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Malignant Neoplasms 175
ba
Fig. 9.15. a Schematic drawing of a naso-ethmoidal mass with intracranial extradural extent. In this setting, if the histological
type does not contraindicate surgery, anterior cranial resection is required. b Naso-ethmoidal squamous cell carcinoma (T)
causes focal invasion of the planum sphenoidale where the CSF signal is effaced. Tumor extends intracranially (arrowheads)
a
Fig. 9.16. a Schematic drawing of a naso-ethmoidal mass with intracranial intra-
dural extent. In this setting, if the histological type does not contraindicate surgery, anterior craniofacial resection is indicated. b Large naso-ethmoidal neuroendocrine carcinoma with bilateral orbital involvement, with marked displacement
of orbital muscles on right side (short arrows). Intracranial intradural invasion is
also present (long arrows). Breaking of the dura, replaced by tumor signal (white
arrows), is better shown on the sagittal enhanced T1 image (c). Adjacent thickened
dura (black arrows)
b
c
176
R. Maroldi et al.
ba
Fig. 9.17a–c. Adenocarcinoma of right ethmoid sinus with in-
tracranial intradural invasion. a On axial T2, bilateral edema of
the olfactory lobe (white arrows) raises the suspect of cerebral
invasion. On left side, an oval area with signal lower that the
edematous surrounding brain tissue effaces the bright signal
of CSF - close to the left aspect of the crista galli (black arrows).
Post-contrast sagittal images (b) demonstrate invasion of the
anterior skull base fl oor (white arrowheads) with intracranial
spread and upwards displacement of an irregularly thickened
dura (white arrows). Posterior to the area of intracranial invasion the dura is regularly thickened suggesting reactive change.
c Linear enhancement into the sulci (arrows) on both olfactory
lobes is consistent with leptomeningeal invasion. The ill-defi ned hypointensity surrounding the tumor invading the right
c
olfactory groove indicates brain invasion and edema
remodeling is not exclusively related to tumor growth,
as it may occur also in case of a mucocele secondary
to mucus drainage blockage by a neoplasm.
Furthermore, intestinal-type adenocarcinoma,
which is one of the most frequently encountered
naso-ethmoidal malignancies, has a proper fl uid
component mimicking a mucocele (Fig. 9.10, 9.11b).
Therefore, in presence of a naso-ethmoidal mass,
any solid tissue within a mucocele-like lesion should
raise the suspect of intestinal-type adenocarcinoma.
Conversely, true mucoceles should be differentiated
from fl uid-content areas of this specifi c histotype.
Meticulous attention should be paid to the evaluation of lacrimal system, particularly if epiphora is
present, as imaging is highly accurate in predicting
neoplastic invasion (89%) (Eisen et al. 2000). CT and
MR fi ndings indicating lacrimal pathways involvement
are: dilation of the lacrimal sac, lacrimal bone and/or
nasolacrimal duct walls erosion, and abnormal signal
within the duct replacing its normal mucosa.
Malignant Neoplasms 177
9.2
Adenoid Cystic Carcinoma
9.2.1
Defi nition, Epidemiology, Pattern of Growth
Adenoid cystic carcinoma accounts for 1% of all head
and neck malignancies; it occurs more frequently in
minor than in major salivary glands. In the head and
neck, the sinonasal tract is the most common localization for adenoid cystic carcinoma of the minor
salivary glands (Kim et al. 1999b). The majority of
the lesions occur in middle-aged patients; there are
very few cases below the age of 20 and over the age
of 80.
Histologically, three patterns with different distribution are recognized: cribriform, tubular, and
solid. Arrangement of tumor cells according to a
“Swiss cheese” pattern is the distinctive hallmark of
cribriform lesions, which are the most frequently observed.
