Ewing sarcoma

Ewing sarcoma of the mandible: A rare case report and literature review

Ewing sarcoma (ES) usually arises from long bones and affects the head and neck region in only 1%-4% of cases. We reported clinical, radiographic, cytomorphologic, and histomorphologic findings of the ES in the mandible, because of its rarity and radiologically misinterpreted as a parotid gland tumor. A 26-year-old male patient presented with a history of painfull cheek swelling. On magnetic resonance imaging, a mass measuring 50 × 48 × 45 mm was found eroding mandible and pushing back the parotid gland. Aspiration cytology was performed with suspicion of parotid gland tumor. Small, nucleated cells with nuclear indentation, inconspicuous nucleoli, and occasionally rosette-like arrangement were observed. Neuroendocrine immune markers were positive on cell block. It was diagnosed as small round cell neoplasm with neuroendocrine differentiation and biopsy was suggested. The differential diagnosis considered soft tissue and parotid gland tumors. The small round cell tumor morphology was seen on biopsy specimen and immunostaining was applied. The diagnosis for this case was ES of the mandible. ES of the mandible is unusual. Although the histogenesis is still unknown, various cells have been proposed as cells of origin namely, endothelial, hematopoietic, fibroblastic, mesenchymal stem cells or neural derived mesenchymal stem cells. Small cell morphology, CD99, CD56, neuron specific enolase, and synaptophysin expressions confirmed the diagnosis of ES. The differentiation of the ES from other small cell tumors may be difficult and requires awareness for histological and immunohistochemical features. It should be kept in mind that the diagnosis can be challenging due to uncommon locations and radiological misinterpreted.

Proximal femur alloprosthesis in a pediatric patient with Ewing sarcoma: Case report

INTRODUCTION AND IMPORTANCE

Ewing sarcoma is a primary malignant tumor of bone and, to a lesser extent, soft tissues. Within oncological management, surgery with extensive local control and reconstruction is the most accepted option, however, the size, extension of the tumor, the age of the patient and distant involvement can make this option difficult.

CASE PRESENTATION

We present a clinical case of a 3-year-old infant with Ewing sarcoma in the proximal femur, who was managed with wide resection of the tumor plus proximal humerus allograft, which acted as a proximal femur for 2 years and then presented joint failure due to what was done was the application of a cemented stem over the remnant of the allograft to save the hip.

CLINICAL DISCUSSION

In the presented case, similar to the report by Zoccali a malignant tumor in the proximal femur of a pediatric patient is documented. In these cases, where the distal femoral growth plate is disease-free, a reconstruction technique preserving the growth plate is proposed.

CONCLUSION

The technique of proximal femoral allograft with a proximal humeral graft is an acceptable reconstructive treatment alternative for young patients with Ewing sarcoma, especially when conventional treatment options are limited. This approach helps avoid limb-threatening surgeries such as amputation or rotationplasty, providing a viable and functional solution for limb salvage in these cases.

Extraskeletal Ewing Sarcoma of the Gastrointestinal and Hepatobiliary Tract: Deceptive Immunophenotype Commonly Leads to Misdiagnosis

Ewing sarcoma (ES) is an uncommon mesenchymal neoplasm that typically develops as a bone mass, although up to 30% arise in extraskeletal sites. ES of the gastrointestinal (GI) and hepatobiliary tract is rare and may be misdiagnosed as other, more common neoplasms that occur in these sites. However, the correct classification of extraskeletal ES is important for timely clinical management and prognostication. We reviewed our experience of ES in the GI and hepatobiliary tract in order to further highlight the clinicopathologic features of these neoplasms and document the potential for misdiagnosis in this setting. The archives and consultation files of 6 academic institutions were retrospectively queried for cases of ES occurring in the GI and hepatobiliary tract. The histologic slides and ancillary studies were reviewed and clinical data were retrieved for each case through the electronic medical records, when available. Twenty-three patients with ES in the GI and/or hepatobiliary tract were identified from 2000 to 2022. Of these, 11 were women and 12 were men with a median age of 38 years (range, 2 to 64). Tumor locations included the pancreas (n=5), liver (n=2), stomach (n=3), colorectum (n=3), and small intestine (n=5), as well as tumors involving multiple organs, pelvis and retroperitoneum (n=5). Tumor size varied between 2 cm and 18 cm. Twenty were primary and 3 were metastases. Of the 23 cases, only 17% were initially diagnosed as ES. The most common misdiagnoses involved various forms of neuroendocrine neoplasia due to expression of synaptophysin and other neuroendocrine markers (22%). A wide variety of diagnoses including GI stromal tumor was considered due to aberrant CD117 expression (4%). The diagnosis of ES was ultimately confirmed by detection of the EWSR1 rearrangement in 22 cases. The remaining case was diagnosed using traditional immunohistochemistry. Follow-up information was available in 20 cases, with follow-up time varying between 2 and 256 months. Six patients with follow-up died of disease between 6 and 60 months following initial presentation. Our data indicate ES in the GI and hepatobiliary tract is commonly misdiagnosed leading to a delay in therapy. In light of the attendant therapeutic and prognostic implications, ES should be considered in the differential diagnosis of any GI or hepatobiliary tumor with epithelioid and/or small round cell morphology.

Ewing sarcoma with intra thoracic and multiple extra thoracic metastases in a young adult male: A case report

INTRODUCTION

Primary chest wall tumors arise from muscle, fat, blood vessels, the nerve sheath, cartilage, or bone of the chest wall. One of the chest wall sarcomas is Ewing Sarcoma (ES), first described in 1921 by James Ewing, which is a highly aggressive bone and soft-tissue cancer. This case report aimed to present an Ewing Sarcoma with intra thoracic and multiple extra thoracic metastases in young adult male patient.

PRESENTATION OF CASE

We describe a unique case of metastatic of ewing's sarcoma in a 23-year-old male that showed a mass on the right lower posterior lung with pleural effusion, which was initially thought to be lung tumor that metastasized to the pleura. A thoracic CT scan showed a lobulated soft tissue mass on the right posterolateral thoracic wall, or pleura, with an expansion of soft tissue mass on the rib. Thoracal MRI showed tumor in the posterior right lower thoracic wall area, metastases of the left lateral rib, and right pleural effusion with atelectasis in the right inferior lobe of the lung. The patient also underwent a bone scan, scheduled for palliative radiotherapy and chemotherapy, and consulted to oncology surgeon.

DISCUSSION

Ewing sarcoma is a small, round, blue-cell mesenchymal malignancy. ES mainly affects children, adolescents, and young adults, with >1.5 cases per million children. Males are slightly more affected than females (sex ratio of 3:2). The definitive diagnosis requires biopsy proof (achieved by fine needle or core biopsy). The most common regions of metastasis are the lungs, pleural cavity, skeletal system, bone marrow, or combinations of these.

