Primary extraskeletal intradural Ewing sarcoma with acute hemorrhage: a case report and review of the literature.

BACKGROUND: Spinal cord tumors present a challenge in diagnosis and treatment due to their varied histopathological characteristics. While Ewing sarcoma is a rare malignant tumor typically originating from skeletal bone, cases of primary intradural extraskeletal Ewing sarcoma are exceptionally rare. The similarity of its presentation to other spinal tumors further complicates its identification and management. CASE PRESENTATION: We report a case of a 58-year-old Palestinian male with intradural extraskeletal lumbar Ewing sarcoma. The patient initially presented with lower back pain and bilateral S1 radiculopathy, with more severe symptoms on the left side. Magnetic resonance imaging revealed a 7 cm oval-shaped mass with homogeneous contrast enhancement, obstructing the spinal canal from L3/L4 to L5/S1 levels. Initially, a myxopapillary ependymoma was suspected, but the patient's sensory and motor functions suddenly deteriorated during hospitalization. Repeat magnetic resonance imaging indicated heterogeneous contrast enhancement, indicating acute intratumoral hemorrhage. Consequently, the patient underwent emergent L3-L5 laminotomy, with successful gross total resection of the tumor. Histopathological and immunohistochemical analyses confirmed the diagnosis of intradural extraskeletal Ewing sarcoma. Adjuvant therapy was administered to minimize the risk of local recurrence or distant metastasis. A systematic review of relevant literature, along with retrospective analysis of medical records, operative reports, radiological studies, and histopathological findings of similar cases, was also conducted. CONCLUSIONS: Intradural extraskeletal Ewing sarcoma is an infrequently encountered condition in adult patients, emphasizing the importance of considering it in the differential diagnosis of spinal tumors. Surgeons must possess a comprehensive understanding of this rare entity to ensure accurate staging and optimal management, particularly in the early stages when prompt intervention may improve prognosis.

Use of modern three-dimensional imaging models to guide surgical planning for local control of pediatric extracranial solid tumors.

INTRODUCTION: In complex pediatric surgical oncology, surgical planning is contingent upon data gathered from preoperative imaging. Three-dimensional (3D) modeling and printing has been shown to be beneficial for adult presurgical planning, though pediatric literature is less robust. The study reviews our institutional experience with the use of 3D image segmentation and printed models in approaching resection of extracranial solid tumors in children. METHODS: This is a single institutional series from 2021 to 2023. Models were based on computed tomography and magnetic resonance imaging studies, optimized for 3D imaging. The feasibility and creation of the models is reviewed, including specific techniques, software, and printing materials from our institution. Clinical implications for surgical planning are also described, along with detailed preoperative and intraoperative images. RESULTS: 3D modeling and printing was performed for four pediatric patients diagnosed with extracranial solid tumors. Diagnoses included Ewing sarcoma, hepatoblastoma, synovial sarcoma, and osteosarcoma. No intraoperative complications or discrepancies with the preoperative 3D-printed model were noted. No evidence of local recurrence was identified in any patient thus far. CONCLUSION: Our institutional series demonstrates a wide spectrum of clinical application for 3D modeling and printing technology within pediatric surgical oncology. This technology may aid in surgical planning for both resection and reconstruction, can be applied to a diverse breadth of diagnoses, and may potentially augment patient and/or family education about their condition.

Ewing sarcoma of the cervix: an unusual site of presentation.

Ewing sarcoma is an exceedingly rare form of cancer that affects the cervix. It falls within the spectrum of neoplastic diseases known as Ewing's family of tumours, typically observed in osseous tissues. A woman in her 40s, experiencing symptoms of leucorrhoea and transvaginal bleeding that commenced 3 months before her consultation, was referred to our gynaecological oncology clinic with a preliminary diagnosis of ovarian teratoma. A colposcopy procedure was conducted unveiling a complete loss of cervical anatomy with friable and malodorous tissue. Pelvic ultrasound identified a lesion of uncertain origin in the cervix, suggestive of malignancy. Histopathological assessment of cervical biopsy specimens confirmed the presence of a small, round, blue cell neoplasm consistent with Ewing sarcoma. She underwent chemotherapy and pelvic radiotherapy, achieving complete remission 9 months after diagnosis, without experiencing any systemic adverse effects or sequelae.

