n Case Report
Totally Cystic Schwannoma of the
Lumbar Spine
Desheng Wu, MD; Zhaoyu Ba, MD; Yufeng Huang, MD; Weidong Zhao, MD;
Bin Shen, MD; Heng Kan, MD
abstract
Full article available online at Healio.com/Orthopedics. Search: 20130426-36
A schwannoma is a benign tumor arising from a schwann cell and occurs mainly in the
nerve sheath in the intradural extramedullary region. Schwannomas have been well
described as occurring in the lumbar spine, but total cystic degeneration of schwannomas is rarely reported. The authors describe the clinical and radiographic evaluations
and treatment of a rare case of an intraextradural totally cystic schwannoma on the
lumbar spine.
Two patients reported a history of 6 to 12 months of pain accompanied by weakness in the lower extremities. On examination, 1 patient had bilateral lower-extremity
muscle strength graded at 4/5, and magnetic resonance imaging revealed a cystic
schwannoma (1.532.0 cm in the sagittal dimension) at L2-L3. The other patient had a
right lower-extremity muscle strength graded at 3/5, and magnetic resonance imaging
revealed a cystic schwannoma (2.033.0 cm in the sagittal dimension) at L4-L5. The
patients underwent operative treatment, and the tumors were completely removed,
as were the filum terminale adhered to the tumor. Pedicle screws were used to maintain stability of the lumbar spine. Gross examination of the tumors showed yellowishwhite soft contents. Histologic examination confirmed that they were benign totally
cystic schwannomas. Postoperatively, the patients’ neurologic symptoms completely
resolved.
A
B
Figure 2: Photograph of a strand of filum terminale
adhered to the tumor for patient 1 (A). Photograph
of a strand of filum terminale adhered to the tumor
for patient 2 (B).
Cystic schwannomas can be diagnosed using preoperative magnetic resonance imaging. The filum terminale cut off the tumor walls did not cause the clinical symptoms
in the 2 patients.
The authors are from the Department of Spine Surgery (DW, ZB, YH, WZ, BS), Shanghai East
Hospital, Tongji University School of Medicine, Shanghai, China; and the School of Medicine (HK),
University of Western Sydney, Penrith, New South Wales, Australia.
The authors have no relevant financial relationships to disclose.
Drs Wu, Ba, and Huang contributed equally to this work.
The authors thank Drs Yan Zhang, Ju Liu, and Yang Meng for their help.
Correspondence should be addressed to: Desheng Wu, MD, Department of Spine Surgery, Shanghai
East Hospital, Tongji University School of Medicine, 150 Jimo Rd, Shanghai 200120, China (eastspine@
yahoo.com).
doi: 10.3928/01477447-20130426-36
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n Case Report
S
chwannomas are benign tumors of
nerve sheath cell of a schwann cell
that account for 0.3% of primary
intraspinal tumors.1 However, totally cystic schwannomas of the lumbar spine are
rare.2-4 The current report describes 2 patients with totally cystic schwannomas of
the lumbar spine.
Case Report
Patient 1
A 62-year-old man reported pain and
motor weakness of both lower extremities
for 1 year. Examination revealed muscle
strength graded at 4/5 in both legs. Both
patella tendon reflexes were hyperreflexia. Magnetic resonance imaging (MRI) of
the lumbar spine showed an intrathecal
lesion at L2-L3 (Figure 1 A). The lesion
was nearly isointense with the spinal cord
on T1-weighted MRI. The contrast MRI
revealed a ring-like enhancement of the
tumor (Figure 1B). A diagnosis of a cystic schwannoma was made preoperatively,
and a laminectomy was performed at L2L3 to remove the tumor.
The large tumor arising from the cauda
equina was found after opening the dura
(Figure 2A). The authors completely removed the tumor and cut off the filum
terminale that had adhered to the tumor.
Macroscopically, the tumor was found to
be totally cystic. Immunohistochemistry
examination confirmed the diagnosis of
totally cystic schwannoma (Figure 2B).
The patient experienced significant pain
relief at the 2-week postoperative examination. At the 2-year follow-up, no
schwannoma recurrence was observed
(Figure 3A).
Patient 2
A 63-year-old man presented with a
6-month history of radicular pain of the
right lower extremity. On examination,
motor weakness was observed in his right
lower limb, which had a muscle strength
grade of 3/5 and absent knee and ankle
reflexes on the right extremity. Magnetic
resonance imaging of the lumbar spine
e680
revealed a homogeneous cystic mass extending from L4-L5
that was causing cauda equine compression (Figure 1C). The
contrast MRI revealed
a ring-like enhancement of the lesion
(Figure 1D). The patient underwent laminectomy from L3-L5.
A large schwannoma originating from
the filum terminale of
cauda equina was immediately observed.
The tumor was completely extirpated, and
the filum terminale
adhering to the tumor
was cut off (Figure
2C). Histological diagnosis confirmed a
totally cystic schwannoma (Figure 2D).
The patient had complete recovery of his
symptoms postoperatively. At the 2-year
follow-up, no recurrence was observed
(Figure 3B).
1A
1B
1C
1D
Figure 1: Median sagittal T1-weighted magnetic resonance imaging (MRI)
without contrast showing an intrathecal lesion at L2-L3 in a 62-year-old
man (A). A ring-like enhancement of the lesion was observed on contrast
T1-weighted MRI (B). Median sagittal T1-weighted MRI without contrast
of the lumbar spine showing an intrathecal lesion at the level of L4-L5 in a
63-year-old man (C). A ring-like enhancement of the lesion was observed
on contrast T1-weighted MRI (D).
