Primary intracranial chondrosarcoma is an extremely rare malignant tumor of the central
nervous system, which accounts for less than 0.16% of all primary intracranial tumors.[1] Most are located at the skull base, where they are thought to arise from cartilage
of the synchondroses. Less commonly, chondroid tumors arise from the choroid plexus,
dura mater, or brain parenchyma. Histologically, three variants of chondrosarcoma
have been described: myxoid, mesenchymal, and classic chondrosarcoma. Since the first
description of intracranial chondrosarcoma by Mott in 1899, only 53 cases chondrosarcomas
arising above the skull base have been reported and most of these are of the highly
malignant mesenchymal variant.[1]
[2]
[3]
[4]
[5]
[6]
[7]
[8]
[9]
[10]
[11]
[12] Only 12 cases of classic variant chondrosarcomas have been reported in the falcine/parafalcine
location ([Table 1]).[2]
[3]
[4]
[5]
[6]
[7]
[8]
[9]
[10]
[11]
[12] The authors report one more case of classic chondrosarcoma arising in such an unusual
location.
Table 1
Clinical characteristics of all the 12 cases including our case of classic variant
of extraskeletal chondrosarcomas at falx and parasagittal locations
|
Year
|
Article
|
Age/sex
|
Location
|
Pathology
|
Follow–up
|
Recurrence
|
Alive/dead
|
|
Adapted from Krishnan et al.[12]
|
|
1978
|
Alvira and McLaurin[2]
|
21/F
|
Left frontal subdural and interhemispheric
|
Low–grade chondrosarcoma
|
No follow–up
|
No follow–up
|
No follow–up
|
|
1985
|
Cybulski et al[3]
|
58/M
|
Anterior falx
|
Low–grade chondrosarcoma
|
18 mo
|
No
|
Alive
|
|
1998
|
Gerszten et al[4]
|
12/F
|
Falx
|
Low–grade chondrosarcoma
|
9 mo
|
No
|
Alive
|
|
1998
|
Forbes and Eljamel[5]
|
19/F
|
Anterior falx
|
Nonmesenchymal chondrosarcoma
|
2 y
|
No
|
Alive
|
|
2001
|
Oruckaptan et al[6]
|
56/F
|
Anterior falx
|
Low–grade classic chondrosarcoma
|
3 y
|
No
|
Alive
|
|
2003
|
Kothary et al[7]
|
28/F
|
Frontoparietal parasagittal
|
Classic chondrosarcoma
|
No follow–up
|
No follow–up
|
No follow–up
|
|
2005
|
Tosaka et al[8]
|
18/F
|
Frontal parasagittal
|
Low–grade chondrosarcoma
|
No follow–up
|
No follow–up
|
No follow–up
|
|
2008
|
Kathiravel and Finnis[9]
|
32/F
|
Left Frontoparietal parasagittal
|
Classic chondrosarcoma
|
15 mo
|
No
|
Alive
|
|
2009
|
Boccardo et al[10]
|
32/F
|
Anterior falx
|
Low–grade chondrosarcoma
|
NA
|
NA
|
NA
|
|
2009
|
Güneş et al[1]
|
25/M
|
Posterior falx
|
Low–grade chondrosarcoma
|
No follow–up
|
No follow–up
|
No follow–up
|
|
2011
|
Krishnan et al[12]
|
23/F
|
Anterior falx
|
Grade I classic chondrosarcoma
|
16 mo
|
No
|
Alive
|
|
2011
|
Krishnan et al[12]
|
19/M
|
Right frontal parasagittal
|
Grade I classic chondrosarcoma
|
12 mo
|
No
|
Alive
|
|
2018
|
Present case
|
30/F
|
Left parieto–posterior parafalcine
|
Grade I classic chondrosarcoma
|
12 mo
|
No
|
Alive
|
Case Report
A 30-year-old woman presented with history of headache and vomiting associated with
episodes of giddiness of 5-month duration. She also noticed clumsiness of her right
hand. Clinical examination revealed subtle pyramidal signs in her right upper limb.
Magnetic resonance imaging (MRI) of the brain revealed an extra-axial lobulated posterior
parafalcine lesion. The lesion was predominantly composed of components that was hypointense
on T1-and hyperintense on T2-weighted images ([Fig. 1A]). The lesion showed mild, heterogeneous contrast enhancement ([Fig. 1B]). She underwent a left parieto-occipital craniotomy and total excision of the lesion.
