A 32-year-old female presented with a left facial nerve schwannoma. Imaging showed a bilobed hyperintense mass in the left parotid and mastoid regions on T2-weighted imaging, connected by an interconnecting stalk along the vertical segment of the facial nerve. There was restricted diffusion seen within the peripheral rim of the tissue. Schwannomas are benign nerve sheath tumors that commonly occur in the head and neck region, arising from the cranial nerves. They appear as well-defined masses that are iso- to hyperintense on T1- and T2-weighted MRI relative to muscle. Characteristic features include identification of the nerve of origin and restricted diffusion.

1. Radiological Imaging of Neck Schwannoma.
Dr/ ABD ALLAH NAZEER. MD.

2. Schwannomas are benign neoplasms of the
peripheral nerves originating in the Schwann cells.
They are rare and usually solitary, with clearly
delimited capsules. They occur in the head and neck
region in only 25 % of the cases, and may be associated
with Von Recklinghausen’s disease. Schwannomas are
always a diagnostic dilemma as they are asymptomatic
for long time and histopathology is the gold standard
for diagnosis. The nerves affected included the brachial
plexus, vagus nerve, sympathetic chain and lingual
nerve. The nerve of origin was identified based on
intra-operative findings and post-operative neurological
deficits. Schwannomas are generally benign, and rarely
recur.

3. Schwannoma is a benign, slow growing encapsulated perineural
tumour of neuro ectodermal derivation, originating from
Schwann cells of the neural sheath of motor and sensitive
peripheral nerves. As a slowly growing benign tumour, it has
been reported that 25–45 % of schwannomas were located in the
extracranial head and neck region. It involves the cranial nerves
such as V, VII, X, XI, and XII or sympathetic and peripheral nerves.
Extracranial head and neck schwannoma is a challenging
condition to the head and neck surgeons. For tumours arising
from the major cranial nerves, excision of tumour with the
division of the nerve of origin (NOO) renders lifelong morbidity to
the patients. On the other hand, other nerve-preserving excision
method, e.g. intracapsular enucleation, does not guarantee intact
nerve function after surgery. Because of the substantial chance of
nerve palsy after operation, obtaining an accurate preoperative
diagnosis, and preferably, with the identification of the NOO is
crucial in the management of the disease.

4. Neurilemmoma also known as schwannoma is a benign tumor of nerve sheath
origin, arising from any nerve covered with a schwann cell sheath, which includes
the cranial nerves (except for optic and olfactory), the spinal nerves, and autonomic
nervous system. Schwannomas occurring in the head and neck region are frequent,
with 25–45% of all reported schwannomas being found in this region. These tumors
are generally encapsulated except from the sinonasal tract and nasopharynx.
Most often these tumors are solitary but can occur in multiple areas also.
Multiple occurrences are usually associated not only with neurofibromatosis II but
also schwannomatosis. Head and neck are the most commonly affected regions
(25–45%) with the lateral neck being the frequently involved site. Cytogenetic
abnormality of chromosome 22 is seen in 50% cases, and those are associated with
neurofibromatosis II. Sinonasal schwannoma contributes about 4% of head and
neck schwannomas. It remains asymptomatic for a quite long period because of
slow growth. Nasal obstruction is the main symptom of this tumor. Pain, bony
dehiscence including skull base and neural symptoms develop later as the tumor
enlarges. It can also simulate rhinosinusitis as clinical features are similar. Brachial
plexus tumors are rare comprising of only 5% of all tumors of upper limb. The most
frequent site is in the head and neck, which comprises 25% of all schwannomas and
only about 5% of schwannomas present as brachial plexus tumors. The two most
common brachial plexus region tumors are the schwannomas and neurofibromas,
both of which are benign and arise from the nerve sheath.

