Base of Skull Chordomas in Children and Adolescents

Hematoporphyrin derivative-mediated photodynamic techniques for the diagnosis and treatment of chordoma

BACKGROUND

Chordoma is a rare congenital low-grade malignant tumor characterized by infiltrative growth. It often tends to compress important intracranial nerves and blood vessels, making its surgical treatment extremely difficult. Besides, the efficacy of radiotherapy and chemotherapy is limited. The photosensitizer hematoporphyrin derivative (HPD) can emit red fluorescence under 405 nm excitation and produce reactive oxygen species for tumor therapy under 630 nm excitation. Herein, we investigated the effects of the photosensitizer hematoporphyrin derivative (HPD) on different cell lines of chordoma and xenograft tumors under 405 nm and 630 nm excitation.

METHODS

The photosensitizer hematoporphyrin derivative (HPD) and Two different chordoma cell lines (U-CH1, JHC7) were used for the test. The in vitro experiments were as follows: (1) the fluorescence intensity emitted by chordoma cells excited by different 405 nm light intensities was observed under a confocal microscope; (2) the Cell Counting Kit-8 (CCK-8) assay was performed to detect the effects of different photosensitizer concentrations and 630 nm light energy densities on the activity of chordoma cells. In the in vivo experiments, (3) Fluorescence visualization of chordoma xenograft tumors injected with photosensitizer via tail vein under 405 nm excitation; (4) Impact of 630 nm excitation of photosensitizer on the growth of chordoma xenograft tumors.

RESULTS

(1) The photosensitizers in chordoma cells and chordoma xenografts of nude mice were excited by 405 nm to emit red fluorescence; (2) 630 nm excitation photosensitizer reduces chordoma cell activity and inhibits chordoma xenograft tumor growth in chordoma nude mice.

CONCLUSION

Photodynamic techniques mediated by the photosensitizer hematoporphyrin derivatives can be used for the diagnosis and treatment of chordoma.

Degenerative Atypia in Clival Chordoma: Two Case Reports

In this study, we report surgical management combined with radiotherapy in two patients with typical chordoma. Different types of radiation have varied effects on chordomas when they are radiated. Classical cases display cellular atypia and fibrosis following irradiation, while necrosis and fibrosclerosis are observed after carbon ion therapy, implying that it is possible to control the tumor more effectively using carbon ion therapy with minimal side effects.

Chordoma: Genetics and Contemporary Management

Chordomas, arising from notochord remnants, are rare neoplasms with aggressive growth patterns despite their histologically low-grade nature. This review explores their embryological origins, molecular markers like brachyury, and genetic alterations driving pathogenesis. Diagnosis relies on advanced imaging and biopsy confirmation due to overlapping features with chondrosarcoma. The WHO classification distinguishes conventional, dedifferentiated, and poorly differentiated chordomas, each with distinct prognostic implications. Recent genomic analyses uncovered recurrent mutations in PI3K signaling pathways and chromatin remodeling genes, informing prognostic models. Surgery remains the cornerstone of treatment, though adjuvant radiation complements surgical resection. Although chordomas are generally considered refractory to medical therapy, emerging targeted molecular strategies show potential promise in ongoing trials. This review aims to provide a concise yet comprehensive overview of chordomas, guiding clinicians in diagnosis, treatment, and prognostication for improved patient outcomes.

The Use of Proton and Carbon Ion Radiation Therapy for Sarcomas

The unique physical and biological characteristics of proton and carbon ions allow for improved sparing of normal tissues, decreased integral dose to the body, and increased biological effect through high linear energy transfer. These properties are particularly useful for sarcomas given their histology, wide array of locations, and age of diagnosis. This review summarizes the literature and describes the clinical situations in which these heavy particles have advantages for treating sarcomas.

Special Considerations in Pediatric Endoscopic Skull Base Surgery

Originally pioneered in adults, endoscopic endonasal approaches for skull base pathology are being increasingly applied as a minimally invasive alternative for young children. Intrinsic anatomic differences between these patient populations have sparked discussions on the feasibility, safety, and efficacy of these techniques in pediatric patients. This work aims to serve as a primer for clinicians engaged in the rapidly evolving field of pediatric endoscopic skull base surgery. A succinct overview of relevant embryology, sinonasal anatomy, and diagnostic workup is presented to emphasize key differences and unique technical considerations. Additional discussions regarding select skull base lesions, reconstructive paradigms, potential surgical complications, and postoperative care are also highlighted in the setting of multidisciplinary teams.

Integrated Molecular and Histological Insights for Targeted Therapies in Mesenchymal Sinonasal Tract Tumors

PURPOSE OF REVIEW

This review aims to provide a comprehensive overview of mesenchymal sinonasal tract tumors (STTs), a distinct subset of STTs. Despite their rarity, mesenchymal STTs represent a unique clinical challenge, characterized by their rarity, often slow progression, and frequently subtle or overlooked symptoms. The complex anatomy of the sinonasal area, which includes critical structures such as the orbit, brain, and cranial nerves, further complicates surgical treatment options. This underscores an urgent need for more advanced and specialized therapeutic approaches.

RECENT FINDINGS

Advancements in molecular diagnostics, particularly in next-generation sequencing, have significantly enhanced our understanding of STTs. Consequently, the World Health Organization has updated its tumor classification to better reflect the distinct histological and molecular profiles of these tumors, as well as to categorize mesenchymal STTs with greater accuracy. The growing understanding of the molecular characteristics of mesenchymal STTs opens new possibilities for targeted therapeutic interventions, marking a significant shift in treatment paradigms. This review article concentrates on mesenchymal STTs, specifically addressing sinonasal tract angiofibroma, sinonasal glomangiopericytoma, biphenotypic sinonasal sarcoma, and skull base chordoma. These entities are marked by unique histopathological and molecular features, which challenge conventional treatment approaches and simultaneously open avenues for novel targeted therapies. Our discussion is geared towards delineating the molecular underpinnings of mesenchymal STTs, with the objective of enhancing therapeutic strategies and addressing the existing shortcomings in the management of these intricate tumors.

Immunomodulation exerted by galectins: a land of opportunity in rare cancers

Rare cancers represent only 5% of newly diagnosed malignancies. However, in some cases, they account for up to 50% of the deaths attributed to cancer in their corresponding organ. Part of the reason is that treatment options are generally quite limited, non-specific, and very often, only palliative. Needless to say, research for tailored treatments is warranted. Molecules that exert immunomodulation of the tumor microenvironment are attractive drug targets. One such group is galectins. Thus, in this review we summarize the current knowledge about galectin-mediated immunomodulation in rare cancers, highlighting the research opportunities in each case.

