Primary Ewing's Sarcoma of the Sternum in an Adult Male: A Rare Case Report.

Ewing's sarcoma, a rare primary bone malignancy primarily affecting adolescents and young adults, typically manifests in the pelvic bones and femur. Primary Ewing's sarcoma of the sternum is exceptionally rare, constituting less than 1% of cases. We present a case of a 34-year-old man with a 2-month history of anterior chest wall pain initially attributed to muscular spasm. Subsequently, the patient developed a palpable mass and imaging demonstrated a mid-lower sternal lesion with cortical destruction and soft tissue involvement, confirmed as Ewing's sarcoma on biopsy. In addition, a suspicious lesion was identified in the left distal tibia, which was histologically confirmed as a metastasis from the primary sternal sarcoma. Neoadjuvant chemotherapy preceded partial sternotomy with rib resection and reconstruction, achieving clear surgical margins. Postoperative evaluation showed shrinkage in the sternal lesion and near-resolution of the tibial metastasis. Subsequent chemotherapy cycles resulted in no evidence of the disease on the follow-up positron emission tomography scan. This case underscores the diagnostic challenges of primary sternal Ewing's sarcoma and emphasizes the importance of early recognition and comprehensive evaluation in managing such rare presentations.

Case report and literature review: A young man with giant intra-abdominal Ewing sarcoma.

RATIONALE: Extraosseous Ewing sarcoma (EES) is a rare manifestation within the Ewing sarcoma tumor family (ESFT). Its clinical manifestations lack specificity, intestinal obstruction is the main symptom but can also present with abdominal pain, gastrointestinal bleeding, and other discomforts, making it prone to misdiagnosis as intestinal mesenchymal tumor. PATIENT CONCERNS: A 29-year-old male was admitted to the hospital with intestinal obstruction symptoms and abdominal CT suggesting "left abdominal occupation." DIAGNOSIS: The patient was initially misdiagnosed as intestinal mesenchymal tumor, and was later definitively diagnosed as abdominal Ewing sarcoma by postoperative pathology and genetic testing. INTERVENTIONS: Due to the patient's surgical indication, surgical resection with exploratory laparotomy was performed and then the patient underwent systemic chemotherapy. OUTCOMES: Intraoperatively, we found a 15-cm tumor originating from the proximal jejunum, with invasion into the peritoneum, duodenum, jejunum, and colon. Finally, the pathological report revealed Ewing sarcoma. LESSONS: Giant abdominal Ewing sarcoma with a diameter of 15 cm is rare. Considering postoperative pathology and genetic testing, abdominal Ewing sarcoma was suspected. The patient was successfully treated using surgery.

Evaluating Circulating Biomarkers for Diagnosis, Prognosis, and Tumor Monitoring in Pediatric Sarcomas: Recent Advances and Future Directions.

Pediatric sarcomas present a significant challenge in oncology. There is an urgent need for improved therapeutic strategies for high-risk patients and better management of long-term side effects for those who survive the disease. Liquid biopsy is emerging as a promising tool to optimize treatment in these patients by offering non-invasive, repeatable assessments of disease status. Circulating biomarkers can provide valuable insights into tumor genetics and treatment response, potentially facilitating early diagnosis and dynamic disease monitoring. This review examines the potential of liquid biopsies, focusing on circulating biomarkers in the most common pediatric sarcomas, i.e., osteosarcoma, Ewing sarcoma, and rhabdomyosarcoma. We also highlight the current research efforts and the necessary advancements required before these technologies can be widely adopted in clinical practice.

Monostotic femoral Caffey disease masquerading as Ewing sarcoma.

