chondrosarcoma of the thoracic spine a rare case
DESCRIPTION
This a case of a female, in her 3rd decade of life complained of back pain. Undergone thoracostomy, and histopathology report revealed chondrosarcoma. Few cases of a dumbbell shaped chondrosarcoma have been reported. And this is an addition.TRANSCRIPT
DUMBBELL-SHAPED
CHONDROSARCOMA
OF THE
THORACIC SPINE
A Rare Case
ABSTRACT
This is a case of a 37 year old female who presented with a 6
months history of gradual onset of lower extremity weakness, followed
by numbness of both lower extremities, which occurred 4 months later
with associated constipation. Chest x-ray revealed a right hilar mass,
which on lateral view x-ray of the thoracolumbar spine showed that it
was a paravertebral mass. MRI of the thoracic spine was also done
which revealed a dumbbell-shaped tumor, which was hypointense on
T1W images, hyperintense on T2W images, and heterogenous
enhancement on contrast study. Differential considerations for this
kind of tumor presentation are meningiomas and nerve sheath tumors.
Patient underwent laminectomy and thoracotomy and final
histopathologic examination, surprisingly, were read as well-
differentiated chondrosarcoma, a rare case of malignant spinal tumor,
which can arise de novo or from a pre-existing benign cartilaginous
tumor. Retrospective analysis of the case revealed that MRI was not
adequate to derive to the diagnosis, but also CT scan was necessary.
2
INTRODUCTION
One of the commonly involved diseased organ system is the
nervous system, and is considered to be the “computer system” of our
body. It is divided mainly into two, the central nervous system and the
peripheral nervous system . The brain constitutes the central nervous
system, while the spinal cord and its nerve roots constitute the
peripheral nervous system.
Peripheral nerves serve as intricate conduction system which
serve as mediator of neural impulses traveling in both directions
between the CNS and other tissues of the body through which many
important body functions are regulated. Therefore, any lesions
involving the CNS and PNS, be it due to trauma, infection, metabolic
derangements, and tumors will always cause malfunctioning of at least
one part of the body or at most paralysis of the entire body.
Tumors of the spinal cord are much less frequent than
intracranial tumors with overall prevalence approximating one spinal
tumor for every four intracranial lesions. However, although rare, it is
an important inclusion in the differential diagnosis for any patient
experiencing myelopathy, radiculopathy, neck or back pain. These
tumors may either be intramedullary, intradural extramedullary,
extradural extramedullary or both.
3
For its imaging, magnetic resonance imaging is the most
important diagnostic modality for patients with spinal cord tumors. It
provides spatial and contrast resolution of neural structures that is
unattainable by any other imaging
modality. And plain x-rays have minimal role in the modern diagnosis
of spinal cord tumors as they do not image soft tissue adequately.
However, the effects of intraspinal tumors on the vertebral elements
are sometimes evident. Computed Tomography (CT) on the otherhand,
is more useful in assessing the body structures of the spine.
This paper will present a rare case of spinal cord tumor
diagnosed pre-operatively as a benign tumor using the patient’s
presenting signs and symptoms, and by MRI. Which, however, post-
operative histopathological result revealed a more rare case of spinal
cord tumor, chondrosarcoma, and wherein complementary CT scan of
the spinal cord may have altered the MRI diagnosis.
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CASE REPORT
Clinical Presentation
This is a case of a 37 year old female who presented with a six
(6) months history of gradual onset of weakness of both lower
extremities, which she initially ignored. This was followed by numbness
of both lower extremities, which occurred four (4 ) months later. Three
(3) months prior to admission, patient started complaining of right
back pain, which the patient claimed to be aggravated by movement.
And (1) one month prior to admission, she noted feeling of heaviness
of both lower extremities while walking, more in the right, causing her
to drag her right leg. She also complained of constipation for three
months. No cough, urinary incontinence nor bladder retention were
noted. Past
medical history revealed that she was admitted last 2005 and had an
operation due to ruptured appendicitis. Family history is
unremarkable.
Pertinent physical examination on admission were as follows:
MSE : awake, alert, oriented to time place and person, ambulatory
with assist.
5
Cranial Nerves: intact
Motor : R L Sensory: R
L
Upper 5/5 5/5 Upper 100% 100%
Lower 3/5 4/5 Lower 70%
80%
Relexes : intact
Work-ups and Diagnosis
With the above presenting signs and symptoms, the initial
working impressions were demyelinating disease and spinal cord
compression. To confirm these, initial work-ups made were chest x-ray
and x-ray of the thoracolumbar spine. Chest x-ray revealed a soft
tissue mass in the right hilar area. Fibrocalcific opacities in the left
upper lung were also noted, wherein PTB was considered. The
optimally visualized osseous structures were unremarkable. (Figure
1) .
