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Chondrosarcoma of the skull base
CASE REPORT
Chondrosarcoma of the Skull Base — Report of Two Cases
1
2
Pei-Yi Chu, Chih-Peng Wei , Yu-Fong Tsai , Tsung-Han Teng, Chin-Cheng Lee
1
2
Department of Pathology and Laboratory Medicine, Neurosurgery , Radiology , Shin Kong Wu Ho Su Memorial Hospital,
Taipei, Taiwan
ABSTRACT
Chondrosarcoma of the skull base is a rare slow-growing tumor with a potentially lethal outcome due to compression of adjacent
tissues. Total surgical excision is often difficult due to local anatomical limitations. The differential diagnosis among chondrosarcoma,
chordoma, and chondroid chordoma is important due to their different prognoses. We describe two cases of chondrosarcoma with
initial presentations of diplopia. Magnetic resonance imaging (MRI) in each case revealed a skull base tumor. After tumor excision,
histopathologic examination showed a grade I chondrosarcoma. In conclusion, accurate diagnosis and careful surgical treatment
play important roles in the management of chondrosarcoma. (Tzu Chi Med J 2006; 18:229-231)
Key words: chondrosarcoma, skull base, chordoma
INTRODUCTION
Chondrosarcoma of the skull base is a slow-growing indolent tumor with a potentially lethal outcome due
to compression of adjacent tissues such as the carotid
artery and cranial nerves. Radical excision is usually
difficult. It accounts for 6% of all skull base lesions [1].
Chondrosarcoma is mostly divided into three histological grades, grade I (well differentiated), grade II
(moderately differentiated), and grade III (poorly
differentiated). The 5-year survival rates for grade I, II
and III chondrosarcomas of bone from all body sites are
90%, 81%, and 43%, respectively [2]. Surgical treatment with radiotherapy, particularly carbon ion
radiotherapy, has been reported to achieve a better outcome than simple local control [3]. We report two cases
of chondrosarcoma of the skull base.
CASE REPORTS
Case 1: Clinical summary and pathological findings
A 49-year-old woman complained of left progressive diplopia for several months. She had a partial excision of a left parasellar chondrosarcoma seven years
previously. On physical examination, limitation of eye
movement from right to left was noted. Magnetic resonance imaging revealed a large tumor involving the
sellar, suprasellar, left parasellar and left temporal areas.
Dense heterogenous ring-shaped calcifications were
noted in the medial aspect of this tumor. The heterogenous ring form or C-shaped calcification is characteristic of a chondroid tumor (Fig. 1). During surgery, a calcified tumor was found around the sellar portion with
left internal carotid artery and abducens nerve encasement. The main tumor was almost totally removed except for the suprasellar and cavernous portions.
Histopathologic examination showed a low grade
chondrosarcoma with proliferation of chondrocytes containing hyperchromatic nuclei. Occasional bi-nucleated
cells with eosinophilic cytoplasm were seen (Fig. 2).
Immunohistochemical stains of the tumor cells were
positive for S-100, but negative for cytokeratin.
The post-operative course of the patient was smooth
and she is still followed up regularly in the outpatient
Received: November 8, 2005, Revised: November 29, 2005, Accepted: December 19, 2005
Address reprint requests and correspondence to: Dr. Chin-Cheng Lee, Department of Pathology and Laboratory Medicine,
Shin Kong Wu Ho Su Memorial Hospital, 95, Wen Chang Road, Taipei, Taiwan
Tzu Chi Med J 2006 18 No. 3
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P. Y. Chu, C. P. Wei, Y. F. Tsai, et al
department.
Case 2: Clinical summary and pathological findings
A 25-year-old man complained of right progressive
diplopia for 2 years. His past medical history was not
significant. On physical examination, limitation of eye
movement from left to right was noted. Magnetic resonance imaging revealed a 3 × 3 × 2 cm tumor originat-
ing from the dura or clivus, with heterogeneous enhancement and brainstem compression (Fig. 3). Because this
tumor had high signal intensity on T2WI and a rather
well-defined border, it was more likely to be from a chondroid group than to be a chordoma. The tumor was totally removed surgically.
