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A Comprehensive Review of Intracranial Chordomas Eren Erdem, M.D., Edgardo J.C. Angtuaco, M.D., Muhammad Husain, M.D., Ossama Al-Mefty, M.D. University of Arkansas for Medical Sciences, Little Rock, Arkansas Introduction Cranial chordomas are relatively rare, aggressive and locally destructive tumors of the skull base. 35% of all chordomas occur along the vicinity of the clivus (sphenooccipital bones). They represent 1% of intracranial and 4% of all primary bone tumors. Chordomas may occur at any age but are usually seen in adults with a peak incidence in the 4th decade of life with a male predominance of 2:1. Although generally slow growing, the tumors’ intimate relation to critical structures and extremely high local recurrence rate has led to most of the patients dying from the primary intracranial disease. Recent advances in skull base surgery and radiation therapy provides an opportunity for cure. This can be achieved with precise knowledge of tumor extent and its relationship to vital neural and vascular structures provided by advanced imaging capabilities of computed tomography (CT) and magnetic resonance imaging (MRI). Tumor Spread Imaging Characteristic Imaging Features CT MRI Chordomas present a lobulated tumor having a pushing margin and sharp pseudoencapsulated appearance (Fig. 2). Such a demarcation from normal tissue is not present in bone where they infiltrate along the lines of least resistance. Trabecular bone is entrapped leading to dystrophic calcifications (Fig.3). The classic CT appearance is a centrally located wellcircumscribed expansile soft tissue mass arising from the clivus with associated extensive lytic bony destruction (Fig. 6). T1-Weighted Chordomas are intermediate to low signal on T1-W images and are easily recognized within high intensity fat of clivus (Fig. 8). Small foci of hyperintensity can sometimes be visualized in the tumor correlating to intratumoral hemorrhage or mucous pool (Fig. 9-24). Fig. 2- T2 -weighted MR image shows tumor septations and pseudoencapsulated appearance. 2 Fig. 3- CT of skull base demonstrates infiltration of tumor into the clivus and pre-pontine cistern leading to trabecular entrapment and dystrophic calcification. 3 Cranial chordomas most often originate from the sphenooccipital synchondrosis of the clivus. They may also involve the upper (basisphenoid) or lower (basiocciput) clivus (Fig. 4). 6C Intratumoral calcification seen on CT appears irregular and is thought to represent the bony sequestra from destroyed bone (Fig. 7A). Chondroid variant is most likely to show real intratumoral calcification (Fig. 7B). Occasionally they arise from the petrous apex (Fig. 5). Fig. 5– Unenhanced CT (A) shows lytic lesion of the petrous apex Enhanced axial T1-weighted MR (B) demonstrates strongly enhancing mass in the right petrous apex with extension into the adjacent cavernous sinus and sella. CT and MRI are required in the pretreatment evaluation. Their unique location at the skull base and their proximity to critical soft tissue structures makes critical assessment necessary. 7A 14A Fig. 8- Unenhanced MR studies of two patients. Axial T1-weighted MR (A) shows small hypointense mass within the right side of the clivus. Sagittal T1-weighted MR (B) shows large hypointense soft tissue mass from the distal clivus with anterior extension into the nasopharynx and extradural extension into the posterior fossa. Fig. 9- Sagittal unenhanced T1-weighted MR shows rim of hyperinintensity along a posteriorly projecting retroclival mass indicative of highly proteinaceous material or blood products. T2-Weighted The classical chordoma is extremely high signal on T2-W images (Fig. 10) which likely reflect the high fluid content of vacuolated cellular components. T2-W images are superior in separating tumor from contiguous neural structures (Fig. 11). Areas of hypointensity and heterogenous signal are the result of calcification, hemorrhage and highly proteinaceous mucous pools (Fig. 12). 