CONCLUSION

The 5-year survival rate is approximately 70 % when there is no metastasis; this rate falls to around 30 % when metastasis is present.

Malignant tumour in pregnancy: Ewing-like sarcoma of the gluteal region

We report a case of an Ewing-like sarcoma of the gluteal region with ongoing growth during the second trimester of pregnancy and noted during the third trimester. This lesion was consequently studied to infer its malignant potential. Several examinations were conducted to characterise this lesion, such as ultrasound and MR, which showed signs of tumourous invasion of the deep tissues of the gluteal region.Given that the pregnancy was at the end of the third trimester, the decision was made to schedule the delivery at 37 weeks of gestation and treat the tumour afterwards to balance maternal and fetal health.This case illustrates the need for a detailed investigation and guidance by a multidisciplinary team to provide prenatal counselling regarding a malignant tumour during pregnancy.

Gastrointestinal Ewing Sarcoma: A Clinicopathological and Molecular Genetic Analysis of 25 Cases

Occurrence of extraskeletal Ewing sarcoma (ES) in the gastrointestinal (GI) tract is extremely rare. Here, we report 25 cases of ES arising primarily in the GI tract with a focus on the clinicopathological and molecular features, differential diagnosis, and biological behavior. Thirteen patients (52%) were male, and 12 (48%) were female with age ranging from 9 to 59 years (mean: 36.2 years; median: 38 years). Twenty-one tumors (84%) occurred in the small intestine, 3 (12%) in the stomach, and 1 (4%) in the anal canal. At operation, 8/18 (44.4%) patients presented with abdominopelvic disseminated disease. Tumor size measured from 2 to 25 cm (mean: 8.2 cm; median: 6 cm) in maximum size. Microscopically, the tumors were composed of infiltrative small round, ovoid, or short spindle cells arranged mostly in lobular and solid sheet-like patterns with a rich capillary vasculature. Focal formation of Homer Wright-type rosettes and pseudoalveolar architecture was noted each in 2 (8%) cases and 3 (12%) cases. Besides CD99 (25/25; 100%), Fli-1 (15/15, 100%), and NKX2.2 (14/16; 87.5%), the tumor cells also showed variable staining of CD117 (14/17; 82.4%). Of 25 cases, 23 (92%) demonstrated EWSR1 rearrangement by fluorescence in situ hybridization analysis. The 2 cases with negative fluorescence in situ hybridization results were found to harbor EWSR1::ERG and EWSR1::FLI1 fusion by further RNA sequencing, respectively, with a median follow-up of 12 months (range: 1 to 42 months), 5/19 (26.3%) patients developed visceral metastasis and 12/19 (63.2%) patients died of the disease (range:1 to 33 months; median: 9 months). This study showed that GI ES had a predilection for the small intestine, although other sites of the GI tract could also be involved. GI ES had a poor prognosis with a high rate of mortality, particularly in patients with abdominopelvic disseminated disease. In light of appropriate therapeutic strategies and prognostic considerations, it is essential not to misdiagnose GI ES as gastrointestinal stromal tumor owing to the expression of aberrant CD117.

Glycolysis-Metabolism-Related Prognostic Signature for Ewing Sarcoma Patients

Ewing sarcoma (EwS) is a malignant sarcoma which occurs in bone and soft tissues commonly happening in children with poor survival rates. Changes in cell metabolism, such as glycolysis, may provide the environment for the transformation and progression of tumors. We aimed to build a model to predict prognosis of EwS patients based on glycolysis and metabolism genes. Candidate genes were obtained by differential gene expression analysis based on GSE17679, GSE17674 and ICGC datasets. We performed GO and KEGG pathway enrichment analysis on candidate genes. Univariate Cox and LASSO Cox regression analyses were conducted to construct a model to calculate the Risk Score. GSEA was done between high-risk and low-risk groups. CIBERSORT was applied to analyze the immune landscape. We got 295 candidate glycolysis-metabolism-related genes which were enriched in 620 GO terms and 18 KEGG pathways. 12 Genes were selected by univariate Cox model and 5 of them were determined by LASSO Cox regression analysis to be used in the construction of the Risk Score model. The Risk Score could be considered as an independent prognosis factor. The immune landscape and immune checkpoints' expression significantly differed between high- and low-risk groups. Our research constructed a new glycolysis-metabolism-related genes (FABP5, EMILIN1, GLCE, PHF11 and PALM3) based prognostic signature for EwS patients and assisted in gaining insight into prognosis to improve therapies further.

Drop metastasis from the extradural to the intradural space in spinal Ewing's sarcoma - a novel case report

Spinal Ewing's Sarcoma is a rare tumour predominantly affecting children and adolescents. We describe the case of an 18-year-old male patient who first presented with a primary extradural cervical Ewing's sarcoma tumour, and 5 years later had a recurrence with thoracolumbar and lumbosacral intradural extramedullary Ewing's sarcoma tumours. Both presentations were successfully treated by surgical resection and adjuvant chemo- and radiotherapy, and he remains disease-free at 12 months follow-up. This is the first reported case of seeding of tumour from an extradural primary Ewing's sarcoma to intradural metastases. Total surgical resection of his initial cervical tumour, performed at another centre, was complicated by a dural tear and CSF leak. Thus, we propose that isolated drop metastasis via CSF fistula is the most likely mechanism for tumour spread in this case. Thus, clinicians may wish to counsel patients on the possibility of such spread if a CSF leak is encountered, and potentially increase the frequency of imaging surveillance of the whole spine in this context.

Recognizing and treating patients with Ewing sarcoma

ABSTRACT

This article reviews the cause, presentation, diagnosis, and management of Ewing sarcoma, the second most common primary bone malignancy in children and young adults. Recent research has provided advances in understanding the cause of Ewing sarcoma as well as improved treatment regimens. However, much is still unknown and additional research is needed to continue to improve the overall prognosis, which ranges from 70% to 80% 5-year survival for patients with localized disease. Improving clinician knowledge about Ewing sarcoma will help shorten time to diagnosis and improve survival rates.

CD43-positive, EWSR1::FLI1 -rearranged Soft Tissue Sarcoma in a Pediatric Patient With History of B-Cell Acute Lymphoblastic Leukemia

Ewing sarcoma is a small round blue cell tumor typically characterized by an EWSR1 rearrangement and expression of CD99 and NKX2.2, without expression of hematopoietic markers such as CD45. CD43 is an alternative hematopoietic immunohistochemical marker often utilized in the workup of these tumors and its expression typically argues against Ewing sarcoma. We report a 10-year-old with history of B-cell acute lymphoblastic leukemia presenting with an unusual malignant shoulder mass with variable CD43 positivity, but with an EWSR1::FLI1 fusion detected by RNA sequencing. Her challenging workup highlights the utility of next-generation DNA-based and RNA-based sequencing methods in cases with unclear or conflicting immunohistochemical results.