Discussion
Schwannoma, the
most common peripheral nerve benign tumor, is a slow-growing nerve tumor.5 The
lumbar region is one of the most common
sites for spinal schwannoma, but totally
cystic schwannomas in the lumbar spine
are rarely documented in the English literature.1,4,6-11 Schwannoma of the cauda
equina has no specific clinical presentation, thus the slow-growing lesions in the
lumbar region are often ignored for a long
period of time, which accounts for their
large size at presentation.10 In this report,
2 cases of totally cystic schwannoma of
the cauda equina are presented.
Magnetic resonance imaging of the
lumbar spine revealed a lesion at L2L3 for patient 1 and at L4-L5 for patient 2. The contrast MRIs revealed a
ring-like enhancement of the tumors in
both patients. Therefore, contrast MRI
should be performed to diagnose cystic
schwannomas because they have a wellenhanced wall compared with other
cystic lesions, which usually lack this
structure.1 Both tumors were associated
with compression of the spinal nerve
roots and stenosis of the lumbar spinal
canal, so a posterior approach was used
to remove the lesions. A comparison of
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Totally Cystic Schwannoma of the Lumbar Spine | Ba et al
the current patients with previous reports is provided in the Table.
Schwannoma is a mostly solid tumor.
Cystic degeneration can occur in the peripheral nerve root; due to the rarity of the
totally cystic schwannoma, it is necessary
to distinguish it from other cystic lesions,
such as Tarlov, arachnoid, or neurenteric
cysts. The importance of diagnosing this
tumor cannot be overemphasized in view
of their varied biological behavior and
prognosis.8 Postoperative histopathological examination forms the mainstay of
differentiation.
The prognosis for cystic schwannomas
is similar to that of solid schwannomas,
and the treatment of cystic schwannomas
is also similar to that for other solid spinal
schwannomas. For the 2 current patients, a
laminectomy was performed (at L2-L3 for
patient 1 and at L3-L5 for patient 2) and
the lesions were completed excised. Most
of the filum terminale were pushed dor-
sally by the tumor, although
a single strand
of filum terminale adhered to
the tumor for
both patients.
The tumor was
completely removed by cutting off the single strand of the
filum terminale
without
any
complications.
Kim et al12 reported that the
involved nerve
roots or cauda
equinas were
nonfunctional
at the time of
surgery
and
2A
2B
2C
2D
Figure 2: Photograph of a strand of filum terminale adhered to the tumor for patient
1 (A) and low-power histopathology view of the spindle cell tumor showing cystic
change (B). Photograph of a strand of filum terminale adhered to the tumor for
patient 2 (C) and low-power histopathology view of the spindle cell tumor showing
cystic change (D) (hematoxylin-eosin stain; original magnification, 3100).
Table
Comparision of the Current Study With Previously Reported Patients
Authors
Current study
1
No. of
Patients
Sex/
Age, y
Tumor
Location
Imaging Characteristics
Follow-up
2
M/62
L2-L3
MRI revealed a ring-like enhancement of the 2 lesions.
2y
M/63
L4-L5
MRI revealed a ring-like enhancement of the 2 lesions.
2y
Turgut & Erkus
1
F/43
L1-L5
An intrathecal mass nearly filled the thecal sac.
16 mo
Parmar et al4
5
F/26
L2-L4
The intensity of the lesion was higher than the surrounding
cerebrospinal fluid. The lesion showed a ring-like enhancement
with irregular nodular margins.
6 mo
F/34
L1-L2
The lesion was hyperintense on the T2-weighted MRI, and a
homogenous ring-like enhancement was observed.
None
F/56
L1
The lesion was hypointense on T1- and T2-weighted MRI.
Contrast MRI revealed a thick, irregularly enhanced wall.
None
F/30
L2-L3
The lesion was hypointense on T1- and T2-weighted MRI.
Contrast MRI revealed a homogenous enhancement of the wall.
None
M/32
L1
The lesion was hypointense on T1- and T2-weighted MRI.
Contrast MRI revealed enhancement of the wall and septa.
3 mo
Borges et al7
1
M/55
L4-L5
Contrast MRI revealed a ring-like enhancement of the cyst.
1y
Kasliwal et al 8
1
M/70
L3
Characteristic ring-like enhancement was seen on MRI.
None
Saiful Azli et al 9
1
M/54
L4-S1
Contrast MRI revealed a ring-like enhancement of the wall.
1y
Abbreviation: MRI, magnetic resonance imaging.
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n Case Report
the true mechanism needs to be further
studied.
Conclusion
3A
3B
Figure 3: At the 2-year follow-up, no schwannoma
recurrence was seen on the sagittal T2-weighted
magnetic resonance imaging without contrast for
patient 1 (A) or the sagittal contrast T2-weighted
magnetic resonance imaging for patient 2 (B).
Totally cystic schwannoma of the cauda equina is a rare, benign tumor.
Operative intervention is needed if the tumor causes stenosis of the lumbar spinal
canal or compression of the nerve root.
Totally cystic schwannoma can be diagnosed using preoperative MRI. Filum terminale adhered to the wall of the tumor
can been cut off, which may not cause any
neurologic deficit.
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