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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_4434_Библиотеки_им_академика_М_И_Перельмана.pdf
Salivary Glands Tumours andIts
Surgery
8
NorhazaMat Lazim
8.1 Introduction
Salivary gland surgery is critical in the head and
neck surgical armamentarium as it involves many
vital structures involved in many of the human
basic functioning. For instance, parotid gland
surgery is intricately involved with facial nerves,
which supply the motor bres for facial muscle
of expression. Muscle of facial expression is
important for protecting the eyes, aiding the mastication process, and maintaining the facial aesthetic for social integration. Submandibular gland
disease and tumour will also cause impairment
and aesthetic embarrassment with the presence of
level Ib mass. Passing of submandibular duct
stones into the mouth vestibule causes signicant
pain. If infected, the opening of Wharton’s duct
at the oor of mouth can be inamed and discharging pus. Tumour arising from the submandibular glands, if extensive enough, may cause
skin xation, mandibular erosion, or compression on the hypoglossal nerve. Hypoglossal nerve
palsy will result in the deviation of tongue and
muscle atrophy and interfere with effective
speech and swallowing. All of these complications will interfere with patients’ daily function-
N. Mat Lazim (*)
Department of Otorhinolaryngology-Head and Neck
Surgery, School of Medical Sciences, Universiti Sains
Malaysia, Health Campus, Kubang Kerian,
Kelantan, Malaysia
e-mail: norhaza@usm.my
ing and quality of life (QOL). Sublingual gland is
rarely affected by the pathology with the exception that it is at risk of malignant tumour development. The incidence however is low.
Tumours of the salivary glands, for example,
are common and on the rise, but their aetiology
and pathophysiology are largely unknown,
despite the identication of some risk factors [1].
There are multiple risk factors that have been
identied as the risk factors for salivary gland
cancers. These risk factors display geographical
and racial difference due to the degree of exposure and familial factors that may also play additive roles. These risk factors include chemical
exposure, oncogenic viruses, familial inheritance, and genetic predisposition. Certain occupations are however associated with salivary
gland cancer including rubber product manufacturing, asbestos mining, plumbing, and some
types of woodworking [2].
Pleomorphic adenoma is the most common
benign tumour of salivary glands. It commonly
arises from the parotid glands and submandibular
glands. It accounts for 60–70% of all benign
tumours of the parotid gland. This tumour shows a
female predominance and frequently arises in
patients in the fourth to sixth decades of life [3].
The most common salivary gland neoplasm with a
variety of histologic appearances is pleomorphic
adenoma. Because of this variety, precise preoperative diagnosis via ne needle aspiration cytology is challenging [4]. The malignant salivary
© The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2022
N. Mat Lazim et al. (eds.), Head and Neck Surgery : Surgical Landmark and Dissection Guide,
https://doi.org/10.1007/978-981-19-3854-2_8
191
192
Fig. 8.1 A parotid mass at right level Ib with overlying
skin is erythematous and xed. This is a submandibular
gland carcinoma with skin inltration
N. Mat Lazim
Fig. 8.2 It is important to assess the facial nerve function
preoperatively in order to determine a specic surgical
approach for the facial nerve branches if it is inltrated by
the tumour. In this case, both the upper and lower branches
of facial nerve are intact (stars). Thus, if these facial nerve
branches can be skeletonized from the mass, it should be
preserved
Fig. 8.3 Submandibular gland is closely related to muscles like mylohyoid and hypoglossal nerve, which can be inltrated by aggressive malignant tumour
gland tumour commonly involves the submandibular glands (Fig. 8.1) and minor salivary glands.
The commonest malignancy is mucoepidermoid
carcinoma, accounting for 10–15% of cases [5].
Adenoid cystic carcinoma is the aggressive type of
salivary gland malignancy with the predilection of
lung metastases and perineural spread. Most commonly, facial nerve can be inltrated with malignant tumour from parotid glands (Fig.8.2). Other
structures like mylohyoid muscle, hypoglossal
nerve, and mandible can be affected by malignant
tumour of submandibular gland (Fig.8.3).