The lesion was hard lobulated, grayish colored, and moderately vascular. Histologic
examination of excised lesion revealed lobules of cartilage containing atypical chondrocytes
consistent with low-grade chondrosarcoma (grade I). The tumor lobules were large,
irregular with thin intervening minimal fibrous stroma. There was no necrosis or significant
atypia ([Fig. 2]). S-100 protein (1:300; Dako), vimentin, and epithelial membrane antigen (EMA, 1:100,
Dako) were used for immunocytochemical study of the specimen. The neoplastic chondrocytes
showed both cytoplasmic and nuclear staining for S-100 protein and vimentin, but not
for EMA. The diagnosis of well-differentiated chondrosarcoma was made.
Fig. 1 (A) Magnetic resonance images showing the lesion in left parieto posterior parafalcine
location that was predominantly composed of components that was hyperintense on T2-weighted
and hypointense on T1-weighted sequences. (B) Postcontrast T1-weighted coronal and saggital magnetic resonance images showing heterogeneous
contrast enhancement resembling honeycomb pattern of enhancement seen in classic variant
of chondrosarcomas.
Fig. 2 Histologic examination of excised lesion revealed lobules of cartilage containing
atypical chondrocytes consistent with low-grade chondrosarcoma (grade I). The tumor
lobules were large, irregular with thin intervening minimal fibrous stroma. There
was no necrosis or significant atypia.
Follow-up MRI at 12 months after surgery showed no residual or recurrent lesion ([Fig. 3]).
Fig. 3 Magnetic resonance images done at 12-month follow-up showing no evidence of recurrence.
Discussion
Intracranial chondrosarcoma is a rare malignant cartilaginous tumor that was first
reported by Mott in 1899. They can be associated with Maffucci's and Olliers’ syndrome.
They frequently arise at the skull base from the undifferentiated embryonic cells
of the cartilaginous synchondroses.
Intracranial chondrosarcomas of dural origin are very rare, and only 53 cases have
been reported till date.[1]
[2]
[3]
[4]
[5]
[6]
[7]
[8]
[9]
[10]
[11]
[12] Though majority of the skull-base chondrosarcomas are of classic variant (> 80%),
dural-based chondrosarcomas are predominantly of mesenchymal variant (60%). Of the
25 falcine and parasagittal chondrosarcomas reported so far, only 12 cases were of
classic variant ([Table 1]).[1]
[2]
[3]
[4]
[5]
[6]
[7]
[8]
[9]
[10]
[11]
[12] The remaining cases were predominantly mesenchymal with only one myxoid variant.
There was a strong female preponderance.[1]
[2]
[3]
[4]
[5]
[6]
[7]
[8]
[9]
[10]
[11]
[12] In this article, the authors report a case of classic variant of chondrosarcoma
that was dural based and parafalcine in location.
According to review of chondrosarcomas by Korten et al,[13] 37% of tumors were located in the petrous bone, whereas 23% were found in the occipital
bone and clivus; 20% in the sphenoid bone; and 14% in the frontal, ethmoidal, and
parietal bones. In only 6% of cases was the primary location in dural tissue, which
normally does not contain cartilage.
Generally, patients present with an extensive history of headaches and symptoms associated
with increased intracranial pressure. Cranial nerve palsies or hemiparesis may also
occur with such lesions, as can dizziness, tinnitus, sensory disturbances of the face,
and decreased visual acuity.
Several theories regarding the histogenesis of dural derived cartilaginous lesions
have been proposed. One theory suggests that the meninges contain primitive multipotential
mesenchymal cells that potentially could give rise to chondrosarcomas.[12] Other theory suggest that meningeal fibroblasts located in the undersurface of the
dura and arachnoid were the origin of such tumors.[13] Pluripotential mesenchymal cells of the meninges along the falx cerebri, tentorium,
and cerebral convexity as well as the skull base occasionally act as precursor cells
to these tumors. The rare intraparenchymal tumors are thought to arise from the pia-arachnoid
cells of the Virchow-Robin spaces of intracerebral vessels.[3]
[6]
Three histopathologic variants of intracranial chondrosarcomas have been described:
classic (well-differentiated), myxoid (intermediate), and mesenchymal (undifferentiated).
