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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_4458_Библиотеки_им_академика_М_И_Перельмана
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C. Meco and H. Basak
and orbital contents, as well as nerves, dura, brain
and cavernous sinus. MR provides crucial diagnostic key information that directly affects staging and the optimal management modality.
Combined ndings of CT and MRI alone may be
diagnostic for certain lesions.
Tumour Biopsy
Radiological features may help focus the list of
differential diagnoses, but a biopsy is usually still
be essential to reach a denitive diagnosis especially for soft tissue tumours.
Alternatively, radiological evaluation avoids
the risk of unnecessary and potentially dangerous
biopsies, either from highly vascular tumours,
like JNA, or neural lesions involving the intracranial cavity like meningoencephaloceles.
Unlike soft tissue lesions, bony lesions within
the nasal cavity can be diagnosed with reasonable
accuracy by nasal endoscopy and CT scan in the
absence of histological analysis.
Most biopsies can be performed endoscopically
transnasally and generally provide a denitive
diagnosis. Nevertheless, it should be borne in mind
that tissue samples may not be representative of the
tumour. Misleading results could arise from supercial samples or biopsy of overlying inammatory
tissue obscuring the actual pathology. Whenever
there is doubt over the histopathological typing
failing to reect the clinical and imaging ndings,
further biopsies should be taken. Consideration
should be given to whether the biopsy can be done
safely and adequately in the outpatient clinic, particularly if bleeding is likely to occur, or whether it
is more suitable in the operating theatre, and if necessary, under general anaesthesia. Another factor to
consider during tissue sampling is to restrict sampling to biopsy needs and avoid disturbing tumour
attachment areas; total resection should be reserved
for denitive surgery as sinonasal tumours are best
treated de novo, rather than treating residual or
recurrent disease l [1, 2, 4–6].
Fibro-Osseous Lesions (FOLS)
FOLS of the sinonasal cavity yield a variety of
histopathological entities. This chapter will focus
on the most common, namely, osteoma, brous
dysplasia and ossifying broma. In common, the
normal bone architecture of these proliferative
disorders or neoplasms is replaced with varying
amounts of collagen, broblasts and bone. In
general, they may present within the sinonasal
cavity from small, asymptomatic ndings to massive symptomatic lesions (Fig.31.1) resulting in
a
Fig. 31.1 Massive intranasal osteoma (*) causing nasal obstruction and right-sided maxillary mucus retention ($) (a)
Coronal CT scan, (b) axial CT scan
b
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Table 31.3 Main characteristics of bro-osseous lesions [1, 5]
Fibrous dysplasia Ossifying broma Osteoma
Incidence Not known Not known 0.43–3%
Most frequent
side of origin
Histology Replacement of the
Age of
presentation
Male-to-female
ratio
Radiology ‘Ground-glass’
Symptoms Facial asymmetry Painless swelling, nasal
Malignant
transformation
Treatment Observation; surgery
CT computed tomography
Mandible and maxilla Mandible Frontal sinus
Fibrous tissue, calcication Ivory, mature and mixed type
bone by brous tissue
First to second decades Second to fourth decades Third to fourth decades
1:1 1:5 1.5–3.1:1
appearance on CT
0.5% in polyostotic
form
only in symptomatic
cases
Expansile mass with sharp
demarcation
obstruction
Not known No reports
Observation; if possible
complete surgical resection in
extended cases
Homogenous, dense, well
circumscribed
Frontal headache
Observation in asymptomatic cases;
surgery in symptomatic patients and
complications
395
aesthetic deformities. Their key characteristics
are summarised in Table31.3 [1].
Osteoma
Osteomas are the most common sinonasal cavity
benign tumour, in which malignant transformation does not occur [7, 8]. They are present in
approximately 3% of all CT scans for sinus
symptoms [9]. The frontal sinuses are the most
common site of occurrence, followed by the ethmoid, maxillary and rarely the sphenoid sinuses
[1, 9, 10]. Even though about half of them do not
grow after initial diagnosis, the rest grow slowly
from 0.44 to 6.0 mm per year [11–13]. Whilst
they can occur at any age, most are diagnosed
between the third and fourth decades of life with
a slight male predominance (range 1.5 to 3.1
male: 1 female) [10, 14–16].
The aetiology of osteomas is debated with
developmental, traumatic and infectious theories.
Among them, the developmental theory argues
that uncontrolled bone formation is the result of
activated embryogenic stem cells that were previously silent earlier in life. On the contrary, traumatic and infectious theories propose an
inammatory process as the initiating factor in
bony tumour formation [16–18].