In otolaryngology, salivary gland surgery is a
common procedure. In benign and malignant
salivary gland tumours, parotidectomy and submandibulectomy represent the most common
forms of surgical treatment. With parotidectomy,
facial nerve identication and preservation are
vital especially in benign tumour surgery like
pleomorphic adenoma. In malignant parotid and
submandibular tumour, the facial nerve and its
branches may be involved at the initial presentation (Fig. 8.4). A lower branch like marginal
mandibular nerve paresis is commonly associated with malignancy of submandibular gland
tumour (Fig.8.5). There are, however, no guidelines for specic imaging modalities to benign
and malignant salivary gland tumours (Table8.1).
(marginal mandibula
d
8 Salivary Glands Tumours andIts Surgery
Facial nerve
(temporal branch)
Facial nerve
(zigomatic branch)
Facial nerve
(buccal branch)
Facial nerve
193
Parotid duct
Parotid gland
Fig. 8.4 Anatomical relationship of facial nerve and
parotid glands with critical adjacent structures in the neck
region is important for the conduct of safe surgery. There
are ve main peripheral branches of the nerve, temporal,
Fig. 8.5 The marginal mandibular nerve, the lower
branch of facial nerve which supplies the orbicularis oris,
is intact with the evident of symmetry of oral commissure.
In marginal mandibular nerve paresis, the lower lip of the
affected side will be elevated due to loss of depression of
depressor angular oris, which is supplied by the marginal
mandibular nerve
branch)
Facial nerve
(cervical branch)
Submandibular gland
Greater auricular nerve
Masetter muscle
Sternocleidomastoi
muscle
zygomatic, buccal, marginal mandibular, and cervical
branch, which are located beneath the supercial lobe of
parotid gland
Table 8.1 Histology of the common salivary gland
tumours
Benign Malignant
1. Pleomorphic
adenoma
Mucoepidermoid
carcinoma
2. Warthin’s tumour Acinic cell
carcinoma
3. Myoepithelioma Epithelial
myoepithelial
carcinoma
4. Basal cell adenoma Adenoid cystic
carcinoma
5. Oncocytoma Salivary duct
carcinoma
6. Cystadenoma Carcinoma ex
pleomorphic
adenoma
7. Lymphadenoma Carcinosarcoma
194
N. Mat Lazim
8.2 Clinical Presentation
ofSalivary Gland Tumour
Clinical presentation of salivary gland tumours
varies. The majority however will present with
the mass at the parotid or submandibular areas,
respectively. The associated symptoms include
pain, mass that gradually enlarges, associated
swelling at the neck, and numbness in the cervicofacial region. For instance, the carcinoma ex
pleomorphic adenoma normally presents with a
sudden increase in size of a long-standing parotid
mass [6]. This should raise the suspicion of
malignant transformation. Another presenting
feature which suggests malignancy includes
facial nerve palsy. A malignant submandibular
mass may present with the involvement of lower
branches of facial nerve like marginal mandibular nerve paresis (Fig.8.6), neck nodes, skin xation, skin ulceration, and symptoms of distant
metastases such as bone pain and haemoptysis.
During clinical examination, it is crucial to do the
sternocleidomastoid contraction (Fig. 8.7) in
order to assess the tumoural mass and its margins
to the sternomastoid muscle as well as to rule out
the inltration to the muscle.
Submandibular gland tumour may present
with different characteristics of submandibular
Fig. 8.6 A submandibular mass (arrow) at right level Ib
with minimal asymmetry of oral commissure. There is
right marginal mandibular nerve palsy as evident from the
loss of depression of right lower lip (star). The marginal
mandibular nerve supplies both the levator angular oris
and depressor angular oris, but the majority of bres
innervate the depressor angular oris
Fig. 8.7 A submandibular mass at right level Ib with extension into level Ia and II right-neck region. During clinical
examination of the neck, it is vital to perform SCM contrac-
tion and assess the inferior border of mass in relation to
SCM muscle in order to rule out SCM muscle involvement,
which necessitates resection during the neck dissection
ab
cd
8 Salivary Glands Tumours andIts Surgery
195
Fig. 8.8 Multiple presentation of submandibular
tumours. (a) Submandibular gland mass occupy level Ib
and II of right neck. (b) Anterior view showed right submandibular mass. The submandibular mass should be bal-
mass (Fig. 8.8). Importantly, if malignancy is
suspected, assessment of mandible, neck nodes,
and distant metastases should be performed as a
routine assessment.
