# The Management of Sacral Schwannoma: Report of Four Cases

Authors: Chandhanarat Chandhanayingyong; Apichat Asavamongkolkul; Nittaya Lektrakul; Sorranart Muangsomboon
Journal: Sarcoma
 (2008)

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## Abstract

Sacral schwannoma is a rare retrorectal tumor in adults.  Postoperative sacral neurological deficit is difficult to avoid.  Currently, there is no established consensus regarding best treatment options.  We present the management and outcomes of sacral schwannoma in 4 patients treated with intralesional curettage and postoperative radiation. There were 3 women and one man (average age: 45.5 years) with long duration of lumbosacral pain with or without radiculopathy. Intralesional curettage was performed by posterior approach and adjuvant radiation therapy with dosage of 5000–6600 cGy was given after surgery. The mean follow-up time was 18 months (range 4–23 months).  Symptoms of radiculopathy had decreased in all patients. The recent radiographic findings show evidence of sclerosis at the sacrum one year postoperatively, but the size was unchanged. Intralesional curettage and adjuvant radiation therapy can be used in the treatment of sacral schwannoma to relieve symptoms and preserve neurological function.


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## Body

## 1. Introduction

Schwannoma is a benign neoplasm of schwann cell, arising
along sensory nerve roots in the extremities and upper thorax.  These tumors rarely arise within bone, among
which mandible and sacrum are the most common sites of involvement. Only 79
intraosseous schwannomas have been reported in English literature and 21 were
located at the sacrum [1]. Most of the cases were treated by curettage and
overall results were favorable due to preservation of sacral nerve roots [1–14].
However, the rate of local recurrence was reported to be relatively high (54
percent) when treated by conservative means. Abernathey et al. suggested wide
excision of sacral schwannoma to prevent tumor recurrence [6].  Many authors reported that sacral amputation
and lumbopelvic fixation allowed total removal of sacral schwannoma
[4, 6–14].  The patients who were treated with sacral
amputation had greater chance of having postoperative bowel and bladder
dysfunction, in addition to decreased sensation and motor weakness of lower
extremities due to sacral nerve roots injury. Excision of the tumor might cause
extensive blood loss from combined anterior and posterior approaches. The surgical
technique is needed
and instrumentation is required to maintain spinal stability. Even though
attempts to minimize such complications were done by laparoscopic or gamma knife
surgery, the results are still in their study periods and only a limited number
of cases were included [15–19]. We report a series of 4 cases
of sacral schwannoma treated by intralesional curettage and postoperative
radiation therapy. Relatively conservative methods were used due to the benign
condition of the tumor. The clinical outcomes and sequential radiographic
results are presented.