Surgery and proton radiation therapy for pediatric base of skull chordomas: Long-term clinical outcomes for 204 patients

BACKGROUND

Data on clinical outcomes for base of skull (BOS) chordomas in the pediatric population is limited. We report patient outcomes after surgery and proton radiotherapy (PRT).

METHODS

Pediatric patients with BOS chordomas were treated with PRT or combined proton/photon approach (proton-based; for most, 80% proton/20% photon) at the Massachusetts General Hospital from 1981 to 2021. Endpoints of interest were overall survival (OS), disease-specific survival, progression-free survival (PFS), freedom from local recurrence (LC), and freedom from distant failure (DC).

RESULTS

Of 204 patients, median age at diagnosis was 11.1 years (range, 1-21). Chordoma location included 59% upper and/or middle clivus, 36% lower clivus, 4% craniocervical junction, and 1% nasal cavity. Fifteen (7%) received pre-RT chemotherapy. Forty-seven (23%) received PRT, and 157 (77%) received comboRT. Median total dose was 76.7 Gy (RBE) (range, 59.3-83.3). At a median follow-up of 10 years (interquartile range, 5-16 years), 56 recurred. Median OS and PFS were 26 and 25 years, with 5-, 10-, and 20-year OS and PFS rates of 84% and 74%, 78% and 69%, and 64% and 64%, respectively. Multivariable actuarial analyses showed poorly differentiated subtype, radiographical progression prior to RT, larger treatment volume, and lower clivus location to be prognostic factors for worse OS, PFS, and LC. RT was well tolerated at a median follow-up of 9 years (interquartile range, 4-16 years). Side effects included 166 patients (80%) with mild/moderate acute toxicities, 24 (12%) patients with late toxicities, and 4 (2%) who developed secondary radiation-related malignancies.

CONCLUSION

This is the largest cohort of BOS chordomas in the literature, pediatric and/or adult. High-dose PRT following surgical resection is effective with low rates of late toxicity.

Outcomes of Endoscopic Resection in Pediatric Skull Base Chordoma: A Systematic Review

The endoscopic approach has been recommended as a primary option for treating chordomas, and it is associated with better resection rates and fewer surgical complications than transcranial surgery. This review aimed to assess the long-term consequences and evidence in the current literature regarding the endoscopic approach's efficacy in treating skull-base chordoma in children. A systematic review was conducted based on the PubMed, Web of Science, and EMBASE databases to examine the clinical outcomes of endoscopic endonasal surgery for pediatric skull base chordoma tumors. The review included studies published in English that employed specific research designs and reported on pediatric patients with skull base chordoma. Of the 268 studies initially considered, 25 met our eligibility criteria and were included in the final analysis. The average age of the patients was 11.5 years, with approximately equal number of males and females. The endoscopic endonasal approach (EEA) was the most commonly used modality. Gross total resection (GTR) was achieved in 62.7% of patients, while 18.09% had a subtotal resection (STR), and 13.83% had near-total resection only. Most patients showed significant to moderate improvement from their baseline condition and had no recurrence during their follow-up. Our findings further endorse that the endoscopic approach is a viable primary treatment option for pediatric skull base chordoma.

The NIH pediatric/young adult chordoma clinic and natural history study: Making advances in a very rare tumor

BACKGROUND

Chordomas are rare tumors arising from the skull base and spine, with approximately 20 pediatric chordoma cases in the Unitedn States per year. The natural history and optimal treatment of pediatric chordomas, especially poorly differentiated and dedifferentiated subtypes, is incompletely understood. Herein, we present findings from our first National Cancer Institute (NCI) chordoma clinic and a retrospective analysis of published cases of pediatric poorly differentiated chordomas (PDC) and dedifferentiated chordomas (DC).

METHODS

Patients less than 40 years old with chordoma were enrolled on the NCI Natural History and Biospecimens Acquisitions Study for Children and Adults with Rare Solid Tumors protocol (NCT03739827). Chordoma experts reviewed patient records, evaluated patients, and provided treatment recommendations. Patient-reported outcomes, biospecimens, and volumetric tumor analyses were collected. A literature review for pediatric PDC and DC was conducted.

RESULTS

Twelve patients (median age: 14 years) attended the clinic, including four patients with active disease and three patients with PDC responsive to systemic therapy. Consensus treatment, management, and recommendations were provided to patients. Literature review returned 45 pediatric cases of PDC or DC with variable treatments and outcomes.

CONCLUSIONS

A multidisciplinary expert clinic was feasible and successful in improving understanding of pediatric chordoma. While multimodal approaches have all been employed, treatment for PDC has been inconsistent and a recommended standardized treatment approach has not been defined. Centralized efforts, inclusive of specialized chordoma-focused clinics, natural history studies, and prospective analyses will help in the standardization of care for this challenging disease.

SMARCB1 Loss in Poorly Differentiated Chordomas Drives Tumor Progression

Poorly differentiated (PD) chordoma, a rare, aggressive tumor originating from notochordal tissue, shows loss of SMARCB1 expression, a core component of the Switch/Sucrose Non-Fermentable (SWI/SNF) chromatin remodeling complexes. To determine the impact of SMARCB1 re-expression on cell growth and gene expression, two SMARCB1-negative PD chordoma cell lines with an inducible SMARCB1 expression system were generated. After 72 hours of induction of SMARCB1, both SMARCB1-negative PD chordoma cell lines continued to proliferate. This result contrasted with those observed with SMARCB1-negative rhabdoid cell lines in which SMARCB1 re-expression caused the rapid inhibition of growth. We found that the lack of growth inhibition may arise from the loss of CDKN2A (p16INK4A) expression in PD chordoma cell lines. RNA-sequencing of cell lines after SMARCB1 re-expression showed a down-regulation for rRNA and RNA processing as well as metabolic processing and increased expression of genes involved in cell adhesion, cell migration, and development. Taken together, these data establish that SMARCB1 re-expression in PD chordomas alters the repertoire of SWI/SNF complexes, perhaps restoring those associated with cellular differentiation. These novel findings support a model in which SMARCB1 inactivation blocks the conversion of growth-promoting SWI/SNF complexes to differentiation-inducing ones, and they implicate SMARCB1 loss as a late event in tumorigenic progression. Importantly, the absence of growth inhibition after SMARCB1 restoration creates a unique opportunity to identify therapeutic vulnerabilities.

Top 10 Clear Cell Head and Neck Lesions to Contemplate

BACKGROUND

Optically clear cytoplasm may occur in neoplastic and non-neoplastic conditions, either as a characteristic feature of a disease entity or as a morphologic rarity, potentially creating diagnostic dilemmas in various organ systems. In the head and neck, clear cell change can occur in lesions of salivary, odontogenic, thyroid, parathyroid, or sinonasal/skull base origin, as well as in metastases to these regions.