Identification of small extracellular vesicle protein biomarkers for pediatric Ewing Sarcoma

Ewing Sarcoma (EWS) is the second most common osseous malignancy in children and young adults after osteosarcoma, while it is the fifth common osseous malignancy within adult age population. The clinical presentation of EWS is quite often non-specific, with the most common symptoms at presentation consisting of pain, swelling or general discomfort. The dearth of clinically relevant diagnostic or predictive biomarkers continues to remain a pressing clinical challenge. Identification of tumor specific biomarkers can lend towards an early diagnosis, expedited initiation of therapy, monitoring of therapeutic response, and early detection of recurrence of disease. We carried-out a complex analysis of cell lines and cell line derived small extracellular vesicles (sEVs) using label-free-based Quantitative Proteomic Profiling with an intent to determine shared and distinct features of these tumor cells and their respective sEVs. We analyzed EWS cells with different EWS-ETS fusions (EWS-FLI1 type I, II, and III and EWS-ERG) and their corresponding sEVs. Non-EWS controls included osteosarcoma, rhabdomyosarcoma, and benign cells, i.e., osteoid osteoma and mesenchymal stem cells. Proteomic profiling identified new shared markers between cells and their corresponding cell-derived sEVs and markers which were exclusively enriched in EWS-derived sEVs. These exo-biomarkers identified were validated by in silico approaches of publicly available protein databases and by capillary electrophoresis based western analysis (Wes). Here, we identified a protein biomarker named UGT3A2 and found its expression highly specific to EWS cells and their sEVs compared to control samples. Clinical validation of UGT3A2 expression in patient tumor tissues and plasma derived sEV samples demonstrated its specificity to EWS, indicating its potential as a EWS biomarker.

Highlighting the Diversity of Desmoplastic Small Round Cell Tumor: A Case Series

Desmoplastic small round cell tumor (DSRCT) is a rare malignant tumor that occurs mainly in the retroperitoneum of children and young adults. In its prototypical form, DSCRT displays characteristic morphology with nested primitive small round cells in a desmoplastic stroma and a distinctive immunophenotype with polyphenotypic differentiation. However, DSCRT can also exhibit a broader clinical, histologic and immunohistochemical spectrum and, therefore, cause diagnostic difficulties. Given that DSCRT is an aggressive and nearly universally fatal disease, making the correct diagnosis is critically important. Herein, we report three patients with DSRCT and unusual clinical, morphologic or immunohistochemical characteristics, in order to highlight its remarkable diversity and increase awareness of this unusual, distinctive neoplasm.

Extraskeletal Ewing sarcoma of the sciatic nerve

Extraskeletal Ewing sarcoma (EES) is a rare tumor diagnosed in children or young adults and is even more unusual in individuals over 30 years of age. Due to its rare occurrence and low index of suspicion, this tumor can pose diagnostic and therapeutic challenges. We present a case of a 60-year-old male with EES of the sciatic nerve, an unexpected entity given the patient's age, tumor type, and tumor location. This can mimic a nerve sheath tumor on imaging.

Ewing's sarcoma masquerading as an odontogenic infection

ABSTRACT

Ewing's sarcoma (ES) is a small, blue, malignant, round cell tumor of unknown origin. ES is the fourth most common malignant bone tumor, whereas among children, it is found to be the second most common primary malignant bone tumor after osteosarcoma. Swelling is usually the first clinical presentation, followed by pain. ES is an aggressive tumor showing rapid growth and metastasis with complex diagnosis. Because mandibular involvement is rare, it can be misdiagnosed as an odontogenic infection/tumor. We report an unusual case of ES in a 13-year-old female treated for an odontogenic infection before a diagnosis of ES was finally made to make the clinicians aware of this rare entity. Emphasis is also given that ES and odontogenic infections/tumors can masquerade each other with delays in diagnosis and the possibility of devastating results.

Splicing-Disrupting Mutations in Inherited Predisposition to Solid Pediatric Cancer

The prevalence of hereditary cancer in children was estimated to be very low until recent studies suggested that at least 10% of pediatric cancer patients carry a germline mutation in a cancer predisposition gene. A significant proportion of pathogenic variants associated with an increased risk of hereditary cancer are variants affecting splicing. RNA splicing is an essential process involved in different cellular processes such as proliferation, survival, and differentiation, and alterations in this pathway have been implicated in many human cancers. Hereditary cancer genes are highly susceptible to splicing mutations, and among them there are several genes that may contribute to pediatric solid tumors when mutated in the germline. In this review, we have focused on the analysis of germline splicing-disrupting mutations found in pediatric solid tumors, as the discovery of pathogenic splice variants in pediatric cancer is a growing field for the development of personalized therapies. Therapies developed to correct aberrant splicing in cancer are also discussed as well as the options to improve the diagnostic yield based on the increase in the knowledge in splicing.

Unusual presentation of Ewing sarcoma; a case report and literature review

Introduction and importance

Ewing's sarcoma is an aggressive malignancy primarily affecting skeletal system in children and young adults.

Case presentation

We report an unusual case of Ewing sarcoma in a 14-year-old boy with clinical and radiological features of rapid onset metachronous skeletal metastasis (within 4 weeks of diagnosis).

Clinical discussion

Although the deterioration of symptoms was very rapid, it is unusual to note that in the presence of such widespread metastatic disease the lungs per se remained uninvolved.

Conclusion

We describe a unique case of metastatic Ewing's sarcoma who showed rapid systemic disease progression with widespread skeletal metastases (and CNS involvement) but without any evidence of pulmonary involvement.

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Ewing sarcoma is considered aggressive malignancy primarily affecting skeletal system.

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It is usually very slowly progressive in nature (years).

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This case presentation showed aggressiveness behavior with very unpredictable outcomes short period from diagnosis to metastasis.

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Up to our knowledge, this atypical and rapid disease progression (within a month of diagnosis) was not previously reported in literature.

Sacral Ewing sarcoma with rib, lung, and multifocal skull metastases: A rare case report and review of treatments

Ewing sarcoma (ES) rarely derives from the sacrum or mobile spine. The discovery of primary ES with multimetastatic involvements is exceedingly less frequent in clinical practice. A 23-year-old man with initial primary sacral ES developed metastases of rib, lung, and multifocal skull after receiving surgical intervention and series of adjuvant therapies. We provide this very rare case consisting of its clinical features, imaging findings, treatments, and outcomes. Therapeutic modalities of ES are also reviewed in previous published articles. The prognosis of metastatic ES remains dismal; effective therapeutic modalities for ES require multidisciplinary collaboration, with more high-quality clinical trials to promote the optimal protocols.