Long-Term Survival after Primary Ewing's Sarcoma of the Skull with Intracranial Extension.

BACKGROUND AND OBJECTIVE: Primary Ewing's sarcoma of the skull is a very rare malignant neoplasm, predominantly occurring in children and adolescents. We describe here the clinical, neuroradiologic, and histopathologic features of a patient with primary Ewing's sarcoma of the skull and discuss the standards of therapy for this type of tumor. CLINICAL PRESENTATION: This 18-year-old male patient presented with a primary Ewing's sarcoma of the skull, involving the dura of the frontal and parietal lobes of the left cerebral hemisphere. He was treated with gross total surgical excision of tumor, skull reconstruction, chemotherapy, and irradiation. Twelve years after the surgery, the patient has no evidence of local recurrence or distant metastases. Radical surgical excision of the primary tumor with safety margins is thought to play a role in the favorable clinical course. CONCLUSION: The presented case is the longest surviving patient after treatment of primary Ewing's sarcoma of the skull bone. This rare type of tumor may allow better survival rates under adequate management than sarcoma elsewhere in the body.

Primary Ewing's sarcoma of the talus.

Ewing's sarcoma is a malignant round cell tumour of bones and soft tissues that usually arises from the diaphyseal or meta-diaphyseal parts of long bones and less commonly from flat bones. It occurs rarely in the foot and if occurs, the calcaneus and the metatarsals are commonly involved. We present a case of a young woman diagnosed with primary Ewing's sarcoma of the talus with local spread to adjacent tarsals and the ankle joint. Ewing's sarcoma of feet, if present with even a trivial suspicion of spread either locally or distant, makes limb salvage surgery difficult. So, the treatment with radical surgery or by combined chemotherapy and radiotherapy should be considered-keeping in mind the complex anatomy of the foot and the difficulty in achieving tumour-free margins. Based on this experience, she underwent below-knee amputation. The patient received adjuvant chemotherapy and survived with a disease-free survival at the latest follow-up of 1 year.

A 13-Year-Old Boy with Chest Wall Actinomycosis Mimicking Ewing Sarcoma on Imaging.

BACKGROUND Actinomyces, a filamentous, branching, anaerobic gram-positive bacillus, typically found as a commensal organism in the oral cavity, can lead to rare chronic bacterial infections in various anatomical regions. Chest wall involvement represents an uncommon presentation, posing significant diagnostic challenges. This report focuses on the case of a 13-year-old boy presenting with chest wall actinomycetoma that closely resembled Ewing sarcoma on imaging. CASE REPORT We present the case of a 13-year-old male with no previous medical history who presented to the Emergency Department with progressive left-sided chest pain following a sports-related fall. Physical examination revealed mild swelling and tenderness on the left anterior chest wall. A chest computed tomography (CT) scan revealed a large tumor involving the lower left chest wall, suggesting Ewing sarcoma. However, a histopathological examination unexpectedly confirmed actinomycosis of the chest wall. Intravenous penicillin G was promptly initiated for 4 weeks. A follow-up CT scan after 4 weeks of therapy demonstrated a significant response with notable reduction in the size of the chest wall mass. The patient then continued with maintenance therapy using oral amoxicillin for 12 months. Throughout this period, complete resolution of the chest wall mass occurred, with no significant adverse events or complications observed. CONCLUSIONS This case highlights the importance of considering uncommon differential diagnoses like chest wall actinomycosis in patients presenting with chest wall masses. The diagnostic complexities associated with this rare condition emphasize the need for a comprehensive evaluation strategy, incorporating histopathological examination and imaging.

Radiomics analysis based on CT for the prediction of pulmonary metastases in ewing sarcoma.