## 2. Patients and Methods

Between July 2005 and March 2008, three women and one man
with sacral schwannoma were treated in our institute.  Mean age of the patients was 45.5 years (range
29–62 years). All
patients presented with lumbosacral pain, of duration from 8 months to six
years (mean 3.4 years). Three patients complained of pain that later progressed
to sciatica and dysethesia of one or both legs. One of them developed
difficulty in urination and also had constipation.  Neurological examination of patient no. 2
revealed no lower extremity weakness, but decreased deep tendon reflex of the left
ankle joint, and diminished left anterior thigh and perianal sensation.  The other three patients present no
neurological deficit except a loss of sensation in the left great toe in
patient no. 3 (Table1).Table 1
Clinical
Summary of the patients.
Age/sexSymptoms/durationMRIF/U time (months)Follow-upCase 162 FSacral pain, radiates to rectal vault/8 monthsMulticystic lesions of S1-2, posteriorly invaded
extradural, adjacent to thecal sac27Asymptomatic, no recurrence on MRICase 229 FLumbosacral pain, radiculopathy, and decrease sensation of
Rt. leg and Lt. thigh, decrease perianal sensation, urinary hesitancy,
constipation/5 yearsSolid-cystic lesions of S2-4, anterior extension21Asymptomatic in lumbosacral and radicular pain, subsequent
improvement in urinary function, incomplete improvement on perianal
sensation, amenorrhea, small residual tumor on MRI, nondisplaced fracture S1Case 339 MLumbosacral pain, radiculopathy of Lt. leg, loss sensation
of Lt. great toe/2 yearsSolid dumbbell shape mass in S1-2, intrasacral18Asymptomatic, no recurrence on MRICase 452 FLumbosacral pain, radicular pain of Rt. leg/6 yearsSolid mass of S1-2, anterior extension7Asymptomatic, small residual tumor with seroma on MRIPlain radiographic findings showed an extensive osteolytic
lesion with sclerotic border which involved the whole sacrum of two patients
(nos. 2 and 4) (Figure1) and only an ill-defined osteolytic lesion mainly
occupying the left side of S2-3 area in the other two patients (nos. 1 and 3).  MRI revealed iso-intensity to hypointensity
imaging on T1-weighted sequence and hyperintensity imaging on T2 weighted in
all patients.  Mean maximal length of the
tumor was 8.1 cm (range 4.4–11.0 cm) and mean volume was 259.8 cm3 (range 50.6–770.0 cm3).
The tumor extended into surrounding tissue and displaced abdominal structures
anteriorly in two patients (nos. 2, 4), but the fat plain between tumor and
abdominal cavity was evidenced in all cases
(Figure 2). This finding indicated that there was no tumor invasion into
internal organs.  In one patient (no. 1),
the tumor expanded only posteriorly and compressed the dural sac, with multicystic
lesions (Figure 3).  All MRI findings
demonstrated tumor extension from neural foramen (Figure 4), and one was seen
as a dumbbell-shaped configuration (Figure 5).  This appearance clarified by tumor
arising within the sacral foramina as the narrowest part and expanded
intrasacral and displaced pelvic organs anteriorly, which could be seen in axial
MR imaging.Figure 1
Plain radiograph shows osteolytic bony destruction at body of
sacrum and bilateral neural foramens.MR examination of pelvis demonstrates bony destruction at
sacrum and neural foramen from S1–S4 levels with soft tissue mass
formation.  This mass appears as low
signal intensity on sagittal T1-weighted MR image (Figure2(a)),
heterogeneous
increased signal intensity on sagittal and axial T2-weighted MR image (Figures
2(b)
and 2(c)).  Tumor extended and displaced
uterus and urinary bladder anteriorly, but not invaded, evidenced by fat plane
(arrows).
(a)(b)(c)Sagittal (Figure3(a)) and axial (Figure 3(b)) T1-weighted/GD/FS MR
images show a well-defined extradural cystic mass with multiple enhanced
septations and thin enhanced solid nodule, originating from the posterior
aspect of S1–S3 region.
(a)(b)Coronal (Figure4(a)) and axial (Figure 4(b)) T2-weighted MR images
show tumor with heterogeneous signal intensity involving left S1 foramen.
(a)(b)Figure 5
Axial T1-weighted MR image demonstrates dumbbell-shaped tumor
which arising from sacral foramen and extended anteriorly to pelvic cavity in
patient no. 4.In all patients, intralesional curettage was performed by
posterior approach through sacral laminectomy. The tumor capsule remained
intact. Two tumors were intrasacrally confined and 2 extended extrasacrally,
but all were extradural.  Intraoperative
nerve stimulators were not performed. After tumor removal, lumbosacral and
sacroiliac stability of all patients was not changed. No reconstruction and
instrumentation was performed in any patients. Histological finding showed
typical schwannoma in all 4 cases.  There
was no appearance of degenerated neurilemmoma (ancient schwannoma) or
hypercellular tumor (cellular schwannoma) in this series.After the wounds had healed at six to eight weeks, radiation
therapy was performed in the out-patient clinic using dosage of 5000–6600 cGy.


## 3. Results

At the mean follow-up time of 18 months, all patients
experienced relief of lumbosacral and radicular pain after surgery.  Urinary hesitancy was improved in patient no.
2. Perianal sensation was subsequently improved at six months
postoperatively.  No neurological
worsening occurred in any patients.  No
recurrent symptoms were evidenced afterward.
The patients could walk well without gait aids.Plain radiographs showed marginal sclerosis at the lesion and
destruction of the sacrum had not progressed (Figure6).
Only  patient no. 2 showed a nondisplaced
fracture of S2 on the left side as a result of preoperative massive bony
damage. MRIs were performed two months after surgery and revealed that tumors
were eradiated resulting as cystic portion, but two patients demonstrated small
amount of residual tumor (Table 1). The presacral cysts were persistent in the
same size as before surgery.  Although
the cystic lesion did not disappear, its progress was stopped by radiation.Figure 6
Plain radiograph, 1 year post operative shows sclerosis of
bony destruction at sacrum. MR examination of pelvis one year after surgery demonstrates
no significant change in size and aggressiveness of the tumor, but not
increase.Patient no. 2 had amenorrhea permanently after radiation. She
was counseled earlier and decided to have radiation therapy due to the large
size of the tumor and a postoperative residual tumor that was evidenced through
MRI.