Molecular classification of soft tissue sarcomas for adequate diagnosis: A study on the northeast population of Morocco

Background

Soft tissue sarcomas (STS) are a heterogeneous group of tumors. For adequate therapeutic management, an accurate diagnosis is necessary. In Morocco, the diagnosis is essentially based on the morphological and immunohistochemical study. Compared to other techniques, fluorescence in situ hybridization (FISH) is easier to develop and less expensive. This study aims to assess the feasibility and utility of implementing FISH technique to improve diagnostic accuracy and establish a good classification.

Material and methods

This is a retrospective cohort study. 211 cases of mesenchymal tumors were included. Hematoxylin Eosin Safran (HES) staining was performed in all cases followed by immunohistochemistry (IHC). FISH was performed in all cases with suspected STS. The probes used were EWSR1, MDM2 and SS18. The performance of FISH and histopathological test were evaluated by the ROC curve method (receiver operating characteristic). We evaluated the concordance between FISH and real time PCR by Cohen test.

Results

The real-time PCR technique showed good agreement with the FISH test by a Kappa coefficient of 60% (p = 0.035). FISH was able to confirm that it is more accurate (Youden's Index = 91%) than histological/immunohistochemical analysis (Youden's Index = 51%), as well as the positive predictive value was higher (100%) with an ROC curve finding a larger area under the curve of 0.953 (95% CI: 0.918-0.988), p = 0.000 which supports that FISH shows high performance to present an accurate final diagnosis.

Conclusion

This is the first and the largest Moroccan series for the molecular diagnosis of STS by FISH. Our study shows that paraffin FISH is a sensitive and specific ancillary tool in the diagnosis of STS when used in the appropriate clinicopathological context.

Primary Ewing’s sarcoma of sphenoid sinus: A case report and literature review

Background

Primary Ewing’s sarcoma of sphenoid sinus, observed in children and adolescents, is an extremely rare malignancy. Such rarity makes the imaging features and treatment strategies for Ewing’s sarcoma of sphenoid sinus unclear. This study aimed to offer guidance for treating this very disease by describing a patient with a rare primary Ewing’s sarcoma of sphenoid sinus and reviewing the available data in the literature.

Case description

A case of Ewing’s sarcoma in sphenoid sinus treated with multidisciplinary treatment approaches, including tumor resection, radiotherapy, chemotherapy, and antiangiogenic therapy, was presented in this study. Moreover, literature for Ewing’s sarcoma in the head was systematically searched, and two cases in the sphenoid sinus and five cases in the sphenoid bone were identified. Furthermore, the clinical features, imaging findings, pathological characteristics, treatment, and prognosis were summarized.

Conclusion

Tumor resection combined with radiotherapy and chemotherapy may provide favorable results for patients with Ewing’s sarcoma of sphenoid sinus and bone. However, more reports are still necessary to further clarify optimal management.

Canonical Hedgehog Pathway and Noncanonical GLI Transcription Factor Activation in Cancer

The Hedgehog signaling pathway is one of the fundamental pathways required for development and regulation of postnatal regeneration in a variety of tissues. The pathway has also been associated with cancers since the identification of a mutation in one of its components, PTCH, as the cause of Basal Cell Nevus Syndrome, which is associated with several cancers. Our understanding of the pathway in tumorigenesis has expanded greatly since that initial discovery over two decades ago. The pathway has tumor-suppressive and oncogenic functions depending on the context of the cancer. Furthermore, noncanonical activation of GLI transcription factors has been reported in a number of tumor types. Here, we review the roles of canonical Hedgehog signaling pathway and noncanonical GLI activation in cancers, particularly epithelial cancers, and discuss an emerging concept of the distinct outcomes that these modes have on cancer initiation and progression.

Precision Medicine Highlights Dysregulation of the CDK4/6 Cell Cycle Regulatory Pathway in Pediatric, Adolescents and Young Adult Sarcomas

Simple Summary

This review provides an overview of clinical features and current therapies in children, adolescents, and young adults (AYA) with sarcoma. It highlights the basic and clinical findings on the cyclin-dependent kinases 4 and 6 (CDK4/6) cell cycle regulatory pathway in the context of the precision medicine-based molecular profiles of the three most common types of pediatric and AYA sarcomas—osteosarcoma (OS), rhabdomyosarcoma (RMS), and Ewing sarcoma (EWS).

Abstract

Despite improved therapeutic and clinical outcomes for patients with localized diseases, outcomes for pediatric and AYA sarcoma patients with high-grade or aggressive disease are still relatively poor. With advancements in next generation sequencing (NGS), precision medicine now provides a strategy to improve outcomes in patients with aggressive disease by identifying biomarkers of therapeutic sensitivity or resistance. The integration of NGS into clinical decision making not only increases the accuracy of diagnosis and prognosis, but also has the potential to identify effective and less toxic therapies for pediatric and AYA sarcomas. Genome and transcriptome profiling have detected dysregulation of the CDK4/6 cell cycle regulatory pathway in subpopulations of pediatric and AYA OS, RMS, and EWS. In these patients, the inhibition of CDK4/6 represents a promising precision medicine-guided therapy. There is a critical need, however, to identify novel and promising combination therapies to fight the development of resistance to CDK4/6 inhibition. In this review, we offer rationale and perspective on the promise and challenges of this therapeutic approach.

Cancer-Derived Extracellular Vesicles: Their Role in Sarcoma

Soft tissue sarcomas (STS) are rare malignancies with limited responses to anticancer therapy. Extracellular vesicles (EVs) are a heterogeneous group of bi-lipid layer sacs secreted by cells into extracellular space. Investigations of tumor-derived EVs have revealed their functional capabilities, including cell-to-cell communication and their impact on tumorigenesis, progression, and metastasis; however information on the roles of EVs in sarcoma is currently limited. In this review we investigate the role of various EV cargos in sarcoma and the mechanisms by which those cargos can affect the recipient cell phenotype and the aggressivity of the tumor itself. The study of EVs in sarcoma may help establish novel therapeutic approaches that target specific sarcoma subtypes or biologies, thereby improving sarcoma therapeutics in the future.