METHODS

This review elaborates the top ten clear cell lesions in the head and neck, emphasizing their distinguishing histologic, immunohistochemical, and molecular attributes, and presents a rational approach to arriving at an accurate classification.

RESULTS

Cytoplasmic pallor or clearing may be caused by accumulations of glycogen, lipid, mucin, mucopolysaccharides, water, foreign material, hydropic organelles, or immature zymogen granules. Overlapping morphologic features may present a diagnostic challenge to the surgical pathologist. Similarity in immunohistochemical profiles, often due to common cell type, as well as rare non-neoplastic mimics, furthers the diagnostic conundrum.

CONCLUSIONS

The top ten lesions reviewed in this article are as follows: (1) clear cell carcinoma (salivary and odontogenic), (2) mucoepidermoid carcinoma, (3) myoepithelial and epithelial-myoepithelial carcinoma, (4) oncocytic salivary gland lesions, (5) squamous cell carcinoma, (6) parathyroid water clear cell adenoma, (7) metastatic renal cell carcinoma (especially in comparison to clear cell thyroid neoplasms), (8) sinonasal renal cell-like adenocarcinoma, (9) chordoma, and (10) rhinoscleroma.

Poorly Differentiated Chordoma of the Clivus With Loss of SMARCB1 Expression in a Pediatric Patient: A Case Report

Poorly differentiated chordoma (PDC) is a rare, aggressive subtype of chordoma. A two-year-old girl presented with cervical pain, limb paralysis and respiratory failure. Magnetic resonance imaging and positron emission tomography-computed tomography revealed a tumor compressing the pons at the clivus and osteoblastic metastatic lesions of the left upper arm and right iliac bone. Her tumors shrank substantially after treatment with chemotherapy and proton beam therapy. Our initial diagnosis was an atypical teratoma/rhabdoid tumor, but final diagnosis of PDC was made on the basis of the immunohistochemical expression of brachyury. In addition, the detection of SMARCB1/INI1 mutation confirmed the diagnosis of PDC.

Differences in stromal component of chordoma are associated with contrast enhancement in MRI and differential gene expression in RNA sequencing

Chordoma is a malignant bone neoplasm demonstrating notochordal differentiation and it frequently involves axial skeleton. Most of chordomas are conventional type with varying amount of myxoid stroma. Previously known prognostic factors for conventional chordoma are not specific for chordoma: old age, metastasis, tumor extent, and respectability. Here, we aimed to investigate the histologic, radiologic, and transcriptomic differences in conventional chordoma based on the stromal component. A total of 45 patients diagnosed with conventional chordoma were selected between May 2011 and March 2020 from a single institution. Electronic medical records, pathology slides, and pretreatment magnetic resonance imaging (MRI) scans were reviewed. Of the 45 patients, ten cases (4 stroma-rich and 6 stroma-poor tumor) were selected for RNA sequencing, and available cases in the remainder were used for measuring target gene mRNA expression with qPCR for validation. Differential gene expression and gene set analysis were performed. Based on histologic evaluation, there were 25 (55.6%) stroma-rich and 20 (44.4%) stroma-poor cases. No clinical differences were found between the two groups. Radiologically, stroma-rich chordomas showed significant signal enhancement on MRI (72.4% vs 27.6%, p = 0.002). Upregulated genes in stroma-rich chordomas were cartilage-, collagen/extracellular matrix-, and tumor metastasis/progression-associated genes. Contrarily, tumor suppressor genes were downregulated in stroma-rich chordomas. On survival analysis, Kaplan–Meier plot was separated that showed inferior outcome of stroma-rich group, although statistically insignificant. In conclusion, the abundant stromal component of conventional chordoma enhanced well on MRI and possibly contributed to the biological aggressiveness that supported by transcriptomic characteristics. Further extensive investigation regarding radiologic-pathologic-transcriptomic correlation in conventional chordoma in a larger cohort could verify additional clinical significance.

Proton beam therapy for skull base chordomas: a systematic review of tumor control rates and survival rates

The management of base of skull (BS) chordomas is a neurosurgical conundrum owing to their close proximity to the critical neurovascular structures. Surgical resection is the gold standard treatment followed by adjuvant radiotherapy which includes photon therapy, proton beam therapy (PBT), gamma knife radiosurgery, etc. PBT has become an unparalleled therapeutic modality in the management of BS chordomas. The aim of this systematic review was to assess the outcomes in BS chordoma patients who received PBT as a primary or adjuvant therapy. PubMed and Cochrane databases were screened till May 2022. Following the PRISMA guidelines, studies were reviewed thoroughly, and the data of the included study was extracted. Statistical analysis was performed using the SAS 9.4 with P value < .05 considered as significant. Sixteen studies with 752 patients were included. The majority of the patients were adults (> 18 years) with a male:female ratio of 1.2. The most common clinical features were cranial nerve (3rd, 6th, or 12th) palsy and hearing impairment. Ninety-five percent of the patients underwent surgical resection before PBT. The mean PBT dose received was 74.02 cGe (cobalt gray equivalent). Eighty percent of the patients showed a positive response to the therapy defined in terms of tumor regression. Five-year local control (LC), overall survival (OS), and progression-free survival (PFS) were calculated as 76.6%, 79.6%, and 89%, respectively. Statistical analysis revealed none of the factors had any significant association with 5-year LC. PBT is a growing therapeutic technique that has revolutionized the treatment of BS chordomas.

Chordoma: To know means to recognize

Chordoma is a rare type of bone cancer characterized by its locally aggressive and destructive behavior. Chordoma is located in one of the three primary regions: skull base/clivus, sacrum or mobile spine. Chordoma grows slowly, therefore its insidious onset leads to delayed diagnosis, accounting for the low survival rates. Treatment centers around successful en bloc resection with negative margins, though, considering the anatomically constrained site of growth, it frequently requires adjuvant radiotherapy. This article analyzes the existing literature with the aim to provide a better insight in the current state of research in chordoma classification, characteristics, and management.

New molecular entities of soft tissue and bone tumors

PURPOSE OF REVIEW

The advances of molecular techniques have led to the refinement of the classification of mesenchymal tumors, leading to newly introduced entities in the recently published fifth edition of the WHO Classification of Soft Tissue and Bone Tumors, which are discussed in this review.

RECENT FINDINGS

For the first time, entities are included of which the name refers to the underlying molecular alteration including round cell sarcoma with EWSR1 -non-ETS fusions, CIC -rearranged sarcoma, and sarcoma with BCOR genetic alteration. EWSR1-SMAD3 -positive fibroblastic tumor and NTRK -rearranged spindle cell neoplasm are provisionally included as 'emerging' entities based on the underlying molecular alteration, though the entity still needs to be better defined. Other newly recognized entities are not named after their molecular change, but the molecular alteration helped to delineate them from others: atypical spindle cell/pleomorphic lipomatous tumor, anastomosing hemangioma, angiofibroma of soft tissue, myxoid pleomorphic liposarcoma, and poorly differentiated chordoma.

