
extension of the incision for tumors extending to
the infra-temporal fossa.
The most important step in tumor removal is
superior and inferior control of the blood vessels.
This includes identication of the IJV, CCA, and
ICA, and placing vessel loops on each. If not
involved by the tumor, the hypoglossal nerve and
vagus nerve should be exposed and followed cranially. Identication of the accessory nerve and
glosso-pharyngeal nerve is also performed; in
certain cases, the digastric muscle must be sacriced for better exposure.
The small feeding vessels, together with some
branches of the ECA, are ligated. Dissection
between the ECA and ICA exposes the larger
feeding vessels, most commonly the ascending
pharyngeal artery. This is followed by a craniocaudal dissection of the tumor from the carotid
vessels. In tumors that are identied intraoperatively as Shamblin type III, the plane of dissection can be found on either the dorsolateral side
of the ICA or the ventrolateral side of the ECA.
Dissection of the CBT is performed in the
sub-adventitial plane using either loupes or
microscope, as described by Gordon-Taylor. This
is supplemented with the use of bipolar cautery,
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10 Lateral Cervical Swellings
215
which limits blood loss and controls bleeding.
Any injury to the carotid vessel requiring clamping of the CCA or ICA needs temporary heparinization with a low risk of complications; this is
often followed by vascular reconstruction [32].
Postoperative Care andFollow-Up
In the immediate postoperative period, the patient
should be carefully observed for any complication of the procedure, including postoperative
hemorrhage or late stroke. In patients who underwent vascular reconstruction, admission to the
ICU is recommended, along with heparinization.
Patients should be closely observed for any
local recurrence, although these are usually rare.
If the patient has no morbidity from the initial
surgery, contralateral tumors should also be
resected. In patients with signicant permanent
morbidities to cranial nerves, radiation to the
contralateral side might be considered.
Complications
The highest risk of “vascular” complications is
observed in tumors larger than 5cm and/or grade
III by Shamblin classication [26]. Careful subadventitial dissection of the tumor and control of
the proximal and distal carotids minimizes vascular complications. A recent study by Kim etal.
(2017) indicated that in CBT resection, for every
1 cm reduction in tumor distance to the skull
base, the risk of a greater than 250mL blood loss
increases 1.8 times, and the risk of cranial nerve
injury increases 1.5 times [33].
The most commonly injured “nerve” is the
superior laryngeal nerve (SLN), which supplies
the cricothyroid muscle and provides sensation to
the supra-glottic larynx. The patient might suffer
postoperatively from some degree of aspiration
and inability to create high-pitched sounds.
Injury to the vagus nerve results in vocal cord
paralysis with resultant hoarseness and increased
risk of aspiration. Speech and swallowing problems result from a hypoglossal nerve injury. If the
nerve is accidentally cut, primary re-anastomosis
should be attempted rst. If this fails, then other
options include a greater auricular nerve (GAN)
graft. Postoperative shoulder pain and weakness
are typically a result of an accessory nerve injury.
This results in signicant disability for the
patient.
Radiotherapy (RT)
In general, the principal indications of radiotherapy (RT) (using
131
I-MIBG) as primary treatment
for CBTs include extensive tumors where resection would result in signicant morbidity as well
as patient-related high-risk factors such as age
and adverse medical condition [20, 34]. While,
some studies have demonstrated excellent results
with RT as primary treatment for CBTs, others
believe that RT is just palliative and best be
reserved for unresectable, multifocal tumors
[20], and metastatic disease [9, 35]. The reason is
that recurrence has been reported after initial
control in addition to the potential complications
of RT such as necrosis of the mandible, carotid
artery, and larynx [20].
10.4.4.4 Glomus Vagale
Vagal para-gangliomas arise from nests of paraganglionic tissue within the perineurium of the
vagus nerve at its ganglion nodosum, that is just
below the skull base. In large tumors, there may
be a small intracranial extension through the
foramen jugulare. Intravagal tumors, however,
are not restricted to this site and may be found at
various sites along the nerve and down to the
level of the carotid artery bifurcation.
