Analysis of radiological features relative to histopathology in 42 skull-base chordomas and chondrosarcomas

Spontaneous Shrinking and Growing Skull Base Chordoma

Background

Chordomas are rare slow-growing tumors occurring in the axial skeleton and can demonstrate local aggressive behavior, typically extending from the median axis, compressing surrounding tissue. Complete surgical resection and adjuvant radiotherapy are the preferred treatments. We present an unusual case of a spontaneously shrinking and growing off-midline petroclival chordoma.

Case Description

A 23-year-old woman presented with right abducens nerve palsy. Computed tomography and magnetic resonance imaging (MRI) revealed an off-midline petroclival lesion compressing the abducens nerve with characteristics of a chondrosarcoma. Preoperative MRI indicated spontaneous lesion regression, and the abducens nerve showed clinical improvement. Hence, the planned surgery was canceled. During the wait-and-scan period, abducens nerve palsy recurred. MRI confirmed lesion growth and showed an intratumoral linear structure indicative of blood. Even though preoperative MRI again demonstrated shrinkage, the lesion was surgically removed. Despite the unusual presentation, histopathological examination diagnosed a conventional chordoma. A second surgery was required to remove the residual tumor, after which the patient received high-dose photon beam therapy.

Conclusion

This article discusses the uncommon presentation and behavior of a petroclival chordoma, showing fluctuating cycles of off-midline growth and spontaneous regression. While intratumoral hemorrhage is hypothesized to explain this tumor behavior, the exact etiology needs further investigation. The case presented here emphasizes the importance of considering chordoma in the differential diagnosis despite an atypical disease course.

Preoperative Diagnosis of a Central Skull Base Giant Schwannoma From Tumoral Microhemorrhages Visualized on Susceptibility-Weighted Imaging

A 64-year-old female presented with extensive osseous erosion of the central skull base from a large tumor, which was evaluated with a combination of CT and MRI. Susceptibility-weighted imaging (SWI) aided the correct preoperative diagnosis of giant skull base schwannoma by demonstrating intratumoral microhemorrhages, later confirmed on histology. Other imaging features on CT and MRI were not helpful to identify the schwannoma in this case.

Low-dose GBCA administration for brain tumour dynamic contrast enhanced MRI: a feasibility study

A key limitation of current dynamic contrast enhanced (DCE) MRI techniques is the requirement for full-dose gadolinium-based contrast agent (GBCA) administration. The purpose of this feasibility study was to develop and assess a new low GBCA dose protocol for deriving high-spatial resolution kinetic parameters from brain DCE-MRI. Nineteen patients with intracranial skull base tumours were prospectively imaged at 1.5 T using a single-injection, fixed-volume low GBCA dose, dual temporal resolution interleaved DCE-MRI acquisition. The accuracy of kinetic parameters (ve, Ktrans, vp) derived using this new low GBCA dose technique was evaluated through both Monte-Carlo simulations (mean percent deviation, PD, of measured from true values) and an in vivo study incorporating comparison with a conventional full-dose GBCA protocol and correlation with histopathological data. The mean PD of data from the interleaved high-temporal-high-spatial resolution approach outperformed use of high-spatial, low temporal resolution datasets alone (p < 0.0001, t-test). Kinetic parameters derived using the low-dose interleaved protocol correlated significantly with parameters derived from a full-dose acquisition (p < 0.001) and demonstrated a significant association with tissue markers of microvessel density (p < 0.05). Our results suggest accurate high-spatial resolution kinetic parameter mapping is feasible with significantly reduced GBCA dose.

Differentiation of Skull Base Chondrosarcomas, Chordomas, and Metastases: Utility of DWI and Dynamic Contrast-Enhanced Perfusion MR Imaging

BACKGROUND AND PURPOSE

Differentiation of skull base tumors, including chondrosarcomas, chordomas, and metastases, on conventional imaging remains a challenge. We aimed to test the utility of DWI and dynamic contrast-enhanced MR imaging for skull base tumors.

MATERIALS AND METHODS

Fifty-nine patients with chondrosarcomas, chordomas, or metastases between January 2015 and October 2021 were included in this retrospective study. Pretreatment normalized mean ADC and dynamic contrast-enhanced MR imaging parameters were calculated. The Kruskal-Wallis H test for all tumor types and the Mann-Whitney U test for each pair of tumors were used.

RESULTS

Fifteen chondrosarcomas (9 men; median age, 62 years), 14 chordomas (6 men; median age, 47 years), and 30 metastases (11 men; median age, 61 years) were included in this study. Fractional plasma volume helped distinguish all 3 tumor types (P = .003, <.001, and <.001, respectively), whereas the normalized mean ADC was useful in distinguishing chondrosarcomas from chordomas and metastases (P < .001 and P < .001, respectively); fractional volume of extracellular space, in distinguishing chondrosarcomas from metastases (P = .02); and forward volume transfer constant, in distinguishing metastases from chondrosarcomas/chondroma (P = .002 and .002, respectively) using the Kruskal-Wallis H test. The diagnostic performances of fractional plasma volume for each pair of tumors showed areas under curve of 0.86-0.99 (95% CI, 0.70-1.0); the forward volume transfer constant differentiated metastases from chondrosarcomas/chordomas with areas under curve of 0.82 and 0.82 (95% CI, 0.67-0.98), respectively; and the normalized mean ADC distinguished chondrosarcomas from chordomas/metastases with areas under curve of 0.96 and 0.95 (95% CI, 0.88-1.0), respectively.

CONCLUSIONS

DWI and dynamic contrast-enhanced MR imaging sequences can be beneficial for differentiating the 3 common skull base tumors.

