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Manifestations of Schwannoma in the
Neuraxis and Peripheral Nerves:
A Radiological Spectrum
eEdE-243a
Viet Nguyen, MD
Maria Valencia, MD
Achint Singh, MD
Wilson Altmeyer, MD
Carlos Bazan III, MD
Bundhit Tantiwongkosi, MD
Disclosure Statement
The authors have no financial interest to disclose.
Objectives
• Review the characteristic imaging findings of
schwannoma with respect to the neuraxis and peripheral
nerves
• Understand the radiologic spectrum seen with
schwannomas
• Become familiar with the appearances and locations of
schwannoma outside the neuraxis
Table of Contents
Introduction
Cranial Nerves
Spine
Skull base / Neck
Chest
Abdomen
Extremities / MSK
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Introduction
• Concept of schwannoma involving cranial nerves is well
known in the radiology literature
• Benign, slow growing tumors arising from differentiated
neoplastic Schwann cells of any cranial, peripheral, or
autonomic nerves
• Classic imaging appearance of sharply marginated
enhancing mass with smooth enlargement of the bony
foremen involved
Frequency of Schwannomas
• Intracranium
– 95% vestibulocochlear nerve (CN VIII)
• vestibular >> cochlea division
– 1-5% other CNs
99% arise
from cranial
• Trigeminal nerve (CN V), most common
nerve
• CN IX > X > VII > XI > XII
• CN III, IV, & VI more associated with
neurofibromatosis 2 (NF 2)
• Spine
– <70-75% intradural extramedullary
– 15% completely extradural
– 15% both intra- and extradural (transforaminal, dumbbellshaped)
CN VIII
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Enhancing mass with fusiform (IAC) or “ice scream (CPA) on cone (IAC)”
appearance
Bilateral CPA-IAC metastases may be confused with vestibular schwannomas
in NF2
Cystic component is more common in schwannoma than meningioma
MR images reveal the IAC & CPA components of a vestibular schwannoma, which
has increased T2 signal & heterogeneous enhancement. Residual enhancing
tumor is evident within the IAC after this patient underwent resection.
CN VIII
Axial MR IAC imaging reveals a CPA-IAC cystic mass
with heterogenous intermediate T2 signal &
enhancement. There is associated mass effect on the
brainstem, right middle cerebellar peduncle & 4th
ventricle. Subsequent axial MR imaging post resection
via right occipital craniectomy & fat grafting
demonstrates residual enhancing tumor. Note the right
cerebellar edema with high T2 signal & CT hypodensity.
Cochlear Division of CN VIII
Coronal MR T1W image through the IAC demonstrates a round, enhancing lesion
in the inferior compartment of the left IAC.
CN V
Multiplanar MR imaging shows a large dumbbell-shaped,
extra-axial mass with heterogenous high T2 signal &
enhancement in the left superior CPA extending anteriorly
into the Meckel’s cave. Note the dumbbell waist located at
trigeminal porus. There is associated mass effect on the
brainstem, cerebellum & 4th ventricle. Foci of gradient
susceptibility indicate hemorrhages within the mass. An
enlarged foramen ovale with smooth margin is evident on
CT.
CN VII
Coronal MR T2W image through the IAC
demonstrates a T2 hypointense mass in
the superior compartment of the right IAC.
This lesion shows avid enhancement with
extension to the geniculate ganglion, an
important distinguishing feature from CN
VIII lesion.
CN V1
Coronal & axial MR images demonstrate an orbital mass with heterogeneous high
T2 signal & intense enhancement in the right superomedial extraconal space that
displaces the globe & superior rectus muscle inferolaterally. This was proven to be
schwannoma in the expected course of CN V1.
CN III
Axial & coronal MR imaging shows a tubular, intraconal
orbital mass with low T1/high T2 signal & intense
enhancement in the superior orbital fissure extending
posteriorly into the cavernous sinus. Note the medial
displacement of the tortuous CN II.
CN IX, X, or XI
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•
•
Fusiform, enhancing mass in an enlarged jugular foramen
Lack of flow voids help differentiate from glomus jugulare paraganglioma
(most common jugular foramen tumor)
90% present with SNHL clinically similar to vestibular schwannoma
Heterogeneously enhancing mass with increased T2 signal & calcifications (rarely
seen) appears to arise from the left jugular foramen & produces mass effect on
the brainstem & effacement of the fourth ventricle.
CN IX, X, or XI
Nonvestibular schwannoma in another patient with heterogeneous low T1/high T2
signal & enhancement. This mass arises from the left cerebellomedullary cistern,
which is inferior to the cerebellopontine cistern. Similar mass effect on the
brainstem & effacement of the 4th ventricle is identified.
Cervical Spine (C3)
Solitary extradural schwannoma within the right C2-C3 neural foramen
demonstrates predominantly hyperintense T2 signal, homogenous enhancement
& neural foraminal enlargement.
Cervical Spine (C5)
Well circumscribed, “dumbbell shaped” mass within the expanded left C4-C5
neural foramen demonstrates heterogeneous low T1/high T2 signal &
homogenous enhancement. There is spinal cord compression. The lesion also
exerts mild mass effect & cause luminal narrowing of the left vertebral artery.
Lumbar Spine (L3)
A small intradural, extramedullary mass at the L3 level reveals T2 hypointensity &
homogenously intense enhancement favoring schwannoma. Other consideration
includes drop metastasis, ependymoma, & granuloma. The resected mass was
proven to be schwannoma on histology.