SUMMARY

Classification of mesenchymal tumors is increasingly based on the underlying molecular changes, although this cannot be interpreted separately from clinical, morphological, and immunohistochemical characteristics.

Guidelines for magnetic resonance imaging in pediatric head and neck pathologies: a multicentre international consensus paper

The use of standardized imaging protocols is paramount in order to facilitate comparable, reproducible images and, consequently, to optimize patient care. Standardized MR protocols are lacking when studying head and neck pathologies in the pediatric population. We propose an international, multicenter consensus paper focused on providing the best combination of acquisition time/technical requirements and image quality. Distinct protocols for different regions of the head and neck and, in some cases, for specific pathologies or clinical indications are recommended. This white paper is endorsed by several international scientific societies and it is the result of discussion, in consensus, among experts in pediatric head and neck imaging.

Update of Key Clinical, Histological and Molecular Features of Malignant Bone Tumours Arising in the Craniofacial Skeleton

The craniofacial skeleton is a highly complex and specialized anatomic region containing and protecting the brain and sensory organs. Bone sarcomas arising here comprise a heterogeneous group of tumours, some of which differ in their biological behaviour compared to their peripheral counterparts. The reasons for this seem to lie, at least partially, in the embryonal development of the craniofacial bones. For reaching the correct diagnosis as the cornerstone of optimal personalised treatment planning, a multidisciplinary team of specialists, including pathologists, radiologists, oncologists, and head and neck surgeons needs to be involved. The most common tumours arising in the craniofacial bones are bone-forming tumours, cartilage-forming tumours, fibro-osseous lesions, giant cell-rich lesions, and notochordal tumours. While morphology remains the backbone for the diagnosis, the last decade has witnessed tremendous advances in the molecular characterization of tumours, and molecular testing is increasingly becoming a part of the diagnostic process. The integration of these new molecular markers into the diagnostic approach has undoubtedly increased the diagnostic accuracy and objectivity, and holds great promise to also identify new therapeutic targets for precision medicine in the future. Examples include HEY1-NCOA2 in mesenchymal chondrosarcoma, IDH1/2 mutations in chondrosarcoma and TFCP2 rearrangements in rhabdomyosarcoma. In this article, key clinical, histological and molecular features of malignant bone tumours arising in the craniofacial region are discussed, with a special focus on the differential diagnosis and prognostic considerations.

Management of pediatric clival chordoma with extension to the craniocervical junction and occipito-cervical fusion: illustrative case

BACKGROUND

Chordomas are rare malignant neoplasms that develop from the primitive notochord with < 5% of the tumors occurring in pediatric patients younger than the age of 20. Of these pediatric chordomas, those affecting the craniocervical junction (C1–C2) are even more rare; therefore, parameters for surgical management of these pediatric tumors are not well characterized.

OBSERVATIONS

In this case, a 3-year-old male was found to have a clival chordoma on imaging with extension to the craniocervical junction resulting in spinal cord compression. Endoscopic-assisted transoral transclival approach for clival tumor resection was performed first. As a second stage, the patient underwent a left-sided far lateral craniotomy and cervical laminectomy for resection of the skull base chordoma and instrumented fusion of the occiput to C3. He made excellent improvements in strength and dexterity during rehab and was discharged after 3 weeks.

LESSONS

In pediatric patients with chordoma with extension to the craniocervical junction and spinal cord compression, decompression with additional occipito-cervical fusion appears to offer a good clinical outcome. Fusion performed as a separate surgery before or at the same time as the initial tumor resection surgery may lead to better outcomes.

Notochordal Tumors

This review provides an overview of the spectrum of tumors showing notochordal differentiation. This spectrum encompasses benign entities that are mostly discovered incidentally on imaging, reported as benign notochordal cell tumor, usually not requiring surgical intervention; slowly growing and histologically low-grade tumors referred to as conventional chordoma but associated with a significant metastatic potential and mortality; and more aggressive disease represented by histologically higher-grade tumors including dedifferentiated chordoma, a high-grade biphasic tumor characterized by a conventional chordoma juxtaposed to a high-grade sarcoma, usually with a spindle or pleomorphic cell morphology, and associated with a poor prognosis and poorly differentiated chordoma.

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.

Recurrent loss of chromosome 22 and SMARCB1 deletion in extra-axial chordoma: A clinicopathological and molecular analysis

Extra-axial chordoma is a rare neoplasm of extra-axial skeleton and soft tissue that shares identical histomorphologic and immunophenotypic features with midline chordoma. While genetic changes in conventional chordoma have been well-studied, the genomic alterations of extra-axial chordoma have not been reported. It is well known that conventional chordoma is a tumor with predominantly non-random copy number alterations and low mutational burden. Herein we describe the clinicopathologic and genomic characteristics of six cases of extra-axial chordoma, with genome-wide high-resolution single nucleotide polymorphism array, fluorescence in situ hybridization and targeted next-generation sequencing (NGS) analysis. The patients presented at a mean age of 33 years (range: 21-54) with a female to male ratio of 5:1. Four cases were histologically conventional type, presented with bone lesions and three of them had local recurrence. Two cases were poorly differentiated chordomas, presented with intra-articular soft tissue masses and both developed distant metastases. All cases showed brachyury positivity and the two poorly differentiated chordomas showed in addition loss of INI-1 expression by immunohistochemical analysis. Three of four extra-axial conventional chordomas showed simple genome with loss of chromosome 22 or a heterozygous deletion of SMARCB1. Both poorly differentiated chordomas demonstrated a complex hyperdiploid genomic profile with gain of multiple chromosomes and homozygous deletion of SMARCB1. Our findings show that heterozygous deletion of SMARCB1 or the loss of chromosome 22 is a consistent abnormality in extra-axial chordoma and transformation to poorly differentiated chordoma is characterized by homozygous loss of SMARCB1 associated with genomic complexity and instability such as hyperdiploidy.

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.

Chordoma: Current status, problems, and future directions

Chordoma is a rare tumor that occurs along the axial spine in pediatrics and adults, with an incidence of approximately 350 cases per year in the United States. While typically described as slow-growing, many patients will eventually develop loco-regional relapse or metastatic disease with few treatment options. Despite numerous efforts over the last 10+ years, effective treatments for patients are lacking. As subtypes of chordoma are identified and described in more detail, further knowledge regarding the natural history of each type, tumor location, age differences, genomic variability, and an overall better understanding of chordoma may be the key to developing meaningful clinical trials and effective therapies for patients with chordoma.