We describe a rare case of monostotic infantile cortical hyperostosis (Caffey disease) involving the left femur of an infant, who presented with recent onset left thigh swelling, following vaccination. Radiological workup showed a lamellated periosteal reaction involving the left femoral diaphysis on radiographs masquerading as a bone tumour. The child underwent MRI of the left thigh, which showed extensive muscle oedema without any abnormal soft-tissue proliferation, marrow signal alteration, cortical breach or collection. The follow-up radiograph showed exuberant new bone formation in the second week. The patient was given symptomatic treatment and the parents were counselled. The child recovered well with gradual resolution of symptoms and bony remodelling on a 6-month follow-up radiograph. Here, we describe the serial changes on the radiographs in Caffey disease with monostotic involvement and the role of MRI in difficult cases to differentiate it from other common mimickers, such as infections and neoplasia.

Sarcoma de Ewing extraesquelético: reporte de caso / Extraskeletal Ewing's Sarcoma: a Case Report

Introducción: El sarcoma de Ewing es un tumor maligno de alto grado con localización principalmente ósea; se han reportado aproximadamente 12% con presentación extra-esquelética. Actualmente, existen alrededor de 20 casos descritos en la literatura con origen mediastinal y 10 casos con origen pulmonar. Caso clínico: Se presenta el caso de una mujer de 25 años con un mes de disnea y dolor torácico, con el hallazgo de derrame pleural masivo y tumoración mediastinal en hemitórax derecho. Se le realiza toracotomía anterior bilateral con esternotomía transversa de Clamshell, con resección parcial que demuestra, por patología, sarcoma monomórfico de alto grado e inmunohistoquímica concluyente de sarcoma de Ewing. Conclusión: Este caso es una entidad rara y conlleva un reto diagnóstico para el clínico; sin embargo, debe sospecharse considerando la presentación clínica y radiológica del paciente, buscando incrementar la tasa de supervivencia mediante el diagnóstico y tratamiento oportuno.

Introduction: Ewing's sarcoma is a high-grade malignant tumor with mainly bony lo-calization; approximately 12% have been reported with extraskeletal presentation. Currently, there are about 20 cases described in the literature with mediastinal origin and 10 pulmonary cases. Case Report: We present the case of a 25-year-old woman with one month of dysp-nea and chest pain, with massive pleural effusion and mediastinal tumor in the right hemithorax who underwent bilateral anterior thoracotomy with Clamshell transverse sternotomy, with partial resection demonstrating, by pathology, high-grade monomorphic sarcoma and conclusive immunohistochemistry of Ewing's sarcoma. Conclusion: This case is a rare entity and involves a diagnostic challenge for the clinician; however, it should be suspected considering the clinical and radiological presentation of the patient, seeking to increase the survival rate through timely diagnosis and treatment.

Ewing sarcoma presenting in the lung: a case report.

BACKGROUND: Ewing sarcoma is a malignant round-cell tumor that primarily affects bones in children. It can also arise in extraosseous tissues, such as the lung, kidneys, and liver. The presentation symptoms of Ewing sarcoma may include cough, dyspnea, and chest pain. CASE PRESENTATION: This report details the history of a 15-year-old Syrian boy with a previous diagnosis of Hodgkin lymphoma who presented with chronic shoulder pain. Imaging studies revealed an 80 mm mass in the apex of the left lung, which was confirmed through histopathological examination to be Ewing sarcoma following a computed-tomography-guided biopsy. The patient received multiple cycles of chemotherapy and subsequently underwent surgical resection of the remaining mass. CONCLUSIONS: This case highlights the rare occurrence of Ewing sarcoma in the lung and the unusual clinical presentation of shoulder pain without other accompanying symptoms.

Prognostic factors and outcome of relapsed/progressive pediatric Ewing sarcoma: single-center 10-year experience.