Histopathologic examination showed a low grade
chondrosarcoma with proliferation of polygonal cells
Fig. 1.
Magnetic resonance imaging reveals a large tumor
involving the sellar, suprasellar, left parasellar and
left temporal areas. The heterogenous ring form or
C-shaped calcification is characteristic of a chondroid
tumor.
Fig. 3.
Magnetic resonance imaging reveals a tumor originating from the dura or clivus, with heterogeneous
enhancement and brainstem compression.
Fig. 2.
Histopathologic examination shows a low grade
chondrosarcoma. Bi-nucleated cells with eosinophilic
cytoplasm are also seen (black arrow) (H&E × 200).
Fig. 4.
Histopathologic features show a low grade chondrosarcoma, similar to case 1. A bi-nucleated cell with
eosinophilic cytoplasm is seen (black arrow). No mitoses or tumor necrosis is noted (H&E × 200).
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Tzu Chi Med J 2006 18 No. 3
Chondrosarcoma of the skull base
containing hyperchromatic nuclei and eosinophilic cytoplasm in a chondromyxoid background. Occasional
bi-nucleated cells were seen (Fig. 4). No mitoses or tumor necrosis was seen. Immunohistochemical stains of
the tumor cells were positive for S-100, but negative for
cytokeratin.
The post-operative course was smooth and the patient is still followed up regularly in the outpatient
department.
DISCUSSION
Chondrosarcoma of the skull base is rare and accounts for 6% of all skull base lesions [1] and 0.1% of
all head and neck tumors [4].
Several hypotheses have been elicited to explain how
a chondrosarcoma develops in the skull base. The
histogensis of chondrosarcoma is postulated either to
associate with the remnant of the fetal cartilage and notochord in the skull base or to arise from pluripotent
mesenchymal cells involving the embryonogenesis of
the skull base.
Chondrosarcoma can be subclassified, in order of
frequency, into the conventional (hyaline or myxoid),
dedifferentiated, clear cell, and mesenchymal subtypes.
According to a review of 200 cases by Rosenberg et al,
conventional chondrosarcoma is the most common subtype [5]. Dedifferentiated chondrosarcoma is the most
malignant with a high risk of metastasis.
The most important differential diagnosis for chondrosarcoma of the skull base is chordoma. Although they
are similar in management, distinction between chordoma and chondrosarcoma is important due to different
prognoses and outcomes. They are difficult to differentiate with imaging alone [6] and a misdiagnosis may be
made even on histological examination. A chordoma
typically contains cohesive nests and cords of large cells
with bubbly eosinophilic cytoplasm called physaliphorous cells.
Although physaliphorous cells may be present in
chondrosarcoma, they are smaller and have less cytoplasm than those seen in a chordoma, and lack cohesive
nests or cords. Chondroid chordoma has features of chondrosarcoma and chordoma. Chondroid chordoma is similar to chondrosarcoma in the cartilaginous areas and
contain the cohesive nests and cords of physaliphorous
cells that are typical features of chordoma [7].
Immunohistochemical study is helpful in puzzling
cases. Chondrosarcoma is usually positive for S-100 and
Tzu Chi Med J 2006 18 No. 3
negative for epithelial membrane antigen (EMA) and
cytokeratin (CK). Chordoma, in contrast, is usually positive for EMA, CK and S-100 [8]. Borba et al [9] concluded that a diffuse chordoma background with areas
of chondroid patterns immunonegative for CK staining
is more suggestive of chondroid chordoma.
Treatment of chondrosarcoma includes careful preoperative evaluation and surgical resection or radiotherapy, particularly carbon ion radiotherapy which has been
reported to achieve a better outcome than simple local
control [3]. Computed tomography (CT) is useful in
evaluating bone destruction and showing the characteristic calcified rim formation of chondrosarcoma. The soft
tissue part of the skull base and chondrosarcoma are welldemonstrated in magnetic resonance imaging [10].
In summary, a chondrosarcoma of the skull base is
a rare, slowly growing tumor. It should be differentiated from chordoma due to different clinical outcomes.
Once the diagnosis of chondrosarcoma is made, careful
preoperative image evaluation and radical excision with
radiotherapy is the currently accepted management.
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