OBJECTIVES: This study aimed to develop and validate radiomics models on the basis of computed tomography (CT) and clinical features for the prediction of pulmonary metastases (MT) in patients with Ewing sarcoma (ES) within 2 years after diagnosis. MATERIALS AND METHODS: A total of 143 patients with a histopathological diagnosis of ES were enrolled in this study (114 in the training cohort and 29 in the validation cohort). The regions of interest (ROIs) were handcrafted along the boundary of each tumor on the CT and CT-enhanced (CTE) images, and radiomic features were extracted. Six different models were built, including three radiomics models (CT, CTE and ComB models) and three clinical-radiomics models (CT_clinical, CTE_clinical and ComB_clinical models). The area under the receiver operating characteristic curve (AUC), and accuracy were calculated to evaluate the different models, and DeLong test was used to compare the AUCs of the models. RESULTS: Among the clinical risk factors, the therapeutic method had significant differences between the MT and non-MT groups (P＜0.01). The six models performed well in predicting pulmonary metastases in patients with ES, and the ComB model (AUC: 0.866/0.852 in training/validation cohort) achieved the highest AUC among the six models. However, no statistically significant difference was observed between the AUC of the models. CONCLUSIONS: In patients with ES, clinical-radiomics model created using radiomics signature and clinical features provided favorable ability and accuracy for pulmonary metastases prediction.

Postoperative Relapse Prediction in Patients With Ewing Sarcoma Using Computed Tomography-Based Radiomics Models Covering Tumor Per Se and Peritumoral Signatures.

OBJECTIVE: We aimed to develop and validate a computed tomography (CT)-based radiomics model for early relapse prediction in patients with Ewing sarcoma (ES). METHODS: We recruited 104 patients in this study. Tumor areas and areas with a tumor expansion of 3 mm were used as regions of interest for radiomics analysis. Six different models were constructed: Pre-CT, CT enhancement (CTE), Pre-CT +3 mm , CTE +3 mm , Pre-CT and CTE combined (ComB), and Pre-CT +3 mm and CTE +3 mm combined (ComB +3 mm ). All 3 classifiers used a grid search with 5-fold cross-validation to identify their optimal parameters, followed by repeat 5-fold cross-validation to evaluate the model performance based on these parameters. The average performance of the 5-fold cross-validation and the best one-fold performance of each model were evaluated. The AUC (area under the receiver operating characteristic curve) and accuracy were calculated to evaluate the models. RESULTS: The 6 radiomics models performed well in predicting relapse in patients with ES using the 3 classifiers; the ComB and ComB +3 mm models performed better than the other models (AUC -best : 0.820-0.922/0.823-0.833 and 0.799-0.873/0.759-0.880 in the training and validation cohorts, respectively). Although the Pre-CT +3 mm , CTE +3 mm, and ComB +3 mm models covering tumor per se and peritumoral CT features preoperatively forecasted ES relapse, the model was not significantly improved. CONCLUSIONS: The radiomics model performed well for early recurrence prediction in patients with ES, and the ComB and ComB +3 mm models may be superior to the other models.

Pediatric presacral tumors with intraspinal extension: a rare entity with diagnostic challenges.

The presacral space is a potential space located between the rectum and the lumbosacral spine. It contains various primitive germ cell types that serve as the origin for a range of tumors. Imaging is crucial in characterizing, assessing the extent of and evaluating the treatment response to these tumors. We report a series of six cases of pediatric presacral tumors with intraspinal extension, including an immature sacrococcygeal teratoma (Altman type II), a malignant sacrococcygeal teratoma (Altman type IV), a neuroblastoma, a rhabdomyosarcoma, a clear cell sarcoma and an Ewing's sarcoma of the ilium. These tumors can be broadly categorized as tumors of germ cell, neuroblastic, mesenchymal and osteogenic origin. Despite overlapping imaging features, a review of the existing literature and careful retrospective observation revealed several distinctive features that aid in the optimal characterization of tumors. These include the tumor's epicenter, the pattern and degree of bone involvement, the status of sacral foramina and neural elements, and internal tumor characteristics such as the presence of fat, calcification, hemorrhage and necrosis.

Practical Management of Adult Ultra-Rare Primary Retroperitoneal Soft Tissue Sarcoma: A Focus on Perivascular Epithelioid Tumours and Extraosseous Ewing Sarcoma.