Characteristics and overall survival in pediatric versus adult skull base chordoma: a population-based study

PURPOSE

Less than 5% of chordomas occur in pediatric patients. While many studies have explored the treatment and outcomes of skull base chordomas, few have focused on the differences between pediatric and adult populations. The aim of this study is to analyze the epidemiological variables and clinical outcomes between pediatric and adult skull base chordomas using a large-sample, population-based cancer database.

METHODS

The National Cancer Database was queried between 2004 and 2015 for skull base chordomas. We stratified patients as pediatric (<18 years) and adults (≥18 years). We compared several clinical covariates between the two groups.

RESULTS

Our cohort consisted of 658 patients, 61 pediatric (9.3%), and 597 adults (90.7%). Pediatric patients were more likely to have larger tumor size (41.4 ± 15.7 mm versus 34.1 ± 15.8 mm, p < 0.01) and universally treated at academic facilities. There was no significant difference in overall survival.

CONCLUSIONS

Pediatric skull base chordomas are rare tumors that are managed with aggressive surgical resection, followed by radiation. While there may be difference between tumor presentation, outcomes between pediatric and adult patients are similar.

A clinical approach to parasellar lesions in the transition age

Many reviews have summarised the pathology and management of the parasellar region in adult patients, although an analysis of these aspects in the transition years, from puberty onset to the age of peak bone mass, has been lacking. A comprehensive search of English-language original articles, published from 2000 to 2020, was conducted in the MEDLINE database (December 2019 to March 2020). We selected all studies regarding epidemiology, diagnosis and management of the following parasellar lesions: germinoma, craniopharyngioma, Langerhans cell histiocytosis, optic glioma, hypothalamic hamartoma, tuber cinereum hamartoma, cranial chordoma, Rathke cleft cyst, hypophysitis and hypothalamitis during the transition age from childhood to adulthood. In the present review, we provide an overview of the principal parasellar lesions occurring in the transition age. Symptoms are usually a result of the mass effect of the lesions on nearby structures, as well as anterior pituitary deficits. Diabetes insipidus occurs frequently in these patients. In this age group, pubertal developmental disorders may be more evident compared to other stages of life. Parasellar lesions in the transition age mostly include neoplastic lesions such as germinomas, hamartomas, optic gliomas, craniopharyngiomas Langerhans cell histiocytosis and chordomas, and rarely inflammatory lesions (hypophysitis, hypothalamitis). There are limited data on the management of parasellar lesions in the transition age. Endocrine evaluation is crucial for identifying conditions that require hormonal treatment so that they can be treated early to improve the quality of life of the individual patient in this complex age range. The clinical approach to parasellar lesions involves a multidisciplinary effort.

The 2020 WHO Classification of Tumors of Bone: An Updated Review

Bone tumors are a rare and heterogeneous group of neoplasms that occur in the bone. The diversity and considerable morphologic overlap of bone tumors with other mesenchymal and nonmesenchymal bone lesions can complicate diagnosis. Accurate histologic diagnosis is crucial for appropriate management and prognostication. Since the publication of the fourth edition of the World Health Organization (WHO) classification of tumors of soft tissue and bone in 2013, significant advances have been made in our understanding of bone tumor molecular biology, classification, prognostication, and treatment. Detection of tumor-specific molecular alterations can facilitate the accurate diagnosis of histologically challenging cases. The fifth edition of the 2020 WHO classification of tumors of soft tissue and bone tumors provides an updated classification scheme and essential diagnostic criteria for bone tumors. Herein, we summarize these updates, focusing on major changes in each category of bone tumor, the newly described tumor entities and subtypes of existing tumor types, and newly described molecular and genetic data.

Local Control After Proton Therapy for Pediatric Chordoma

PURPOSE

Due to the location and high dose required for disease control, pediatric chordomas are theoretically well-suited for treatment with proton therapy, but their low incidence limits the clinical outcome data available in the literature. We sought to report the efficacy and toxicity of proton therapy among a single-institution cohort.

METHODS AND MATERIALS

Between 2008 and 2019, 29 patients with a median age of 14.8 years (range, 3.8-21.8) received passive-scattered proton therapy for nonmetastatic chordoma. No patient received prior irradiation. Twenty-four tumors arose in the clivus/cervical spine region and 5 in the lumbosacral spine. Twenty-six tumors demonstrated classic well-differentiated histology and 3 were dedifferentiated or not otherwise specified. Approximately half of the tumors underwent specialized testing: 14 were brachyury-positive and 10 retained INI-1. Three patients had locally recurrent tumors after surgery alone (n = 2) or surgery + chemotherapy (n = 1), and 17 patients had gross disease at the time of radiation. The median radiation dose was 73.8 Gy relative biological effectivness (range, 69-75.6).

RESULTS

With a median follow-up of 4.3 years (range, 1.0-10.7), the 5-year estimates of local control, progression-free survival, and overall survival rates were 85%, 82%, and 86%, respectively. No disease progression was observed beyond 3 years. Excluding 3 patients with dedifferentiated/not-otherwise-specified chordoma, the 5-year local control, progression-free survival, and overall survival rates were 92%, 92%, and 91%, respectively. Serious toxicities included 3 patients with hardware failure or related infection requiring revision surgery, 2 patients with hormone deficiency, and 2 patients with Eustachian tube dysfunction causing chronic otitis media. No patient experienced brain stem injury, myelopathy, vision loss, or hearing loss after radiation.

CONCLUSIONS

In pediatric patients with chordoma, proton therapy is associated with a low risk of serious toxicity and high efficacy, particularly in well-differentiated tumors. Complete resection may be unnecessary for local control, and destabilizing operations requiring instrumentation may result in additional complications after therapy.

Clival Chordoma in an Adolescent: A Perspective from Primary Care

Clival chordoma is a rare malignant tumor of the brain that typically occurs in older adults. It has a high local recurrence rate and is hence associated with poor prognosis. Here, we report a case of an adolescent who presented with a 1-month history of worsening headache and blurring of vision, as well as a 6-month history of left-sided facial and body numbness. Clinical findings were consistent with left upper motor neuron lesion of the seventh cranial nerve with involvement of the fifth cranial nerve. He was also found to have a sixth cranial nerve palsy demonstrated by diplopia upon lateral gaze with no evidence of papilledema. Magnetic resonance imaging of the brain suggested clival chordoma. He was subsequently referred to the neurosurgical team, and he successfully underwent an endoscopic trans-sphenoidal surgery to excise the lesion. He recovered well, continued his follow-ups with the neurosurgical team, and showed good progress. He also attended regular follow-ups with his primary care physician to ensure ongoing psychosocial support and monitoring of his overall health status. This case demonstrates the importance of prompt identification and treatment of clival chordoma in an adolescent. Long-term follow-ups and shared care between primary and secondary care physicians are essential to monitor recurrence of tumor and to provide psychosocial support.