MRI enhancement patterns in 28 cases of clival chordomas

Clival chordomas are classically thought of as locally aggressive tumors of the skull base and differentiate themselves from their benign counterparts by demonstrating moderate to marked contrast enhancement, reported as 95-100% in prior studies. The purpose of this review was to evaluate the imaging characteristics of lesions from a single institution classified as clival chordomas with an emphasis of highlighting lesions that do not follow the prevalent current description for chordoma. We searched our institutional databases for all patients with pathologically proven clival chordomas from 1997 to 2017 who had pre-operative imaging available. The images were evaluated for degree of contrast enhancement, MRI signal characteristics, osseous involvement, location, aggressiveness of appearance, and presence of calcifications. 28 cases were identified that had preoperative imaging available for review. Over half of the patients demonstrated either no/minimal (11/28, 39%) or mild enhancement (7/28, 25%). The remaining cases demonstrated moderate (4/28, 14%) and marked enhancement (6/28, 21%). The 4 lesions measuring less than 20 mm all had mild to minimal/no enhancement and lacked aggressive features on CT. Our experience finds that over half (64%) of clival chordomas will demonstrate mild or no enhancement at all. These findings suggest that the lack of MRI contrast enhancement should not be synonymous with a benign clival mass.

Pediatric Petrous Apex Lesions: A Radiological Classification and Diagnostic Algorithm

The petrous apex (PA) is involved in a myriad of pathological conditions, some of which are exclusive in children. Diagnosis may be difficult due to vague clinical presentation, and local examination is challenging owing to its inaccessible location. This is further complicated by multiple unfused sutures and ongoing PA pneumatization in children. Cross-sectional imaging is vital for the evaluation of the PA lesions, due to their precarious location and proximity to the major neurovascular structures. Several classification systems have been proposed for these lesions based on their site of origin, solid or cystic appearance, surgical or non-surgical (no touch lesions) management, and benign or malignant nature. In this article, we emphasize the distinctive role of different cross-sectional imaging modalities in the diagnosis of pediatric PA lesions, with special attention to normal variants that should not be mistaken for pathology. We also propose a radiological classification and algorithmic approach to aid in the precise diagnosis and facilitate appropriate management of the various PA lesions in children.

Current Management and Image Review of Skull Base Chordoma: What the Radiologist Needs to Know

Chordomas of the skull-base are typically slow-growing, notochord-derived tumors that most commonly originate along the clivus. Skull base chordoma is treated with surgery and radiotherapy. Local recurrence approaches 50% at 10 years. Radiologists play a critical role in diagnosis, treatment planning, and follow-up. Surgeons and radiation oncologists rely on radiologists for pre-operative delineation of tumor and adjacent anatomy, identification of post-treatment changes and disease recurrence, and radiation treatment effects. This review provides an overview of clinical characteristics, surgical anatomy, indications for radiotherapy, identification of treatment complications, and patterns of disease recurrence for radiologists to provide value in the management of these lesions.

Peri-operative prognostic factors for primary skull base chordomas: results from a single-center cohort

BACKGROUND

Skull base chordomas (SBC) are rare malignant tumors and few factors have been found to be reliable markers for clinical decision making and survival prognostication. The aim of the present work was to identify specific prognostic factors potentially useful for the management of SBC patients.

METHODS

A retrospective review of all the patients diagnosed and treated for SBC at the Fondazione IRCCS Istituto Neurologico "Carlo Besta" between January 1992 and December 2017 has been performed. Survival analysis was performed and a logistic regression model was used. Statistically significant predictors were rated based on their log odds in order to preliminarily build a personalized grading scale-the Peri-Operative Chordoma Scale (POCS).

RESULTS

Fifty-nine primary chordoma patients were included. The average follow-up from the first treatment was 82.6 months (95% CI, 65.5-99.7). POCS was built over PFS and MR contrast enhancement (intense vs mild/no, value 4), preoperative motor deficit (yes vs no, value 3), and the development of any postoperative complications (yes vs no, value 2). POCS ranges between 0 and 9, with higher scores being associated with reduced likelihood of survival and progression-free state.

CONCLUSIONS

Our results show that preoperative clinical symptoms (motor deficits), surgical features (extent of tumor resection and surgeon's experience), development of postoperative complications, and KPS decline represent significant prognostic factors. The degree of MR contrast enhancement significantly correlated to both OS and PFS. We also preliminarily developed the POCS as a prognostic grading scale which may help neurosurgeons in the personalized management of patients undergoing potential adjuvant therapies.

Radiation therapy strategies for skull-base malignancies

INTRODUCTION

The management of skull base malignancies continues to evolve with improvements in surgical technique, advances in radiation delivery and novel systemic agents.

METHODS

In this review, we aim to discuss in detail the management of common skull base pathologies which typically require multimodality therapy, focusing on the radiotherapeutic aspects of care.

RESULTS

Technological advances in the administration of radiation therapy have led to a wide variety of different treatment strategies for the treatment of skull base malignances, with outcomes summarized herein.

CONCLUSION

Radiation treatment plays a key and critical role in the management of patients with skull base tumors. Recent advancements continue to improve the risk/benefit ratio for radiotherapy in this setting.

Skull base chordomas review of current treatment paradigms

Background

Chordomas are locally invasive neoplasms, arising from notochordal remnants and can appear anywhere along the axial skeleton. Local recurrences are common, and distant metastases may occur years after the initial presentation.

Methods

Literature review of current treatment strategies for chordomas of the skull base.

Results

Surgery is the mainstay of treatment and complete resection has paramount importance for prognosis.

When complete resection is not achieved recurrent disease is common. The anatomical complexity of the skull base makes resection complex. Endonasal endoscopic approaches to the clivus has become increasingly favored in recent years although addressing reconstruction of the skull base to prevent CSF leak may be challenging.