With the exception of well-differentiated liposarcoma, dedifferentiated liposarcoma, leiomyosarcoma, solitary fibrous tumour, malignant peripheral nerve sheath tumour, and undifferentiated pleomorphic sarcoma, the majority of the ≈70 histologic subtypes of retroperitoneal sarcoma are defined as 'ultra-rare' sarcomas, with an incidence of ≤1-5/1,000,000 persons/year. For most of these ultra-rare RPS subtypes, diagnosis and treatment follows international guidelines for the management of more common RPS histologies, with en bloc surgical resection as the mainstay of curative treatment, and enrolment in clinical trials where possible. Because the treatment of RPS is heavily driven by histology, the surgeon must be familiar with specific issues related to the diagnosis and management of ultra-rare sarcoma subtypes. Expert radiological and surgeon reviews are required to differentiate similarly presenting tumours where surgery can be avoided (e.g., angiomyolipoma), or where upfront systemic therapy is indicated (e.g., extraosseous Ewing's sarcoma). Thus, the management of all retroperitoneal sarcomas should occur at a sarcoma referral centre, with a multidisciplinary team of experts dedicated to the surgical and medical management of these rare tumours. In this focused review, we highlight how diagnosis and management of the ultra-rare primary RPS histologies of malignant perivascular epithelioid cell tumour (PEComa), extraosseous Ewing sarcoma (EES), extraosseous osteosarcoma (EOS), and rhabdomyosarcoma (RMS) critically diverge from the management of more common RPS subtypes.

Ewing's sarcoma of the duodenum: a rare clinical condition managed with surgical resection.

A man in his 40s with no medical history presented with right-sided abdominal and chest pain. A CT scan of the abdomen demonstrated a 7.7 cm heterogeneous mass arising from the second part of the duodenum. Oesophagogastroduodenoscopy confirmed a malignant-appearing duodenal lesion, with biopsy showing features consistent with small cell carcinoma. The patient underwent three cycles of neoadjuvant chemotherapy, followed by elective Kausch-Whipple pancreaticoduodenectomy. A combination of immunohistochemistry and molecular studies confirmed the diagnosis of a rare Ewing's sarcoma tumour originating from the duodenum with invasion into the duodenal lumen. The patient recovered well from surgery and remains disease-free 18 months following resection.

Primary Extraskeletal Ewing Sarcoma of the Duodenum Revealed by 18 F-FDG PET/CT.

ABSTRACT: Extraskeletal Ewing sarcoma of the duodenum is a relatively uncommon entity tumor. We report a case of extraskeletal Ewing sarcoma in a 21-year-old woman. She complained of abdomen pain and melena. 18 F-FDG PET/CT showed an intense uptake by the duodenum mass along with multiple FDG-avid enlarged lymph nodes in the mesentery, which was pathologically proven as extraskeletal Ewing sarcoma.

Large retroperitoneal extraskeletal Ewing's sarcoma with renal pedicle invasion: a case report.

BACKGROUND: Extraskeletal Ewing's sarcoma (EES) is a rare malignant tumor primarily found in children and young adults. Localized disease can present with nonspecific symptoms such as local mass, regional pain, and increased skin temperature. More severe cases may present with systemic symptoms such as malaise, weakness, fever, anemia, and weight loss. Among these lesions, retroperitoneal sarcomas are relatively uncommon and difficult to diagnose. Since they are usually asymptomatic until large enough to compress or invade the surrounding tissues, most are already advanced at first detection. Traditionally, the treatment of choice is complete surgical resection, sometimes combined with postoperative radiotherapy and chemotherapy. We report a case of EES with left renal artery invasion in the left retroperitoneal cavity successfully treated with transarterial embolization and surgery. CASE PRESENTATION: A 57-year-old woman with a negative family history of cancer presented at our Urology Department with a large left retroperitoneal tumor found by magnetic resonance imaging during the health exam. Physical examination showed a soft abdomen and no palpable mass or tenderness. Imaging studies showed that the tumor covered the entire left renal pedicle, but the left kidney, left adrenal gland, and pancreas appeared tumor free. Since the tumor tightly covered the entire renal pedicle, tumor excision with radical nephrectomy was advised. The patient underwent transarterial embolization of the left renal artery with 10 mg of Gelfoam pieces daily before surgical excision. Tumor excision and left radical nephrectomy were uneventful the day after embolization. Post-operatively, the patient recovered well and was discharged on day 10. The final histopathological analysis showed a round blue cell tumor consistent with an Ewing sarcoma, and the surgical margins were tumor free. CONCLUSIONS: Retroperitoneal malignancies are rare but usually severe conditions. Our case report showed that retroperitoneal EES with renal artery invasion could be treated safely with transarterial embolization and surgery.

