Chondrosarcomas of the skull base: review of the literature and report of two cases

Journal of Cranio-Maxillofacial Surgery (1997) 25, 322-327 © 1997 European Association for Cranio-Maxillofacial Surgery

Chondrosarcomas of the skull base: review of the literature and report of two cases A. D. Rapidis, G. Archondakis, D. Anteriotis, C. A. Skouteris

Departments of Maxillofacial Surgery (Head." Dr A. D. Rapidis DDS) and Neurosurgery (Head." Dr N. Kordiolis MD), Greek Anticancer Institute, Saint Savvas Hospital, Athens, Greece SUMMARY. Chondrosarcomas are malignant mesenchymal tumours occurring only rarely in the bones of the cranium. Less than 5% of all chondrosarcomas are located in the head and neck area and their commonest location is the ethmoids and the sphenoid sinus. They are slow-growing tumours with low malignancy rate and unclear histopathogenesis. The prevailing hypothesis is that they arise from cartilaginous remnants in the petro-clival, spheno-occipital and fronto-nasal synchondroses. Diagnosis is only made after biopsy since clinical signs and symptoms and radiological findings are not pathognomonic. Symptomatology mainly derives from tumour encroachment and infiltration of adjacent intracranial structures. Surgery is the treatment of choice, while radiotherapy has an adjunctive role. Chemotherapy is not effective. Partial tumour excision to alleviate symptoms is an acceptable surgical technique since diagnosis is usually late, but treatment can be repeated when recurrence occurs.

During the last year, two cases of chondrosarcoma of the skull base were treated in our institution. Both patients were female, aged 62 and 73, respectively. Computerized Tomography and Magnetic Resonance Imaging were inconclusive and diagnosis was established after biopsy. Treatment for both cases was surgical, with partial excision due to intracranial involvement of the internal carotid artery. In one case, a temporal approach was used, whereas the other patient was operated on via a naso-orbital approach. One patient received postoperative radiotherapy. The postoperative course was uneventful in both patients and marked clinical improvement was noted 18 months and 1 year after surgery. We support the view that partial resection of chondrosarcomas of the base of the skull to alleviate symptoms is an acceptable surgical treatment.

INTRODUCTION

structures, both intra- and extra-cranially. Early symptoms are rather vague and long delays in proper diagnosis are frequently reported. Headache is a constant early symptom followed by 6th nerve palsy. The latter occurs in those patients in whom the turnout involves the clivus, and palsy is thought to be due to impingement on the nerve in Dorello's canal. Tumours may show an extensive involvement of the base of the skull, and in such a case palsies of the 2rid, 3rd, 4th, 5th and 6th cranial nerves may be present. When the tumour involves the foramina and enters the cranium, symptomatology from the 9th, 1lth, and 12th cranial nerves may occur. Further symptoms may be present either from the expansion of the lesion anteriorly to the sphenoid sinus and the ethmoids or they can result from increased intracranial pressure (Volpe et al., 1993). The interval between onset of symptoms and final diagnosis may vary and in some series is reported to be between 18 and 60 months (Volpe et al., 1993). Patients with chordomas and chondrosarcomas may also present with nasopharyngeal symptoms. Nasal and eustachian tube obstructions, throat fullness, epistaxis with the presence of a nasal mass, paralysis of the tongue, dysphagia and dysarthria are some of the symptoms encountered (Batsakis and Kittleson, 1963; Perzin and Pushparaj, 1986).

Skull base chondrosarcomas are rare malignant turnouts derived from cartilaginous remnants of skull synchondroses (Weber et al., 1995). They may arise de novo or as a malignant transformation in a pre-existing benign chondroma. Malignant tumours are more common by far than benign cartilaginous lesions. There are no pathognomonic signs or symptoms presented by chondrosarcoma and it cannot be differentiated from the chondroma or chordoma purely on the basis of clinical signs (Volpe et al., 1993). The base of the skull is the site of 5 to 7% of all chondrosarcomas. The lesion can occur at any age and shows no sex predilection. The reported cases show a peak incidence in the fourth and sixth decades of life (Dahlin and Henderson, 1956; Meyers et al., 1992). They are slow-growing tumours and sizes of less than 2 cm in diameter are rarely encountered at the time of diagnosis (Weber et al., 1995).