Imaging assessment and tissue diagnostic procedures are necessary for an accurate nal diagnosis of salivary gland tumours. Ultrasound, CT
scan, MRI, and PET scan are the common imaging methods used depending on the patient’s
characteristics and requirement of tissues or
organs of involvement. CT scan and MRI are
complementary tools that provide useful information. In the majority of cases, the CT scan is
preferable as it allows assessment of the tumoural
lotable from the oor of the mouth. (c) Submandibular
mass occupy level Ib &, II, of right neck. (d) The submandibular mass view from lateral side of neck
mass and also the adjacent bony involvement,
neck node metastases, or distant metastases
(Fig.8.9). Although advanced imaging methods
such as diffusion-weighted imaging and PET-CT
aid in characterization, biopsy or excision is frequently required for denitive tissue diagnosis
[7]. In our practice, a ne needle aspiration cytology is needed to ascertain the tissue diagnosis
before embarking on any surgery as indicated.
Nowadays, surgeons have many options for
treating the benign parotid surgery depending on
the extent of the mass involvement and patient
desire. Most of the time, either partial lobectomy,
total lobectomy, or supercial parotidectomy can
196
Fig. 8.9 CT scan of right parotid gland showing a heterogenous mass (arrow) arising from the supercial lobe of parotid gland
N. Mat Lazim
be performed. Extracapsular dissection (ECD) is
one of the many surgical techniques available in
parotid surgery and, with proper training and if
used for proper indications, can achieve excellent
results.
In the majority of benign parotid surgery
cases, supercial parotidectomy represents a universal solution and should be the rst technique
that young surgeons learn. In order to select the
most appropriate surgical technique, surgeons
need to carefully consider the patient and his/her
preoperative imaging, as well as his/her own special expertise [8]. Supercial parotidectomy is
the mainstay of surgical treatment of benign
parotid tumour, which is commonly involved
with the supercial lobe of the parotid glands.
However, it is not recommended for malignant
salivary gland tumours, as total parotidectomy
should be performed.
Submandibular gland, on the other hand, has a
close relationship with multiple cranial nerves,
namely hypoglossal nerve, lingual nerve, glossopharyngeal nerve, and marginal mandibular
nerve. Both benign and malignant tumours of
submandibular glands mandate a submandibulectomy. Any surgeon performing submandibulectomy for a benign tumour should be able to
identify these nerves and preserve it in addition
to the vascular and other structure preservation.
Additionally in extensive cases, submandibular
tumour may cause oropharyngeal and airway
impairment (Fig.8.10).
Neck dissection is necessary as a treatment of
malignant salivary gland tumour. The most common neck node involvement is at levels Ia, Ib, II,
II, and IV.For submandibular malignancy, levels
I–III should be addressed, whereas for parotid
malignancy level II–IV neck nodes ipsilaterally
should be addressed.
The morbidity following such traditional surgery is well documented and includes postsurgical complications such as post-operative partial
or complete facial nerve damage, Frey’s syndrome, facial scarring, greater auricular nerve
numbness, sialocoeles, and salivary stula [9].
The incidence of facial palsy in parotid surgeries
is up to 26.7% transient and 1.7% complete facial
palsy, despite good surgical knowledge of parotid
gland anatomy and meticulous surgical technique. In cases of malignancy and revision, the
risk of facial palsy increases further [10].
Evidence of facial nerve paresis preoperatively reects facial nerve involvement by the
tumour. The surgeon might anticipate the need to
sacrice the facial nerve and should discuss with
the patient preoperatively if facial nerve needed
to be resected and grafted. If the facial nerve
function is intact preoperatively, in malignant
8 Salivary Glands Tumours andIts Surgery
197
a
Fig. 8.10 (a) CT scan image showed right submandibular gland mass with medial extension to oropharyngeal airway
(b) and abutting the thyroid cartilage (c)
cases, careful observation of the facial nerve calibre and vessel patterns by microscopes or magni-
b
8.3 Surgical Anatomy ofSalivary
Glands
c
fying loupes can give a clue to the nerve
inltration. There is no imaging modality that
can give conrmation on facial nerve inltration.