5. Most often, early in the course, minimal neurological deficit will be present, or there will
be none at all. Manipulation of the mass can produce paraesthesias or “shocks” in the
distribution of the affected nerve, and this can be an important aid to diagnosis. Side-to-
side mobility greater than longitudinal mobility of the mass from the nerve is more
common in cases of benign lesions, whereas malignancy is associated with firmness and
immobility. In cases of brachial plexus lesions, MR imaging is the study of choice to
delineate the margins of the tumor from surrounding tissues with greatest contrast.
Importantly, however, MR imaging is currently unable to differentiate between
schwannoma and neurofibroma.
Computerized tomography scanning is optimal at revealing osseous erosion around the
spine or changes in neural foramina. A newer modality, MR neurography (MR-magnetic
resonance), has the potential to demonstrate the entire course of visualized peripheral
nerves. Schwannomas of the vagus nerve grow between the common carotid artery and
the internal jugular vein. This growth pattern often leads to a divergence of both
structures, which is visible in CT scan or MRI.
Cervical vagal schwannomas constitute about 2–5% of neurogenic tumors. These tumors
usually present as asymptomatic masses as in our case, if symptomatic patients will
present with hoarseness as the main symptom. The sign usually seen in these cases is
unilateral vocal cord paralysis. The reported incidence of preoperative vocal cord paralysis
is about 12%. Clinical sign elicited in case of vagal schwannoma is a paradoxical cough on
palpating the mass due to vagal stimulation. The presence of this sign together with
palpation of mass medial to the sternocleidomastoid should arouse the suspicion of a
neurogenic tumor

6. A 32-year-old female
with left facial nerve
schwannoma. Sagittal
T2 weighted image (A)
showing hyperintense
bilobed mass in the
left parotid region
(thin arrow) and the
left mastoid region
(dashed arrow).
Interconnecting stalk
seen along the vertical
(mastoid) segment of
facial nerve (squiggly
arrow). Diffusion-
weighted image at b =
0 (B), b = 1000 (C)
s/mm2, and ADC map
(D) show restricted
diffusion in the lesion
(thick arrows).

8. Intraparotid schwannoma. (A) Axial T2-weighted MR image shows a hyperintense well-
defined mass (arrow) in the left parotid gland. (B) Axial fs gadolinium-enhanced T1-
weighted MR image of the same tumour (arrow) shows intense peripheral enhancement.

9. Intraparotid Facial Nerve Schwannoma:
A, Axial T1-weighted image (spin-echo: TR/TE, 650/10.7) shows a low-signal-
intensity well-defined mass in the right parotid gland.
B, Axial T2-weighted image (fast spin-echo: TR/TE, 3150/108) shows peripheral
high signal intensity surrounding a central region of lower signal intensity.

10. Intraparotid fascial nerve Schwannoma.
A, Axial T1-weighted image (spin-echo: TR/TE, 650/9.3) shows a
lobulated mass in the right parotid gland, with a low-signal-
intensity well-defined mass in the right parotid gland.
B, Axial T2-weighted image (fast spin-echo: TR/TE, 3150/108)
shows a heterogeneous hyperintense mass.
C, Axial gadolinium-enhanced T1-weighted image (spin echo;
TR/TE, 650/9.3) shows a mass in the right parotid gland with
heterogeneous enhancement.
D, Coronal STIR image (TR/TE/TI, 3216/36/165) shows a
hyperintense mass in the right parotid gland. The tumor is
situated directly caudal to the stylomastoid foramen and
protrudes into it (arrow).

11. Schwannoma of the parapharyngeal space. A rounded, regular, well defined,
encapsulated soft tissue mass is seen at the left parapharyngeal space. it
compresses the pharyngeal air column and displaces the carotid
vessels/jugular vein laterally. It exhibits low T1, bright T2/STIR signal with
patchy moderate enhancement after contrast administration.

12. Parapharyngeal
Schwannoma.

13. Parapharyngeal Space Schwannoma.

14. Parapharyngeal Space Schwannoma.

15. The schwannoma shows intense heterogeneous enhancement on the postgadolinium fat-
saturated T1WI (A) and appears heterogeneously bright on the fat-saturated T2WI (B). The
nonenhancing areas in the center of the mass correspond to the areas of fluid signal intensity
seen in the T2WI. The entire carotid sheath (arrows) is displaced in an anterolateral direction.

16. Coronal MRI T1-weighted image reveals mass
in left parapharyngeal space Schwannoma.

17. A 35-year-old female with left parapharyngeal space schwannoma. Axial T2 weighted
fat-saturated image (A) showing well-defined heterogeneously hyperintense mass in
the left parapharyngeal space. Central area of the lesion (double ended arrow) is
more hyperintense than the peripheral (dashed arrow). Diffusion-weighted image
at b = 1000 (B) s/mm2 and ADC map (C) show restriction at the peripheral rim of the
tissue (thin arrows) with free diffusion in the centre (thick arrows).