CLINICAL PICTURE AND RADIOLOGICAL FINDINGS Signs and symptoms depend upon the anatomical location of the turnout and its relationship to critical 322

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Pain or hypaesthesia in the distribution of the trigeminal nerve alone or in association with symptoms resulting from facial and acoustic nerve involvement can also be the initial manifestations. Visual loss as the presenting symptom is rather uncommon and usually occurs in lesions with expansion to the anterior part of the skull base. It is interesting to note that although visual loss as a result of chondrosarcomas is rather common, decreased visual acuity in patients with good vision is infrequently encountered. Blindness seems to occur very rapidly when the tumour invades the optic chiasma and the optic nerve without a transient period of a gradual decreasing visual acuity. Rapid visual loss can be misleading and may be attributed to optic neuritis, the reason being that in chondrosarcomas fundoscopic findings are usually absent (Bagan and Hollenhorst, 1980). Chondrosarcomas of the skull base have also been associated with the clinical course of a variety of heterogenous conditions including Paget's disease, osteocartilaginous exostoses, Maffucci syndrome, Ollier's disease and osteochondromas, but the association of these conditions with the presence of chondrosarcomas has not been documented (Weber et al, 1995). It is not uncommon for patients suffering from chondrosarcomas of the base of the skull to be sent for radiological examinations several months or even years following treatment for headaches and other vague neurological symptoms, having been misdiagnosed as suffering from disorders of psychosomatic origin. Plain radiographs have little to offer. Computerized Tomography (CT) and Magnetic Resonance Imaging (MRI) are usually sufficient to assess the extent of the disease. To determine the relationship of these tumours to vascular structures, especially in cases with temporal extension, Magnetic Resonance Angiography (MRA), and digital as well as conventional angiography, are used (Yaghami, 1978; Meyers et al., 1992, Weber et al., 1995). The bony destruction of the skull base by chondrosarcomas is best seen using CT, which has the advantage of showing areas of bone destruction and the ability to delineate areas of calcification and mineralization within the tumour (Weber et al., 1995). Most of the tumours show marked contrast enhancement of their soft tissue components (Oot et al., 1988). The demonstration of tumour margins in relation to the brain and other extracranial soft tissues cannot always be defined. In those cases, MRI is beneficial, especially when combined with a fat suppression technique (Tien, 1992). MRI is recommended not only for the evaluation of soft tissue changes but also for evaluating the lesions post-operatively (Brown et al., 1994). It can also provide information on the anatomical location of the tumour in relation to neighbouring neurovascular structures, thus diminishing the necessity for further angiographic studies.

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HISTOLOGICAL FEATURES Diagnosis of chondrosarcoma is only made after histological examination. The microscopic examination of cartilaginous tumours commonly leads to a false diagnosis when insufficient tissue is available for study, since different areas of the same lesion may show considerable variation (Shafer et al., 1983). Histologically, chondrosarcomas are sub-classified into conventional, mesenchymal, dedifferentiated and clear cell lesions (Barnes, 1991). Conventional chondrosarcoma is the commonest form and can be subdivided into grades 1 to 4 on the basis of cellularity, nuclear pleomorphism and mitotic rate. The dominant histopathological finding is the presence of many round or oval cartilaginous cells with single, large or multiple nuclei. The cartilage may appear typical but calcification or ossification is usually abnormal. Mesenchymal chondrosarcoma consists of sheets of small round or ovoid undifferentiated cells interspersed with small islands of well differentiated cartilage that often shows calcification and metaplastic bone formation (Shafer et al., 1983), Dedifferentiated chondrosarcoma is a rare variant, characterized by the presence of highly anaplastic foci within a low-grade cartilaginous tumour (Huvos, 1991). Finally, the clear cell chondrosarcoma consists of clusters of benign giant cells and tumour cells with clear cytoplasm.