10B 14B 13A Fig.13– Unenhanced axial T1-weighted MR (A) shows isointense mass along right side of clivus and petrous apex. On enhanced studies (B) there is marked diffuse homogeneous enhancement of the mass. Fig. 15– Axial enhanced T1-weighted MR shows variable enhancement (honeycomb appearance) of a large midclival mass with extension to the sella and adjacent cavernous sinuses. Note lateral displacement of right cavernous internal carotid artery. 18B Fig. 10– T2-weighted MR images of chordomas in different patients show (A) homogeneous diffuse hyperintensity; (B) heterogenous hyperintensity most likely due to small mucous lakes; (C) Diffuse hyperintensity of tumor in clivus with intradural extension into posterior fossa. Fig. 18– MR studies (A,B) demonstrate a mass extending to the left middle cranial fossa (A) with suprasellar extension (B). Left carotid angiogram (C) show narrowing of the distal left internal carotid artery and upward displacement.of the left middle cerebral artery. Fig. 17– Coronal T1-weighted MR (A) shows tumor extension to the right cavernous sinus with displacement and partial encasement of the cavernous internal carotid artery. Composite image of MRA (B) shows posterior displacement of the right posterior cerebral artery. Sagittal T1-weighted MR (C) demonstrates posterior and superior elevation of the right cavernous internal carotid artery. Fig. 7– Sagittal CT reformation (A) reveals bony sequestra at the distal end of the lytic clival lesion. Unenhanced CT (B) shows intratumoral calcification adjacent to lytic clival lesion. Fig. 19– Sagittal unenhanced T1-weighted MR (A) show mass involving the posterior fossa with large extracranial soft tissue extension to the face. The recurrent tumor on left external carotid arteriogram (B) demonstrate tumor vascularity from branches of the posterior auricular artery. 19B Fig. 28– Surgical resection through midline transmaxillary approach. Sagittal and axial MR before (A, C) and after surgery (B, D) reveal complete resection of the clival and intradural extension of tumor (arrows). Local 28B 28A 4 3 3-Inferior Fig. 32– Initial studies (A) shows mass primarily in sellar area. Transmaxillary approach to tumor was done and postsurgical MR a year after surgery showed recurrent tumor at the site of the surgical approach: in the nasal region (B) and in the clival area (C). 29A posterior fossa 1- Dahlin DC, Mac Charty CS: Chordoma. A study of 59 cases. Cancer 5: 1170-1178 (1952) 2- Raffel C, Wright DC, Gutin PH, Wilson CB. Cranial chordomas: Clinical presentation and results of operative and radiation therapy in twenty-six patients. Neurosurgery 17: 703-710 (1985) 3- Al-Mefty O,Borba LAB: Skull base chordomas: a management challenge. J Neurosurgery 86: 182-189 (1997) 4- Oot RF, Melville GE. The Role of MR and CT in evaluating clival chordomas and chondrosarcomas.AJR 151:567-575 (1988) 5- Larson TC, Houser W, Laws ER. Imaging of cranial chordomas. Mayo Clin Proc 62:886-893 (1987) 6- Doucet V, Viton PP, Branger DF,et al. MRI of intracranial chordomas. Extent of tumor and contrast enhancement: criteria for differential diagnosis. Neuroradiology 39:571-576 (1997) Fig. 31– Massive intra-and extracranial recurrence of chordoma in a 14 year old patient referred from an outside institution following an initial partial resection. Note extensive soft tissure recurrence with extension in the posterior fossa and retropharyngeal space. Recurrence remote from the origin along surgical pathway is a known feature (Fig. 32). Fig. 29– Surgical resection through cranioorbitozygomatic approach (arrows). Presurgical MR (A) Postsurgical MR (B) show radical resection of the tumor. 3-Posterior 31C Surgical Pathway 2-Lateral middle cranial fossa nasopharynx 31A 28D cavernous sinus References 19A Post-surgical follow up is best achieved with MRI. 28C 17C Angiographic evaluation is nonspecific and abnormal tumor vascularity or stain is rare (Fig. 19). Fig. 12– T2-weighted MR demonstrates multiseptated hyperintense mass with extension into the sella and left cavernous sinus. Mass exhibits variable signal intensity with areas of hypointensity. 