Evidence suggests that radiotherapy should not be considered as a primary single modality when trying to achieve cure of the disease. Nonetheless, immediate post-operative radiotherapy improves survival. Many strategies have been suggested to preserve sensitive vital structures in the skull base during treatment but as for survival there is no evidence of advantage when comparing adjuvant therapy with photon radiotherapy, gamma knife surgery, proton beam therapy, and carbon ion radiation therapy.

There is no evidence to support cytotoxic chemotherapy in the treatment of chordomas but targeted therapies have started to show promise. Several optional molecular targets exist. Brachyury is overexpressed in 95% of chordomas but not in other mesenchymal neoplasms. However, its precise role in chordoma pathogenesis is currently unclear, and its cellular location in the nucleus makes it difficult to target. The inhibition of brachyury in chordoma cell lines induces growth arrest and apoptosis. This does not have clinical application to date. There are retrospective results with different molecular targeted therapies for advanced chordomas with some effectiveness.

Conclusion

Despite improvements made in the past 10 years in our knowledge of chordoma biology, available therapies still offer a limited benefit. There is an unmet need for new therapeutic options for patients with advanced disease. Therefore, patients with advanced disease should be encouraged to participate in clinical trials when and where available.

Soft Tissue Special Issue: Chondroid Neoplasms of the Skull

Clinically, radiologically, and pathologically, chondroid neoplasms of the skull can be diagnostically challenging due to overlapping features in each of these domains. Compounding the problem for the pathologist, there is also significant morphologic, immunophenotypic, and molecular genetic overlap between benign and malignant cartilaginous lesions, and the majority of these lesions are encountered quite rarely in routine surgical pathology practice. Each of these factors contribute to the diagnostic difficulty posed by these lesions, highlighting the importance of radiologic-pathologic correlation in the diagnosis. This review is intended to provide an update for surgical pathologists on some of the most commonly encountered chondroid neoplasms in the skull, and includes the following lesions: chondromyxoid fibroma, synovial chondromatosis, chondrosarcoma and variants, and chordoma and variants. For each of these lesions, the differential diagnosis and useful ancillary tests will be discussed in the context of a broad range of additional primary and secondary lesions.

Long and Very-Long-Chain Ceramides Correlate with A More Aggressive Behavior in Skull Base Chordoma Patients

BACKGROUND

Skull base chordomas are rare tumors arising from notochord. Sphingolipids analysis is a promising approach in molecular oncology, and it has never been applied in chordomas. Our aim is to investigate chordoma behavior and the role of ceramides.

METHODS

Ceramides were extracted and evaluated by liquid chromatography and mass spectrometry in a cohort of patients with a skull base chordoma. Clinical data were also collected and correlated with ceramide levels. Linear regression and correlation analyses were conducted.

RESULTS

Analyzing the association between ceramides level and MIB-1, total ceramides and dihydroceramides showed a strong association (r = 0.7257 and r = 0.6733, respectively) with MIB-1 staining (p = 0.0033 and p = 0.0083, respectively). Among the single ceramide species, Cer C24:1 (r = 0.8814, p ≤ 0.0001), DHCer C24:1 (r = 0.8429, p = 0.0002) and DHCer C18:0 (r = 0.9426, p ≤ 0.0001) showed a significant correlation with MIB-1.

CONCLUSION

Our lipid analysis showed ceramides to be promising tumoral biomarkers in skull base chordomas. Long- and very-long-chain ceramides, such as Cer C24:1 and DHCer C24:1, may be related to a prolonged tumor survival and aggressiveness, and the understanding of their effective biological role will hopefully shed light on the mechanisms of chordoma radio-resistance, tendency to recur, and use of agents targeting ceramide metabolism.

Radiomic analysis of multiparametric magnetic resonance imaging for differentiating skull base chordoma and chondrosarcoma

PURPOSE

Patients with skull base chordoma and chondrosarcoma have different prognoses and are not readily differentiated preoperatively on imaging. Multiparametric magnetic resonance imaging (MRI) is a routine diagnostic tool that can noninvasively characterize the salient characteristics of tumors. In the present study, we developed and validated a preoperative multiparametric MRI-based radiomic signature for differentiating these tumors.

METHOD

This retrospective study enrolled 210 patients and consecutively divided them into the primary and validation cohorts. A total of 1941 radiomic features were acquired from preoperative T1-weighted imaging, T2-weighted imaging and contrast-enhanced T1-weighted imaging for each patient. The most discriminative features were selected by minimum-redundancy maximum-relevancy and recursive feature elimination algorithms in the primary cohort. The multiparametric and single-sequence MRI signatures were constructed with the selected features using a support vector machine model in the primary cohort. The ability of the novel radiomic signatures to differentiate chordoma from chondrosarcoma were assessed using receiver operating characteristic curve analysis in the validation cohort.

RESULTS

The multiparametric radiomic signature, which consisted of 11 selected features, reached an area under the receiver operating characteristic curve of 0.9745 and 0.8720 in the primary and validation cohorts, respectively. Moreover, compared with each single-sequence MRI signature, the multiparametric radiomic signature exhibited better classification performance with significant improvement (p <  0.05, Delong's test) in the primary cohorts.

CONCLUSION

By combining features from three MRI sequences, the multiparametric radiomics signature can accurately and robustly differentiate skull base chordoma from chondrosarcoma.

Chordoma located in the jugular foramen: Case report

RATIONALE

Chordomas are rare malignant neoplasms arised from residual embryonic notochordal tissue, mostly located in the axial midline. Tumors along extra-axial locations in the head and neck are rare. Chordomas located in the jugular foramen are extremely rare, with a low incidence of 0.2%.