TREATMENT The only beneficial treatment of chondrosarcoma is surgery. Not very long ago, and especially before the advent of improved imaging techniques, lesions in the base of the skull were considered inoperable and only palliative treatment was given. During the last 15 to 20 years, multi-disciplinary surgical teams have developed new surgical approaches so that these tumours are today readily amenable to surgery with excellent post-operative results. Despite the great advances in skull base surgery, few chondrosarcomas can be completely resected (Chetiyawardana, 1984; Munzenrider et al., 1993; Weber et al., 1995). Since they rarely metastasize and are slow growing, even partial excision can provide alleviation of symptoms for several years. Surgical approaches may vary considerably according to the anatomical location of the tumour and the desirable area for decompression. Subtemporal-infratemporal, basal subfrontal, frontozygomatic, naso-orbital, midfacial, trans-oral, trans-palatal and LeFort I or II osteotomies for access to the cranial base are a few of the reported surgical approaches, each of which have good indications. The approach should be tailored to the specific tumour, bearing in mind the main objective which is to achieve maximal tumour resection

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Fig. 1 - Photograph of the first patient showing ptosis of the left upper lid and paresis of the 3rd and 6th cranial nerves.

Fig. 2 CT scan showing a space-occupying lesion in the skull base (arrow).

with minimal morbidity and allow for re-operation should recurrence occur (Stapleton et al., 1993). The role of radiotherapy in the management of skull base chondrosarcoma remains controversial. Radiotherapy has been used either post-operatively or as the sole treatment. Various types of radiation therapy have been used. Charged particle radiation treatment and stereotactic radiosurgery seem to achieve better therapeutic results than fractionated external beam radiotherapy and brachytherapy (Kondziolka et al., 1991; Stapleton et al., 1993; Castro et al., 1994). Chemotherapy provides no beneficial results in skull base chondrosarcoma and is not recommended.

CASE REPORTS

Fig. 3 - Sagittal MRI section showing the location of the tumour in the cranial base (arrow).

Case No 1

A 62-year-old white female presented in November 1995 with a left-sided strabismus and partial ptosis of the upper lid of six-months duration and a progressive dysphagia and dysarthria. Ophthalmological examination showed normal visual acuity. Paresis of the 3rd cranial nerve and complete paralysis of the 6th cranial nerve were noted (Fig. 1). Clinical examination revealed tongue and soft palate paresis due to involvement of the 9th and 1 lth cranial nerves. Ear, nose and throat examination revealed complete loss of hearing in the left ear and hoarseness, apparently due to 8th and 10th cranial nerve involvement. Examination of the rest of the cranial nerves was within normal limits. The patient was referred for CT and MRI scans. CT revealed the presence of an extensive, partially calcified tumour on the left side of the cranial base, measuring 8 x 8 x 4 cm. There was marked destruction of the lesser and greater wings of the sphenoid, the clivus and the petrosal bone (Fig. 2). MRI showed that the lesion did not invade the brain but its

extracranial extension was in close proximity to the skull base foraminae (Fig. 3). Angiography showed partial occlusion of the internal carotid artery at the origin of its intra-cranial course. The patient was scheduled for a biopsy via a parietal approach. A lateral craniotomy with reflection of a large osteoplastic parietal flap was performed and the dura was exposed. The brain was retracted and the tumour was visualized extradurally. The internal carotid artery was identified surrounded by the mass. Tissue samples were taken and frozen sections as well as cytological examination revealed the presence of a chondrosarcoma. The tumour was excised with curettes and bone rongeurs in piecemeal fashion. The flap was repositioned and the wound was closed in layers. Histological examination showed a conventional Grade 1 chondrosarcoma. The patient had an uneventful recovery. External beam irradiation was administered and, one year post-operatively, the function of all cranial nerves, with the exception of the 8th, had returned to normal (Fig. 4).

Chondrosarcomas of the skull base 325

MRI scan of the patient. The dimensionsof the lesion in the base of the skull are shown.

Fig. 6 -

The patient, 4 months post-operatively,during treatment with radiotherapy.There is completeremission of the neurological signs.

Fig. 4 -

Fig. 7 - Photomicrographof the histologicalspecimen.The characteristicround or oval cartilaginous cellswith mostlysingle large nuclei and areas of abnormal calcificationand metaplastic bone formation are noted (H. and E. x 100).

5 CT scan of the secondpatient. The ethmoids and sphenoid sinus are invaded by the tumour (arrow).

Fig.