A 3D Platform to Investigate Dynamic Cell-to-Cell Interactions Between Tumor Cells and Mesenchymal Progenitors

We here investigated the dynamic cell-to-cell interactions between tumor and mesenchymal stromal/stem cells (MSCs) by the novel VITVO^Ⓡ 3D bioreactor that was customized to develop in vivo-like metastatic nodules of Ewing’s sarcoma (ES). MSCs are known to contribute to tumor microenvironment as cancer associated fibroblast (CAF) precursors and, for this reason, they have also been used as anti-cancer tools. Using dynamic conditions, the process of tissue colonization and formation of metastatic niches was recreated through tumor cell migration aiming to mimic ES development in patients. ES is an aggressive tumor representing the second most common malignant bone cancer in children and young adults. An urgent and unmet need exists for the development of novel treatment strategies to improve the outcomes of metastatic ES. The tumor-tropic ability of MSCs offers an alternative approach, in which these cells can be used as vehicles for the delivery of antitumor molecules, such as the proapoptotic TNF-related apoptosis inducing ligand (TRAIL). However, the therapeutic targeting of metastases remains challenging and the interaction occurring between tumor cells and MSCs has not yet been deeply investigated. Setting up in vitro and in vivo models to study this interaction is a prerequisite for novel approaches where MSCs affinity for tumor is optimized to ultimately increase their therapeutic efficacy. Here, VITVO^Ⓡ integrating a customized scaffold with an increased inter-fiber distance (VITVO50) was used to develop a dynamic model where MSCs and tumor nodules were evaluated under flow conditions. Colonization and interaction between cell populations were explored by droplet digital PCR (ddPCR). VITVO50 findings were then applied in vivo. An ES metastatic model was established in NSG mice and biodistribution of TRAIL-expressing MSCs in mice organs affected by metastases was investigated using a 4-plex ddPCR assay. VITVO^Ⓡ proved to be an easy handling and versatile bioreactor to develop in vivo-like tumor nodules and investigate dynamic cell-to-cell interactions with MSCs. The proposed fluidic system promises to facilitate the understanding of tumor-stroma interaction for the development of novel tumor targeting strategies, simplifying the analysis of in vivo data, and ultimately accelerating the progress towards the early clinical phase.

Adding Perplexity to Rarity: Diffuse S100-Protein and SOX10 Expression in a Molecularly Confirmed PAX7-Positive Primary Cutaneous Ewing Sarcoma

ABSTRACT

Primary cutaneous Ewing sarcoma (EWS) is a very rare neoplasm that shares similar morphologic, immunohistochemical, and molecular features with its osseous counterpart. Herein, we present an extraordinarily rare case of PAX7-positive cutaneous EWS in a 9-year-old girl that was also diffusely positive for SOX10 and S100-protein. Next generation sequencing detected the EWSR1-FLI1 fusion supporting the diagnosis, which was further validated by break-apart EWSR1 fluorescence in situ hybridization. Diffuse S100-protein and SOX10 expression has been reported only in a handful of cases of EWS and may pose significant diagnostic challenges for dermatopathologists. PAX7 is a recently introduced marker, which is highly sensitive for EWS and can potentially have discriminatory power in the differential diagnosis of cutaneous undifferentiated round blue cell tumors.

Case Report: A New Tool for Anterior Chest Wall Reconstruction After Sternal Resection for Primary Or Secondary Tumors

Sternal resection and anterior chest wall reconstruction techniques for malignant processes are not always standardized. We report an innovative method of sternal osteosynthesis in two patients, 65-year-old and 41-year-old women, with Ewing's sarcoma, and infiltrating thymoma, respectively. The first case manifested itself as a voluminous palpable mass while the second case was characterized for a paramediastinal mass widely extended to the anterior chest wall. Reconstruction with titanium mesh allowed the quick restoration of parietal stability, facilitating respiratory dynamic and recovery of patients.

Ewing Sarcoma of the Craniofacial Bones: A Qualitative Systematic Review

OBJECTIVES

To conduct a systematic review on the demographics, characteristics, management, treatment, complications, and outcomes of Ewing sarcomas in the craniofacial bones.

DATA SOURCES

Using Cochrane Library, EmBase, and PubMed, the authors identified 71 studies to be included.

REVIEW METHODS

The Cochrane Library, EmBase, and PubMed databases were used to identify literature relating to Ewing sarcomas in the craniofacial bone to conduct a systematic review. Patient demographics, clinical characteristics, and treatment strategies were extracted.

RESULTS

Seventy-one studies encompassing 102 patients were identified. The most common craniofacial locations involved were the frontal bone (16.7%, n = 17), nasal cavity (16.7%, n = 17), and temporal bone (14.7%, n = 15). Stratified by location, the most common presenting symptoms were frontal bone (palpable mass, n = 8, 47.1%), nasal cavities (epistaxis, n = 9, 52.9%), and temporal bones (headache, n = 5, 33.3%). The 3 most commonly used treatment strategies were a combination of surgical intervention/radiotherapy/chemotherapy (n = 43, 43%), a combination of radiotherapy/chemotherapy (n = 18, 18%), and a combination of surgical intervention/chemotherapy (n = 15, 15%). Patients who received a combination of surgical intervention/radiotherapy/chemotherapy experienced local recurrence rate of 16.6%. However, other combinations of therapies such as surgical intervention/chemotherapy and radiotherapy/chemotherapy had a lower local recurrence rate but were limited by small sample size. Most patients (79.0%) were disease free without evidence of recurrence.

CONCLUSION

Ewing Sarcoma of the craniofacial bones has a good prognosis when treated appropriately. Given that our study was limited by retrospective data, we advise clinicians to use the findings of this article with their own clinical judgment to determine which treatment strategy they should pursue.

Pharmacological and nutritional targeting of voltage-gated sodium channels in the treatment of cancers

Voltage-gated sodium (NaV) channels, initially characterized in excitable cells, have been shown to be aberrantly expressed in non-excitable cancer tissues and cells from epithelial origins such as in breast, lung, prostate, colon, and cervix, whereas they are not expressed in cognate non-cancer tissues. Their activity was demonstrated to promote aggressive and invasive potencies of cancer cells, both in vitro and in vivo, whereas their deregulated expression in cancer tissues has been associated with metastatic progression and cancer-related death. This review proposes NaV channels as pharmacological targets for anticancer treatments providing opportunities for repurposing existing NaV-inhibitors or developing new pharmacological and nutritional interventions.

Osteosarcoma, chondrosarcoma and Ewing sarcoma: Clinical aspects, biomarker discovery and liquid biopsy

Bone sarcomas, although rare, are associated with significant morbidity and mortality. The most frequent primary bone cancers include osteosarcoma, chondrosarcoma and Ewing sarcoma. The treatment approaches are heterogeneous and mainly chosen based on precise tumour staging. Unfortunately, clinical outcome has not changed significantly in over 30 years and tumour grade is still the best prognosticator of metastatic disease and survival. An option to improve this scenario is to identify molecular biomarkers in the early stage of the disease, or even before the disease onset. Blood-based liquid biopsies are a promising, non-invasive way to achieve this goal and there are an increasing number of studies which investigate their potential application in bone cancer diagnosis, prognosis and personalised therapy. This review summarises the interplay between clinical and molecular aspects of the three main bone sarcomas, alongside biomarker discovery and promising applications of liquid biopsy in each tumour context.