Thus, intraoperative nding is crucial in determining the facial nerve involvement and deciding
on the degree of resectability of facial nerve [11].
This is important in order to achieve better oncological outcomes for this type of tumour.
In patients with salivary gland carcinoma, distant metastases are the leading cause of treatment
failure. The locoregional recurrence is also common in aggressive histology type of tumour. For
instance, adenoid cystic carcinoma has strong
predilection for lung metastases and perineural
spread. Characteristically, the perineural spread
is a skipped lesion along the nerve, which poses
difculty in determining the free margins of the
nerve if transection of the facial nerve and grafting are planned. Survival is negatively associated
with high-grade histology, bone metastases, and
total number of distant metastases in patients
with distant metastases of salivary gland carcinoma. Metastasectomy can help to increase
disease- free survival time [12].
The major salivary glands have complex anatomical relationships with the surrounding structures,
especially with regard to the neurovascular structures. Apart from the facial nerve which lies in
close proximity with the parotid glands, the hypoglossal nerve and lingual nerve also lie intimately
with the submandibular glands. Other soft-tissue
structures are equally important. This includes the
muscles, the artery and veins, the mandible, which
are all critical when deciding the surgery for
tumour of salivary glands. This implies that any
surgeon involved in the management of salivary
gland disease should acquire a sound understanding of surgical anatomy of the salivary glands and
its surrounding structures [13].
When addressing the parotid glands, there are
several important structures that are commonly
used as surgical landmarks in identifying the
facial nerve. The facial nerve main trunk should
be rst identied during the dissection, so that
the peripheral branches can be followed and
safely preserved. Among these common landmarks are tympanomastoid suture, mastoid tip,
198
(zigomatic branch)
(cervical branch)
Temporal bone
Facial nerve
(temporal branch)
Facial nerve
Facial nerve
(buccal branch)
Facial nerve
(marginal mandibula branch)
N. Mat Lazim
Tympanomastoid suture
Facial nerve
Mastoid tip
Digastric muscle
Styloid process
Facial nerve
Fig. 8.11 Anatomical relationship of facial nerve trunk with digastric muscle, tympanomastoid suture, and mastoid tip
Fig. 8.12 Main trunk of facial nerve is located just above
the posterior belly of digastric. It divides into two main
branches, the upper temporo-zygomatic branch and the
lower cervico-marginal mandibular branch
anterior belly of digastric muscle, tragal cartilage, and styloid process (Fig.8.11).
foramen, it descends shortly before lying medial
to the anterior belly of digastric muscle and
makes it way by curving forward to branch into
two segments of upper temporo-zygomatic and
lower cervico-mandibular branch (Fig.8.12).
When the facial nerve exits the stylomastoid
8.4 Facial Nerve Surgical
Anatomy
It is known that at the stylomastoid foramen, the
facial nerve exits the skull base and then splits into
a superior temporofacial trunk and an inferior cervicofacial trunk, generally within the parotid
gland. Then these trunks divide into many tiny
rootlets, forming a parotid plexus. Ultimately,
these parotid plexus rootlets join the ve branches
classically taught: temporal, zygomatic, buccal,
mandibular marginal, and cervical. Such branches,
however, are variable and often present in duplicates or triplicates [14]. The nerve lies supercial
to the facial and retromandibular vein and facial
and maxillary artery. Its ducts arise from the anterior part of the glands and pierce the masseter
muscle (Fig.8.13) before end at the area of second
upper molar tooth in the gingivobuccal sulcus.
During parotid tumour resection, reliable preoperative facial nerve mapping may help to avoid
External jugular vein
Sternocleidomastoid
Facial nerve (marginal
8 Salivary Glands Tumours andIts Surgery
Parotid duct
Parotid gland
Masseter muscle
199
Facial nerve
(temporal branches)
Facial nerve
(zygomatic branches)
Facial nerve
(buccal branches)
mandibular branches)
muscle
Fig. 8.13 Other critical structures adjacent to facial nerve, which need to be addressed during parotidectomy (facial
artery and vein, retromandibular vein, masseter muscle, SCM, and parotid duct)
or minimize facial nerve injury. In order to perform a safe parotid surgery, precise knowledge of
facial nerve anatomy is crucial. It should be borne
in mind that variation to the normal anatomy contributes to the challenges in parotidectomy.