Case No 2

A 73-year-old white female presented in April 1996 complaining of blindness in the left eye, headaches of 1-year duration and epistaxis from the left nostril. She also reported progressive hypaesthesia over the distribution of the left trigeminal nerve. Clinical examination was negative with the exception of blindness in the left eye. Fundoscopy revealed slightly indistinct borders of the optic papilla. CT and M R I scans revealed a mass obliterating the left frontal sinus, left anterior and posterior ethmoids with protrusion into the nasopharynx (Figs 5 and 6). An intranasal biopsy established the diagnosis of chondrosarcoma. The patient underwent an extensive craniofacial resection of the tumour which included a left orbital exenteration, ethmoidectomy, frontal sinus ablation and removal of the involved anterior cranial fossa, nasopharynx and skull base. There was no intracranial involvement and the dura was not invaded by the tumour. Following tumour removal, a left temporalis

muscle flap was elevated via a hemicoronal incision. The flap was brought into the resection area through the lateral orbital wall and was placed over the exposed dura thus filling the defect in the anterior cranial fossa. Surgical wounds were closed in layers. The patient had an uneventful recovery. Histological examination confirmed the diagnosis of conventional chondrosarcoma (Fig. 7). One year postoperatively, the patient remained free of symptoms (Fig. 8).

DISCUSSION Multiple approaches to the skull base have been developed since the early days of neurosurgery. In recent years, the emergence of new surgical specialties and interdisciplinary teamwork have increased our options immensely. However, total removal of many skull base tumours is not always possible. In cases like the ones reported here, we should be concerned with control of the tumour rather than cure. Surgery is the treatment of choice for cranial base chondrosarcomas and the goal of this type of surgery is to achieve maximum tumour

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Fig. 8 - Post-operative CT scan. The temporalis flap covers the area of resection and fills in the defect.

resection with minimal morbidity. Long-term followup is necessary as tumour recurrence is likely and further surgery may be needed (Stapleton et al., 1993). When chondrosarcomas are located in the temporal bone area, early involvement of cranial nerves 6, 7 and 8 is commonly observed. In our first case, paresis of the 6th and 9th nerve was the initial sign. Involvement of the abducent nerve associated with a normal radiographic evaluation can commonly lead to misdiagnosis and treatment for strabismus (Sakalas et al., 1975; Grossman and Davis, 1981; Currie et al., 1983; Galetta and Smith, 1989). In a high percentage of patients, the initial symptom is diplopia associated with a rapid decrease in visual acuity resulting in blindness. The latter was the case in our second patient. Frequently ocular symptoms are misdiagnosed as progressive optic neuritis (Heffelfinger et al., 1973; Seth and Singh, 1973; Raffel et al., 1985; Bates and Herdman, 1988; Volpe et al., 1993). Progressive tumour growth may result in nausea and vomiting from increased intracranial pressure or occipitocervical destabilization necessitating posterior fusion (Weber et al., 1995). Involvement of other cranial nerves further complicates the clinical picture thus making the diagnosis extremely difficult. CT and MRI are essential for accurate tumour location and clarification of its relationship with adjacent structures. Simple, digital or magnetic resonance angiography is used to determine turnout involvement with the internal carotid artery and cavernous sinus (Bahr and Gayler, 1977; Grossman and Davis, 1981). MRI is best used to show soft tissue invasion, with a low intensity signal in T1 cuts and medium to high intensity in T2 cuts (Oot et al., 1988). In MRA, the signal is low except for the mesenchymal chondrosarcoma which can mimic arteriovenous malformations (Kehri and Rauchfuss, 1990). Chondrosarcomas may be locally aggressive but they rarely metastasize. The 5-year control rate after