Adenoid cystic carcinoma is a slow-growing but
aggressive malignancy, with a peculiar tendency
for local perineural invasion and spread along major nerves as well as along periosteal planes and for
distant metastases, which are rare at diagnosis (5%),
but occur during the course of the disease in over
50% of patients. Distant localizations mainly involve
lungs, brain, and liver and may present even 15–20
years after the initial diagnosis. Regional metastases
are instead uncommon (5%), not only at presentation
but also as a late event. Overall, only a minority of
patients is defi nitively cured on the long term.
9.2.2
Clinical and Endoscopic Findings
Due to their slow and silent growth, most adenoid
cystic carcinomas of the sinonasal tract are diagnosed at a locally advanced stage (Wiseman et al.
2002). Apart from the usual signs and symptoms
associated with malignancies of the sinonasal tract,
persistent pain in the trigeminal territory is a fi nding
occurring in 20% of patients, which should prompt
the physician to rule out the presence of an adenoid
cystic carcinoma with nerve involvement.
At endoscopy, the lesion usually appears as a mass
covered by an apparently normal mucosa, with a lobulated surface and a color varying from white to gray.
Very rarely, adenoid cystic carcinoma presents as a
polypoid mass. Macroscopically, it is very diffi cult to
assess the extent of submucosal growth.
9.2.3
Treatment Guidelines and Outcome
Surgery is the mainstay of treatment for adenoid
cystic carcinoma. Fulfi lling the oncologic principle
of achieving clear margins is more diffi cult in this
tumor than in other malignant lesions, due to its
insidious submucosal and subperiosteal growth as
well as to the tendency to spread along named nerves
even far from the site of the lesion. Therefore, the
surgeon should be aware of the need to check the
radical tumor removal with multiple frozen sections
and, possibly, to extend the resection to obtain clear
margins. This principle is even more relevant in the
sinonasal tract, where, for instance, adenoid cystic
carcinoma may invade the sphenopalatine fossa and
spread intracranially along the maxillary and vidian
nerves. Post-operative radiotherapy is commonly indicated, particularly in sinonasal localizations, with
the intent to treat residual microscopic disease. A 66
Gy dose is recommended whenever multiple margins
are positive or there is extensive soft tissue involvement (Garden et al. 1995).
Overall and disease-free survival of patients with
adenoid cystic carcinoma typically declines along the
years. In a recent report strictly focused on sinonasal
localizations, Wiseman et al. (2002) found a 5-year,
10-year, and 15-year overall survival of 65%, 55%, and
28%, respectively. Interestingly enough, sinonasal
primaries have a poorer prognosis when compared
with primaries in the major salivary glands and oral
cavity/oropharynx (Khan et al. 2001).
Treatment with radiation alone is indicated for unresectable lesions or recurrences. Fast neutron radiotherapy has been shown to give a better local-regional
control of the disease than photon beam radiotherapy
(Griffi n et al. 1988). Encouraging results have been
obtained with this technique as a post-operative adjunct even in patients who had undergone only surgical “debulking” (Douglas et al. 2000). However, base
of the skull invasion has still a negative impact on
both local-regional control and survival (Douglas et
al. 2000). Very recently, Schulz-Ertner et al. (2004)
have reported a good local-regional control on unfavorable adenoid cystic carcinomas with combined
photon and carbon ion radiotherapy.
Adenoid cystic carcinoma is considered a chemoinsensitive tumor, so that chemotherapy is only in
very rare instances indicated as a fi rst-line treatment.
However, encouraging results in the management of
recurrent adenoid cystic carcinoma have been reported by using a combination of vinorelbine and
cisplatin (Airoldi et al. 2001).
178
R. Maroldi et al.
Unlike other malignant tumors of the head and
neck, patients with adenoid cystic carcinoma may
survive for years with distant metastases, which
can be even resected in carefully selected patients.
Therefore, the presence at diagnosis of secondary lesions does not “per se” exclude to treat the primary
with a curative intent.
Advanced T stage (Spiro and Huvos 1992; Khan
et al. 2001; Mendenhall et al. 2004) and positive
margins (Garden et al. 1995; Prokopakis et al. 1999)
have been shown to have a negative impact on local
control of the disease. More controversial results
have been reported instead on histological subtype
(Khan et al. 2001) and local microscopic perineural
invasion (Vrielinck et al. 1988; Prokopakis et al.