1 2 3rd ventricle 17B Angiography Fig. 11– T2-weighted MR shows well demarcated hyperintense mass with anterior extension into the sella and left ethmoid sinuses and lateral extension to the right middle cranial fossa, compressing the uncus. chiasm 4-Superior 17A Aggressive surgical removal followed by high dose radiation is the most effective treatment. Recurrence free survival rate at 5 years is about 55-65% following combined surgical-radiation therapy. 1-Anterior Tumor displacement (Fig. 16) or partial encasement (Fig. 17) of intracranial arteries is often visualized. Arterial narrowing is rare with chordomas, which may correlate with the observation these tumors are generally soft and easily dissected from adjacent vessels (Fig. 18). Fig. 16– IVI reprojection of a magnetic resonance angiogram (MRA) of the vertebrobasilar artery delineates superior and posterior displacement of vertebrobasilar junction by large clival chordoma. Recurrence 31B Magnetic Resonance Angiography 10C 7B orbit & nasal cavity sphenoid sinus 13B Fig. 14– Sagittal unenhanced T1-weighted MR (A) shows large isointense soft tissue mass in distal clivus exhibiting little to no enhancement on enhanced studies (B). 18A 10A 5B 8B 6B notochord remnants 5A Fig. 1- Histologic slide showing vacuolated cells with intracytoplasmic mucous droplets (physaliferous appearance) typical of chordoma Fig. 6– CT scans of different cases showing lytic lesions of the: (A) mid-clivus; (B) distal clivus with involvement of adjacent occipital condyles; (C) distal clivus with associated soft tissue nasopharyngeal mass. 6A Location Histopathology Chordomas are neoplasms of vestigial notochord tissue. Remnants of the notochord may remain in the midline, usually entrapped within bone along the ends of the spinal column. Clivus and coccyx serve as the main site of origin of chordomas. The tumor cells tend to be arranged in cords set in a pale matrix of mucopolysaccharide with characteristic physaliferous appearance (Fig 1). 8A Enhanced Studies Moderate to marked enhancement is very common (Fig. 13) but, not the rule (Fig. 14). Sometimes a honeycomb pattern of enhancement can also be seen (Fig. 15). Treatment Fig. 30– Presurgical evaluation of petrous apex chordoma. Presurgical MR studies (A, B) demonstrate right petrous apex mass with extension to foramen lacerum and occlusion of petrous internal carotid artery. Presurgical angiograms (lateral projections) confirms occlusion of right internal carotid artery on a right common carotid arteriogram (C) and collateral filling of the branches of the right internal carotid circulation with associated dysplastic aneurysm of the right posterior communicating artery on a left vertebral angiogram (D). With detailed knowledge of the lesion gained from imaging studies, total tumor resection and clipping of the aneurysm were achieved (E, F). 30A 32A 32B 29B 32C 30B Distant Metatasis 30C 30D 30E 30F Fig. 33– Postsurgical axial CT (A) shows a soft tissue mass in the left infratemporal fossa (surgical approach). Axial CT of the thoracic spine (B) with bone and soft tissue settings show metastatic destructive lesion in the left pedicle with adjacent soft tissue extension. This represents distal metastatic spread of chordoma. 33A 33B Conclusion Intracranial chordomas are rare, midline tumors of clival origin. MRI and CT imaging are the modality of choice for diagnosis, treatment planning and follow up. Bone destruction and the presence of intratumoral calcification is visualized on CT, and MR imaging delineates soft tissue extension and the relation of the tumor to vital structures and intracranial vessels. Radical surgical resection followed by proton beam radiation therapy achieves the best results. Local recurrence is not uncommon with an unfavorable prognosis.