Benign notochordal lesions of the axial skeleton: a review and current appraisal

Application of cementoplasty in patients with symptomatic benign osteopathy disease

BACKGROUND

The optimal treatment for some symptomatic, benign osteopathy lesions is yet to be identified.

PURPOSE

To investigate the clinical efficiency of cementoplasty in managing symptomatic, benign osteopathy.

MATERIAL AND METHODS

Between June 2006 and January 2020, we retrospectively enrolled 31 patients (10 men, 21 women; mean age = 46.5 ± 16.6 years; age range = 20-85 years), accounting for 34 treatment sites, who underwent percutaneous osteoplasty (14 treatment sites) and percutaneous vertebroplasty (20 treatment sites) with digital subtraction angiography (DSA) or DSA combined with computed tomography (CT). All the participants experienced different degrees of clinical symptoms with benign osteopathy lesions. The technical success of the procedure and occurrence of complications were recorded. Follow-up examinations were conducted to assess the treatment outcome using the MacNab criteria.

RESULTS

All the participants had a diagnosis of benign osteopathy lesions before or after the cementoplasty. Surgery was successfully completed in all patients. Cement distributions were diffuse and homogeneous, with the complication of cement leakage occurring in 17.6% (6 of 34) of the lesions. The leakage occurred in the intervertebral disc (n = 1), the intra-articular space (n = 1), and the surrounding soft tissue (n = 4). Analysis of the treatment outcome using the MacNab criteria revealed that all patients showed improvement in their clinical symptoms to some extent and in the quality of life.

CONCLUSION

Cementoplasty is an effective treatment for symptomatic, benign osteopathy, with the advantage of favorable clinical outcomes, and low complication rate.

Primary Benign Neoplasms of the Spine

Benign tumours comprise the majority of primary vertebral tumours, and these are often found incidentally on imaging. Nonetheless, accurate diagnosis of these benign lesions is crucial, in order to avoid misdiagnosis as more ominous malignant lesions or infection. Furthermore, some of these tumours, despite their benign nature, can have localised effects on the spine including neural compromise, or can be locally aggressive, thus necessitating active management. Haemangiomas and osteomas (enostosis) are the commonest benign tumours encountered. Others include osteoid osteoma, osteoblastoma, fibrous dysplasia, osteochondroma, chondroblastoma, haemangioma, simple bone cysts, aneurysmal bone cysts, giant cell tumours, eosinophilic granuloma and notochordal rests. The majority of lesions are asymptomatic; however, locally aggressive lesions (such as aneurysmal bone cysts or giant cell tumours) can present with nonspecific symptoms, such as back pain, neurological deficits and spinal instability, which may be indistinguishable from more commonly encountered mechanical back pain or malignant lesions including metastases. Hence, imaging, including radiography, computed tomography (CT) and magnetic resonance imaging (MRI), plays a critical role in diagnosis. Generally, most incidental or asymptomatic regions are conservatively managed or may not require any follow-up, while symptomatic or locally aggressive lesions warrant active interventions, which include surgical resection or percutaneous treatment techniques. Due to advances in interventional radiology techniques in recent years, percutaneous minimally invasive techniques such as radiofrequency ablation, sclerotherapy and cryoablation have played an increasing role in the management of these tumours with favourable outcomes. The different types of primary benign vertebral tumours will be discussed in this article with an emphasis on pertinent imaging features.

Imaging of spinal chordoma and benign notochordal cell tumor (BNCT) with radiologic pathologic correlation