Immunomodulatory Effects of Radiotherapy

Radiation therapy (RT), an integral component of curative treatment for many malignancies, can be administered via an increasing array of techniques. In this review, we summarize the properties and application of different types of RT, specifically, conventional therapy with x-rays, stereotactic body RT, and proton and carbon particle therapies. We highlight how low-linear energy transfer (LET) radiation induces simple DNA lesions that are efficiently repaired by cells, whereas high-LET radiation causes complex DNA lesions that are difficult to repair and that ultimately enhance cancer cell killing. Additionally, we discuss the immunogenicity of radiation-induced tumor death, elucidate the molecular mechanisms by which radiation mounts innate and adaptive immune responses and explore strategies by which we can increase the efficacy of these mechanisms. Understanding the mechanisms by which RT modulates immune signaling and the key players involved in modulating the RT-mediated immune response will help to improve therapeutic efficacy and to identify novel immunomodulatory drugs that will benefit cancer patients undergoing targeted RT.

Dedifferentiated Chordoma: Clinicopathologic and Molecular Characteristics With Integrative Analysis

Dedifferentiated chordoma is a rare chordoma subtype characterized by a high-grade sarcoma juxtaposed to conventional chordoma. We identified a series of dedifferentiated chordomas, reviewed clinicopathologic features, performed next-generation sequencing in select cases, and analyzed all related English-language publications. Our series included 7 men and 3 women (age 15 to 80 y [median: 54 y]; <1% of >1000 chordomas surveyed). The tumor (2.8 to 24.5 cm [median: 5.8 cm] in size) presented de novo or as recurrence (including postradiotherapy) in sacrum (n=5), skull base (n=2), lumbar spine (n=1), thoracic/mediastinum (n=1), and lung (n=1; as metastasis). Histologically, the dedifferentiated component (3% to 95% [median: 60%]) was pleomorphic-to-fibrosarcomatous, juxtaposed to conventional (n=8) or chondroid (n=2) component. By immunohistochemistry, the conventional/chondroid component consistently expressed cytokeratin and brachyury, whereas the dedifferentiated component showed loss of both. We identified a sacral conventional chordoma with INI1 loss, with one of the lung metastases showing biphasic histology with loss of cytokeratin and brachyury in the dedifferentiated component. Sequencing identified tumor suppressor mutations in 4 tumors, including TP53 mutations in the dedifferentiated component in 3 tumors. Of 7 patients with follow-up, 6 developed metastases; 4 died at 15 to 99 months (median: 24 mo) after dedifferentiated chordoma diagnosis. Collectively, of 87 dedifferentiated chordoma patients described in 1913-2020 (including 10 herein), the median overall survival was 20 months. In summary, dedifferentiated chordoma involves diverse sites and presents de novo, postradiotherapy, or as recurrence/metastasis months-to-years after initial diagnosis. The dedifferentiated component shows loss of brachyury and cytokeratin staining and harbors recurrent TP53 mutations, implicating tumor suppressor dysregulation in chordoma dedifferentiation.

Poorly differentiated chordoma with whole-genome doubling evolving from a SMARCB1-deficient conventional chordoma: A case report

Evolution of poorly differentiated chordoma from conventional chordoma has not been previously reported. We encountered a case of a poorly differentiated chordoma with evidence of whole-genome doubling arising from a SMARCB1-deficient conventional chordoma. The tumor presented as a destructive sacral mass in a 43-year-old man and was comprised of a highly cellular poorly differentiated chordoma with small, morphologically distinct nodules of conventional chordoma accounting for <5% of the total tumor volume. Immunohistochemistry (IHC) revealed both components were strongly reactive for brachyury and lacked normal staining for INI1. Single nucleotide polymorphism (SNP) array analysis identified multiple genomic imbalances in the conventional component, including deletions of 1p, 3p, and 22q (involving SMARCB1) and loss of chromosomes 5 and 15, while the poorly differentiated component exhibited the same aberrations at a more profound level with additional loss of chromosome 4, low level focal deletion of 17p (involving TP53), and tetraploidy. Homozygous deletion of SMARCB1 was present in both components. Fluorescence in situ hybridization (FISH) analysis confirmed the relevant deletions in both components as well as genome doubling in the poorly differentiated tumor. This case suggests that SMARCB1 loss is an early event in rare conventional chordomas that could potentially evolve into poorly differentiated chordoma through additional genomic aberrations such as genome doubling. Further studies with additional patients will be needed to determine if genome doubling is a consistent pathway for evolution of poorly differentiated chordoma.

SWI/SNF complex-deficient soft tissue neoplasms: An update

The SWItch Sucrose Non-Fermentable (SWI/SNF) chromatin remodeling complex is a large multi-subunit protein assembly that orchestrates chromatin compaction and accessibility for gene transcription in an ATP-dependent manner. As a key epigenetic regulator, the SWI/SNF complex coordinates gene expression, cell proliferation and differentiation, and its biologic functions, in part, antagonize the polycomb repressive complex 2. The mammalian SWI/SNF complex consists of 15 subunits encoded by 29 genes, some of which are recurrently mutated in human cancers, in the germline or sporadic setting. Most SWI/SNF-deficient tumors share common "rhabdoid" cytomorphology. SMARCB1 (INI1) is the subunit most frequently inactivated in soft tissue neoplasms. Specifically, SMARCB1 deficiency is observed as the genetic hallmark in virtually all malignant rhabdoid tumors, and most cases of epithelioid sarcoma and poorly differentiated chordoma. In addition, subsets of myoepithelial carcinoma (10-40%), extraskeletal myxoid chondrosarcoma (20%), epithelioid schwannoma (40%), and epithelioid malignant peripheral nerve sheath tumor (70%) demonstrate SMARCB1 loss. The gene encoding the SS18 subunit is involved in the SS18-SSX rearrangement, which is pathognomonic of synovial sarcoma and indirectly inactivates SMARCB1. Finally, undifferentiated SMARCA4-deficient thoracic sarcomas are defined by SMARCA4 subunit inactivation, leading to SMARCA4 and SMARCA2 loss. Rarely, inactivation of alternate but biologically equivalent key regulators can substitute for canonical subunit deficiency, such as SMARCA4 inactivation in cases of SMARCB1-retained epithelioid sarcoma. This review briefly highlights SWI/SNF complex biologic functions and its roles in human cancer and provides a detailed update on recent advances in soft tissue neoplasms with canonical SWI/SNF complex deficiency, correlating morphologic, genomic, and immunohistochemical findings.