1999). According to Garden et al. (1995) perineural
involvement was an adverse prognostic factor only
when perineural spread along a major (named) nerve
was present.
Considering the natural history of adenoid cystic
carcinoma, periodic follow up evaluations, adjusted
for stage of the disease and response to treatment,
should be extended far longer than the traditional 5year period.
9.2.4
Key Information to Be Provided by Imaging
(Kuhel et al. 1992; Beckhardt et al. 1995; Ginsberg
and DeMonte 1998). MR is the imaging technique of
choice, as its superior contrast resolution enables to
early detect signal changes due to the peculiar patterns of growth of this histotype.
However, both the CT density and the signal intensity on MR studies are non-specifi c and do not permit
to differentiate adenoid cystic carcinoma from other
malignancies (Fig. 9.18). Not even the signal intensity
of adenoid cystic carcinoma on T2 sequences ensures
to distinguish the solid subtype from the cribriform
one (Yousem et al. 2000), although initial reports
suggested (Sigal et al. 1992).
Nevertheless, adenoid cystic carcinoma may be
suspected on imaging studies when a submucosal lesion is associated with fi ndings indicating perineural
spread, particularly if the neoplasm is located in the
postero-inferior aspect of maxillary sinus and close
to the hard palate (Maroldi et al. 1999).
Though perineural spread along named nerves
may be thoroughly delineated by MR, there are two
less evident patterns of spread that require dedicated
techniques of study and meticulous images analysis: subperiosteal bone invasion and extent into fat
spaces. Both patterns arise from the tendency of adenoid cystic carcinoma to invade fat and bone similarly to lymphomas (i.e., with permeative rather than
Assessment of critical extent (particular attention
should be paid to detect perineural and subperiosteal spread) and volume of the primary lesion
(see section 9.1.6)
Presence of distant metastases
9.2.5
Imaging Findings
Imaging fi ndings of adenoid cystic carcinoma depend on its particular pattern of growth which is
characterized by early submucosal spread eventually
leading to subperiosteal bone invasion, permeative
invasion of adjacent connective spaces containing fat
tissue and muscles, and by perineural spread. In addition, adenoid cystic carcinoma has a peculiar natural
history, consisting of a protracted clinical course with
a slow but relentless rate of growth, the occurrence
of multiple recurrences, and late distant metastases
(Kim et al. 1994; Fordice et al. 1999).
The sinonasal tract may be either the site of origin
of the neoplasm or it may be invaded by a lesion arising from adjacent sites, more often the hard palate
Fig. 9.18 Adenoid cystic carcinoma of left maxillar y sinus. Postcontrast CT shows a mass with a pattern of growth similar
to an antrochoanal polyp: the tumor extends from maxillary
sinus into the nasopharynx. Nonhomogeneous enhancement
and the association of erosion and sclerosis of the residual
maxillary sinus wall suggest a tumor
Malignant Neoplasms 179
ba
Fig. 9.19a,b. Recurrent adenoid cystic carcinoma primary arising from left maxillary sinus, treated by surgery and radiation
therapy 6 years before. The patient complained of periorbital pain for two months on left side, and had left exophthalmos.
a Coronal plain T1 shows replacement of fat tissue within the masticator space (asterisk) without displacement of adjacent
pterygoid muscles. In addition, nonhomogeneous hypointensity replaces the bone marrow signal of left sphenoid bone (arrows)
(pterygoid process, greater wing, anterior clinoid, and sphenoid sinus fl oor). The cortical lining of these bony structures is not
detectable. b Administration of contrast agent causes enhancement of neoplastic tissue permeating the masticator space, of
pterygoid muscles – which maintain their organization in bundles. Enhancement of the diploic bone of the sphenoid (up to the
left clinoid) is consistent with extensive lymphomatous-like invasion. Perineural spread is demonstrated by nodular thickening
and enhancement of the third nerve (thick white arrow) and maxillary nerve (arrowhead). Irregular meningeal thickening is
present along middle cranial fossa fl oor (thin white arrows)
expansive growth. As a result, even extensive replacement of fat by the hypointense tumor may be associated with few mass-effect signs on plain SE T1. In fact,
muscles and vessels appear encased by tumor, which
shows bright enhancement after contrast agent administration (Fig. 9.19).