Benign notochordal cell tumor (BNCT) and chordoma are neoplasms of notochordal differentiation. BNCT represents notochordal rests, commonly an incidental lesion present in the spine in 19% of cadaveric specimens. BNCTs are often radiographically occult. CT of BNCT frequently reveals patchy sclerosis between areas of maintained underlying trabeculae. BNCT demonstrates marrow replacement on T1-weighted MR images with high signal intensity on T2-weighting. BNCTs are frequently smaller than 35 mm and lack significant enhancement, bone destruction, cortical permeation, or soft tissue components. Biopsy or surgical resection of BNCT is usually not warranted, although imaging surveillance may be indicated. Chordoma is a rare low-grade locally aggressive malignancy representing 1-4% of primary malignant bone tumors. Chordoma is most frequent between the ages of 50-60 years with a male predilection. Clinical symptoms, while nonspecific and location dependent, include back pain, numbness, myelopathy, and bowel/bladder incontinence. Unfortunately, lesions are often large at presentation owing to diagnosis delay. Imaging of chordoma shows variable mixtures of bone destruction and sclerosis, calcification (50-70% at CT) and large soft tissue components. MR imaging of chordoma reveals multilobulated areas of marrow replacement on T1-weighting and high signal intensity on T2-weighting reflecting the myxoid component within the lesion and areas of hemorrhage seen histologically. Treatment of chordoma is primarily surgical with prognosis related to resection extent. Unfortunately, complete resection is often not possible (21-75%) resulting in high local recurrence incidence (19-75%) and a 5-year survival rate of 45-86%. This article reviews and illustrates the clinical characteristics, pathologic features, imaging appearance spectrum, treatment, and prognosis of BNCT and spinal chordoma.

Tumors of the Spine: When Can Biopsy Be Avoided?

Regarding osseous tumors of the spine, characteristic morphology is encountered in hemangioma of the vertebral body, osteoid osteoma (OO), osteochondroma, Paget's disease, and bone islands. In these cases, radiologic imaging can make a specific diagnosis and thereby avoid biopsy, especially when the radiologist has chosen the correct imaging modality to establish the diagnosis, such as thin-slice computed tomography in suspected OO. A benign lesion is suggested by a high amount of fat within the lesion, the lack of uptake of the contrast agent, and a homogeneous aspect without solid parts in a cystic tumor. Suspicion of malignancy should be raised in spinal lesions with a heterogeneous disordered matrix, distinct signal decrease in T1-weighted magnetic resonance imaging, blurred border, perilesional edema, cortex erosion, and a large soft tissue component. Biopsy is mandatory in presumed malignancy, such as any Lodwick grade II or III osteolytic lesion in the vertebral column. The radiologist plays a crucial role in determining the clinical pathway by choosing the imaging approach wisely, by narrowing the differential diagnosis list, and, when characteristic morphology is encountered, by avoiding unnecessary biopsies.

Chordoma: 18F-FDG PET/CT and MRI imaging features

OBJECTIVE

Examine the ¹⁸F-FDG PET/CT and MRI imaging characteristics of chordoma.

MATERIALS AND METHODS

Biopsy-proven chordoma with a pre-therapy ¹⁸F-FDG PET/CT from 2001 through 2019 in patients > 18 years old were retrospectively reviewed. Multiple PET/CT and MRI imaging parameters were assessed.

RESULTS

A total of 23 chordoma patients were included (16 M, 7 F; average age of 60.1 ± 13.0 years) with comparative MRI available in 22 cases. This included 13 sacrococcygeal, 9 mobile spine, and one clival lesions. On ¹⁸F-FDG PET/CT, chordomas demonstrated an average SUVmax of 5.8 ± 3.7, average metabolic tumor volume (MTV) of 160.2 ± 263.8 cm³, and average total lesion glycolysis (TLG) of 542.6 ± 1210 g. All demonstrated heterogeneous FDG activity. On MRI, chordomas were predominantly T2 hyperintense (22/22) and T1 isointense (18/22), contained small foci of T1 hyperintensity (17/22), and demonstrated heterogeneous enhancement (14/20). There were no statistically significant associations found between ¹⁸F-FDG PET/CT and MRI imaging features. There was no relationship of SUVmax (p = 0.53), MTV (p = 0.47), TLG (p = 0.48), maximal dimension (p = 0.92), or volume (p = 0.45) to the development of recurrent or metastatic disease which occurred in 6/22 patients over a mean follow-up duration of 4.1 ± 2.0 years.

CONCLUSION

On ¹⁸F-FDG PET/CT imaging, chordomas demonstrate moderate, heterogeneous FDG uptake. Predominant T2 hyperintensity and small foci of internal increased T1 signal are common on MRI. The inherent FDG avidity of chordomas suggests that ¹⁸F-FDG PET/CT may be a useful modality for staging, evaluating treatment response, and assessing for recurrent or metastatic disease.