BACKGROUND: Ewing sarcoma (ES) is the second most common primary malignant bone tumor in children and adolescents. Despite more intensive chemotherapy regimens and improved local control therapy, there is still a considerable rate of recurrent/progressive disease. METHODS: A retrospective study of 50 relapsed/progressive ES patients who were treated at the National Cancer Institute (NCI), Cairo University, during the period from 1st of January 2008 to the end of December 2018, to assess different prognostic variables and disease outcomes. RESULTS: Out of fifty eligible cases, 32 patients (64%) had disease recurrence, and 18 (36%) developed disease progression on treatment. The median follow-up period was 7.4 months. The median overall survival (OS) was 7.5 months, and the cumulative OS was 64% at 6 months and 32.6% at 1 year. The cumulative event-free survival (EFS) was 41.3% at 6 months and 22.3% at 1 year. Patients with disease recurrence had better OS and EFS than patients with disease progression (p = 0.019). Patients who underwent local control at relapse/progression had a significantly better outcome than patients who received chemotherapy only (p < 0.001). Recurrence > 2 years from initial diagnosis was the only independent predictor of better survival outcome. CONCLUSIONS: Patients with relapsing/progressive ES portended a poor outcome, with disease progression on treatment faring worse than relapse. Better outcome was observed in patients who experienced recurrence > 2 years after diagnosis, patients with disease recurrence rather than disease progression on treatment, and patients who underwent local control along with intensive chemotherapy.

Extraosseous Ewing Sarcoma Manifesting as an Acute Abdomen in a Young Adult Male: a Case Report.

Ewing sarcoma is a tumor primarily affecting children and young adults, and usually affects long bones. Extraosseous Ewing sarcoma (EES) is a rare primary tumor of soft tissues. We present a case of abdominal EES with metastasis to thoracic cavity, which presented as abdominal pain and vomiting in a 21-year-old previously healthy gentleman.

[Experience in diagnosis and treatment of 6 cases of renal Ewing's sarcoma with venous thrombus].

OBJECTIVE: To review and analyze the clinical diagnosis and treatment of renal Ewing's sarcoma with venous tumor embolus, to follow up the survival and prognosis of the patients, and to provide help for the diagnosis and treatment of the disease. METHODS: Clinical data (including general data, surgical data and postoperative pathological data) of patients diagnosed with renal Ewing's sarcoma with venous tumor embolus in Peking University Third Hospital from June 2016 to June 2022 were collected, and the prognosis of the patients was followed up to analyze the influence of diagnosis and treatment process on the prognosis of the disease. RESULTS: There were 6 patients, including 1 male and 5 females. There were 4 cases of left renal tumor and 2 cases of right renal tumor. The median age at diagnosis was 28 years (16-52 years). The imaging findings were all exogenous tumors with internal necrotic tissue and hemorrhage. The mean maximum tumor diameter was 12.6 cm, and the mean tumor thrombus length was 7.8 cm. Four patients underwent open surgery and 2 patients underwent laparoscopic surgery. The postoperative pathological results were renal Ewing sarcoma. Immunohistochemical results showed 3 cases of CD99 (+), 2 cases of FLI-1 (+), and 1 case of CD99, FLI-1 (-). 3 patients received chemotherapy (cyclophosphamide, doxorubicin, vincristine/ifosfamide, etoposide), 1 case received chemotherapy combined with radiotherapy, and 2 cases received no adjuvant therapy. The mean overall survival (OS) of the 6 patients was 37 months, and the mean OS of the 4 patients (47 months) who received chemotherapy was significantly higher than that of the 2 patients (16 months) who did not receive chemotherapy (P=0.031). CONCLUSION: Renal Ewing's sarcoma with venous tumor embolus is rare in clinic, and it is common in young female patients. The operation is difficult and the prognosis is poor. Surgical resection, adjuvant radiotherapy and chemotherapy can improve the overall survival rate of the patients.

Extraskeletal Ewing Sarcoma Disguised as a Vascular Malformation.

Extraskeletal Ewing sarcoma (EES) is a rare entity, accounting for only 3% of lesions encountered in upper extremity. We present two paediatric patients, who were initially diagnosed with a vascular malformation based on clinical assessment and imaging. Final histopathology revealed Ewing sarcoma of soft tissue origin, confirmed by immunohistochemical analysis. Hand surgeons, who are routinely approached for a myriad of hand pathologies, should be wary and consider EES as a differential when treating such lesions. A multidisciplinary approach with an appropriate treatment algorithm can help in a speedy diagnosis, improving the long-term prognosis of the disease. Level of Evidence: Level V (Therapeutic).