6Figure 1. PA chest x-ray
With the x-ray findings, a demyelinating disease, which is more
of a white matter disease was readily ruled out. Soft tissue mass in the
right hilar area on PA chest x-ray could be anywhere in the
mediastinum, and the differential diagnosis will greatly vary. Such that,
if it is in the anterior mediastinum, teratomas, thymomas, and
lymphomas could be the differential considerations. However, if it is in
the posterior mediastinum, neurogenic tumor could be the major
differential consideration. Atlhough a lateral view x-ray of the chest is
of help in arriving a more specific diagnosis, a chest computed
tomography scan was suggested for further evaluation. In computed
tomography of the chest, the location of the right hilar mass could
clearly be identified as well as other lung parenchymal and bony
lesions. However, because of the presenting neurologic symptoms of
lower extremity weakness and numbness with associated constipation,
in a relatively young patient, the working impression was more inclined
to a spinal cord compression secondary to the soft tissue mass. And
for suspicions of spinal tumors, the imaging modality of choice is spinal
MRI scan with and without intravenous gadolinium. 1 These scans
adequately image the spinal cord and its associated nerves. Detail of
the bony vertebral column is not as good as CT scan, but is usually
adequate. Other radiographic studies such as CT-myelography or spine
x-rays may also be necessary depending on the type and location of
spinal tumor and its effect on the spine.
7
Thoracolumbar spine x-ray was done on this patient, and the soft
tissue paravertebral mass at the level of T4 – T6 was the only
significant finding (Figure 2). The optimally visualized bony structures
were intact.
CBC, electrolytes, BUN, and creatinine were also requested to
rule out any metabolic abnormalities that could cause weakness and
numbness of the lower extremities. However, all the laboratory results
were normal.
Figure 2. AP and lateral view of the thoracolumbar spine shows a soft tissue mass in the right hilar area at the level of T4-T6 with lucency in the central area. No calcifications were noted. Osseous structures were unremarkable.
MRI of the thoracic spine was then done which revealed a 4.7 x 3.2 cm
right paravertebral, extramedullary, and combined intra-and extradural
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lobulated, dumbbell-shaped soft tissue mass at the level of T4-T6.
The mass is isointense with the adjacent muscle on T1WI, hyperintense
on T2WI and shows heterogenous strong enhancement on contrast
administration, with the periphery of the mass enhancing more
intensely than the center. The mass widens the right neural foramina
at the level of T4-T5 and compresses and displaces the spinal cord
anterolaterally to the left. Impression was a right paravertebral mass,
causing compression of the adjacent spinal cord.
Figure 3. MRI of the thoracic spine showing a dumbbell-shaped tumor at the level of T4-T6, displacing the cord to the left. a) sagitttal contrast enhanced scan showing heterogenous enhancement , with the periphery of the mass enhancing more intensely than the center, b) sagittal T2W images showing hyperintense signal of the tumor, c) axial T1W images showing hypointense signal to the spinal cord, and d) axial contrast enhanced scan showing heterogenous enhancement.
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A B
C D
Figure 4. Sagittal MRI of the thoracic spine showing the hypointense lesion in T1W images with heterogenous enhancement on T2W images. The cord is displaced anteriorly.
Primary considerations for this kind of tumor are meningioma, and
nerve sheath tumors. Spinal meningiomas are the most common
benign intradural spinal tumor, which arise from arachnoid cluster cells
and thus can be seen from the nerve roots. It may occur in any age
group, but mostly in the 5th and 7th decade of life with female
preponderance. Nerve sheath tumor, on the otherhand, arise from the
dorsal roots, relatively avascular and shows no calcification. Based on
the incidence of a combined intra- and extradural tumor (dumbbell-
shaped tumor), the most common are nerve sheath tumors which
comprises 15% of intraspinal masses. 2,3
Management
Hence, patient was scheduled for operation with pre-operative
diagnosis of a nerve sheath tumor. Medications were Decilone forte,
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vitamin B-complex, ranitidine and mefenamic acid for symptomatic
relief. A two-step operation, laminectomy and thoracotomy, were done
on the patient excising the right paravertebral and spinal mass.
Specimens were sent to the laboratory for histologic examination and
were labeled as follows: a) paravertebral mass, b) spinal mass, and c)
bone from spine.