Beyond the brain: Extra-axial pathology on diffusion weighted imaging in neuroimaging

Diffusion-weighted imaging (DWI) has a central role in the assessment of the brain parenchyma, particularly in the context of acute stroke. However, the applications of DWI extend far beyond the brain parenchyma and include the assessment of the extra-axial structures of the head and neck that are included in routine brain imaging. In this pictorial review, the added-value of DWI over other conventional sequences is illustrated through discussion of a broad range of disorders affecting the vasculature, skull, orbits, nasal cavity and salivary glands. This article highlights the requirement for all structures, both intra- and extra-axial, to be carefully reviewed on DWI.

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.

Skull Base Chordomas and Chondrosarcomas

Skull base chordomas account for less than 0.2% and chondrosarcomas for less than 0.15% of all intracranial tumors. Although their clinical and imaging presentations are similar, they derive from different origins. Chordomas arise from embryonic remnants of the primitive notochord and chondrosarcomas from primitive mesenchymal cells or from the embryonic rest of the cranial cartilaginous matrix. Both entities are characterized by infiltration and destruction of the surrounding bone and soft tissue and a high locoregional recurrence rate. Chondrosarcomas, when treated with similar complex strategies, display a much better prognosis than chordomas. The overall survival is approximately 65% for chordomas and 80% for chondrosarcomas at 5 years and 30 and 50%, respectively, at 10 years. Chordomas are divided into the following 3 histological types: classical (conventional), chondroid, and dedifferentiated. Chondrosarcomas have conventional, mesenchymal, clear cell, and dedifferentiated subgroups. Both tumor entities often present with nonspecific symptoms, and headaches are the most reported initial symptom. Computed tomography and magnetic resonance imaging are required to determine the tumor localization and the extent of tumor growth. The treatment philosophy is to maximize tumor resection, minimize morbidity, and preserve function. Neurosurgical approaches commonly used for the resection of intracranial chordomas and chondrosarcomas are transsphenoidal, transbasal, cranio-orbitozygomatic, transzygomatic extended middle fossa, transcondylar, and transmaxillary approaches. Chordomas and chondrosarcomas are not sensitive to chemotherapy and there are no approved drugs for their treatment. The present treatment concept is a combination of surgical resection with a maximal excision and preserving patients' quality of life by adjuvant radiotherapy for both chordomas and chondrosarcomas.

Metastatic poorly differentiated chordoma: the eyes do not see what the mind does not know

Chordoma is a rare tumor. It has unique clinical, pathological and immunohistochemical characteristics. Accurate diagnosis is essential as the tumor shows an aggressive clinical course and requires a multimodal therapeutic approach. A case with wide spread distant metastatic disease that was initially thought to represent metastatic thyroid carcinoma is presented. Appropriate clincopathologic correlation and the histologic findings raised the possibility of poorly differentiated chordoma. The diagnosis was confirmed by immunohistochemistry for INI-1 and Brachyury. The approach to the diagnosis emphasizing the clinical and pathologic findings of this case is discussed and reviewed in the context of the published literature.

Treatment of dedifferentiated chordoma: a retrospective study from a large volume cancer center

OBJECTIVE

Dedifferentiated chordomas (DC) are genetically and clinically distinct from conventional chordomas (CC), exhibiting frequent SMARCB1 alterations and a more aggressive clinical course. We compared treatment and outcomes of DC and CC patients in a retrospective cohort study from a single, large-volume cancer center.

METHODS

Overall, 11 DC patients were identified from 1994 to 2017 along with a cohort of 68 historical control patients with CC treated during the same time frame. Clinical variables and outcomes were collected from the medical record and Wilcoxon rank sum or Fisher exact tests were used to make comparisons between the two groups. Kaplan-Meier survival analysis and log-rank tests were used to compare DC and CC overall survival.

RESULTS

DC demonstrated a bimodal age distribution at presentation (36% age 0-24; 64% age > 50). DC patients more commonly presented with metastatic disease than CC patients (36% vs. 3% p = 0.000). DC patients had significantly shorter time to local treatment failure after radiation therapy (11.1 months vs. 34.1 months, p = 0.000). The rate of distant metastasis following treatment was significantly higher in DC compared to CC (57% vs. 5%, p = 0.000). The median overall survival after diagnosis for DC was 20 months (95% CI 0-48 months) compared to 155 months (95% CI 94-216 months) for CC (p = 0.007).

CONCLUSION

DC patients exhibit significantly higher rates of both synchronous and metachronous metastases, as well as shorter overall survival rates compared to conventional chordoma. The relatively poor survival outcomes with conventional therapies indicate the need to study targeted therapies for the treatment of DC.

[Pathological and molecular features of malignancies underlined by BAF complexes inactivation]

BAF complexes are chromatin remodelling complexes made up of 15 subunits which overview transcription regulation. A subset of their subunits are notoriously linked to cancer, with the examples of SMARCB1, SMARCA4, ARID1A/1B and PBRM1. The complexes act as tumor suppressor genes, commonly mutated in a wide array of malignancies with an overrepresentation of sarcomas and tumors of the central nervous system. The recurrent inactivation of their genes points towards their driving role in the tumorigenesis of SMARCB1 in malignant rhabdoid tumors and SMARCA4 in small cell carcinoma of the ovary, hypercalcemic type. These tumors are morphologically similar composed of solid sheets of cells displaying vesicular nuclei dotted with clear chromatin and conspicuous nucleoli. Genomically, they share simple diploid profiles with no other alterations than in the culprit gene. Other mesenchymal tumors, distinct from malignant rhabdoid tumors are associated with BAF alterations, namely epithelioid sarcomas, SMARCA4-deficient thoracic sarcomas. BAF subunits are mostly inactivated through mutations or deletions but also occur through translocations in medullary carcinoma of the kidney and synovial sarcomas. Apart from tumors displaying recurrent alterations of the complexes, some variants or tumor variants display BAF alterations, including epithelioid malignant peripheral nerve sheet tumors and poorly differentiated chordomas. Lastly, some malignancies display low frequency of BAF alterations, in keeping with their passenger role in tumorigenesis with the example of dedifferentiated carcinomas, especially in colon, lung and uterus. BAF complexes alterations correlate with morphological features recognizable by microscopy, paving the way for their routine diagnosis and potential therapeutic prospects.

Molecular characteristics of poorly differentiated chordoma

Pediatric poorly differentiated chordoma is a subtype of chordoma with a much more aggressive clinical course and has been characterized by loss of SMARCB1. This study characterizes the molecular features of these tumors in comparison to conventional chordoma. A search of records between 1990 and 2017 at Massachusetts General Hospital identified two patients with sufficient excess tissue for molecular analysis and a third patient diagnosed with a highly cellular conventional chordoma. The three tumors were sent for array comparative genomic hybridization for genome-wide copy number variants; multiplex PCR for single-nucleotide variants; and RNA-sequencing for fusions. Poorly differentiated chordoma showed chromosome 22q loss, including SMARCB1, with no identifiable mutations on multiplex PCR. The cellular conventional chordoma showed a complex pattern of chromosomal gains and losses involving 12 chromosomes, and an RB1 mutation at low allelic frequency. RNA-Seq identified no disease-defining gene fusion events. Poorly differentiated chordoma appears to represent a distinct type of tumor that is genetically unrelated to conventional chordoma. Recognition of this subtype is important because these malignancies should be treated aggressively with multimodality therapy, and possibly targeted therapy.