PATIENT CONCERNS

A 64-year-old male with 20 years of dizziness history complaining of 6 months of severe dizziness: significant with the changing of the body posture, vertigo which can be self-remissioned within 1 minute and hearing loss of both ears, without headache, nausea, dysphagia, or otalgia. Computed tomography and magnetic resonance imaging (MRI) were performed before surgery which suggests various possibilities. Immunohistochemistry helped to confirm the final diagnosis.

DIAGNOSES

Immunohistochemistry demonstrated diffuse positivity for S100 (+++), positivity for D2-40 (focal +), EMA (+), and PR (+). Ki-67 labeling index was estimated at 2% focally. The final diagnosis was chordoma.

INTERVENTIONS

The tumor was excised via retro-sigmoid approach without postoperative radiotherapy.

OUTCOMES

Facial paralysis occurred in this case. House-Brackmann facial nerve grading system was used to evaluate the facial paralysis of this patient. It is considered as H-B grade IV. The patient was followed up regularly every month after operation, totally for 9 months. An MRI of the brain was performed 6 months after surgery which shows a small range of abnormal signals similar to the previous MRI in the jugular foramen, suggesting that there may be residual or recurrent tumor. And facial paralysis stays at H-B grade IV without any recovery.

LESSONS

It is a big challenge for us to remove giant tumors located in the jugular foramen because of its unique anatomy. Access should be combined with retro-sigmoid or infra-temporal fossa approach to remove such tumors. Chordomas is a malignant neoplasm which may need radiotherapy after surgery, particularly those with subtotal and partial resection.

Ear and Temporal Bone: Cartilaginous and Osseous Pathologies

Although the majority of conditions involving the ear and temporal bone are inflammatory or epithelial based, cartilage and osseous entities will also be encountered. The pathologic examination of these underlying cartilaginous and osseous structures and their histologic findings and associated differential diagnoses will be discussed. Correlation with clinical and imaging findings are also critical for accurate determination of the pathologic entity.

Prognostic Implications of Gadolinium Enhancement of Skull Base Chordomas

BACKGROUND AND PURPOSE

Skull base chordomas often demonstrate variable MR imaging characteristics, and there has been limited prior research investigating the potential clinical relevance of this variability. The purpose of this retrospective study was to assess the prognostic implications of signal intensity on standard imaging techniques for the biologic behavior of skull base chordomas.

MATERIALS AND METHODS

Medical records were retrospectively reviewed for 22 patients with pathologically confirmed skull base chordomas. Clinical data were recorded, including the degree of surgical resection, the presence or absence of radiation therapy, and time to progression/recurrence of the tumor or time without progression/recurrence of the tumor following initial treatment. Pretreatment imaging was reviewed for the presence or absence of enhancement and the T2 signal characteristics. Tumor-to-brain stem signal intensity ratios on T2, precontrast T1, and postcontrast T1 spin-echo sequences were also calculated. Statistical analysis was then performed to assess correlations between imaging characteristics and tumor progression/recurrence.

RESULTS

Progression/recurrence of skull base chordomas was seen following surgical resection in 11 of 14 (78.6%) patients with enhancing tumors and in zero of 8 patients with nonenhancing tumors. There was a statistically significant correlation between skull base chordoma enhancement and subsequent tumor progression/recurrence (P < .001), which remained significant after controlling for differences in treatment strategy (P < .001). There was also a correlation between postcontrast T1 signal intensity (as measured by postcontrast T1 tumor-to-brain stem signal intensity ratios) and recurrence/progression (P = .02). While T2 signal intensity was higher in patients without tumor progression (median tumor-to-brain stem signal intensity ratios on T2 = 2.27) than in those with progression (median tumor-to-brain stem signal intensity ratios on T2 = 1.78), this association was not significant (P = .12).

CONCLUSIONS

Enhancement of skull base chordomas is a risk factor for tumor progression/recurrence following surgical resection.

Giant cranionasal epithelioid haemangioendothelioma with invasive growth pattern mimicking a skull base chondrosarcoma

Epithelioid haemangioendothelioma (EHE) is a rare low-grade vascular neoplasm that is composed of mostly epithelioid cells. EHE may arise as a solitary tumour or in the form of multiple body lesions, and commonly occurs in soft tissues, liver, pleura, lung, peritoneum, lymph nodes, breast, and many other sites. EHE in the cranionasal region is extremely rare. There are very few reports of cases of skull-base EHE. We discuss an extremely rare presentation of an aggressive EHE that originated from the sellar region. Based on literature review, our patient is the first reported case of a giant solitary EHE with prepontine cistern invasion and abducens nerve encroachment mimicking a chondrosarcoma. We treated this rare tumour by near subtotal surgical excision with subsequent radiotherapy, considering that complete tumour resection with free margins in both cavernous sinus and clival region avoiding neural and vascular structure encroachment becomes technically difficult.

Diagnostic accuracy of DW MR imaging in the differentiation of chordomas and chondrosarcomas of the skull base: A 3.0-T MRI study of 105 cases

PURPOSE

To determine the diagnostic accuracy of DW MR imaging with apparent diffusion coefficient (ADC) mapping for the distinction of skull base chordoma from skull base chondrosarcoma.

PATIENTS AND METHODS

From October 2009 to April 2014, 105 consecutive patients (chordomas (n = 70), and chondrosarcomas (n = 35) who were planned to receive proton or heavy-ion beam therapy underwent DW MR imaging on a 3.0 T. MR images were assessed by means of consensus of three experienced radiologists who were blinded to pathologic and clinical information. ADC values (mean, minimum, maximum, and normalized) of the solid tumor component were evaluated. Group means and cut-off points were established to separate skull base chordoma from skull base chondrosarcoma, and statistical significances were calculated by Student's t or Mann-Whitney-U tests, and receiver operating characteristic (ROC) curve analyses. The prospective study was approved by the institutional ethics committee.