Most chondrosarcomas arising above the skull base are of the mesenchymal subtype.[13] Though mesenchymal chondrosarcomas occur mainly in the younger patients (between
10 and 30 years of age), grade I classic chondrosarcomas have no clear age preference.[13] The tumor in this case exhibited classic features. Korten et al[13] reviewed 192 cases of chondrosarcoma and reported that, in general, the mesenchymal
type is malignant and occasionally spreads to distant areas, whereas the classic subtype
is the most benign of the three subtypes.
Histopathologically, classic variant shows less prominent cellular stroma with predominant
cartilaginous lobules with pleomorphic cartilage cells. Classic variant has three
histological grades: grades I, II, and III. Grade I tumors resemble benign cartilaginous
tumors, whereas grades II and III tumors are more cellular and exhibit more mitoses
and less chondroid matrix. Mesenchymal chondrosarcomas have a biphasic pattern with
undifferentiated mesenchymal cells among scattered islands of well-defined cartilage.
Myxoid chondrosarcomas are intermediate-grade lesions that can be differentiated histologically
by the presence of mucinous supporting stroma.[13]
On immunologic examination, chondrosarcomas usually exhibit significant positivity
for S-100 and vimentin, whereas only scattered proliferating cells exhibit positivity
for the proliferative marker, Ki-67. These features differentiate chondrosarcoma from meningioma, hemangiopericytoma,
metastasis, and vascular malformations.
On imaging, these lesions are often mistaken as meningiomas due to their extra-axial
location. Computed tomographic (CT) scan usually reveals an isodense/hyperdense mass
with heterogeneous enhancement and varying degrees of calcification in patients with
chondrosarcomas.[13]
On MRI, they are typically hyperintense on T2-weighted and hypointense on T1-weighted
images. Variable shortening of T1 and T2 relaxation times due to scattered mature
cartilage cells makes them heterogenous. On postcontrast study, classic variant shows
a “honeycomb” pattern of enhancement whereas mesenchymal variant shows homogenous
enhancement. Brighter signal on T2-weighted images and absence of dural tail differentiate
them from meningiomas.[6]
[7] The MRI findings in this case was similar to those described in most prior reports.
Gross total resection would be the mainstay of treatment as recurrences and metastases
are rare in the dural classic variant. Mesenchymal and myxoid chondrosarcomas have
significantly higher recurrence rates than the classic variants, even after gross
total excision. An infrequent tendency to distant metastasis is another indicator
of poor outcome in these variants.[12]
[13] This aggressive behavior pattern has led many authors to consider adjuvant radiotherapy
even after the successful radical resection of mesenchymal and myxoid chondrosarcomas.
In contrast, if a complete resection is achieved, limiting treatment to surgery alone
is a frequent therapeutic strategy for classic chondrosarcomas.
On review of the literature, the authors found there were no recurrences for dural-based
classic chondrosarcomas after gross resection (the maximum follow-up period noted
was 6 years).[1]
[2]
[3]
[4]
[5]
[6]
[7]
[8]
[9]
[10]
[11]
[12] High-dose photon and/or proton beam therapy, which both have acceptable side effects,
have been used for residual skull base chondrosarcomas and seem to provide superior
results to conventional radiation techniques.[13]
In this case, the treatment was limited to surgery alone as the tumor exhibited good
dissection margins from the surrounding tissue, and hence total resection was achieved.
The patient subsequently exhibited a favorable prognosis after surgery, and there
was no recurrence at 12 months of follow-up.
Conclusion
Chondrosarcomas are rare cartilaginous tumors of the CNS and are not limited to the
skull base even in classic variants. Because of its rarity and similar imaging findings
with meningioma, a differential diagnosis is often challenging. Higher signal intensity
on T2- and lower on T1-weighted images, absence of edema and dural-tail sign, a peculiar
honeycomb pattern of enhancement, and a well-preserved pial barrier around the tumor
are important suggestive criteria for chondroid tumors. Pathologic diagnosis is the
gold standard, and neurosurgical resection is the mainstay of therapy. Classic chondrosarcomas
have a better prognosis compared with myxoid and mesenchymal variants and usually
do not require adjuvant treatment modalities as long as surgery allows a radical resection
of tumor.
Source of Support
None.