Osteomas have three distinct histological
types. Eburnated or ivory osteomas are composed
of a lobulated compact dense cortical bone that
contains a minimal amount of brous tissue without evidence of Haversian ducts. Osteoma spongiosum or the mature osteomas are composed of
spongy cancellous bone that are characterised by
bony trabeculae divided by conspicuous amount
of brous tissue, containing broblasts in different stages of maturation and a great number of
collagen bres, whilst the connective tissue may
often contain distended thin-walled vessels. The
third type, the mixed osteomas, contains elements from both ivory and mature types [10, 14,
18–22].
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a
Fig. 31.2 Relatively small frontal osteoma (*) (a) Coronal CT showing obstructed left frontal sinus outow tract by
osteoma causing frontal sinusitis, (b) resected surgical specimen
b
Clinical Features
Most osteomas are asymptomatic and diagnosed
as incidental radiological ndings [23], commonly found in frontal and fronto-ethmoidal
sinuses, and frontal headache and facial pain are
the most commonly associated clinical symptoms. These symptoms are a consequence of a
compromised sinus outow tract rather than the
osteoma causing pain itself. Even though
tumours may be small (Fig.31.2), the drainage
obstruction of the sinus triggers inammation
leading to chronic or recurrent acute rhinosinusitis, as well as mucus retention and mucocele
formation. Furthermore, symptoms such as
facial deformity, exophthalmia, diplopia, epiphora, blindness and intracranial complications
are likely to develop with intraorbital or intracranial expansion with encroachment of perior-
bita or dura. (Fig.31.3). If the barrier function
of dura is involved, serious intracranial complications such as cerebrospinal uid (CSF) leak,
meningitis or brain abscess, as well as an intracranial mucocele or pneumatocele, could occur.
The initial presentation of the lesion could, on
occasions, be due to the secondary effects of the
bony lesion.
If the lesion is visible within the nasal cavity,
endoscopy may reveal the rm nasal mass typically covered with normal mucosa. The CT scan
appearances may show a well-circumscribed,
very dense and homogeneous cortical lesion for
the eburnated histological type or a ground-glass
pattern with a gradually decreasing density for
the mature or spongiose histological type. Thus,
the diagnosis can be made without further imaging [24].
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a
b
Fig. 31.3 Sinonasal osteoma (*) with intraorbital extension displacing right optic nerve superiorly, (a) preoperative coronal CT scans, Red arrow—Right optic nerve,
Should multiple osteomas be present, this
could reect the rare diagnosis of Gardner syndrome. Gardner syndrome is an autosomal
dominant disease with benign skin/soft tissue
neoplasms and colorectal polyposis that requires
timely assessment due to high incidence of
malignancy.
Imaging
The origin and attachment sites of an osteoma
can normally be seen by reviewing tri-planar
CT images. This three-dimensional understand-
Yellow arrow—Left optic nerve, (b) postoperative immediate CT scan and surgical specimen after endonasal
endoscopic removal
ing is essential, especially if surgery is planned;
the osteoma should be carefully delineated to
evaluate a tailored surgical approach. However,
the lobulated nature of some osteomas and
invaginations into the contours of the sinuses
may mask the exact site of origin. In this situation, MRI imaging is recommended, especially
when the osteoma encroaches adjacent periorbita and dura. MRI denes the relationship with
critical neurovascular structures and adjacent
soft tissues (Fig.31.4) [1]. MRI is the modality
of choice during pregnancy, if proptosis occurs.
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a
b
Fig. 31.4 Sinonasal osteoma (*) with intraorbital extension displacing right optic nerve inferiorly, Red arrow—
Right optic nerve, Yellow arrow—Left optic nerve, (a)
coronal CT scan (b) coronal T2-weighted MRI scan
It can also reveal subtle ndings including heterogenous low-to-intermediate signal intensity,
in comparison to the hyper-attenuation detected
in CT scans [24].
Management ofOsteomas
The management of osteomas is based on presenting symptoms. As most small osteomas are
C. Meco and H. Basak
incidental ndings and principally slow-growing
tumours, current consensus suggests ‘watchful
waiting’ with periodic scans, typically with MRI
to reduce radiation exposure [1, 13]. Surgical
resection is indicated should there be signicant
symptoms either at the time of presentation or
during follow-up. Other indications for surgery
include rapid growth of the tumour (over 1mm
in diameter per year), even though asymptomatic. More denitive indications for surgery
include extensive invasion or encroachment
upon skull base, orbit or optic nerve, especially
if there is risk of intracranial and intraorbital
complications.