Overuse Knee Pain in the Pediatric and Adolescent Athlete

Overuse knee pain is common in young athletes. There are many potential overuse injuries which present with insidious onset of pain that can challenge sports medicine providers, including Osgood-Schlatter's disease, patellofemoral syndrome, osteochondritis dissecans, and stress fractures. The differential diagnosis of insidious onset knee pain also includes malignancies, infections, and rheumatologic issues. A thorough history and physical examination can guide the treating provider in making a diagnosis and appropriate treatment plan. Although not always necessary, imaging is often helpful in overuse knee pain, and laboratory workup may be necessary. Conservative treatment is often the first recommendation in the management of overuse knee pain in young athletes, and this may include activity modification, ice, anti-inflammatory medications, bracing, and physical therapy. This review summarizes common overuse knee injuries seen in pediatric and adolescent athletes.

BCOR-CCNB3 rearranged sarcoma arising in neck misdiagnosed as thyroid cancer: A case report

BCOR-rearranged sarcoma is the third common subtype of undifferentiated small round cell sarcoma and was first recognized in 2012 from bone sarcoma with a similar morphological manifestation with undifferentiated round cell but totally different molecular hallmark from Ewing sarcoma. Primary BCOR-rearranged sarcomas were mostly found in bone and soft tissue and were sporadically reported in viscera involving kidney, which add difficulties in differential diagnosis. Here we present a 21 years old male patient with BCOR-CCNB3 in neck, which first diagnosed as thyroid cancer.

Epiphyseal Ewing Sarcoma in a skeletally mature patient: A case report and review of the literature

While Ewing sarcoma of bone is the second most common primary osseous malignancy in childhood where it typically involves the diaphysis or metadiaphyses of long bones of skeletally immature patients, primary epiphyseal involvement of the long bone in skeletally mature patients is rare with no cases reported in the literature to our knowledge, rendering this case the first of its kind.

We present the first case of primary Ewing Sarcoma of the epiphyses of the long bones in a skeletally mature 20-year-old male patient. The patient initially presented with left knee stiffness and pain that was empirically treated with non-steroidal anti-inflammatory medications. His pain progressed despite treatment. An x-ray of the left knee was obtained 5 months later demonstrating an irregular lucent lesion in the medial femoral condyle. A subsequent MRI revealed an enhancing lesion in the medial femoral condyle, and when biopsied it was consistent with Ewing sarcoma (positive for EWSR1gene rearrangement by fluorescence in situ hybridization). The lesion was resected surgically, and the patient underwent neoadjuvant chemotherapy with a good clinical outcome.

Adamantinoma-like Variant of Ewing Sarcoma in the Metatarsal Bone After Chemotherapy: Report of a Case Successfully Treated with Pedicled Osteocutaneous Fibular Transfer

Adamantinoma-like Ewing sarcoma is a rare variant of Ewing sarcoma with histologic and immunohistochemical evidence of squamous differentiation. This variant most commonly occurs in the head and neck region with a few cases reported in the long bones of the limbs. It may be associated with poorer clinical outcome and could pose a diagnostic challenge, particularly if it occurs in older patients or as a metastatic lesion. We present a case of Ewing sarcoma in the metatarsal of an 11-year-old boy that manifested adamantinoma-like morphology after neoadjuvant chemotherapy. Chemotherapy has been reported to induce neuronal maturation and rhabdoid morphology in cases of Ewing sarcoma, but no reports of treatment-induced squamous differentiation with P40/P63 expression have been demonstrated. This is also the first documented case treated with a pedicled osteocutaneous fibular transfer in a metatarsal malignancy, which is usually treated by either ray or below-knee amputation.

Exploiting Gangliosides for the Therapy of Ewing's Sarcoma and H3K27M-Mutant Diffuse Midline Glioma

Simple Summary

Osteosarcoma, Ewing’s sarcoma, and H3K27M-mutant diffuse midline glioma are rare but aggressive malignancies occurring mainly in children. Due to their rareness and often fatal course, drug development is challenging. Here, we repurposed the existing drugs dinutuximab and eliglustat and investigated their potential to directly target or indirectly modulate the tumor cell-specific ganglioside GD2. Our data suggest that targeting and/or modulating tumor cell-specific GD2 may offer a new therapeutic strategy for the above mentioned tumor entities.

Abstract

The ganglioside GD2 is an important target in childhood cancer. Nevertheless, the only therapy targeting GD2 that is approved to date is the monoclonal antibody dinutuximab, which is used in the therapy of neuroblastoma. The relevance of GD2 as a target in other tumor entities remains to be elucidated. Here, we analyzed the expression of GD2 in different pediatric tumor entities by flow cytometry and tested two approaches for targeting GD2. H3K27M-mutant diffuse midline glioma (H3K27M-mutant DMG) samples showed the highest expression of GD2 with all cells strongly positive for the antigen. Ewing’s sarcoma (ES) samples also showed high expression, but displayed intra- and intertumor heterogeneity. Osteosarcoma had low to intermediate expression with a high percentage of GD2-negative cells. Dinutuximab beta in combination with irinotecan and temozolomide was used to treat a five-year-old girl with refractory ES. Disease control lasted over 12 months until a single partially GD2-negative intracranial metastasis was detected. In order to target GD2 in H3K27M-mutant DMG, we blocked ganglioside synthesis via eliglustat, since dinutuximab cannot cross the blood–brain barrier. Eliglustat is an inhibitor of glucosylceramide synthase, and it is used for treating children with Gaucher’s disease. Eliglustat completely inhibited the proliferation of primary H3K27M-mutant DMG cells in vitro. In summary, our data provide evidence that dinutuximab might be effective in tumors with high GD2 expression. Moreover, disrupting the ganglioside metabolism in H3K27M-mutant DMG could open up a new therapeutic option for this highly fatal cancer.

Primary intradural/extradural Ewing's sarcoma of the sacral spine: A case report and literature review

Background:

Ewing’s sarcoma (ES) is a malignant mesenchymal tumor, most often found in the long bones, and usually affecting children and adolescents in the second decade of life. ES of the spine is a clinical rarity.

Case Description:

A 45-year-old male presented with a 3-month history of lower back pain which acutely worsened in conjunction with urinary retention. The magnetic resonance imaging revealed a mass extending from L5 to S2 with additional extension through the left S2-3 neural foramen. The metastatic workup was negative. At surgery, the lesion was both intradural and extradural. Following complete surgical resection, the patient was later treated with radiation and chemotherapy.

Conclusion:

Here, we report an adult male who acutely presented with low back pain attributable to primary intradural/extradural sacral ES.