Chordoma: A Review and Differential Diagnosis

CONTEXT.—

Chordomas are uncommon malignant neoplasms with notochordal differentiation encountered by neuropathologists, bone/soft tissue pathologists, and general surgical pathologists. These lesions most commonly arise in the axial skeleton. Optimal therapy typically involves complete surgical resection, which is often technically difficult owing to the anatomic location, leading to a high rate of recurrence. Lesions have been generally resistant to radiation and chemotherapy; however, experimental studies involving targeted therapy and immunotherapy are currently underway.

OBJECTIVE.—

To summarize the clinical and pathologic findings of the various types of chordoma (conventional chordoma, dedifferentiated chordoma, and poorly differentiated chordoma), the differential diagnosis, and recent advances in molecular pathogenesis and therapeutic modalities that are reliant on accurate diagnosis.

DATA SOURCES.—

Literature review based on PubMed searches containing the term "chordoma" that address novel targeted and immunomodulatory therapeutic modalities; ongoing clinical trials involved in treating chordoma with novel therapeutic modalities identified through the Chordoma Foundation and ClinicalTrials.gov; and the authors' practice experience combined with various authoritative texts concerning the subject.

CONCLUSIONS.—

Chordoma is a clinically and histologically unique malignant neoplasm, and numerous diagnostic considerations must be excluded to establish the correct diagnosis. Treatment options have largely been centered on surgical excision with marginal results; however, novel therapeutic options including targeted therapy and immunotherapy are promising means to improve prognosis.

Primary Tumors of the Sacrum: Imaging Findings

The diagnosis of sacral neoplasms is often delayed because they tend to remain clinically silent for a long time. Imaging is useful at all stages of managing sacral bone tumors: from the detection of the neoplasm to the long-term follow-up. Radiographs are recommended as the modality of choice to begin the imaging workup of a patient with known or suspected sacral pathology. More sensitive examinations such as computerized tomography (CT), magnetic resonance (MRI), or scintigraphy are often necessary. The morphological features of the lesions on CT and MRI help to orientate the diagnosis. Although some imaging characteristics are helpful to limit the differential diagnosis, an imaging-guided biopsy is often ultimately required to establish a specific diagnosis. Imaging is of paramount importance even in the long-term follow-up in order to assess any residual tumor when surgical resection is incomplete, to assess the efficacy of adjuvant chemotherapy and radiotherapy, and to detect recurrence.

[Updates to the WHO classification of bone tumours]

The fourth edition of the WHO Classification of Soft Tissue and Bone Tumours, published in 2013, extends the approach to describe genetics and pathology of these tumours in the context of epidemiological, clinical and imaging data, which was adopted in the third edition. Added are a few new entities, reclassifications and renamings. The most important point, also of clinical relevance and with consequences for treatment, is the introduction of a stratification of bone tumours based on their biological behaviour into three groups (benign, intermediate, malignant) in analogy to soft tissue tumours.

Systematic Review of Clinical, Radiologic, and Histologic Features of Benign Notochordal Cell Tumors: Implications for Patient Management

BACKGROUND

There are no absolute defining criteria for benign notochordal cell tumors; the diagnosis is usually based on small size and the absence of aggressive features. Therefore, by definition, the diagnosis is subjective and usually determined by multidisciplinary consensus. A benign notochordal cell tumor should not grow during surveillance, and this may be used to confirm the diagnosis, but is a tautologic definition. Diagnostic ambiguity leads to uncertainty in management. If a tumor is a small chordoma then early surgery is likely to provide a better outcome. However, unnecessary treatment of a benign tumor may incur unjustified risk.

OBJECTIVE

To propose clearer guidelines for the definition and management of benign notochordal tumors.

METHODS

We performed a PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) review of the reported definitions for benign notochordal tumors and their management.

RESULTS

The accepted features of benign notochordal tumors vary considerably: a typical tumor may be diagnosed in the absence of neurology, radiologically well-corticated bony margins, size <35 mm, no enhancement with contrast, no soft tissue extension, no dural penetration, no progression on scans, histologic absence of extracellular myxoid matrix, and low Ki67 index. If these criteria are fulfilled, it is reasonable to use radiologic surveillance in the first instance. Biopsy may be offered depending on the relative risks of performing the biopsy, or if there are atypical features.