RESULTS

For solid tumor component, there were higher mean, minimum, maximum, and normalized ADC values in chondrosarcomas compared with those in chordomas (all p < 0.001). ROC analysis revealed areas under the curve for mean, minimum, maximum, and normalized ADC values between 0.79 and 0.93. The mean ADC value of the solid tumor components had the best AUC, with a cut-off point of 1585 × 10(-6) mm (2)/s and sensitivity and specificity of 94.3% and 98.6%, respectively.

CONCLUSION

Skull base Chondrosarcomas generally have higher mean, minimum, maximum, and normalized ADC values than skull base chordomas, with the mean ADC value of the solid tumor component offering the highest accuracy for characterization.

State-of-the-Art Imaging in Human Chordoma of the Skull Base

Purpose of Review

Chordoma are rare tumours of the axial skeleton which occur most often at the base of the skull and in the sacrum. Although chordoma are generally slow-growing lesions, the recurrence rate is high and the location makes it often difficult to treat. Both computed tomography (CT) and magnetic resonance imaging (MRI) are crucial in the initial diagnosis, treatment planning and post-treatment follow-up.

Recent Findings

Basic MRI and CT characteristics of chordoma were described in the late 1980s and early 1990s. Since then, imaging techniques have evolved with increased resolution and new molecular imaging tools are rapidly evolving. New imaging tools have been developed not only to study anatomy, but also physiologic changes and characterization of tissue and assessment of tumour biology. Recent studies show the uptake of multiple PET tracers in chordoma, which may become an important aspect in the diagnosis, follow-up and personalized therapy.

Summary

This review gives an overview of skull base chordoma histopathology, classic imaging characteristics, radiomics and state-of-the-art imaging techniques that are now emerging in diagnosis, treatment planning and disease monitoring of skull base chordoma.

Immunophenotypic features of dedifferentiated skull base chordoma: An insight into the intratumoural heterogeneity

Chordomas are rare and low-grade malignant solid tumours, despite their histologically benign appearance, that arise in the bone from embryonic notochordal vestiges of the axial skeleton, a mesoderm-derived structure that is involved in the process of neurulation and embryonic development. Chordomas occurring in the skull base tend to arise in the basiocciput along the clivus. Three major morphological variants have been described (classical, chondroid, and atypical/dedifferentiated). The pathogenesis and molecular mechanisms involved in chordoma development remain uncertain. From a pathological standpoint, the microenvironment of a chordoma is heterogeneous, showing a dual epithelial-mesenchymal differentiation. These tumours are characterised by slow modality of biologic growth, local recurrence, low incidence of metastasis rates, and cancer stem cell (CSC) phenotype. The main molecular findings are connected with brachyury immunoexpression and activation of the downstream Akt and mTOR signalling pathways. The differentiation between typical and atypical chordomas is relevant because the tumoural microenvironment and prognosis are partially different. This review provides an insight into the recent and relevant concepts and histochemical markers expressed in chordomas, with special emphasis on dedifferentiated chordomas and their prognostic implications.

Head and Neck: Skull Base Imaging

There are a myriad of head and neck pathologies that extend from the extracranial to the intracranial compartment, traversing the skull base, and knowledge of the imaging appearance of this pathology is critical to practicing neurosurgeons. This article reviews some of the important inflammatory or acquired head and neck pathology along the skull base, neoplastic skull base lesions, and the intracranial extension of head and neck malignancy. Focus will be on the relevant anatomy, appropriate imaging protocols to evaluate these processes, as well as the differentiating imaging findings on computed tomography and magnetic resonance imaging.

Chordoma of the Head and Neck: A Review

Chordoma is a rare malignant bone tumor that can arise anywhere along the central neural axis and many involve head and neck sites, most commonly the skull base. The relative rarity of these tumors, combined with the complex anatomy of the head and neck, pose diagnostic challenges to pathologists. This article describes the pertinent clinical, pathologic, and molecular features of chordomas and describes how these features can be used to aid in formulating a differential diagnosis. Emphasis is placed on key diagnostic pitfalls and the importance of incorporating immunohistochemical information into the diagnosis.

Is there a role for conventional MRI and MR diffusion-weighted imaging for distinction of skull base chordoma and chondrosarcoma?

BACKGROUND

Chordoma and chondrosarcoma are locally invasive skull base tumors with similar clinical symptoms and anatomic imaging features as reported in the literature.

PURPOSE

To determine differentiation of chordoma and chondrosarcoma of the skull base with conventional magnetic resonance imaging (cMRI) and diffusion-weighted MR imaging (DWI) in comparison to histopathological diagnosis.

MATERIAL AND METHODS

This retrospective study comprised 96 (chordoma, n = 64; chondrosarcoma, n = 32) patients with skull base tumors referred to the Paul Scherrer Institute (PSI) for proton therapy. cMRI signal intensities of all tumors were investigated. In addition, median apparent diffusion coefficient (ADC) values were measured in a subgroup of 19 patients (chordoma, n = 11; chondrosarcoma, n = 8).

RESULTS

The majority 81.2% (26/32) of chondrosarcomas displayed an off-midline growth pattern, 18.8% (6/32) showed clival invasion, 18.8% (6/32) were located more centrally. Only 4.7% (3/64) of chordomas revealed a lateral clival origin. Using cMRI no significant differences in MR signal intensities were observed in contrast to significantly different ADC values (subgroup of 19/96 patients examined by DWI), with the highest mean value of 2017.2 × 10(-6 )mm(2)/s (SD, 139.9( )mm(2)/s) for chondrosarcoma and significantly lower value of 1263.5 × 10(-6 )mm(2)/s (SD, 100.2 × 10(-6 )mm(2)/s) for chordoma (P = 0.001/median test).