Sarcoma de Ewing multifocal: presentación de un caso pediátrico / Multifocal Ewing sarcoma: presentation of a pediatric case / Sarcoma de Ewing Multifocal: apresentação de um caso pediátrico

Introducción: el Sarcoma de Ewing es una neoplasia maligna de origen mesenquimático. Al momento del diagnóstico el 75% se presentan en forma localizada. Objetivo: comunicar un caso que por su presentación multifocal, generó dificultades diagnósticas. Caso clínico: niña de 6 años. Consulta por traumatismo de mano derecha tras caída de su altura 24 horas previas, constatándose en mano y puño derecho edema, calor y eritema, movilidad conservada. No fiebre. Radiografía: aumento del diámetro del tercer metacarpiano, imagen esmerilada, no trazos de fracturas. Ingresa con planteo de celulitis. Anemia leve microcítica, hipocrómica. Proteína C reactiva 82 mg/l. Recibe clindamicina intravenosa 72 horas, completa 14 días vía oral. Persistencia de alteraciones en puño y mano derecha, agrega tumoración de raíz nasal con desviación del eje, indolora. Fosfatasa alcalina, lactato deshidrogenasa, fosfatemia, calcemia normales. Resonancia magnética: alteración morfoestructural de radio, olecranon y tercer metacarpiano, fractura de olecranon y radio, reacción perióstica. Pet-Scan: lesión extensa ósea en macizo facial, tibias, cúbitos, humero derecho y clavícula. Biopsia 3er metacarpiano: tumor de células pequeñas, redondas azules, CD99 y vimentina positivo. Comienza poliquimioterapia y radioterapia sin complicaciones. Conclusiones: es frecuente que las manifestaciones clínicas iniciales sean confundidas con entidades más frecuentes, como post-traumáticas y/o inflamatorias, tal como ocurrió en este caso. Posteriormente, la aparición de nuevas lesiones y compromiso del estado general orientó el abordaje diagnóstico de la patología tumoral. La confirmación exige el estudio anatomopatológico con estudio inmunohistoquímico. La presencia de metástasis óseas constituye un factor de mal pronóstico y dificulta el abordaje terapéutico.

Introduction: Ewing's sarcoma is a malignant neoplasm of mesenchymal origin. At the time of diagnosis 75% of the cases are localized. Objective: to report a case that, due to its multifocal presentation, generated diagnostic difficulties. Clinical case: 6-year-old girl. She consulted for right hand trauma after a fall from her height 24 hours earlier, with edema, warmth and erythema in the right hand and fist, with preserved mobility. No fever. X-ray: increase in the diameter of the 3rd metacarpal, frosted image, no traces of fractures. Admitted with cellulitis. Mild microcytic anemia, hypochromic. C-reactive protein 82mg/l. Receives intravenous clindamycin 72 hours, completes 14 days orally. Persistence of alterations in fist and right hand, adds tumor of nasal root with deviation of the axis, painless. Alkaline phosphatase, lactate dehydrogenase, phosphatemia, normal calcemia. MRI: morphostructural alteration of radius, olecranon and 3rd metacarpal, fracture of olecranon and radius, periosteal reaction. Pet-Scan: extensive bone lesion in facial mass, tibiae, ulnae, right humerus and clavicle. Biopsy 3rd metacarpal: small cell tumor, blue round, CD 99 and vimentin positive. Polychemotherapy and radiotherapy were started without complications. Conclusions: it is frequent that the initial clinical manifestations are confused with more frequent entities, such as post-traumatic and/or inflammatory, as occurred in this case. Subsequently, the appearance of new lesions and compromise of the general condition guided the diagnostic approach of the tumor pathology. Confirmation requires anatomopathological study with immunohistochemical study. The presence of bone metastases constitutes a poor prognostic factor and hinders the therapeutic approach.