18. A 37-year-old man
with right
parapharyngeal
space schwannoma.
Coronal T2 weighted
image (A) shows
fusiform shaped
mass in the right
parapharyngeal
space with
heterogeneous
hyperintense signal
intensity. No central
necrosis seen.
Diffusion weighted
images at b = 0
(B), b = 1000 (C)
s/mm2, and ADC
map (D) show free
diffusion throughout
the mass (thick
arrows).

19. Sympathetic chain schwannomas in a 33-year-old woman (case number 4). (a) Axial T2-weighted image at the C3
level shows the ICA and IJV both displaced anterolaterally by the SC schwannoma, with no separation between them.
On coronal(b) and sagittal (c) MIP of the DW-MRN, both of the SC and the VN seem to connect to the tumor. (d) an
intraoperative photograph revealed the VN coursing downward between the CA and the IJV.

20. Sympathetic chain
schwannoma. Axial T1-
weighted MR image
shows a mass slightly
hypointense to muscle
in the left post-styloid
parapharyngeal space
causing anterior lateral
displacement of
carotid sheath
structures. This mass
increases in signal
intensity on the T2
sequence and
enhances
heterogeneously after
contrast
administration. The
normal anatomic
relationship of the
sympathetic chain
(arrow) and the carotid
sheath are shown in
the illustration.

21. Schwannoma
of cervical
sympathetic
chain at the
left para-
pharyngeal
space.

22. Contrast enhanced computed tomography
scan shows isodense mass in right carotid
space with non homogenous enhancement.
Pre-operative photograph of the
patient with arrow pointing at cervical
sympathetic chain schwannoma.

23. Pre-operative photography, CECT and MRI T1WI of neck showing the parapharyngeal
mass occupying the poststyloid compartment in the vagal schwannoma patient.

24. Neck CT image of a vagal schwannoma patient. Tumor (asterisk) is separating the common
carotid artery (white arrow) anteriorly and internal jugular vein (arrow head) posteriorly.

25. Schwannoma of left cervical vagus nerve. Contrast-enhanced CT scan shows left-sided, well-
circumscribed, heterogeneously hypodense mass with few areas of patchy enhancement.
Anterior displacement of internal carotid artery (ICA), external carotid artery (ECA), and
parapharyngeal fat and medial displacement of visceral space (white arrow) are shown here.
The internal jugular vein is compressed by tumor and hence is not visualized in this image.

26. Schwannoma of left cervical vagus nerve.

27. CT and MRI for schwannoma
of right cervical vagus nerve.

28. Neck CT image of a sympathetic schwannoma patient. Tumor (asterisk) is
anteriorly displacing the common carotid artery (white arrow) and
internal jugular vein (arrow head) together without separating them.

30. Schwannoma of
the carotid sheath:
axial T2-weighted
image and
angiogram.

31. Schwannoma of the carotid sheath, (a) MRI angiography showing splaying of the carotids by
the tumor. (b) T2-weighted coronal cut. (c) T2-weighted axial cut. (d) Postcontrast T1 sagittal cut.

33. left trigeminal nerve
schwannoma. Axial T1
weighted image (A)
showing well-defined left
parapharyngeal space
mass, isointense to muscle,
with few internal
hypointense areas (white
arrow). Axial T2 weighted
image (B) showing
heterogeneous mass with
markedly hyperintense
centre and relatively
isointense periphery. Blood
fluid level noted in central
hyperintense area (double
ended arrow). Coronal T2
weighted image (C)
showing intracranial
extension via left foramen
ovale (dashed arrows).
Diffusion-weighted images
at b = 0 (D), b = 1000 (E)
s/mm2, and ADC map (F)
reveal marked restriction
at the peripheral rim of the
tissue (thin arrows) with
free diffusion in the centre
(thick arrows)

34. Sagittal view of the tumor on MRI. The arrow indicates
a 7x4 cm mass lesion originating from the vagus nerve.

35. A parapharyngeal space schwannoma arising from the vagus nerve.

36. Cystic schwannoma.

37. (A and B): Paraspinal schwannoma: Axial T1 and T2W images show an
oblongated lesion (arrows), which is isointense on T1 and heterogeneously
hyperintense on T2 in the cervical spine, causing widening of the neural canal
(dotted arrows) and extending into the soft tissues of the neck

38. Schwannoma (brachial plexus).

39. Schwannoma, well defined oval shaped enhancing mass is noted at right upper cervical region. Small
focus of calcification is present within the mass. The mass is located between the sternoclidomastoid
muscle and main cervical vessels at the right side. Internal jugular vein and common carotid artery
and its main branches are displaced medially by the mass and there are no frank evidence of local
invasion. Several prominent lymph nodes are identified at right anterior cervical spaces.