CONCLUSION

An off-midline growth pattern can differentiate chondrosarcoma from chordoma on cMRI in a majority of patients. Additional DWI is a promising tool for the differentiation of these skull base tumors.

Neuroendocrine disorders: pituitary imaging

Significant advances in pituitary imaging have taken place in the past several decades, including the introduction of magnetic resonance imaging (MRI). This imaging modality has vastly improved our ability to detect and characterize sellar masses and more accurately characterize the extent and spread of lesions in and around the sella. Intraoperative MRI may help improve the completeness of resection of sellar masses. Other imaging modalities, including magnetic resonance angiography, computed tomography (CT), and CT angiography, have an important role in specific cases. Interventional methods, including bilateral inferior petrosal sinus sampling, may establish the pituitary origin of corticotropin (ACTH) excess in patients with ACTH-dependent Cushing's syndrome. Pituitary imaging should be obtained in patients with pituitary hormone excess, hypopituitarism, or mass effect in the sella. Despite rapid advances in pituitary imaging, there are several diagnostic challenges remaining. Future research may help improve the radiographic detection of small sellar lesions, such as ACTH-secreting adenomas causing Cushing's disease, accurately characterize the type and extent of sellar pathologies, and provide prognostic information regarding their growth potential.

Extra-axial brain tumors

Extra-axial brain tumors are the most common adult intracranial neoplasms and encompass a broad spectrum of pathologic subtypes. Meningiomas are the most common extra-axial brain tumor (approximately one-third of all intracranial neoplasms) and typically present as slowly growing dural-based masses. Benign meningiomas are very common, and may occasionally be difficult to differentiate from more aggressive subtypes (i.e., atypical or malignant varieties) or other dural-based masses with more aggressive biologic behavior (e.g., hemangiopericytoma or dural-based metastases). Many neoplasms that typically affect the brain parenchyma (intra-axial), such as gliomas, may also present with primary or secondary extra-axial involvement. This chapter provides a general and concise overview of the common types of extra-axial tumors and their typical imaging features.

Chondromyxoid fibroma involving the sphenoid sinus: Case report and literature review

We present the case of a 62-year-old woman with chondromyxoid fibroma of the sphenoid sinus. Chondromyxoid fibroma is a rare bone tumor found most prevalently in long bones, so its presence at the cranial base is especially uncommon. The presence of a monoclonal gammopathy of undermined significance (MGUS) prompted consideration and investigation of a plasma cell disorder; however, CT and MRI findings followed by biopsy led to the correct diagnosis of chondromyxoid fibroma.

Gamma Knife surgery for intracranial chordoma and chondrosarcoma: radiosurgical perspectives and treatment outcomes

OBJECT

Intracranial chordomas and chondrosarcomas are histologically low-grade, locally invasive tumors that are reported to be similar in terms of anatomical location, clinical presentation, and radiological findings but different in terms of behavior and outcomes. The purpose of this study was to investigate and compare clinical outcomes after Gamma Knife surgery (GKS) for the treatment of intracranial chordoma and chondrosarcoma.

METHODS

The authors conducted a retrospective review of the results of radiosurgical treatment of intracranial chordomas and chondrosarcomas. They enrolled patients who had undergone GKS for intracranial chordoma or chondrosarcoma at the Yonsei Gamma Knife Center, Yonsei University College of Medicine, from October 2000 through June 2007. Analyses included only patients for whom the disease was pathologically diagnosed before GKS and for whom more than 5 years of follow-up data after GKS were available. Rates of progression-free survival and overall survival were analyzed and compared according to tumor pathology. Moreover, the association between tumor control and the margin radiation dose to the tumor was analyzed, and the rate of tumor volume change after GKS was quantified.

RESULTS

A total of 10 patients were enrolled in this study. Of these, 5 patients underwent a total of 8 sessions of GKS for chordoma, and the other 5 patients underwent a total of 7 sessions of GKS for chondrosarcoma. The 2- and 5-year progression-free survival rates for patients in the chordoma group were 70% and 35%, respectively, and rates for patients in the chondrosarcoma group were 100% and 80%, respectively (log-rank test, p = 0.04). The 2- and 5-year overall survival rates after GKS for patients in the chordoma group were 87.5% and 72.9%, respectively, and rates for patients in the chondrosarcoma group were 100% and 100%, respectively (log-rank test, p = 0.03). The mean rates of tumor volume change 2 years after radiosurgery were 79.64% and 39.91% for chordoma and chondrosarcoma, respectively (p = 0.05). No tumor progression was observed when margin doses greater than 16 Gy for chordoma and 14 Gy for chondrosarcoma were prescribed.

CONCLUSIONS

Outcomes after GKS were more favorable for patients with chondrosarcoma than for those with chordoma. The data also indicated that at 2 years after GKS, the rate of volume change is significantly higher for chordomas than for chondrosarcomas. The authors conclude that radiosurgery with a margin dose of more than 16 Gy for chordomas and more than 14 Gy for chondrosarcomas seems to enhance local tumor control with relatively few complications. Further studies are needed to determine the optimal dose of GKS for patients with intracranial chordoma or chondrosarcoma.

Diffusion-weighted MRI: distinction of skull base chordoma from chondrosarcoma

BACKGROUND AND PURPOSE

Chordoma and chondrosarcoma of the skull base are rare tumors with overlapping presentations and anatomic imaging features but different prognoses. We hypothesized that these tumors might be distinguished by using diffusion-weighted MR imaging.