Moreover, plain SE T1 are particularly useful to detect bone marrow replacement by tumor. One should
carefully search for focal/diffuse hypointense areas
within medullary/diploic bone of the maxillae – particularly the alveolar process - and sphenoid – mostly
the pterygoid root, the greater and lesser wings -. If
these abnormal areas are hypointense also on TSE T2
and enhance on fat-sat T1 sequences, permeative invasion associated with sclerotic changes is suggested.
Though CT may reveal medullary bone sclerosis, its
intrinsic contrast resolution is insuffi cient to detect
bone marrow enhancement. Nevertheless, subperiosteal bone invasion and fat tissue infi ltration by
adenoid cystic carcinoma may be suspected on high
resolution CT whenever the technique shows subtle
areas of cortical bone erosion, particularly if associated with sclerosis and fat tissue effacement.
Although imaging may reveal the occurrence of
these two patterns of growth and detail the gross,
macroscopic, extent of neoplasm, very often adenoid
cystic carcinoma is characterized by extensive and
unexpected submucosal microscopic spread that either imaging techniques or careful surgical examination fail to detect, being demonstrated only by random biopsies.
9.2.5.1
Imaging to Assess Perineural Spread
Tumor extent along the peripheral nerve stroma
(neural sheath) – via endoneurium, perineurium,
or perineural lymphatics – is defi ned as perineural
spread. Although this process occurs more frequently
in a centripetal direction, toward the skull base foramina, perineural spread can extend along the opposite direction (i.e., centrifugal).
180
R. Maroldi et al.
Perineural spread should not be confused with
perineural invasion, which is the microscopic demonstration of tumor cells surrounding very small nerves
branches, namely a process beyond detectability of
radiologic imaging techniques, which is associated
with increased risk of local recurrence and decreased
survival when a major nerve is involved.
Though adenoid cystic carcinoma is very frequently associated with perineural spread, other malignant neoplasms of the head and neck may show
this pattern of growth. Among them are squamous
cell carcinomas arising from either the skin or the
mucosal epithelium, desmoplastic melanoma of the
skin, lymphoma, and virtually any salivary gland carcinoma.
The frequency of perineural spread in adenoid
cystic carcinoma is highly variable in the different
series reported in literature (15-60%) (Vrielinck
et al. 1988; Yousem et al. 2000). It is important to
note that neurological signs and symptoms (dull
pain, paresthesia) are not a reliable clue for early diagnosis of perineural spread. In fact, asymptomatic
patients may account for up to 30-45% (Sur et al.
1997; Caldemeyer et al. 1998; Tom ur a et al. 1999).
Moreover, tumor size or histological subtype should
not be considered predictors of perineural extension
as already observed by van der Wal et al. (1990). As
a result, imaging plays a prominent role in the detection of subclinical spread of adenoid cystic carcinoma along nerve structures.
A key issue to improve perineural spread detection with imaging consists in selecting technical
parameters that maximize both spatial and contrast
resolution. While on CT few parameters have to be
tailored to this purpose – as the choice of small FOV,
thin slices (1-3 mm) and high-resolution bone algorithm – more variations are possible on MR. Apart
from increasing spatial resolution similarly to CT
(small FOV and thin slices), improved contrast resolution is strongly recommended, particularly by
mean of fat-saturated T1 sequences after contrast
agent administration. In our experience, 3D VIBE
sequences provide an excellent solution by obtaining high resolution fat-saturated images in an acceptable study time.