41. Schwannoma.

42. Tongue base
schwannoma.

43. Sinonasal schwannoma is generally a well-defined
soft-tissue mass most frequently occurring in the nasal
cavity and ethmoid sinus and frequently associated
with pressure remodeling of the adjacent bone. These
tumors are isoattenuating on CT and predominantly
isointense on both T1- and T2-weighted MR images,
compared with the brain stem. Mild contrast
enhancement on CT and strong enhancement on MR
images were also demonstrated in most of the tumors.
Although sinonasal schwannomas are rare and their
imaging findings are rather nonspecific, CT and MR
imaging studies are helpful for preoperative diagnosis
and surgical planning in patients with schwannoma of
the sinonasal cavity.

44. Schwannoma of the nasal cavity in a 79-year-old man. A, Pre-contrast axial CT scan with a bone algorithm shows
a polypoid mass in the left anterior nasal cavity, originating from the nasal septum. B, Contrast-enhanced axial CT
scan with a soft-tissue algorithm shows mild and patchy enhancement of the mass. C, Fat-suppressed axial T2-
weighted MR image shows that the mass is isointense to the brain stem. D, Contrast-enhanced fat-suppressed
sagittal T1-weighted MR image shows marked contrast enhancement within the mass.

45. Schwannoma of the nasal cavity in a 22-year-old man. A, Contrast-enhanced coronal CT image shows a
tubular expansile soft-tissue mass in the left nasal cavity, demonstrating mild enhancement. B, Axial
T1-weighted MR image shows the tumor extending in the anteroposterior dimension and remodeling
the lateral nasal wall. C, Fat-suppressed axial T2-weighted MR image shows that the tumor is
hyperintense to the brain stem. D, Contrast-enhanced fat-suppressed axial T1-weighted MR images
show marked homogeneous enhancement within the tumor.

46. Schwannoma of the nasal cavity and ethmoid sinus in a 42-year-old woman. A, Precontrast axial CT scan shows a large
lobulated expansile mass isoattenuating to the brain stem and centered in the right posterior ethmoid sinus. B, Postcontrast
axial CT scan shows marked enhancement of the mass, greater than that of the muscles in the masticator space. The mass
extends to the ipsilateral orbit and maxillary and sphenoid sinuses with scalloping and remodeling of the bony walls of the
nasal septum, maxilla, and sphenoid bone. C, Coronal T2-weighted MR image shows heterogeneous signal intensity of the
mass and signal voids within the lesion, suggestive of prominent vascularity. D, Contrast-enhanced fat-suppressed coronal T1-
weighted MR image shows marked and heterogeneous enhancement of the mass.

47. Schwannoma of the maxillary sinus in a 24-year-old woman. A and B, Precontrast axial and coronal CT
scan with a bone algorithm shows a lobulated expansile mass arising from the left infraorbital canal,
which replaces the left maxillary sinus. Note cortical thinning and remodeling of the orbital floor and
the medial and posterior maxillary sinus walls by the mass. C, Fat-suppressed axial T2-weighted MR
image shows multiple fluid-fluid levels within the lesion, which are suggestive of intratumoral
hemorrhage. D, Contrast-enhanced fat-suppressed coronal T1-weighted MR image shows cystic
change at the lower part of the mass and marked enhancement in the upper solid part of the mass.

48. Schwannoma,
(a) Preoperative
CT showing the
tumor () present
in the posterior
part of the left
maxillary sinus
and the left
nostril. (b)
Postoperative
CT.

49. Conclusion:
Schwannomas are derived from Schwann cells.
They are usually solitary lesions, except in Von
Recklinghausen’s disease. Pain and neurological
symptoms are uncommon, and become evident
only at advanced stages. They are generally benign,
and rarely recur. An accurate preoperative workup
with the identification of NOO is very important
not only for a correct diagnosis, but also for
surgical planning and informing the patient about
the possible complications. This allows the patient
to make an informed decision on whether to
undergo operation or observation.

50. Thank You.