Outcome
The histopathologic report surprisingly revealed not any of the
benign intra-extradural extramedullary spinal tumors mentioned
above. It showed that all the tissues submitted were secondary to a
well-differentiated chondrosarcoma, which is a malignant tumor of
chondrogenic origin that arises from chondoblasts, cells that form the
cartilage.
Her post-operative course was unremarkable, such that on her
3rd post-operative day, she was transferred from the intensive care
unit to a regular room. Intravenous antibiotics and pain relievers were
given as medications. On her 5th post-operative day, she was shifted
to oral medications. She was discharged improved on her 6th post-
operative day, with the following physical examination findings:
Motor : R L Sensory: R
L
Upper 5/5 5/5 Upper 100% 100%
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Lower 3/5 3/5 Lower 100%
100%
Relexes : intact
The patient went for follow-up check-up and for physical rehabilitation
only two times during her 1st post-operative month, and afterwhich,
due to financial constraints, was lost to follow-up. On her 10th post-
operative month, patient was again seen. No complaints of numbness
of both lower extremities nor paresis were noted. Patient now can do
all kinds of household chores, except for complaints of occasional mid
back pain especially while doing her laundry.
Knowing the final histopathologic report of the excised spinal
tumor, patient was advised for follow-up CT scan of the thoracic spine
to re-assess the bony structures around the tumor site. As expected,
the CT scan revealed a bone mass which is of low attenuation,
multiloculated soft tissue mass causing bony expansion of the
transverse process of the 6th thoracic vertebra extending to the right
pedicle, as well as in the costotransverse end of the right 6 th posterior
rib (Figure 5).
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Figure 5. Bone reconstruction of the axial and oblique sagittal views of the thoracic spine show the laminectomy defect from the level of T5 to T7, with an expansile bone lesion in the right transverse process of the 6th thoracic vertebra, and costotransverse segment of the 6th right posterior rib.
Correlating it with the histologic findings, this could be a residual
chondrosarcoma, or one of the expansile benign bone or cartilage
tumors such enchondromas or osteoblastomas, since according to
literatures, these tumors could give rise to chrondrosarcomas .
DISCUSSION
Sarcomas of the bone are rare and represent about 0.2% of all
new cancer cases each year. The two most common forms of bone
cancer are osteosarcoma and Ewing’s sarcoma, followed by the less
common chondrosarcoma, which constitutes 20% - 27% of all primary
malignant tumors.4,5
Chondrosarcoma is a malignant tumor of chondrogenic origin
that remains essentially cartilaginous throughout its evolution. It arises
from the chondroblasts and collagenoblasts. Therefore, it is a type of
sarcoma that is predominantly found in the area around bones. It
occurs most frequently in the pelvis and femur (50%), and less
frequent in the ribs (15%) and spine (less than 7%). 7 It usually occurs
in the 5th and 6th decade of life with a male to female ratio of 1.5-2.0:
1.6 Our case belongs to the less than 7% of all chondrosarcomas (or
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about 1.4% of the primary malignant osseous neoplasms), occurring in
the 3rd decade of life of a female, which is rarely found in literature
reviews.
Murphy et al described the patterns of chondrosarcomas as
primary or secondary. Chondrosarcomas that arise de novo are called
primary chondrosarcomas. Conversely, chondrosarcomas
superimposed on preexisting benign cartilaginous neoplasms such as
enchondroma or osteochondroma are referred to as secondary
chondrosarcomas. They are also categorized as central, peripheral, or
juxtacortical (periosteal) lesions depending on their osseous location.
Central chondrosarcomas are intramedullary in origin, although large
tumors may erode the cortex and invade the surrounding soft tissue.
Peripheral chondrosarcomas are subdivided into those secondary to a
preexisting osteochondroma or enchondroma and those developing
from the bone surface (juxtacortical). Restrospective analysis of the
patient’s case shows that the excised tumor could either be a primary
tumor of the transverse process of the 6th thoracic vertebra with soft
tissue mass extension, or a secondary tumor that arose from the
benign tumor of the transverse process and head of the 6 th posterior
rib.
Moreover, he also said that the soft tissue component of
chondrosarcomas frequently reveal typical punctate or ring-and-arc
matrix mineralization or calcification and that the non-mineralized
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component have high water content due to hyaline cartilage. These
explains the MR imaging findings of the patient, wherein the low signal
intensity of the lesion on T1 is attributed to the calcifications or
mineralized component of the tumor and its water content, while the
heterogenous signal intensity on T2 is attributed to the intense signal
of water on T2 and with the calcified component remaining low in
signal. Reviewing the osseous structures on MRI, since the follow-up
CT scan showed of an expansile bone tumor in, it was really difficult to
assess the aforementioned bone lesions since they were obscured by
the large soft tissue mass. Likewise, although the bony structures can
already be assessed on x-rays alone, especially if the lesion is on the
long bones, because of the location of the tumor wherein structures
overlap, complicated by the soft tissue mass, the presence of the
lesion was not detected. Calcifications were not present on radiograph
study, perhaps due to the tumors higher non-mineralized component.