Diagnosis and management of cancer therapy-related myocarditis in a young female: A case report and review of literature.

BACKGROUND: The treatment of choice for Extra-osseous Ewing's sarcoma/primitive neuroectodermal tumor (ES/PNET), a rare neoplasm, is the VAC/IE regimen. This regimen includes Doxorubicin, Vincristine, Cyclophosphamide, Ifosfamide, and Etoposide, all of which have cardiotoxic effects. Myocarditis, a potentially threatening side effect following cancer therapy, can be accurately managed and diagnosed. CASE PRESENTATION: In the current study, we report the case of a 19-year-old female with a mass on the abdominal wall, diagnosed with ES/PNET. She was treated with the VAC/IE regimen. A month after the last session of chemotherapy, she experienced dyspnea. Upon evaluation, a high level of troponin and a low left ventricular ejection fraction (LVEF) were detected via transthoracic echocardiography. She was treated with anti-heart failure drugs, but the response was unsatisfactory. The possibility of Cancer therapy-related myocarditis was suspected, and cardiac magnetic resonance imaging (CMR) confirmed acute myocarditis. This patient exhibited a significant response to intravenous immunoglobulin (IVIG), with her LVEF improving from 30-35% to 50% within three months. CONCLUSION: In this case, based on negative tests and the absence of viral signs and symptoms, Cancer therapy-related myocarditis is highly suspected as the cause of myocarditis. This case underscores the importance of accurately utilizing CMR as a non-invasive method for diagnosing myocarditis. It effectively highlights the identification of reversible myocarditis with appropriate treatment and the notable response to IVIG, suggesting its potential as a favorable treatment for myocarditis in younger patients.

[Ewing sarcoma/primitive hepatic neuroectodermal tumor]. / Sarcoma de Ewing/tumor neuroectodérmico primitivo hepático.

Ewing sarcoma (ES) and primitive neuroectodermal tumor (PNET) belong to the group of neoplasms called small round cell tumors. PNETs have been divided into central and peripheral. ES and peripheral PNETs arise from bones, soft tissues, or peripheral nerves. We present a case of hepatic ES/PNET in a healthy man that began four months before consultation with abdominal symptoms and weight loss. Upper gastrointestinal endoscopy and laboratory tests revealed no notable findings. The abdominal tomography revealed an enlarged liver due to a solid lesion that involved all its segments with intravenous contrast enhancement and large areas of necrosis. It compressed and displaced neighboring structures. Core needle biopsy of the liver lesion was performed: small round cell neoplasm. Immunohistochemistry revealed negativity for CD45, CKA1/A3, chromogranin, synaptophysin, and cytokeratins CK7 and CK20. Dim CD56 expression and CD99, FLI-1, and NKX2 positivity. He underwent chemotherapy treatment with carboplatin and etoposide for 6 cycles with clinical improvement and tolerance. Control images showed reduction of the mass with involvement of the right hepatic lobe, involvement of the inferior vena cava, infiltration of the right adrenal gland and upper pole of the right kidney. He was referred to hepatobiliary surgery for surgical resection of the residual lesion. The patient rejected the proposed surgical procedure. Our objective is to highlight the clinical and histological diagnostic challenge of this entity that requires ruling out other clinical entities.