combined surgical and proton-beam irradiation treatment can reach 95% (Munzenrider et al., 1993; Castro et al., 1994). As morbidity is also low, surgical treatment of locally recurrent tumours is encouraged (Stapleton et al., 1993). This clinical behaviour of chondrosarcoma of the skull base justifies the diversity in surgical approaches that have been employed by various surgical specialties in the treatment of chondrosarcomas. It is apparent that the ability to treat such lesions has been improved as a result of these newer approaches and techniques. However, the relative rarity of these tumours underlines the need for more multi-institutional co-operative studies in an effort to define clearly the results and complications of the various surgical approaches and determine the therapeutic capability of the various types of irradiation protocols. References Bahr, A. L., B. W Gayler: Cranial chondrosarcomas. Report of four cases and review of the literature. Radiology 124 (1977) 151-156 Bagan, S. M., R. W. Hollenhorst: Ocular manifestations of intracranial chordomas. Trans. Am. Ophthalmol. Soc. 78 (1980) 148-155 Barnes, L.: Pathobiology of selected tumors of the base of the skull. Skull Base Surgery 1 (1991) 207-216 Bates, G J E. M., R. C D. Herdman: Chondrosarcoma of the sphenoid. A case report and review. J. Laryngol. Otol. 102 (1988) 727-735 Batsakis, J G, A. C. Kittleson: Chordomas. Otolaryngologic presentation and diagnosis. Arch. Otolaryngol. 78 (1963) 168-173 Brown, E., E. Hug, A. L. Weber: Chondrosarcoma of the skull base. Neuroimaging Clinics of North America 4 (1994) 529-541 Castro, J R., D. E. Linstadt, J P Bahary, P. L. Petti, I. Daftari, J M. Collier, P H. Gutin, G. Gauger, T. L. Philips: Experience in charged particle irradiation of tumours of the skull base: 1977-1992. Int. J. Radiation Oncology Biol. Phys. 29 (1994) 647-655 Chetiyawardana, A. D.: Chordoma: Results of treatment. Clin. Radiol. 35 (1984) 159 161 Currie, J, J H. Lubin, S. Lessell: Chronic isolated abducens paresis from tumors at the base of the brain. Arch. Neurol. 40 (1983) 226-232 Dahlin, D. C., E. D. Henderson: Chondrosarcoma, a surgical and pathological problem. J. Bone Joint Surg. 18A (1956) 1025-1038 Galetta, S. L., J L. Smith: Chronic isolated sixth nerve palsies. Arch. Neurol. 46 (1989) 79-85 Grossman, R. I., K. R. Davis: Cranial computed tomographic appearances of chondrosarcoma of the base of the skull. Radiology 141 (1981) 403-408 Heffelfinger, M. J, D. C. Dahlin, C. S. Maccarty, J W. Beaubout: Chordomas and cartilaginous turnouts at the skull base. Cancer 32 (1973) 410-420 Huvos, A. G: Turnouts: Diagnosis and Treatment, 2rid edn. WB Saunders, Philadelphia 1991 Kehrl, W, A. Rauchfuss: Zur Differentialdiagnose tumorinduzierter Fazialisparesen. Das Chordom des feraniozervikalen 1)bergangs. HNO 38 (1990) 426-432 Kondziolka, D., D. Lunsford, J C. Fliekinger: The role of radiosurgery in the management of chordoma and chondrosarcoma of the cranial base. Neurosurg 29 (1991) 38-46 Meyers, S., W. L. Hirsch, Jr., H. D. Curtin, L. N. Sekhar, C Sen: Chondrosarcomas of the skull base: MR Imaging features. Radiology 184 (1992) 103-108

Chondrosarcomas of the skull base Munzenrider, J. E., N. J. Liebsch, J.. T. Efirol: Chordomas and chondrosarcomas of the skull base: Treatment with fractionated X-ray and proton radiotherapy. In: Johnson, J. T. and M. S. Didolkar (eds.): Head and Neck Cancer. Elsevier Science, New York 1993 Oot, R. F, G 17. Melville, P. F New: The role of MR and CT in evaluating clinical chordomas and chondrosarcomas. Am. J. Roentgenol. 151 (1988) 567-575 Perzin, K. H., N Pushparaj: Nonepithelial turnouts of the nasal cavity, paranasal sinuses, and nasopharynx. A clinicopathological study. XIV. Chordomas. Cancer 57 (1986) 784-791 Raffel, C., D. C Wright, P. H. Gutin, C. B. Wilson: Cranial chordomas: Clinical presentation and results of operative and radiation therapy in twenty-six patients. Neurosurg. 17 (1985) 703-710 Sakalas, R., J. W Harbison, F S. Vines, D. P. Becker: Chronic sixth nerve palsy. An initial sign of basosphenoid tumors. Arch. Ophthalmol. 93 (1975) 186-192 Seth, H. N , M. Singh: Intracranial mesenchymal chondrosarcoma. Acta Neuropathol. 24 (1973) 86-92 Shafer, W. G., M. K. Hine, B. M. Levy: A textbook of oral pathology, 4th ed. W.B. Saunders, Philadelphia 1983, 179 Stapleton, S. R., P. R. Wilk#zs, D. J.. Archer, D. Uttley: Chondrosarcoma of the skull base: A series of eight cases. Neurosurg. 32 (1993) 348-356

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Paper received 22 May 1997 Accepted 21 August 1997