Introdução: O sarcoma de Ewing é um neoplasma maligno de origem mesenquimatosa. No momento do diagnóstico, 75% dos casos são localizados. Objetivo: Relatar um caso que, devido a sua apresentação multifocal, causou dificuldades diagnósticas. Caso clínico: Menina de 6 anos. Ela consultou por traumatismo à mão direita após cair de sua altura 24 horas antes, com edema, calor e eritema na mão direita e punho, com mobilidade preservada. Sem febre. Raio-X: aumento do diâmetro do 3º metacarpo, imagem fosca, sem vestígios de fraturas. Admitido com a sugestão de celulite. Anemia microcítica leve, hipocrómica. Proteína C reativa 82mg/l. Recebe clindamicina intravenosa por 72 horas, completa 14 dias por via oral. Persistência de alterações no punho e mão direita, tumor indolor da raiz nasal com desvio do eixo. Fosfatase alcalina, desidrogenase láctica, fosfataemia, calcemia normal. IRM: alteração morfo-estrutural do rádio, olecrânio e 3º metacarpo, fratura do olecrânio e do rádio, reação periosteal. Pet-Scan: extensa lesão óssea na massa facial, tíbia, ulnae, úmero direito e clavícula. Biópsia do 3º metacarpo: tumor de pequenas células, redondo azul, CD 99 e vimentina positiva. Ela iniciou a poli-quimioterapia e radioterapia sem complicações. Conclusões: É comum que as manifestações clínicas iniciais sejam confundidas com entidades mais freqüentes, tais como pós-traumáticas e/ou inflamatórias, como ocorreu neste caso. Posteriormente, o aparecimento de novas lesões e o envolvimento do quadro geral levaram a uma abordagem diagnóstica da patologia tumoral. A confirmação requer um estudo anatomopatológico com estudo imuno-histoquímico. A presença de metástases ósseas é um fator de mau prognóstico e dificulta a abordagem terapêutica.

Clinical and imaging features of eight cases of Ewing sarcoma of the jaw.

OBJECTIVES: This study investigate the clinical and imaging features of Ewing sarcoma (ES) of the jaw. METHODS: Eight cases of pathologically diagnosed ES of the jaw from January 2010 to June 2022 were included in the study. Clinical and radiological features were retrospectively analyzed. RESULTS: Among the eight cases, the mean age at onset was 29.4 years, and the male to female ratio was 7∶1. The predilecting site was the posterior part of mandible, accounting for 75% of the cases. The lesions often exhibited early numbness of the lower lip and lymphadenopathy. The main radiographic manifestation of mandibular lesions was ill-defined radiolucency, mixed with fibrous or brush-like tumor matrix, and soft tissue mass. The maxillary ES lesions mainly presented as lytic bone destruction accompanied by adjacent soft tissue mass. Periosteal ossification was rarely seen. CONCLUSIONS: The clinical and imaging characteristics of ES in the jaw are helpful for its diagnosis.

Is Bone Marrow Aspiration and Biopsy of Clinical Importance in the Initial Staging of Extraskeletal Ewing Sarcoma?