El sarcoma de Ewing (ES) y el tumor neuroectodérmico primitivo (PNET) pertenecen al grupo de neoplasias denominadas tumores de células pequeñas y redondas. Los PNET se dividen en centrales y periféricos. El ES y los PNET periféricos surgen del tejido óseo, de los tejidos blandos o nervios periféricos. Presentamos un caso de ES/PNET hepático en un hombre sano que inició cuatro meses antes de la consulta con síntomas abdominales y pérdida de peso. La endoscopia digestiva alta y la analítica no revelaron hallazgos relevantes. En la tomografía de abdomen se evidenció hígado aumentado de tamaño a expensas de lesión sólida que comprometía todos sus segmentos con realce al contraste endovenoso y grandes áreas de necrosis. Comprimía y desplazaba estructuras vecinas. Se realizó biopsia con aguja gruesa de la lesión hepática: neoplasia de células pequeñas y redondas. La inmunohistoquímica reveló negatividad para CD45, CKA1/A3, cromogranina, sinaptofisina y citoqueratinas CK7 y CK20. Expresión tenue de CD56 y positividad de CD99, FLI-1 y NKX2. Realizó tratamiento quimioterápico con carboplatino y etopósido por 6 ciclos con mejoría clínica y tolerancia al mismo. En imágenes de control se evidenció reducción de la masa con afección del lóbulo hepático derecho, compromiso de la vena cava inferior, infiltración de la glándula suprarrenal y polo superior del riñón derechos. Se remitió a cirugía hepatobiliar para resección quirúrgica de la lesión residual. El paciente rechazó el procedimiento quirúrgico. Nuestro objetivo es destacar el desafío diagnóstico clínico e histológico de esta entidad que obliga a descartar otras entidades clínicas.

Biological Sample Collection to Advance Research and Treatment: A Fight Osteosarcoma Through European Research and Euro Ewing Consortium Statement.

Osteosarcoma and Ewing sarcoma are bone tumors mostly diagnosed in children, adolescents, and young adults. Despite multimodal therapy, morbidity is high and survival rates remain low, especially in the metastatic disease setting. Trials investigating targeted therapies and immunotherapies have not been groundbreaking. Better understanding of biological subgroups, the role of the tumor immune microenvironment, factors that promote metastasis, and clinical biomarkers of prognosis and drug response are required to make progress. A prerequisite to achieve desired success is a thorough, systematic, and clinically linked biological analysis of patient samples, but disease rarity and tissue processing challenges such as logistics and infrastructure have contributed to a lack of relevant samples for clinical care and research. There is a need for a Europe-wide framework to be implemented for the adequate and minimal sampling, processing, storage, and analysis of patient samples. Two international panels of scientists, clinicians, and patient and parent advocates have formed the Fight Osteosarcoma Through European Research consortium and the Euro Ewing Consortium. The consortia shared their expertise and institutional practices to formulate new guidelines. We report new reference standards for adequate and minimally required sampling (time points, diagnostic samples, and liquid biopsy tubes), handling, and biobanking to enable advanced biological studies in bone sarcoma. We describe standards for analysis and annotation to drive collaboration and data harmonization with practical, legal, and ethical considerations. This position paper provides comprehensive guidelines that should become the new standards of care that will accelerate scientific progress, promote collaboration, and improve outcomes.

Ewing Sarcoma of the Larynx with Thyroid Cartilage Destruction: A Case Report.

Ewing sarcoma of the larynx is extremely rare, only a few number of cases have been reported. In this report, we describe a case of extraskeletal Ewing sarcoma of the larynx with thyroid cartilage destruction. Laryngoscope, 134:4577-4581, 2024.

Primary Ewing's sarcoma of the uterine cervix: a case report and review of the literature.

BACKGROUND: Ewing's sarcoma (ES) is an aggressive cancer of bone and soft tissue, most of which tend to occur in the bone. Extraosseous Ewing's sarcoma (EES) of the cervix is extremely rare. CASE PRESENTATION: In the present work, we reported a 39-year-old cervical EES patient with a 2.5*2.1*1.8 cm tumor mass. According to previous literatures, our case is the smallest tumor found in primary cervical ES ever. The patient initially came to our hospital due to vaginal bleeding, and then the gynecological examination found a neoplasm between the cervical canal and partially in the external cervical orifice. The diagnosis of EES was confirmed below: Hematoxylin & Eosin staining (H&E) revealed small round blue malignant cells in biopsy specimens. Immunohistochemistry (IHC) showed the positive staining for CD99, NKX2.2, and FLI1. Disruption of EWSR1 gene was found by fluorescence in situ hybridization (FISH), and the EWSR1-FLI1 gene fusion was determined by next-generation sequencing (NGS). The patient received laparoscopic wide hysterectomy, bilateral adnexectomy, pelvic lymphadenectomy, and postoperative adjuvant chemotherapy and remained disease free with regular follow-up for 1 year. CONCLUSIONS: Through a systematic review of previously reported cervical ES and this case, we highlighted the importance of FISH and NGS for the accuracy of ESS diagnosis, which could assist on the optimal treatment strategy. However, due to the rarity of the disease, there is no standard treatment schemes. Investigation on molecular pathological diagnosis and standardization of treatment regimens for cervical ES are critical to patients' prognosis.