Effectiveness of advanced nursing care (ANC) on bone cancer pain, psychological disorders and quality of life in patients with primary bone cancers: A protocol for a PRISMA-compliant meta-analysis

BACKGROUND

Advanced nursing care (ANC) has been reported to effectively relieve bone cancer pain, prevent psychological disorders and improve the quality of life (QoL) in patients with primary bone cancers (PBC) during the treatment. However, the exact effect of ANC remains controversial. This systematic review will aimed to assess the effectiveness of ANC on bone cancer pain, psychological disorders and QoL in patients with PBC.

METHODS

Eligible randomized controlled trials (RCTs) and high-quality prospective cohort studies were searched from Excerpt Medica Database (Embase), PubMed, Google Scholar, Medline, Cochrane Library, Web of Science (WOS), China National Knowledge Infrastructure (CNKI), Chinese Bio Medical Database (CBM), China Scientific Journal Database (CSJD), and Wanfang Database. Papers in English or Chinese published from January 2000 to July 2020 will be included without any restrictions. The clinical outcomes including bone cancer pain, psychological disorders, QoL, and adverse events of ANC in patients with PBC were systematically evaluated.Two reviewers will separately carry out study selection and data extraction. Stata 14.0 and Review Manager 5.3 were used for data analysis. Methodological quality for each eligible clinical trial will be assessed by using Cochrane risk of bias tool. Subgroup and meta-regression analysis will be carried out depending on the availability of sufficient data.

RESULTS

This study will comprehensively summarize all potential evidence to systematically investigate the effects and safety of ANC on bone cancer pain, psychological disorders and QoL in patients with PBC.

CONCLUSION

The findings of this study will help to determine whether ANC is effective or not on bone cancer pain, psychological disorders and QoL in patients with PBC.

INPLASY REGISTRATION NUMBER

INPLASY202090037.

Radiation therapy strategies for skull-base malignancies

INTRODUCTION

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

METHODS

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

RESULTS

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

CONCLUSION

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

The Effects of Genetic and Epigenetic Alterations of BARD1 on the Development of Non-Breast and Non-Gynecological Cancers

Breast Cancer 1 (BRCA1) gene is a well-characterized tumor suppressor gene, mutations of which are primarily found in women with breast and ovarian cancers. BRCA1-associated RING domain 1 (BARD1) gene has also been identified as an important tumor suppressor gene in breast, ovarian, and uterine cancers. Underscoring the functional significance of the BRCA1 and BARD1 interactions, prevalent mutations in the BRCA1 gene are found in its RING domain, through which it binds the RING domain of BARD1. BARD1-BRCA1 heterodimer plays a crucial role in a variety of DNA damage response (DDR) pathways, including DNA damage checkpoint and homologous recombination (HR). However, many mutations in both BARD1 and BRCA1 also exist in other domains that significantly affect their biological functions. Intriguingly, recent genome-wide studies have identified various single nucleotide polymorphisms (SNPs), genetic alterations, and epigenetic modifications in or near the BARD1 gene that manifested profound effects on tumorigenesis in a variety of non-breast and non-gynecological cancers. In this review, we will briefly discuss the molecular functions of BARD1, including its BRCA1-dependent as well as BRCA1-independent functions. We will then focus on evaluating the common BARD1 related SNPs as well as genetic and epigenetic changes that occur in the non-BRCA1-dominant cancers, including neuroblastoma, lung, and gastrointestinal cancers. Furthermore, the pro- and anti-tumorigenic functions of different SNPs and BARD1 variants will also be discussed.

Primary Extraosseous Ewing Sarcoma of the Thoracic Spine Presenting as Chest Pain Mimicking Spinal Schwannoma

BACKGROUND

Extraosseous Ewing sarcoma (EES) usually has a pseudocapsule and high vascularity, making it well circumscribed and focally dense with contrast enhancement on magnetic resonance imaging (MRI). Consequently, it is difficult to diagnose and distinguish from other spinal tumors, based on pretreatment radiologic findings alone. Here, we present a case of EES involving the thoracic spinal column, which was suspected to be spinal schwannoma through pretreatment radiologic findings.

CASE DESCRIPTION

A 54-year-old woman was admitted to our hospital with upper back and left-sided chest pain. Contrast-enhanced MRI of the thoracolumbar spine showed a 17- × 12-mm-sized mass in the epidural region and left neural foramen at the T6-7 level. Our preliminary diagnosis was spinal schwannoma. The patient underwent T6 hemilaminectomy. Intraoperatively, the lesion appeared as gray-colored soft mass with high vascularity, which seemed to have originated from the left T6 nerve root. The tumor was excised with en bloc resection. Histopathologic examination of the lesion revealed classical Ewing sarcoma with high cellularity of small round cells. Immunohistochemistry revealed strong positivity for cluster of differentiation 99 and FLI-1. Intensity-modulated radiation therapy was performed. The patient did not receive chemotherapy. Five years after surgery, follow-up spinal MRI and positron emission tomography computed tomography scan revealed no recurrence of the tumor or new lesions.

CONCLUSIONS

Clinicians should consider EES in the differential diagnosis of other neural foraminal spinal tumors, such as schwannoma. If clinicians are confident that EES has been removed completely and there are no other lesions, radiotherapy is sufficient and additional chemotherapy may not be necessary.

CDKs in Sarcoma: Mediators of Disease and Emerging Therapeutic Targets

Sarcomas represent one of the most challenging tumor types to treat due to their diverse nature and our incomplete understanding of their underlying biology. Recent work suggests cyclin-dependent kinase (CDK) pathway activation is a powerful driver of sarcomagenesis. CDK proteins participate in numerous cellular processes required for normal cell function, but their dysregulation is a hallmark of many pathologies including cancer. The contributions and significance of aberrant CDK activity to sarcoma development, however, is only partly understood. Here, we describe what is known about CDK-related alterations in the most common subtypes of sarcoma and highlight areas that warrant further investigation. As disruptions in CDK pathways appear in most, if not all, subtypes of sarcoma, we discuss the history and value of pharmacologically targeting CDKs to combat these tumors. The goals of this review are to (1) assess the prevalence and importance of CDK pathway alterations in sarcomas, (2) highlight the gap in knowledge for certain CDKs in these tumors, and (3) provide insight into studies focused on CDK inhibition for sarcoma treatment. Overall, growing evidence demonstrates a crucial role for activated CDKs in sarcoma development and as important targets for sarcoma therapy.

[Malignant round cell tumors : The Ewing sarcoma and beyond]

Ewing sarcomas are highly malignant tumors that are mainly found in children and adolescents. In addition to early clinical diagnosis, correct histopathological and molecular genetic classification is the most important step. Although EWSR1-FLI1 fusion is by far the most common detectable change, there are also other representatives of the Ewing sarcoma family that cannot be distinguished histopathologically and immunohistochemically from classical Ewing sarcomas and that have different molecular genetic profiles. Although a precise molecular genetic differentiation of the various representatives of small round blue cell tumors does not yet lead to any change in the standard chemotherapy and surgical treatment applied, it does allow an estimation of the prognosis and will probably contribute in the future to an even more individualized treatment of Ewing sarcomas within the framework of personalized medicine.