BACKGROUND: Extraskeletal Ewing sarcoma are rare tumors within the Ewing sarcoma family. Initial staging studies for extraskeletal Ewing sarcoma historically have included imaging and bone marrow aspiration and biopsy (BMAB). However, recent studies on Ewing sarcoma of bone have questioned the utility of BMAB in the initial staging of patients, but no studies of which we are aware have evaluated the role of BMAB in extraskeletal Ewing sarcoma. We suspected that BMAB was of low diagnostic yield in patients with extraskeletal Ewing sarcoma and exposed patients to potential morbidity without an impact on their clinical course. QUESTION/PURPOSE: Is BMAB a useful test in the staging of extraskeletal Ewing sarcoma? METHODS: Between January 1996 and December 2021, our institution evaluated 109 patients with a listed diagnosis of extraskeletal Ewing sarcoma. Those patients were retrospectively reviewed for this study. Of those, we considered patients with biopsy-confirmed diagnosis of extraskeletal Ewing sarcoma. Biopsy was performed based on institutional protocols, with all diagnoses assigned by a board-certified pathologist. Based on that criteria, 96% (105 of 109) were eligible. An additional 18% (20 of 109) were excluded because records of their initial diagnostic and staging workup were not available. This left 78% (85 of 109) for analysis. Of those, 52% (44 of 85) were male. The average age was 32 ± 16 years. Primary tumor locations included extremities in 26% (22 of 85), paraspinal in 20% (17 of 85), chest in 19% (16 of 85), retroperitoneum in 13% (11 of 85), intraabdominal in 12% (10 of 85), intrapelvic in 7% (6 of 85), and head or neck in 4% (3 of 85). Initial diagnostic and staging information, including the use of PET-CT, bone scan, CT chest, and BMAB, was collected. Metastatic disease at the time of presentation or during follow-up was noted. The utility of BMAB was determined by the rate of positive tests in those undergoing BMAB during the initial staging process. Descriptive statistical analysis was sufficient to address the study question, and therefore no comparative statistics were performed. RESULTS: BMAB was obtained during the initial staging process in 64% (54 of 85) of patients. This BMAB was negative in all 54 patients, including those with known metastatic disease. CONCLUSION: Diagnosing metastatic disease in extraskeletal Ewing sarcoma is important as the presence of metastases at diagnosis adversely affects prognosis. The routine use of BMAB in the staging process of extraskeletal Ewing sarcoma is of low diagnostic yield. BMAB is unlikely to diagnose metastatic involvement even in patients with known metastases to bone. We do not have enough data to suggest whether other modalities, such as PET-CT, might be more useful. Similar studies should be pursued to determine the utility of the remainder of staging modalities in patients with extraskeletal Ewing sarcoma to elucidate the most efficient and effective staging protocol. LEVEL OF EVIDENCE: Level III, diagnostic study.

Primary Intracranial Ewing Sarcoma Invading the Superior Sagittal Sinus with EWSR1-FLI1 Gene Fusion and EWSR1 Gene Mutation: A Case Report and Literature Review.

BACKGROUND: Primary intracranial Ewing sarcoma (ES) is an extremely rare intracranial malignant tumor, mostly occurring in children and adolescents. Because of its rarity, the magnetic resonance imaging (MRI) features and treatment strategies of primary intracranial ES are still unclear. METHODS: The purpose of this study was therefore to report a case of primary intracranial ES, whose molecular features included both EWSR1-FLI1 (EWS RNA binding protein 1- Friend leukemia integration 1) gene fusion and EWSR1 gene mutation. It is worth noting that this is the first reported case of ES invading the superior sagittal sinus and mostly causing occlusion. At the same time, there were polymorphisms of four drug metabolism-related enzymes in the tumor. Subsequently, we conducted a literature review to characterize the clinical features, imaging findings, pathological features, treatments, and prognoses of primary intracranial ESs. RESULTS: A 21-year-old female was admitted to the hospital with headache with nausea and vomiting for 2 weeks. An MRI showed a 3.8 × 4.0 cm large heterogeneous mass in the bilateral parietal lobe with peritumoral edema. The tumor invaded the superior sagittal sinus and mostly caused occlusion of the middle segment of the superior sagittal sinus. The mass was successfully removed using a neuromicroscope. Postoperative pathology indicated a primary intracranial ES. High throughput sequencing (next generation sequencing) showed that there was EWSR1-FLI1 gene fusion and EWSR1 gene mutation in the tumor, with polymorphisms of four drug metabolism-related enzymes and low tumor mutational burden. Subsequently, the patient received intensity modulated radiation therapy. The patient has signed an informed consent form. CONCLUSIONS: The diagnosis of primary intracranial ES depended on histopathology, immunohistochemistry staining, and genetic testing. At present, total tumor resection combined with radiotherapy and chemotherapy is the most effective treatment. We report the first case of primary intracranial ES invading the superior sagittal sinus and causing middle segment occlusion, accompanied by EWSR1-FLI1 gene fusion and EWSR1 gene mutation.