The Surgical Approach
The surgical aim of complete tumour removal
whilst preserving neighbouring neurovascular
structures and avoiding possible complications is
generally best achieved through an endonasal
endoscopic approach (EEA). However, the optimal choice of approach is determined by the
localisation, extent and attachment sites of the
disease and involved critical structures, as well as
the risk of surgical approach. This may include
an endoscopic resection (EEA), a traditional
external approach, or a combination of the two
[1, 25–30]. Additional factors to consider include
paranasal sinus anatomical variations, comorbidities that would affect the duration of surgery, the
availability of required instrumentation and
equipment and the individual surgeon’s experience. These are all key issues in case-based
decision- making, inuenced by the choice and
preferences of the patient and the surgeon.
Figure 31.5 shows a fronto-orbito-ethmoidal
osteoma case with extreme intraorbital extension
operated solely through an EEA.
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a
c
Fig. 31.5 Sinonasal fronto-orbito-ethmoidal osteoma (*)
with extreme intraorbital extension, (a) preoperative coronal CT scan, (b) specimen photo during solely endonasal
b
endoscopic resection, (c) postoperative immediate coronal CT scan
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C. Meco and H. Basak
The Endoscopic Approach
Endoscopic techniques that implement powered
instrumentation and navigation systems have
evolved to address most surgical goals for osteoma removal. Nowadays, even large lesions can
safely be resected endonasally utilising cavitation techniques that drill the core of the lesion
whilst leaving a very thin shell of bone at tumour
edges, which can then be delicately dissected and
removed from the adjacent structures [28]. The
risk of an injury to nearby structures should be
evaluated well before surgery and documented
during informed consent. Accordingly, the surgeon should be prepared to avoid or efciently
manage all potential risks, such as performing a
multilayer duraplasty for a CSF leak should this
occur during surgery. However, considering the
benign nature of osteoma with almost negligible
growth of residual osteoma, it is most important
to limit postoperative morbidity. Leaving a thin
residual shell of osteoma at critical sites, such as
overlying the optic nerve or a thin skull base,
could be a very wise option in some cases.
The frontal sinus poses a specic challenge
for EEA.Grading systems [31] for this region
have been proposed to facilitate recommendations for the optimum approach with regard to
endoscopic, external or combined surgical
resection [26]. These limitations include osteoma extension lateral to sagittal plane of lamina
papyracea, anterior and superior attachment,
intracranial and advanced intraorbital extension,
narrow (<1cm) anterior-posterior frontal sinus
diameter and over 50% obliteration or total
obliteration of the frontal sinus. However, continuously improving instrumentation such as
angled drills and navigation systems, as well as
developments in endoscopic techniques, e.g.
Draf procedures (especially Draf III), has gradually expanded the indications of EEA. In the
hands of experienced surgeons and in suitable
cases, very large osteomas lling the whole
frontal sinus can be removed endonasally. Even
far lateral frontal and supraorbital attachments
can be managed with further advanced techniques that create an endonasal corridor by suspending the periorbita inferolaterally to
temporarily transpose orbital contents away
from the surgical approach to the frontal sinus
lateral portion [32–35].
Case based decision-making should be made
to determine the feasibility of managing intracranial or intraorbital extensions through EEA, as
most dural defects can be repaired endoscopically. The major limiting factors reported are
extreme superior or lateral extension along the
posterior table, beyond the reach of current
instrumentation. For lesions located at the far lateral extreme of pneumatised frontal sinuses, EEA
can be combined with a frontal trephine or transorbital endoscopic approach if necessary [26,
35–39].
Currently, there are limited areas within the
maxillary and frontal sinuses that cannot be
effectively reached endoscopically and may
require a combined or a solely external approach.
Thus, the indications for external approaches
have receded. External approaches are still indicated when adequate access to the tumour cannot
be achieved by EEA alone, in far lateral disease,
where reconstruction of the anterior sinus wall is
needed.
External Approach Surgery
Historically, the Caldwell-Luc procedure, midfacial degloving, lateral rhinotomy, external
frontoethmoidectomy through a Lynch-Howarth
incision and osteoplastic frontal sinus (OFS)
approach through coronal incision are classic
approaches that were all used routinely [1, 5, 8,
11, 22, 23, 25–31, 35]. Recently, the transorbital
endoscopic approach with a near-invisible
blepharoplasty incision could additionally offer
more than the lateral trephination [38]. When
these techniques fall in short, OFS approach is
the approach of choice. With this approach the
whole frontal sinus, including extreme lateral
portion, can be managed perfectly with maxi-
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mum exposure. Classically, after removing the
tumour, the entire frontal sinus mucosa would
be removed, drilling out the sinus walls burred,
the frontal outow tract sealed and the sinus
obliterated by abdominal fat. Provided that the
outow pathway is kept intact, fat obliteration
may be avoided, thus maintaining a functioning
frontal sinus [11, 40]. Traditional external
approaches require skin incisions that could
increase the morbidity through a visible scar,
paraesthesia, pain or mucocele formation.