Lumbar Spine (L5)
Mildly enhancing mass with intermediate T2/STIR signal involves the left L5 nerve
root & extends into the left neural foramen without bony foraminal expansion.
Lumbar Spine
A large, expansile cystic intradural mass spanning T12 – S2 reveals low T1, high
T2/STIR signal intensity & peripheral/internal enhancement. Note the enlarged
spinal canal & osseous remodeling/scalloping of the vertebral bodies.
Ethmoid Sinus
Coronal & axial CECT images demonstrate a well-defined, homogenously
enhancing mass causing smooth bony remodeling of the right ethmoid. A
mucocele can have similar appearance but does not enhance uniformly.
Nasal Cavity
Multiplanar CECT images of the neck reveal a well-defined, mildly enhancing solid
mass in the anterior nasal cavity causing rightward deviation of the nasal septum.
Base of Tongue
Axial & sagittal CECT of the neck reveals a rounded, wellcircumscribed heterogeneously enhancing mass arising
from the base of the tongue resulting in near complete
obliteration of the oropharyngeal airway. The mass
demonstrates heterogeneously high T2/low T1 weighted
signal, & heterogeneous enhancement.
Recurrent Laryngeal Nerve (CN X)
Axial & coronal CECT images through the subglottic region reveal an isodense
mass in the right tracheoesophageal groove causing narrowing of the trachea &
exerting mass effect on adjacent thyroid lobe.
CN XI
Multiplanar CECT neck images demonstrates an elongated, heterogenously
enhancing lesion at left level II, underneath the sternocleidomastoid muscle in
the expected location of CN XI, which was histologically diagnosed as
schwannoma. By location, differential consideration is an enlarged lymph node.
Posterior Cervical Space
Multiplanar CECT neck images demonstrates a lobulated fusiform, peripherally
enhancing lesion in the right posterior cervical space/spinal accessory chain,
which was initially described as reactive level VA lymphadenopathy.
Carotid Space
Two suprahyoid carotid space schwannomas with peripheral
enhancement & central hypodensity on multiplanar CECT neck.
Heterogeneously high T2 signal & heterogeneous enhancement
seen on MR raised concern for necrotic level IIB
lymphadenopathy.
Chest
PA/Lateral radiographs reveal a rounded, wellcircumscribed extrapleural posterior mediastinal
mass arising from the right paraspinal soft tissues at
the level of the T6 vertebral body without osseous
remodeling. Follow up cross-sectional imaging
reveals a paraspinous mass with mild enhancement
on MR as well as heterogenous intermediate T2
signal. The mass is mildly enhancing on CECT.
Thoracic Wall
Multiplanar CECT through the abdomen reveals large, well-defined,
multiseptated, lobulated masses within the subpulmonic extrapleural space & soft
tissues of the chest wall. There is mass effect upon the underlying liver with fat
planes respected.
Visceral Organ
Coronal & axial abdominal CECT shows a large, well-defined soft tissue mass
projecting into the lumen of the gastric fundus, along the greater curvature of the
stomach. This was found to be schwannoma on endoscopic biopsy.
Illiopsoas Compartment
Sagittal & coronal MR imaging through the lower
abdomen reveals a well-circumscribed, multiseptated
predominately low T1/high T2 signal intensity lesion
within the left iliopsoas muscle. Mildly enhancing
rim/septations are seen within the mass. It is
hypodense on NECT with irregular septations. Initial
differential considerations included lymphangioma,
cystic neoplasm, or less likely atypical synovial cyst
extension from the hip joint.
Psoas Muscle
Coronal & axial abdominal CECT shows a hypodense, well circumscribed,
elongated solid mass within the psoas muscle without invasion of the adjacent
soft tissues. This mass demonstrates T2 hyperintensity & heterogenous
enhancement on MR.
Superficial Soft Tissue of Thigh
Axial NECT imaging through the proximal thigh
reveals a round, hypodense mass in the
subcutaneous soft tissues. Axial fused PET/CT
shows intense FDG activity. No significant
internal vascularity is shown on Doppler.
Hands
A round mass in the ulnar soft tissues just
medial to the left small finger MTP joint
demonstrates low T1/high T2 signal intensity
& homogenous enhancement. This mass
appears separate from the underlying joint
capsule but contiguous with the adjacent
musculature. Similar lesion is also seen in the
radial soft tissues of the right ring finger at the
level of the P1 segment.
Ankle
A well circumscribed mass at the level of the posteromedial ankle joint shows
hyperintense T2 signal & diffuse heterogenous enhancement. This mass abuts &
medially displaces the posterior tibial neurovascular bundle.
Ankle
An intermediate T1/high T2 signal intensity, mildly enhancing mass lies within the
tarsal tunnel at the level of the talus in the expected course of the tibial nerve. An
additional partially visualized T2 hyperintense mass on sagittal view is also seen.
Foot
A rounded low T1/intermediate to high T2 signal
intensity superficial soft tissue mass in the dorsum
of the foot demonstrates avid post contrastenhancement. Initial differential considerations
included complex epidermoid cyst, neural-based
tumor, or less likely atypical fibroma, hematoma or
giant cell tumor of tendon sheath.
Summary
• The following imaging findings suggest the diagnosis of
schwannoma: mass lesion within the nerve or nerve
sheath, smooth widening of the neural foramen,
hypodensity on CT, T2 hyperintensity and enhancement.
• Cystic changes are a common finding.
• The above findings should suggest the diagnosis
schwannoma even if the location is atypical.
References
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