Pediatric extraosseous sacral chordoma: case report and literature review of embryonic derivation and clinical implications

An extraosseous intradural presentation for a sacral chordoma in the pediatric age group has not been reported to date. This is a report on an 11-year-old boy who presented with an extraosseous, intradural sacral chordoma. He underwent gross-total resection and received adjuvant proton beam therapy. Neoplastic transformation of the notochord is reviewed to illustrate the developmental basis for the surgical anatomy and pathogenesis of the classic chordoma variant. Clinical and pathological features are reviewed to differentiate this chordoma presentation from classic osseous chordomas and ecchordosis physaliphora, a related benign developmental notochordal lesion. Finally, the role of developmental signaling in the pathogenesis of chordomas from postembryonic notochordal tissue is discussed.

Proton therapy for skull base tumors: A review of clinical outcomes for chordomas and chondrosarcomas

BACKGROUND

Skull base chordomas and chondrosarcomas are rare tumors traditionally treated by surgical resection and adjuvant radiation therapy (RT). We will discuss data evaluating clinical outcomes of proton therapy in the treatment of skull base chordomas and chondrosarcomas.

METHODS

A literature review was performed using a MEDLINE search from January 1990 to January 2017.

RESULTS

The published data suggest that the dose intensification allowed by proton therapy has resulted in good clinical outcomes and a tolerable toxicity profile.

CONCLUSION

Proton therapy is a modern RT technique that has demonstrated improved preliminary clinical outcomes in the treatment of skull base chordomas and chondrosarcomas compared to conventional radiotherapy, and comparable to other advanced photon-based RT techniques.

Clinicopathologic characteristics of poorly differentiated chordoma

Chordoma is a rare malignant tumor of bone with high morbidity and mortality. Recently, aggressive pediatric poorly differentiated chordoma with SMARCB1 loss has been described. This study summarizes the clinicopathologic features of poorly differentiated chordoma with SMARCB1 loss in the largest series to date. A search of records between 1990-2017 at MGH identified 19 patients with poorly differentiated chordoma. Immunohistochemical stains were evaluated. Kaplan-Meier survival statistics and log-rank (Mantel Cox) tests compared survival with other subtypes. The patients (n = 19) were diagnosed at a median age of 11 years (range: 1-29). Tumors arose in the skull base and clivus (n = 10/19; 53%); cervical spine (n = 6/19; 32%); and sacrum or coccyx (n = 3/19; 16%). The clinical stage of these patients (AJCC 7e) was stage 2A (n = 7/16; 44%); stage 2B (n = 6/16; 38%); stage 4A (n = 1/16; 6%); and stage 4B (n = 2/16; 13%). The tumors were composed of sheets of epithelioid cells with nuclear pleomorphism, abundant eosinophilic cytoplasm, and increased mitoses. Tumors were positive for cytokeratin (n = 18/18; 100%) and brachyury (n = 18/18; 100%). Patients were treated with a combination of excision, radiation therapy, and chemotherapy. No difference in overall survival, progression free survival, local control time, and metastasis free survival was identified between poorly differentiated chordoma of the skull base and of the spine. Compared to other chordoma subtypes, poorly differentiated chordoma has a significantly decreased mean overall survival after stratification by site (p = 0.037). Pediatric poorly differentiated chordoma has a distinct clinical and immunohistochemical profile, with characteristic SMARCB1 loss and decreased survival compared to conventional/chondroid chordoma. Recognition of this subtype is important because these malignancies should be treated aggressively with multimodality therapy.

Proton therapy for pediatric malignancies: Fact, figures and costs. A joint consensus statement from the pediatric subcommittee of PTCOG, PROS and EPTN

Radiotherapy plays an important role in the management of childhood cancer, with the primary aim of achieving the highest likelihood of cure with the lowest risk of radiation-induced morbidity. Proton therapy (PT) provides an undisputable advantage by reducing the radiation 'bath' dose delivered to non-target structures/volume while optimally covering the tumor with tumoricidal dose. This treatment modality comes, however, with an additional costs compared to conventional radiotherapy that could put substantial financial pressure to the health care systems with societal implications. In this review we assess the data available to the oncology community of PT delivered to children with cancer, discuss on the urgency to develop high-quality data. Additionally, we look at the advantage of combining systemic agents with protons and look at the cost-effectiveness data published so far.

Evidence-Based Optimization of Post-Treatment Surveillance for Skull Base Chordomas Based on Local and Distant Disease Progression

BACKGROUND

There are no guidelines regarding post-treatment surveillance specific to skull base chordomas.

OBJECTIVE

To determine an optimal imaging surveillance schedule to detect both local and distant metastatic skull base chordoma recurrences.

METHODS

A retrospective review of 91 patients who underwent treatment for skull base chordoma between 1993 and 2017 was conducted. Time to and location of local and distant recurrence(s) were cataloged. Existing chordoma surveillance recommendations (National Comprehensive Cancer Network [NCCN], London and South East Sarcoma Network [LSESN], European Society for Medical Oncology [ESMO], Chordoma Global Consensus Group [CGCG]) were applied to our cohort to compare the number of recurrent patients and months of undiagnosed tumor growth between surveillances. These findings were used to inform the creation of a revised imaging surveillance protocol (MD Anderson Cancer Center Chordoma Imaging Protocol [MDACC-CIP]), presented here.

RESULTS

Thirty-four patients with 79 local/systemic recurrences met inclusion criteria. Mean age at diagnosis and follow-up time were 45 yr and 79 mo, respectively. The MDACC-CIP imaging protocol significantly reduced the time to diagnosis of recurrence compared with the LSESN and CGCG/ESMO imaging protocols for surveillance of local disease with a cumulative/average of 576/16.9 (LSESN), 336/9.8 (CGCG), and 170/5.0 (MDACC-CIP) months of undetected growth, respectively. The NCCN and MDACC-CIP guidelines for distant metastatic surveillance identified a cumulative/average of 65/6.5 and 51/5.1 mo of undetected growth, respectively, and were not significantly different.

CONCLUSION

The MDACC-CIP for skull base chordoma accounts for recurrence trends unique to this disease, including a higher rate of leptomeningeal spread than sacrococcygeal primaries, resulting in improved sensitivity and prompt diagnosis.