CONCLUSIONS

We suggest a clearer definition for a benign notochordal tumor and a management algorithm that incorporates a level of diagnostic uncertainty.

The clincoradiologic spectrum of notochordal derived masses

The notochord is an essential part of human development that regresses with age. Masses derived from notochordal tissue may be encountered during imaging of the neuroaxis. Fortunately, the majority of these are benign and can usually be differentiated by radiological and clinical findings. In this manuscript, we discuss the clinical and radiologic presentation of the four notochordal derived masses and present a brief overview of their management.

Chordomas: Histopathological Study in View of Anatomical Location

BACKGROUND

Chordomas are aggressive bone tumors that have a predilection for the axial skeleton including the skull base and spinal/sacral bones. However, the histopathological and clinical differences between skull base chordoma (SBC) and sacral/spinal chordoma (SC) are unclear as previous studies have been focused on patient prognosis and treatment outcome. This study aimed to evaluate the clinicopathologic features and prognosis of chordoma according to its location.

METHODS

Patients with chordomas were enrolled, and the histopathologic features were compared according to the tumor location.

RESULTS

A total of 52 patients were enrolled. SBCs had more abundant chondroid matrix and diffuse growth pattern, while SCs had non-chondroid, myxoid matrix and a lobulating pattern, typical of chordoma. Old age and residual tumors were risk factors for shorter overall survival in SBCs. The chondroid matrix was an independent risk factor for shorter disease-free survival in the overall population.

CONCLUSION

Chordomas have different histopathologic features depending on the anatomical location.

Computed tomography and magnetic resonance imaging features of cervical chordoma

Computed tomography (CT) and magnetic resonance imaging (MRI) scans of 11 patients with histologically proven cervical chordoma were retrospectively evaluated. Imaging features assessed included location, morphology, association with adjacent structures, vertebral destruction, status of cortical bone, periosteal reaction, attenuation and calcification by CT, and signal intensity and enhancement pattern by MRI. Of 7 cases with CT, 6 exhibited lytic-sclerotic bone destruction. A total of 5 cases exhibited pressure erosion of outer cortex, 3 of which had spiculated periosteal reaction. Calcification was observed in 3 cases. All cases were heterogeneous and hypodense. MRI T2-weighted images (n=10) revealed heterogeneous hyperintense (n=5), intermediate (n=2) and intermediate-hyperintense signal intensity (n=3). Hypointense septa between lobules (n=5) and stripes (n=3) were observed on T2-weighted images. Post-contrast magnetic resonance images (n=6) demonstrated marked heterogeneous (n=3) and ring-like (n=3) enhancement. CT scanning is valuable in revealing the lytic-sclerotic bone destruction, pressure erosion of outer cortex and calcification. MRI is useful in demonstrating the results of soft tissue mass. The two examinations are necessary for differential diagnosis of patients with suspected cervical chordoma.

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.

[Notochordal tumors : Benign notochordal tumors and chordomas]

Benign notochordal tumors (BNCT) and chordomas are primary bone tumors of the spine with a predominant localization in the sacrum and clival region followed by the vertebral bodies. Besides the most common variant (NOS [not otherwise specified] with hepatoid or renal carcinoma cell-like differentiation) chordomas with chondroid, and polymorphic to anaplastic morphology are described. An unfavorable variant are pediatric chordomas with a loss of INI-1. BNCT and chordomas are characterized by the following immunohistological profile: vimentin+, cytokeratin+/-, epithelial membrane antigen (EMA)+/-, S100 protein+/-, brachyury+. This profile helps to distinguish these tumors from other lesions such as chondrosarcoma, chordoid meningioma, and metastases of carcinoma.

Chordoma arising from benign multifocal notochordal tumors

This case reports a 25-year-old woman initially diagnosed with adjacent benign notochordal cell tumors (BNCTs) of L3 and L4 based on needle biopsy of L3 and stable imaging over a 3-year period who was ultimately found to have a chordoma arising from a BNCT at L3. It illustrates the potential relationship between benign and malignant notochordal tumors and the difficulty in distinguishing them by clinical, radiological, and even histopathological means.