MATERIALS AND METHODS

We retrospectively reviewed 19 patients with pathologically confirmed chordoma or chondrosarcoma who underwent both conventional and diffusion-weighted MR imaging. Differences in distributions of ADC were assessed by the Kruskal-Wallis test. Associations between histopathologic diagnosis and conventional MR imaging features (T2 signal intensity, contrast enhancement, and tumor location) were assessed with the Fisher exact test.

RESULTS

Chondrosarcoma was associated with the highest mean ADC value (2051 ± 261 × 10(-6) mm(2)/s) and was significantly different from classic chordoma (1474 ± 117 × 10(-6) mm(2)/s) and poorly differentiated chordoma (875 ± 100 × 10(-6) mm(2)/s) (P < .001). Poorly differentiated chordoma was characterized by low T2 signal intensity (P = .001), but other conventional MR imaging features of enhancement and/or lesion location did not reliably distinguish these tumor types.

CONCLUSIONS

Diffusion-weighted MR imaging may be useful in assessing clival tumors, particularly in differentiating chordoma from chondrosarcoma. A prospective study of a larger cohort will be required to determine the value of ADC in predicting histopathologic diagnosis.

Frequent IDH1/2 mutations in intracranial chondrosarcoma: a possible diagnostic clue for its differentiation from chordoma

Mutations in the genes encoding isocitrate dehydrogenase (IDH) 1/2 have been detected in a significant proportion of diffuse gliomas and in a small fraction of acute myeloid leukemia (AML) cases. Recently, in an examination of various types of mesenchymal tumor, IDH1/2 mutations were only found in cartilaginous tumors including central conventional and periosteal enchondromas/chondrosarcomas. The frequency of IDH1/2 mutations was 56%, and the IDH1 R132C mutation, which is not common in diffuse gliomas or AML, accounted for 40% of these mutations. In this study, we investigated the IDH1/2 mutation status of intracranial chondrosarcomas and chordomas, which are morphologically similar and affect similar regions of the cranial cavity. Of the 13 chondrosarcomas analyzed, six (46.1%) displayed IDH1/2 mutations (the predominant type was IDH1 R132C). Also, an IDH2 mutation (R172S) was observed in one case. Conversely, none of the ten chordomas analyzed displayed any IDH1 or IDH2 mutations. Our data suggest that the IDH1/2 mutation status could be valuable for distinguishing intracranial chondrosarcomas from chordomas.

Imaging of the central skull base

The central skull base (CSB) constitutes a frontier between the extracranial head and neck and the middle cranial fossa. The anatomy of this region is complex, containing most of the bony foramina and canals of the skull base traversed by several neurovascular structures that can act as routes of spread for pathologic processes. Lesions affecting the CSB can be intrinsic to its bony-cartilaginous components; can arise from above, within the intracranial compartment; or can arise from below, within the extracranial head and neck. Crosssectional imaging is indispensable in the diagnosis, treatment planning, and follow-up of patients with CSB lesions. This review focuses on a systematic approach to this region based on an anatomic division that takes into account the major tissue constituents of the CSB.

[Chondrosarcomas of skull base treatment]

BACKGROUND AND PURPOSE

Skull base chondrosarcomas are rare. Gross total removal is the treatment of choice, but can be difficult depending on the closeness of noble structures. Proton beam therapy can be associated in most cases.

METHODS

Retrospective study of five cases treated in 13 years and study of the literature.

RESULTS

Median age of patients was 34 years [28-46]. Cranial nerve palsy was the common clinical presentation. Tumor location was variable but always off midline. Treatment was surgical in all patients with a maximal resection and proton beam therapy associated for two cases. Surgical complications were rare with cranial nerve palsy as the main side effect. Outcomes were good with a median follow-up of 12.4 years [4.3-16.2].

DISCUSSION

The review of the literature showed that chondrosarcomas of skull base are rare. The best outcome is achieved with total surgical resection. Medical imaging can only give clues to the diagnosis. Pathology is required to obtain a precise immunohistochemistry diagnosis. Multidisciplinary treatment using proton beam therapy and surgical removal enables a good local control (90-100%) at 5 years with good quality-of-life. It is difficult to determine how many cases have been published (around 220 cases in the literature) since many surgical or radiotherapy series included the same patients.

Skull base tumours Part II. Central skull base tumours and intrinsic tumours of the bony skull base

With the advances of cross-sectional imaging radiologists gained an increasing responsibility in the management of patients with skull base pathology. As this anatomic area is hidden to clinical exam, surgeons and radiation oncologists have to rely on imaging studies to plan the most adequate treatment. To fulfil these endeavour radiologists need to be knowledgeable about skull base anatomy, about the main treatment options available, their indications and contra-indications and needs to be aware of the wide gamut of pathologies seen in this anatomic region. This article will provide a radiologists' friendly approach to the central skull base and will review the most common central skull base tumours and tumours intrinsic to the bony skull base.

Tumor-biology and current treatment of skull-base chordomas

Chordomas are rare, slow growing tumors of the axial skeleton, which derive from the remnants of the fetal notochord. They can be encountered anywhere along the axial skeleton, most commonly in the sacral area, skull base and less commonly in the spine. Chordomas have a benign histopathology but exhibit malignant clinical behavior with invasive, destructive and metastatic potential. Genetic and molecular pathology studies on oncogenesis of chordomas are very limited and there is little known on mechanisms governing the disease. Chordomas most commonly present with headaches and diplopia and can be readily diagnosed by current neuroradiological methods. There are 3 pathological subtypes of chordomas: classic, chondroid and dedifferentiated chordomas. Differential diagnosis from chondrosarcomas by radiology or pathology may at times be difficult. Skull base chordomas are very challenging to treat. Clinically there are at least two subsets of chordoma patients with distinct behaviors: some with a benign course and another group with an aggressive and rapidly progressive disease. There is no standard treatment for chordomas. Surgical resection and high dose radiation treatment are the mainstays of current treatment. Nevertheless, a significant percentage of skull base chordomas recur despite treatment. The outcome is dictated primarily by the intrinsic biology of the tumor and treatment seems only to have a secondary impact. To date we only have a limited understanding this biology; however better understanding is likely to improve treatment outcome. Hereby we present a review of the current knowledge and experience on the tumor biology, diagnosis and treatment of chordomas.