Hence, although most likely it was already there, its presence prior to
the operation could not really be ascertained and that CT scan could
have been done to derive to a more accurate diagnosis.
The treatment for intradural-extramedullary spinal tumors is
surgical excision. The goal is total removal of the tumor with maximal
preservation of neurological function. These type of tumor are
amenable to total resection with minimal or no neurological problems
post-operatively. Same is true for chondrosarcomas , and
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chemotherapy as well as radiation have very limited role since they
generally are not sensitive to these treatments and maybe employed
for high-grade types due to high metastatic tendencies 7,8. Our case is
of low-grade type, hence surgical excision is adequate enough.
Rehabilitation or physical therapy is also necessary for the affected
area to regain strength and use after surgery.
Because of the rarity of this type of spinal tumor, only few cases
have been reported in the literatures, presenting in different histologic
types and location. Some of which, were not identified pre-operatively
but only after histological examination.
A similar case was reported by Sakayama et al (2004).9 He
reported a case of a 58-year-old male who complained of a right
cervical pain with difficulty of swallowing without apparent cause. MRI
and CT suggested a diagnosis of a dumbbell tumor. Bone scintigraphy
was also done which was negative. Surgery was then performed
assuming the presence of a neurogenic tumor, however, postoperative
histopathological diagnosis revealed a grade II chondrosarcoma.
And in 2005 at the Haseki Eductional and Research Hospital, in
Turkey, a type of chondrosarcoma, myxoid chondrosarcoma in a 40
year old man who experienced a 3 month history of back pain was
reported. 10 MRI was done and pre-operatively, the lesion was not
identified as chondrosarcoma. However, histological examination
revealed a primary myxoid chondrosarcoma. The differential
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consideration of the intradural mass at that time was meningioma,
plasmacytoma and non-neoplastic intradural spinal cord lesion.
Another type was reported by the Christian Medical Colleges and
Hospital in India, wherein a 52-year-old man presented with symptoms
of progressive cervical radiculomyelopathy. Histologic examination
after surgery showed a mesenchymal type of chondrosarcoma.11
Another case occurring in the cervical spine, histologic type not
specified, was reported in a female by another journal.12
Only one literature was found showing the most common
location of spinal chondrosarcomas. Lloret and Server (2006) made a
retrospective review of 5 patients with histopathologically confirmed
primary spinal chondrosarcoma which showed that 3 of them was
thoracic (60%), 1 was cervical (20%) and 1 was lumbar (20%) in
distribution. 13
RECOMMENDATION
Spinal tumors can give us a lot of differential diagnoses
depending on their location (i.e. intramedullary, extramedullary,
intradural, extradural or both). And an accurate pre-operative
diagnosis is so important because the type of management and
surgical procedure will depend on it. At present, clinicians, even
radiologists, when thinking of a spinal cord tumor, magnetic resonance
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imaging is primarily requested after x-ray of the spine, since it directly
image the spinal cord and extent of soft tissue involvement. However,
as in this case, not all paravertebral soft tissue masses that cause
spinal cord compression do readily signify a pure spinal cord lesion, but
it may also arise from the osseous and cartilaginous structures (e.g.
chondrosarcoma). Hence, although MRI can already give us a line up
of differential considerations, correlation with other imaging
modalities is needed, carefully scrutinizing at least plain radiographs
for osseous abnormalities, and if there is something suspicious, then
CT scan and/or other examinations such as bone scintigraphy should
be done.
However, because of the very limited experience on
chondrosarcomas, especially that it has different histological features
with corresponding radiographic patterns, and wherein prognosis vary,
further reviews as to its radiographic, MRI and CT scan appearances is
recommended. In effect, if the radiologist becomes aware of the
imaging features of these tumors, improvement on diagnostic
accuracy, treatment, planning and prognosis is attained.
Accurate description of the imaging features of tumors should
also be given to pathologists to assist them in their histologic
diagnosis.
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And, specifically for this case, since the patient’s thoracic spine
CT scan revealed an expansile bone tumor in the spine and rib, biopsy
is recommended, and whether it is benign or malignant is yet to be
determined. This would aid proper management of the patient and at
the same time, conclude the origin of the excised tumor.
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