Benign notochordal cell tumors

Benign notochordal cell tumors (TBCN) are lesions with notochordal differentiation which affect the axial skeleton. They are characterized by asymptomatic or non-specific symptomatology and are radiologically unnoticed because of their small size, or because they are mistaken with other benign bone lesions, such as vertebral hemangiomas. When they are large, or symptomatic, can be differential diagnosis with metastases, primary bone tumors and chordomas. We present a case of a TBCN in a 50-year-old woman, with a sacral lesion seen in MRI. A CT-guided biopsy was scheduled to analyze the lesion, finding that the tumor was not clearly recognizable on CT, so the anatomical references of MRI were used to select the appropriate plane. The planning of the approach and the radio-pathological correlation were determinant to reach the definitive diagnosis.

SMD Kozlowski type caused by p.Arg594His substitution in TRPV4 reveals abnormal ossification and notochordal remnants in discs and vertebrae

Spondylometaphyseal dysplasia Kozlowski type (SMDK) is a monogenic disorder within the TRPV4 dysplasia spectrum and has characteristic spinal and metaphyseal changes. We report skeletal MR imaging in a two-year-old patient who manifested typical clinical and radiographic features of SMDK. The diagnosis was confirmed by molecular analysis which revealed a mutation NM_021625.4:c.1781G > A - p.(Arg594His) in exon 11 of the TRPV4 gene. We have documented abnormalities in endochondral formation of the long and short tubular bones as well as round bones of the wrists and feet. The vertebral bodies had increased thickness of hyaline cartilage which enveloped ossification centers. The vertebrae and discs also had abnormalities in size, shape and structure. These anomalies were most likely the consequence of notochordal remnants presence within the intervertebral discs and in the vertebral bodies. The advantages of MR imaging in bone dysplasias caused by TRPV4 mutations are emphasized in this article.

Frequency and Risk Factors for Additional Lesions in the Axial Spine in Subjects With Chordoma: Indications for Screening

STUDY DESIGN

Retrospective cohort study.

OBJECTIVE

We aim to evaluate the frequency and clinical significance of additional lesions in the axial spine in subjects with chordoma and to assess the need for screening.

SUMMARY OF BACKGROUND DATA

Chordomas are rare tumors that may be multicentric or metastasize and affect several bones in the axial spine. The incidence of multiple lesions in the axial spine is unknown. Understanding the incidence rate of multiple lesions in the spine in subjects with chordomas will help guide utilization of total spine screening imaging.

METHODS

We performed a retrospective review of medical records of 42 subjects with histologically confirmed chordomas who had complete imaging of the axial spine. Lesions with imaging characteristics suggestive of chordomas/notochordal remnants were identified. Data on age at diagnosis, sex, size (in maximal dimension), type of chordoma (conventional, chondroid, or dedifferentiated), and whether pulmonary metastases were present were recorded. Binomial two-sample tests of proportions were used to compare proportions. Logistic regression was used to assess predictors of additional lesions.

RESULTS

Forty-two subjects (57.1% male) were identified. The proportion of subjects with additional lesions in the axial spine was 16.7% (7/42). Age, sex, size, and subtype of chordoma were not significant predictors of having additional lesions (P > 0.05 for each variable). However, having pulmonary metastases was a significant predictor of having additional lesions (P < 0.05).

CONCLUSION

Approximately 17% of subjects with chordomas had additional lesions in the axial spine. It is unclear whether these represent metastases, synchronous primary chordomas or notochordal remnant tissue. Screening imaging of the axial spine may reveal additional lesions in particular in subjects with pulmonary metastases.

LEVEL OF EVIDENCE

3.

[Chordoma]

PURPOSES

To review in the literature, all the epidemiological, clinical, radiological, histological and therapeutic data regarding chordomas as well as various notochordal entities: ecchordosis physaliphora, intradural and intraparenchymatous chordomas, benign notochordal cell tumors, parachordomas and extra-axial chordomas. To identify different types of chordomas, including familial forms, associations with tuberous sclerosis, Ollier's disease and Maffucci's syndrome, forms with metastasis and seeding. To assess the recent data regarding molecular biology and progress in targeted therapy. To compare the different types of radiotherapy, especially protontherapy and their therapeutic effects. To review the largest series of chordomas in their different localizations (skull base, sacrum and mobile spine) from the literature.