Dynamic enhancement features of cavernous sinus cavernous hemangiomas on conventional contrast-enhanced MR imaging

BACKGROUND AND PURPOSE

The reported MR imaging characteristics of cavernous sinus cavernous hemangiomas (CSCHs) in the literature are nonspecific. The purpose of our study was to explore dynamic enhancement features of CSCHs on conventional contrast-enhanced MR imaging and to correlate these features with histopathologic subtypes.

MATERIALS AND METHODS

Twenty-one patients (8 male and 13 female; age range, 13-63 years; average age, 42.6 years) with surgically confirmed CSCHs were retrospectively investigated. Preoperative MR study was performed in all cases, consisting of T1-weighted axial imaging, T2-weighted axial imaging, T1-weighted sagittal imaging, and contrast-enhanced T1-weighted axial, sagittal, and coronal images.

RESULTS

There were 4.8% (1/21) that showed homogeneous enhancement on all 3 contrast-enhanced sequences, whereas 95.2% (20/21) demonstrated heterogeneous enhancement on the first contrast-enhanced sequence. Among the 20 lesions, on subsequent contrast-enhanced sequences, 55.0% (11/20) showed homogeneous enhancement, whereas 35.0% (7/20) of lesions showed progressive contrast "filling in." The remaining 10% (2/20) exhibited no apparent enhancement changes. The 95.2% (20/21) of lesions with heterogeneous enhancement on the first contrast-enhanced sequence correlated with type B or type C pathologic findings, whereas 4.8% (1/21) with homogeneous enhancement correlated with type A pathologic findings. Among the 20 type B or type C lesions, 80% (16/20) achieved total or near-total resection.

CONCLUSION

Progressive contrast "filling in" in the tumors on conventional contrast-enhanced MR images can aid in differentiating between cavernous sinus lesions and suggest the diagnosis of cavernous hemangiomas.

Imaging of cerebellopontine angle lesions: an update. Part 2: intra-axial lesions, skull base lesions that may invade the CPA region, and non-enhancing extra-axial lesions

Computed tomography (CT) and magnetic resonance (MR) imaging reliably demonstrate typical features of vestibular schwannomas or meningiomas in the vast majority of mass lesions responsible for cerebellopontine angle (CPA) syndrome. However, a large variety of unusual lesions can also be encountered in the CPA. Covering the entire spectrum of lesions potentially found in the CPA, these articles explain the pertinent neuroimaging features that radiologists need to know to make clinically relevant diagnoses in these cases, including data from diffusion- and perfusion-weighted imaging or MR spectroscopy, when available. A diagnostic algorithm based on the lesion's site of origin, shape and margins, density, signal intensity and contrast material uptake is also proposed. Non-enhancing extra-axial CPA masses are cystic (epidermoid cyst, arachnoid cyst, neurenteric cyst) or contain fat (dermoid cyst, lipoma). Tumours can also extend into the CPA by extension from the skull base (paraganglioma, chondromatous tumours, chordoma, cholesterol granuloma, endolymphatic sac tumour). Finally, brain stem or ventricular tumours can present with a significant exophytic component in the CPA that may be difficult to differentiate from an extra-axial lesion (lymphoma, hemangioblastoma, choroid plexus papilloma, ependymoma, glioma, medulloblastoma, dysembryoplastic neuroepithelial tumour).

New candidate chromosomal regions for chordoma development

BACKGROUND

Chordomas are rare, slow growing, infiltrative tumors thought to arise from vestigial or ectopic notochord. Chordoma can occur along the axial skeleton, predominantly in the sphenooccipital, vertebral, and sacrococcygeal regions. Although most chordomas are sporadic, familial cases have also been reported. The most common molecular cytogenetic abnormalities in these tumors are monosomy of chromosome 1 and gain of chromosome 7. In addition, a variety of other chromosomal changes, which are associated with losses and gains of different chromosomes, have also been described in chordomas, such as 1q, 2p, 3p, 5q, 9p, 10, 12q, 13q, 17, and 20q.

METHODS

In this study, using molecular cytogenetics (iFISH), we have studied 1p36, 1q25, 3p13-p14, 7q33, 17p13.1 (p53 gene locus), 2p13 (TGF-alpha locus), 6p12 (VEGF locus), and 4q26-q27 (bFGF/FGF2 locus) loci in chordoma tissues from seven patients with 7 primary tumors and 11 recurrences.

RESULTS

We found that chromosomes 1p36, 1q25, 2p13, and 7q33 are affected in primary chordomas, and these aberrations persist in recurrences. However, the chromosome 6p12 aberration was seen only in primary chordomas, but not in recurrences, indicating that this locus may be associated with chordoma genesis.

CONCLUSIONS

Our descriptive data from interphase FISH analyses suggest that future studies should incorporate a larger number of patients and should focus on identifying the candidate genes in chordoma pathogenesis. Such studies may use a whole-genomic approach, in addition to the regions identified in this study and others.

Infratentorielle Tumoren

This article gives an overview concerning the typical infratentorial tumors of adults.