Breakthrough Technologies Reshape the Ewing Sarcoma Molecular Landscape

Ewing sarcoma is a highly aggressive round cell mesenchymal neoplasm, most often occurring in children and young adults. At the molecular level, it is characterized by the presence of recurrent chromosomal translocations. In the last years, next-generation technologies have contributed to a more accurate diagnosis and a refined classification. Moreover, the application of these novel technologies has highlighted the relevance of intertumoral and intratumoral molecular heterogeneity and secondary genetic alterations. Furthermore, they have shown evidence that genomic features can change as the tumor disseminates and are influenced by treatment as well. Similarly, next-generation technologies applied to liquid biopsies will significantly impact patient management by allowing the early detection of relapse and monitoring response to treatment. Finally, the use of these novel technologies has provided data of great value in order to discover new druggable pathways. Thus, this review provides concise updates on the latest progress of these breakthrough technologies, underscoring their importance in the generation of key knowledge, prognosis, and potential treatment of Ewing Sarcoma.

Tibial Osteomyelitis Caused by Carbapenem-Resistant Enterobacter cloacae

A 31-year-old man presented with a symptomatic tibial non-union following an open tibia fracture sustained in India. The open fracture was persistently draining for 8 months following the initial injury. The decision was made to revise his tibia fracture to promote union. Intraoperative cultures of the non-union site during the revision procedure revealed osteomyelitis caused by carbapenemase-producing Enterobacter cloacae which was multi-drug resistant to all antibiotics except for tigecycline. The patient was treated successfully with a tigecycline-impregnated antibiotic spacer and intravenous tigecycline with repeat bone cultures demonstrating eradication of the infection. Eight weeks into treatment (1 year from initial injury), the patient developed new pain and swelling in the adjacent proximal fibula of the limb treated for osteomyelitis. MRI and biopsy revealed Ewing sarcoma. The patient underwent transfemoral amputation. This report describes a management protocol of carbapenemase-resistant post-traumatic osteomyelitis with no evidence of infection recurrence.

Precision medicine in Ewing sarcoma: a translational point of view

Ewing sarcoma is a rare tumor that arises in bones of children and teenagers but, in 15% of the patients it is presented as a primary soft tissue tumor. Balanced reciprocal chimeric translocation t(11;22)(q24;q12), which encodes an oncogenic protein fusion (EWSR1/FLI1), is the most generalized and characteristic molecular event. Using conventional treatments, (chemotherapy, surgery and radiotherapy) long-term overall survival rate is 30% for patients with disseminated disease and 65-75% for patients with localized tumors. Urgent new effective drug development is a challenge. This review summarizes the preclinical and clinical investigational knowledge about prognostic and targetable biomarkers in Ewing sarcoma, finally suggesting a workflow for precision medicine committees.

Hippo pathway effectors YAP1/TAZ induce an EWS-FLI1-opposing gene signature and associate with disease progression in Ewing sarcoma

YAP1 and TAZ (WWTR1) oncoproteins are the final transducers of the Hippo tumor suppressor pathway. Deregulation of the pathway leads to YAP1/TAZ activation fostering tumorigenesis in multiple malignant tumor types, including sarcoma. However, oncogenic mutations within the core components of the Hippo pathway are uncommon. Ewing sarcoma (EwS), a pediatric cancer with low mutation rate, is characterized by a canonical fusion involving the gene EWSR1 and FLI1 as the most common partner. The fusion protein is a potent driver of oncogenesis, but secondary alterations are scarce, and little is known about other biological factors that determine the risk of relapse or progression. We have observed YAP1/TAZ expression and transcriptional activity in EwS cell lines. Analyses of 55 primary human EwS samples revealed that high YAP1/TAZ expression was associated with progression of the disease and predicted poorer outcome. We did not observe recurrent SNV or copy number gains/losses in Hippo pathway-related loci. However, differential CpG methylation of the RASSF1 locus (a regulator of the Hippo pathway) was observed in EwS cell lines compared with mesenchymal stem cells, the putative cell of origin of EwS. Hypermethylation of RASSF1 correlated with the transcriptional silencing of the tumor suppressor isoform RASFF1A, and transcriptional activation of the pro-tumorigenic isoform RASSF1C, which promotes YAP1/TAZ activation. Knockdown of YAP1/TAZ decreased proliferation and invasion abilities of EwS cells and revealed that YAP1/TAZ transcription activity is inversely correlated with the EWS-FLI1 transcriptional signature. This transcriptional antagonism could be explained partly by EWS-FLI1-mediated transcriptional repression of TAZ. Thus, YAP1/TAZ may override the transcriptional program induced by the fusion protein, contributing to the phenotypic plasticity determined by dynamic fluctuation of the fusion protein, a recently proposed model for disease dissemination in EwS. © 2019 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.

Omic approaches to pediatric bone sarcomas

Over the last decade, next-generation sequencing technologies have improved our ability to assess biological aspects, at genomic and transcriptomic levels, on a large scale- and have been increasingly used for the management of adult cancers. However, their efficacy and feasibility within pediatrics is still under investigation. "Omic" approaches represent an opportunity to understand the oncogenic mechanisms driving the onset and progression of bone sarcoma and improve the clinical management of young patients with bone sarcomas. This review focuses on the current genomic and transcriptomic characteristics of managing pediatric patients, affected by Ewing sarcoma and osteosarcoma.

Primary Ewing's sarcoma of the petroclival bone: A case report and literature review

Background:

Primary Ewing’s sarcoma (ES) is typically seen within the long bones, vertebrae, or pelvis. Uncommonly, it can be found within the cranium among the rarest locations for primary ES are the skull base, in particular, the petroclival bone.

Case Description:

The patient is a 68-year-old female with past medical history of Stage III breast cancer who presented with severe retro-orbital headache and diplopia due to a cranial nerve VI palsy. Magnetic resonance imaging (MRI) revealed a mass at the left petroclival bone with extension into the adjacent left petrous apex and into the posterior aspect of the left cavernous sinus proximal to the carotid artery. The patient subsequently underwent an endoscopic transsphenoidal biopsy. Pathological and molecular analysis supported a diagnosis of ES. The patient then underwent neoadjuvant chemotherapy and radiotherapy. At 12 month-follow-up, her petroclival ES demonstrated significant interval decrease in size on MRI surveillance imaging.

Conclusions:

This is the third case of primary ES of the petroclival bone to be reported in the literature. In this patient, management consisted of surgical incisional biopsy followed by adjuvant radiation and chemotherapy. Knowledge and awareness of this type of tumor is important for the skull base surgeon.