MATERIALS

The series of 136 chordomas treated and followed up over 20 years (1972-2012) in the department of neurosurgery at Lariboisière hospital is reviewed. It includes: 58 chordomas of the skull base, 47 of the craniocervical junction, 23 of the cervical spine and 8 from the lombosacral region. Similarly, 31 chordomas in children (less than 18 years of age), observed in the departments of neurosurgery of les Enfants-Malades and Lariboisière hospitals, are presented. They were observed between 1976 and 2010 and were located intracranially (n=22 including 13 with cervical extension), 4 at the craniocervical junction level and 5 in the cervical spine.

METHODS

In the entire Lariboisière series and in the different groups of localization, different parameters were analyzed: the delay of diagnosis, of follow-up, of occurrence of metastasis, recurrence and death, the number of primary patients and patients referred to us after progression or recurrence and the number of deaths, recurrences and metastases. The influence of the quality of resection (total, subtotal and partial) on the prognosis is also presented. Kaplan-Meier actuarial curves of overall survival and disease free survival were performed in the entire series, including the different groups of localization based on the following 4 parameters: age, primary and secondary patients, quality of resection and protontherapy. In the pediatric series, a similar analysis was carried-out but was limited by the small number of patients in the subgroups.

RESULTS

In the Lariboisière series, the mean delay of diagnosis is 10 months and the mean follow-up is 80 months in each group. The delay before recurrence, metastasis and death is always better for the skull base chordomas and worse for those of the craniocervical junction, which have similar results to those of the cervical spine. Similar figures were observed as regards the number of deaths, metastases and recurrences. Quality of resection is the major factor of prognosis with 20.5 % of deaths and 28 % of recurrences after total resection as compared to 52.5 % and 47.5 % after subtotal resection. This is still more obvious in the group of skull base chordomas. Adding protontherapy to a total resection can still improve the results but there is no change after subtotal resection. The actuarial curve of overall survival shows a clear cut in the slope with some chordomas having a fast evolution towards recurrence and death in less than 4 years and others having a long survival of sometimes more than 20 years. Also, age has no influence on the prognosis. In primary patients, disease free survival is better than in secondary patients but not in overall survival. Protontherapy only improves the overall survival in the entire series and in the skull base group. Total resection improves both the overall and disease free survival in each group. Finally, the adjunct of protontherapy after total resection is clearly demonstrated. In the pediatric series, the median follow-up is 5.7 years. Overall survival and disease free survival are respectively 63 % and 54.3 %. Factors of prognosis are the histological type (atypical forms), localization (worse for the cervical spine and better for the clivus) and again it will depend on the quality of resection.

CONCLUSIONS

Many different pathologies derived from the notochord can be observed: some are remnants, some may be precursors of chordomas and some have similar features but are probably not genuine chordomas. To-day, immuno-histological studies should permit to differentiate them from real chordomas. Improving knowledge of molecular biology raises hopes for complementary treatments but to date the quality of surgical resection is still the main factor of prognosis. Complementary protontherapy seems useful, especially in skull base chordomas, which have better overall results than those of the craniocervical junction and of the cervical spine. However, we are still lacking an intrinsic marker of evolution to differentiate the slow growing chordomas with an indolent evolution from aggressive types leading rapidly to recurrence and death on which more aggressive treatments should be applied.

Difficulty distinguishing benign notochordal cell tumor from chordoma further suggests a link between them

Background

Much discussion about benign notochordal cell tissue in vertebrae has centered on the nature of its relationship, if any, to chordoma. Often referred to as benign notochordal cell tumors (BNCTs), these lesions have unique morphological features, however, differentiating between notochordal cells in discs, BNCT, and chordoma can be difficult. They are described as radiologically distinct from chordoma, with lysis, contrast enhancement, and a soft tissue mass indicating chordoma.

Methods

All chordomas diagnosed at our institution, the Istituto Ortopedico Rizzoli (Bologna, Italy), prior to 2008 were reviewed, yielding 174 cases. Five were limited to bone; one was a recurrent chordoma without original data available. The remaining four were re-evaluated in detail.