Although several surgical landmarks to identify
the facial nerve have been described in literature,
their position is variable, inconsistent, and difcult to follow in some cases [15]. With these differences and variation, added up with the
distortion of the nerve due to expanding tumoural
mass, the dissection requires extra diligence so as
to identify and preserve all ve main peripheral
branches of the nerve.
To help the surgeon identify the facial nerve
when performing parotid gland surgery, many
surgical landmarks have been utilized. However,
no conclusive proof exists that one landmark is
better than the rest. Based on our practice, tragal pointer is the most consistent landmark that
can be used to nd and preserve the facial nerve
trunk. This pointer is the triangular cartilage
end of the external ear canal. The facial nerve
trunk is consistently located 1.0cm medial and
deep to this pointer. During dissection, the ear
can be palpated to orientate the location of the
tragal pointer for estimation of facial nerve
trunk.
The other useful landmark is that the facial
nerve trunk was consistently positioned close to
the midpoint between the inferior mastoid tip and
the superior bony-cartilaginous junction of the
EAC [15]. By palpating the protuberance of mastoid tip, the facial nerve can be expected to lie
superiorly halfway to the bony-cartilaginous
junction of the external ear canal. The distance
between the osteocartilaginous junction and the
mastoid tip ranged from 17 to 21 mm, with a
mean of 19.5mm. The mean distances between
the osteocartilaginous junction and the facial
nerve trunk and between the mastoid tip and the
facial nerve trunk were 9.2 and 10.3mm, respectively [16].
The tympanomastoid suture is another useful
surgical landmark for nding the facial nerve
trunk. The suture of the tympanomastoid was
closest to the main trunk and was therefore
regarded as the most reliable landmark. Its average distance was 2.7mm from the main trunk of
the facial nerve [17]. The author did not recommend this surgical landmark, as by the time the
tympanomastoid suture is found, the facial
nerve might have been injured. A detailed anatomy knowledge and surgical experience are
needed if using this landmark during the
parotidectomy.
Facial nerve
(cervical branches)
200
N. Mat Lazim
In parotid surgeries, the postauricular artery
can be used as another landmark to identify the
main facial nerve trunk. In 12 cadaveric dissections, the posterior auricular artery was found to
run inferior to the facial nerve trunk, while in 2
cadaver dissections, the posterior atrial artery
was found to cross below the main facial trunk.
The mean distance between the facial nerve trunk
and the PAA ranged from 2 to 14mm. In 12 out
of 14, the stylomastoid artery was found to arise
from the posterior auricular artery, and it was
found to run medial to the trunk of the facial
nerve [10].
8.5 Roles ofImaging inParotid
Gland Surgery
Radiological imaging is essential for adequate
management of parotid gland tumour. This is
especially true in the setting of extensive tumours,
with suspicion of lymph node metastases and
adjacent tissue involvement. For benign tumours
of parotid glands such as pleomorphic adenoma,
assessment of deep lobe involvement is achieved
by performing CT scan (Fig.8.14). This is necessary as the decision for supercial parotidectomy
or total parotidectomy with facial nerve preservation should be carried out.
For malignant tumours of parotid glands, CT
scan would be ideal for the assessment of mandibular cortex erosion, presence of lymph node
involvement, masticator muscle inltration, or
skin involvement. These features are crucial for
the surgeon to decide the details of surgical
approach and discuss with the patients and family
members.
In the expert hands, MR imaging can be used
to visualize the facial nerve and the facial nerve
segments in the temporal bone in the intracranial
cisternal and canalicular portions. However, in
parotid glands, it is challenging to identify the
facial nerve on the MRI as the consistency is similar with the adjacent parotid gland tissues. Even
though the MR imaging signal and resolution are
maximized using a localized surface coil, the
Fig. 8.14 CT scan showed a homogenous mass arising from the right parotid glands with minimal deep lobe involvement (green) on the right parotid gland (arrow). The image mapping in colours for other structures’ identication