However, this should be balanced by facilitating
optimum access to large osteomas and faster
tumour resection whilst also enabling obliteration, cranialisation or CSF repair, if required.
Fibrous Dysplasia (FD)
FD is a slowly progressive disease accounting for
5% to 10% of all bone tumours that is characterised by the replacement of medullary bone by
abnormal brous tissue with different stages of
bone metaplasia; thus it rather causes deformation but rarely destruction [1, 41, 42].
It presents in 80% as monostatic (MFD) variant or less commonly as a polyostotic variant.
The MFD typically diagnosed within the rst
three decades of life. The polyostotic variant
(PFD) affects the craniofacial bones, and in particular skull base and maxillary involvement,
much more commonly (50-to-100% times more
common). A subgroup of the PFD variant is
known as McCune-Albright syndrome, and additional features include hyper-functional endocrinopathies and skin discolourations.
Whilst PFD tends to present earlier in childhood, disease progression after adolescence is
rare and minor [41, 42]. The most common
symptom is painless bony enlargement that may
lead to facial asymmetry, followed by proptosis,
diplopia, exophthalmos, vision impairment, cranial nerve compression, obstructive sinusitis and
headache.
CT images show ground-glass appearance
on remodelled bones (Fig.31.6). FD can have
<0.5% incidence of malignant transformation
[1]. Asymptomatic FD patients are best managed with watchful observation. Patients with
encasement of the optic nerve (ON) by FD
require regular ophthalmologic assessment and
long-term radiological surveillance [41–44].
Current evidence indicates that surgery has no
role to pre- emptively decompress ON in
asymptomatic patients. However, surgical
decompression should be prompt if the patient
becomes symptomatic for cranial neuropathies
and impaired vision. Surgery is also indicated
to relieve pain or address facial disgurement.
The location and extent of the disease and the
objective of surgical intervention determine
the surgical approach. Nowadays EEA is the
option of choice, especially for ON decompression. External approaches still have an
important role in correcting facial asymmetry
that may include radical excision and reconstruction (Fig.31.7) [41–45].
Fig. 31.6 Coronal CT of sinonasal brous dysplasia (*)
with ground-glass appearance involving crista galli and
anterior skull base as well as left lamina papyracea
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C. Meco and H. Basak
c
e
d
f
Fig. 31.7 Fibrous dysplasia (*) of the right maxilla causing facial asymmetry (a) Three-dimensional (3D) CT
reconstruction, (b) coronal CT scan, (c) midfacial degloving approach, status after resection and orbital oor reconstruction with titanium plate, (d) maxilla anterior wall
reconstruction with titanium plate, (e) postoperative 3D
CT reconstruction showing orbit oor reconstruction after
tumour resection, (f) postoperative 3D CT reconstruction
showing anterior maxilla anterior wall reconstruction
after tumour resection
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Ossifying Fibroma (OF)
OF is another painless expansile bro-osseous
tumour characterised by its aggressive growth,
especially in its ‘juvenile’ histological subtype
that cause contour deformity and loss of anatomical shape whilst having a high risk for recurrence
after surgical resection.
Juvenile OF is classied into psammomatoid
and trabecular lesions. The psammomatoid OF is
the most commonly encountered and typically
occurs in the sinonasal and orbital bones. The age
of onset of OF has a wider range compared to the
trabecular OF.The trabecular lesions are usually
found in the mandible.
Features include nasal obstruction, ocular
symptoms, facial deformity, proptosis, headache
and sinonasal disease. Females have 5:1 preponderance [1, 46, 47].
a
OF is seen as round to oval expansile masses
on CT, with multiple loculations and foci of calcications as well as soft tissues surrounded by
thick bony walls. The sharply dened outer margins of OF are a characteristic radiological feature for OF. The differential diagnosis includes
brous dysplasia (FD) or a malignant tumour, but
these have poorly dened margins [47]
(Fig.31.8).
The optimum treatment of OF is based on
complete surgical removal, even in the early
stage of disease, in order to avoid extensive
bone destruction due to the locally invasive
behaviour of the tumour. The surgical approach
should be tailored to achieve complete resection where possible, according to the location and extend of the OF, with the intent of
minimising the risk of recurrence [1, 2,
41–47].
b
c
Fig. 31.8 Ossifying broma (*) at left sphenoid sinus with sharply dened outside margins, (a) Axial CT scan, (b)
coronal CT scan, (c) postoperative immediate axial CT scan after endonasal endoscopic resection
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