Clinicopathological and molecular genetic analysis of 13 cases of primary retroperitoneal Ewing sarcoma.

Retroperitoneal Ewing sarcomas (RES) are very rare and mostly described in case reports. The purpose of this study was to retrospectively analyze the clinicopathology, molecular characteristics, biological behavior, and therapeutic information of 13 cases of primary RES with immunohistochemical staining, fluorescence in situ hybridization, RT-PCR and NGS sequencing detection techniques. The thirteen patients included eight males and five females with a mean age of 34 years. Morphologically, the tumors were comprised of small round or epithelial-like cells with vacuolated cytoplasm (6/13,46 %) arranged in diffuse, nested (8/13,62 %) and perivascular (7/13,54 %) patterns. Unusual morphologic patterns, such as meningioma-like swirling structures and sieve-like structures were relatively novel findings. Immunohistochemical studies showed CD99 (12/13; 92 %), CD56 (11/13; 85 %), NKX2.2 (9/13; 69 %), PAX7 (10/11;91 %) and CD117(6/9;67 %) to be positive.12 cases (92 %) demonstrated EWSR1 rearrangement and 3 cases displayed EWSR1::FLI1 fusion by FISH. ERCC4 splice-site variant, a novel pathogenic variant, was discovered for the first time via RNA sequencing. With a median follow-up duration of 14 months (6 to 79 months), 8/13 (62 %) patients died, while 5/13(38 %) survived. Three cases recurred, and five patients developed metastasis to the liver (2 cases), lung (2 cases) and bone (1 case). RES is an aggressive, high-grade tumor, prone to multiple recurrences and metastases, with distinctive morphologic, immunohistochemical, and molecular genetic features. ERCC4 splicing mutation, which is a novel pathogenic variant discovered for the first time, with possible significance for understanding the disease, as well as the development of targeted drugs.

A Systemic Review of Primary Malignant Long Bone Tumors in Children and Adolescents.

PURPOSE OF THE STUDY: Managing bone tumours is complex, relying on limited evidence, expert opinions, and retrospective reviews. Multidisciplinary approaches and early diagnosis are crucial for better outcomes, especially in young patients with growing skeletons. The aim of this systemic review and meta-analysis is to give a comprehensive review of common malignant tumors affecting long bones in children and adolescents. MATERIAL AND METHODS: A PubMed/Medline search for "primary malignant long bone tumours in children" initially retrieved 1120 papers, which were subsequently narrowed down to 110 articles based on inclusion and exclusion criteria. These articles were reviewed, focusing on clinical presentation, diagnostic workup, treatment options, surgical planning, and variations in presentation, including rare tumours. The two most commonly reported tumours were osteosarcoma and Ewing sarcoma, leading to the division of studies into five groups. The inclusion criteria encompassed malignancies in patients aged 2-25 years, work-up, imaging, surgical treatment, rare tumour case reports, and surgical management principles, resulting in a heterogeneous group of articles. To enhance categorisation, it was clarified that studies with 10 or more cases were considered retrospective reviews. RESULTS: Reviewing of results thus demonstrate that the two likely tumours in children under consideration were osteosarcoma and Ewing sarcoma. Their presentation findings and clinical features were discussed in detail in the review. It is worth noting here that in case of differential diagnosis this should be the first on the list. DISCUSSION AND CONCLUSIONS: Although focus of literature is more on the two most common tumours. However, rare tumours should be considered as they can mimic these common tumors. KEY WORDS: primary, malignant, bone tumors, children, adolescent.

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.