## 4. Discussion

Of all malignant tumors originating in sacrum, chordomas,
chondrosarcoma, and metastatic lesions are most frequently observed.  Benign sacral lesions including giant cell
tumor, aneurysmal bone cyst, and osteoblastomas are occasionally evidenced
whereas schwannomas are very rare [20].  There is no sex predilection in this tumor [1, 4, 6, 13, 21, 22]. although in our series male
female ratio was 1:3. Lumbosacral pain with or without radiculopathy were the
most frequent symptoms noted in previous studies and in our patients. Decrease
in lower extremity sensation is the most frequent neurological sign found. A tumor
which was confined in a more proximal spinal level would cause early seeking of
medication and result in earlier detection than a tumor which is contained in the
lower spinal level [3, 13].  In the same way, tumor extension posteriorly
to dural sac and nerve roots would be earlier symptomatic than a tumor which
extends anteriorly adjacent to abdominal structure.Plain radiograph of the lumbosacral area often fail to be noticed
especially when the lesion is undersize. CT is useful to detect degree of bony
destruction, but an MRI provides a better display in multiple views of the
sacral mass.  In all of our patients, MRI
were performed and demonstrated details of intrasacral, intrapelvic, intra- or
extradural, and nerve root compression, as well as displaying the relationship
to neighboring structures. This information aids in preoperative diagnosis and
surgical management.Many studies in surgical treatment for sacral schwannoma have
been reported. Abernathey et al. reported 13 cases of schwannoma of the sacrum [6].  Nine patients in this study who were treated
by intralesional curettage experienced tumor recurrence and underwent
additional surgery (54 percent) with follow-up periods ranging from 5 months to
33 years (mean 9 years). Their study suggested that schwannoma originating in
the sacrum should be aggressively resected with the aim of complete extirpation
and that sacrifice of all or many nerve roots was required to minimize the risk
of recurrence. In contrast, Dominguez et al. reassured us that a conservative approach
with intracapsular enucleation
alone produced a favorable result of only 16 percent recurrence rate [1]. The follow-up period was
range from 18 months to 21 years (average 9.2 years). The follow-up time of our
series might be too early to conclude that, though we used a conservative
approach, the recurrence rate was 0 percent with a follow-up period of 7 months
to 27 months (mean 18 months).Role of adjuvant radiation therapy is controversial.  Kotoura et al. presented one case that was
treated with intralesional curettage and adjuvant radiation therapy [23].  The attempt was made to preserve nerve roots
as much as possible. The patient was followed up for 5 years, and plain
radiograph and CT scan showed arrest of the tumor with marginal sclerosis. However,
Feldenzer et al. revealed that the tumor did not respond at all [24].  Conventionally, radiation therapy is avoided
in the treatment of benign tumors, because of the risk of secondary
carcinogenesis [25].  However, radiation therapy is obligatory in
some cases in which anatomic location of the tumor does not allow total
extirpation, or in which aggressive resection may cause serious functional
damage. It has been reported that cases of giant cell tumor at the lumbosacral
area can be controlled by radiotherapy [26–28].For benign tumors at this particular location, the patients
have minimal risk of distant metastasis, low rate of recurrence, and excellent
prognosis. It is desirable to preserve the functions of lower extremities, as
well as bowel and bladder function after the treatment.


## 5. Conclusions

This is a report of a rare clinical entity.  Although the number of the patients and the
length of follow-up are limited, we made the conclusions as the followings.
Clinical courses were longer in the patient who had anterior tumor extension
and lower level of spinal involvement (average 4.3 years) than posterior
extension and upper level of spinal involvement (8 months) which compress the dural
sac and sacral nerve root more rapidly. But when compared to tumors in other regions,
the duration is still extremely long. The symptoms of radicular pain, loss of
motor power, decreased sensation of lower extremities, and bowel bladder
symptoms would subsequently occur after time.
MRI is an important diagnostic tool because plain X-ray films of the
lumbosacral area are often inconclusive.
The tumors always originate from one side of the sacral foramen and
extend to the adjacent structures, and are recognized as having a dumbbell
shape. This finding is useful for preoperative diagnosis.  Multicystic appearance and small foci of
calcification or residual bone may be evidenced in some tumor. No tumor has
infiltrated to the peritoneum and intra-abdominal organs, as diagnosed before
surgery by appearance of the fat plane.  A
conservative approach by intralesional curettage and radiation is advised in
view of the benign course of the disease. All patients had improvement in
symptoms and none of them experienced clinical worsening after surgery. Recurrence
has not been evidenced in this study. One female patient had permanent
amenorrhea after radiation.  The
treatment by high-dose
postoperative radiation must be judged with regard to risks and benefits
especially in women of reproductive age.
Further follow-up studies must be conducted.



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*Source: 845132-2008-09-02.xml*