Results

There were three women and one man, aged 33–57 years (mean, 48 years). Two were BNCTs and two were mixed lesions containing BNCT and chordoma. On computed tomography, all were radiopaque with areas of lysis. One BNCT was heterogeneous on magnetic resonance imaging, enhancing after contrast. Microscopically, one BNCT had a well-defined cystic area with a sclerotic border. The other had a minute atypical area; it recurred as chordoma. The mixed lesions had areas of definitive BNCT, definitive chordoma, and atypical areas that did not meet the criteria for either. The atypical areas in all three cases ‘blended’ with areas of chordoma or BNCT.

Conclusion

These cases illustrate the ongoing challenges in differentiating between BNCT and chordoma. All had unique imaging features; three had atypical microscopic areas blending with BNCT or chordoma, strengthening the argument for a relationship between the two entities and supporting the idea that some BNCTs may progress to chordoma. Our study dispels the notion that any single radiologic criterion used to distinguish between chordoma and BNCT is reliable, opening the discussion as to whether or how to monitor BNCTs.

Benign Notochordal Cell Tumor of the Sacrum with Atypical Imaging Features: The Value of CT Guided Biopsy for Diagnosis

We report a case of a benign notochordal cell tumor (BNCT) of the sacrum with atypical imaging features, which was incidentally discovered in a 74-year-old man undergoing evaluation for progressively worsening hip and back pain. It is important for radiologists, pathologists and orthopedic surgeons to be aware of the diagnosis of BNCT and be familiar with its radiographic features to avoid unnecessary treatment. This case illustrates the advantage of percutaneous computed tomography (CT)-guided biopsy as a minimally invasive technique for definitive diagnosis of a BNCT with atypical imaging features.

Benign Notochordal Cell Tumors of the Spine

BACKGROUND:

Notochord-related lesions of the spinal column include benign notochordal cell tumors (BNCTs), ecchordosis physaliphora, both generally considered benign lesions, and chordomas, which represent malignant tumors. The histological similarity of these lesions to the notochord and each other and their strong predilection to the axial skeleton have led to the hypothesis that these lesions represent a continuum of malignant transformation from notochordal remnants, BNCTs, and finally chordomas.

OBJECTIVE:

To present a cohort of biopsy-proven BNCTs with a description of radiographic features, histology, and follow-up to help elucidate the optimal management of these lesions.

METHODS:

A retrospective chart review identified 13 patients with notochordal rest lesions confirmed by histology. Histologic inclusion criteria included notochordal features without evidence of septation, myxoid matrix, nuclear atypia, or mitotic figures. Tumors exhibiting evidence of cortical expansion or destruction were excluded. The natural history and histological and radiographic features were examined.

RESULTS:

Sixteen spinal lesions from 8 patients met the diagnostic criteria for BNCTs, identified on imaging after the patient presented with back pain. Radiographically, all lesions were hypointense on T1-weighted magnetic resonance imaging sequences and hyperintense on T2-weighted and short T1 inversion recovery. The median radiographic follow-up was 21.6 months (range, 8.5-71.2 months). None of the lesions exhibited radiographic or symptomatic progression.

CONCLUSION:

Although limited by short follow-up, our series confirms that these lesions may be safely observed without evidence of malignant transformation, which emphasizes the importance of distinction of BNCT from chordoma at diagnosis and the possibility of close follow-up for these lesions instead of aggressive treatment indicated in patients with chordomas.

Paraspinal chordoma mimicking a neurofibroma: a rare but important radiological pitfall

We present an unusual case of a chordoma presenting as an extradural spinal tumour with extension through an expanded intervertebral foramen to form a large paraspinal mass. The magnetic resonance imaging appearances closely mimicked a neurofibroma; however, pre-operative biopsy confirmed the diagnosis of chordoma. This is, to our knowledge, the tenth reported case of chordoma presenting as a mass expanding the intervertebral foramen. Thus, while it is a rare form of chordoma, it can lead to a recognised radiological pitfall. Making the distinction from neurofibroma before surgery is essential, as radical dissection of chordoma is required to reduce the risk of local recurrence.

Entrapped intralesional marrow: a hitherto undescribed imaging feature of benign notochordal cell tumour

We report two cases of histologically proven benign notochordal cell tumour (BNCT) with imaging evidence of entrapped intralesional marrow and discuss the relevance of previously undescribed imaging feature.