In 50% of the patients, there is more than a
3-year history. It most commonly presents as a
slowly growing and painless mass. It is associated with pulsating tinnitus, deafness, syncope
and/or vertigo. Pharyngeal pain is a late sign indicating irritation of the pharyngeal plexus, often
preceding the onset of cranial nerve palsies. The
mass is high in the antero-lateral aspect of the
neck, often noted near the origin of the SCM
muscle with medial displacement of peri- tonsillar
structures.
The diagnosis is conrmed by arteriography
that tends to overestimate size owing to a surrounding pharyngeal plexus of veins. Surgery is
indicated for vagal para-gangliomas because of
their tendency to spread into the cranial cavity.
The approach used is that described for parapharyngeal tumors (trans-oral with mandibu-
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216
M. Sakr
lotomy with transcervical approach or
trans-parotid with transcervical one). The
numerous thin- walled veins should be dealt
with in the same way as for carotid body
tumors. The most dangerous part of the dissection is superiorly where the internal carotid
artery loops over the tumor and then immediately enters the skull. Injury is frequent at this
site and therefore the help of a vascular surgeon
is advisable [36–38].
10.4.4.5 Glomus Jugulare
The glomus jugulare arises from the nonchromafn para-ganglionic cells around the
jugular ganglion in the jugular bulb. There is
usually a similar disease bulk above and below
the skull base, in contrast to the glomus vagale.
Advanced lesions erode the skull base and
extend laterally to the middle ear cleft [36–38].
The cranial nerves of the jugular foramen may
be compressed, resulting in dysphagia or ipsilateral weakness of the upper trapezius and
SCM muscles (from compression of the SAN)
[6].
10.4.4.6 Glomus Tympanicum
Glomus tympanicum arises in the middle ear and
presents with pulsatile tinnitus and hearing loss
[36–38].
10.4.5 Schwannoma
10.4.5.1 Denition
Schwannoma (neurolimmoma or neurinoma) is a
slow-growing, well-encapsulated, benign tumor
of the neurolemma (nerve sheath of Schwann)
composed of Schwann cells, which normally produce the insulating myelin sheath covering
peripheral nerves [39]. These tumors can originate from the cranial nerves (except the optic and
olfactory nerves since they do not have a neurolemmal sheath) [40], peripheral nerves, or sympathetic nerves [31, 41–43]. Approximately,
25–45% of schwannomas originate in the headand-neck region [44] of which about 10% originate from either the vagal or sympathetic nervous
system [45].
10.4.5.2 Epidemiology
The incidence of schwannomas is reported to be
1.2/100,000 people per year. About 90% of
schwannomas are sporadic, 3% are associated
with neurobromatosis type 2 (NF2), 2% with
schwannomatosis, and 5% with meningiomatosis
with or without NF2 [46].
Schwannoma may arise at any age [47, 48],
and there is no gender or race predilection; however, Leu and Chang (2002) [49] reported the
predilection for males in their study of 52 cases.
The extra-cranial schwannomas of the head and
neck region most commonly occur in the parapharyngeal space [49, 50] and rarely in other
regions of the head and neck [51].
10.4.5.3 Pathology
Gross Appearance
Schwannoma is a homogeneous, slow-growing
tumor, usually solitary, and most lesions are
completely encapsulated so surgical removal is
often successful [31]. The tumor may either
push the nerve of origin aside and/or up against
a bony structure thereby possibly causing damage. Cut- section (Fig.10.8) is light tan and glistening and may show yellow patches and
degenerative changes such as cystic alterations
and hemorrhagic necrosis, whereas such
changes are not seen in neurobroma [40].
Schwannomas are mostly benign and <1%
become malignant, degenerating into
neurobrosarcoma.
Histopathological Appearance
Histopathologically, schwannomas comprise fascicles of Schwann cells with spindle cell morphology (Antoni A pattern) that either amalgamate
with or abruptly transition to microcytic or other
more loosely textured areas (Antoni B pattern)
(Fig.10.9) [52]. Schwann cells are usually positively immunoreactive for the cytoplasmic and
nuclear S-100 protein [52]. They are universally
S-100 positive (a marker for cells of neural crest
cell origin) and negative for the neuro-lament
protein. Histological variants of Schwannomas
include cellular, plexiform, and melanotic
Schwannomas [53].
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