On this sequence, the normal nerve is hypointense, clearly detectable where it is surrounded by
enhanced venous plexus, for example along bony
grooves and canals – like the inferior alveolar nerve
within the mandibular canal, the vidian, maxillary
and mandibular nerves through respective foramina,
or the hypoglossal nerve at the condylar canal. In addition, the enhanced hyperintense pterygoid plexus
helps in identifying the branching of the hypointense
mandibular nerve into its major trunks, outside the
skull base foramina (Fig. 9.20).
The purpose of high resolution MR imaging is to
demonstrate even subtle signal changes of the nerve
itself and/or to detect asymmetric thickening of the
enhanced signal surrounding the nerve.
In fact, at histology perineural spread is characterized by a chain of events that MR enables to detect earlier than CT. The progressive accumulation of
neoplastic cells around a nerve leads to an increase
of its diameter, more frequently segmental. A further
step consists in the destruction of the blood-nerve
barrier: when this occurs, extravasation of contrast
material may be observed, resulting in asymmetric
nerve enhancement. In most cases these changes are
beneath the threshold of CT detection. As the nerve
enlarges, foramina/fi ssures through which it courses
are remodeled, widened and, fi nally, eroded (Curtin
et al. 1985; Woodruff et al. 1986; Curtin 1998).
Therefore CT fi ndings of perineural spread include
widening/erosion of foramina/canals and asymmetric enhancement within the same foramina/canals
(Fig. 9.21, 9.22). Also in this setting MR is superior to
CT, as it enables to detect the neoplastic infi ltration of
medullary bone (Fig. 9.19).
Once tumor cells invade the perineural spaces,
they can grow either along a centrifugal direction (to
the periphery) or centripetally (towards skull base,
Meckel’s cave, and cavernous sinus) (Vrielinck et
al. 1988). On enhanced SE T1 and CT images, this
is refl ected by the replacement of the fl uid signal of
Meckel’s cave by solid and enhancing tissue and by
the increase of the convexity of the lateral border of
cavernous sinus.
Chronic atrophy of masticator, tongue or oral fl oor
muscles should be considered an indirect sign of
perineural spread: in such cases CT and T1 weighted
images show degeneration of denervated muscles, in
which muscular tissue has been variably replaced by
fat tissue (Fig. 9.23). Also acute and subacute denervation changes are detectable by MR (Fischbein et
al. 2001). They can be suspected in the presence of
hyperintense T2 signal, abnormal contrast enhancement and increased muscular size, which is secondary to expansion of the extracellular space. As far as
the process progresses to a chronic state, key fi ndings
of denervation are represented by fatty replacement
and volume loss of the muscle.
Two factors may be advocated to explain MR false
negative results, namely the presence of skip lesions
and the resurfacing phenomenon (Ginsberg et al.
1996; Ginsberg 1999; Rice 1999; Ginsberg 2002).
Malignant Neoplasms 181
a
d
b
e
c
Fig. 9.20a-e. Adenoid cystic carcinoma
of right maxillary sinus. Five different
axial levels from enhanced VIBE sequence, isotropic voxels of .5 mm. The
inferior alveolar nerve is demonstrated
(black arrow) as an oval hypointense
structure surrounded by an enhanced
venous pterygoid plexus. Two other
branches of the mandibular are shown
below the foramen ovale (arrowheads).
Hypoglossal nerve (white arrows)
Actually, microscopic tumor nests along the course of
a nerve are undetected because below the threshold
of MR imaging (Pa r k e r and Harnsberger 1991;
Caldemeyer et al. 1998). Therefore, MR may show a
discontinuity of perineural spread along the course of
a nerve (skip lesions) as well as resurfacing of tumor
immediately distal to a foramen or canal (resurfacing
phenomenon). The last is secondary to compression
of nerve and perineural tumor by the surrounding
bone. For these reasons, nerve structures should be
carefully scrutinized, both at preoperative MR and
during surgery, along their entire course to decrease
the risk of underestimation of tumor extension
(Maroldi et al. 1999).
182
a b
R. Maroldi et al.
c
In addition, false positive MR fi ndings may occur
when nerve enhancement is detected. Actually, the
blood-nerve barrier may be disrupted in several conditions such as infl ammation (this may hamper postsurgical and post-RT evaluation), demyelination,
axonal degeneration, ischemia and trauma (Nemzek
et al. 1998).
Fig. 9.21a–c. Adenoid cystic carcinoma of right maxillary sinus. Same case as Fig. 9.20. a From right maxillary sinus the
adenoid cystic carcinoma extends into fat tissue of masticator
space (1), buccal fat pad and premaxillary tissue (2). Posterior
invasion leads to involvement of both pterygoid muscles (3).
The tumor spreads into the pterygopalatine fossa replacing
fat tissue (black arrowhead); while on left side both fat and
vessels are clearly shown within the fossa (white arrowhead).
Enhancing tumor with plaque-like shape spreading into the
nasopharynx is also present (4). b Tumor extends into the
upper pterygopalatine fossa (asterisk), from which it spreads
along the vidian (1) and maxillary nerves (2). Replacement
of the liquid signal of the right Meckel cave indicates perineural extent reaching the trigeminal ganglion (3). Bone marrow enhancement within the right pterygoid process suggests
possible permeative invasion. Laterally the adenoid cystic
carcinoma invades the masticator space (arrowheads). c The
neoplasm extends into the orbital apex (black arrowheads),
and onto the orbital (white arrowheads) and the intracranial
(white arrows) surfaces of the greater sphenoid wing
Beyond identifying the presence of perineural
spread, MR is also expected to provide a precise
map of all neural structures involved in each patient.
Nemzek et al. (1998) obtained an accuracy of 63% for
the complete mapping of perineural spread. In their
series MR underestimation was in most cases related
to the presence of skip lesions.
Malignant Neoplasms 183
a
c d
b
Fig. 9.22a–d. Adenoid cystic carcinoma of right maxillary sinus. Same case as Figs. 9.20 and 9.21. a Coronal VIBE shows inva-
sion of right hard palate, lateral extent into the buccinator muscle insertion (1). Subperiosteal intraorbital invasion lateral to
the infraorbital nerve appears as a round soft tissue mass (2). The intraorbital component reaches the apex (arrowheads on
b). Enhancement along the greater wing of the sphenoid is present (3). c Perineural spread along maxillary nerve (4) and vid-
ian nerve (5) and in the inferior portion of cavernous sinus (6). Abnormal enhancement of the pterygoid process (7). Tumor
spreads into Meckel cave (8), and cavernous sinus, which shows a more convex lateral outline. Abnormal signal of the third
cranial nerve is also present (9)
184
R. Maroldi et al.
d
a
e
f
b
Fig. 9.23a–f. Adenoid cystic carcinoma of left hard palate in-
vading the maxillary sinus. The young patient complained of
left face paresthesias for about one year. a-b Plain CT and enhanced axial MR obtained at the level of the hard palate show
permeative erosion of the pterygoid laminae (arrowheads on
CT, black arrows on MR). The epicenter of tumor is located
at the inferior portion of the pterygopalatine fossa (asterisk).
a On CT, enlargement and subtle erosion of the opening of
the greater palatine canal is demonstrated (white arrow). b
Enhancement along the medial maxillary sinus wall indicates
invasion on MR (arrowheads). Tumor reaches the nasopharynx (white arrow). Atrophy of masticator muscles is present.
Masseter muscle (m); lateral pterygoid muscle (lp). c At the
level of the upper pterygopalatine fossa, a more extensive erosion of its bony boundaries is present with destruction of the
vertical lamina of the palatine bone (white arrow), and of the
pterygoid process (black arrows). d-f Surgery proved perineural spread along left maxillary nerve (V2), ophthalmic nerve
c
(V1), and mandibular nerve (V3)
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