Important Recently Characterized Non-Ewing Small Round Cell Tumors

Pediatric BCOR-Altered Tumors From Soft Tissue/Kidney Display Specific DNA Methylation Profiles

In the pediatric population, BCL6-correpresor gene (BCOR)-upregulated tumors include primitive myxoid mesenchymal tumors/undifferentiated sarcomas (PMMTI/UND), clear cell sarcomas of the kidney (CCSK), and high-grade neuroepithelial tumors (HG-NET). We investigated DNA methylation (DNAm) and copy number variation (CNV) profiling in these tumors (N = 34) using an Illumina EPIC BeadChip to better define the potential use of these tools to confirm diagnosis and predict outcomes. Twenty-seven tumors from 25 patients (age range, 0-10 years), showed molecular confirmation of genetic abnormalities as follows: BCOR internal tandem duplication in 14 PMMTI/UND, 8 CCSK, and 3 HG-NET and YWHAE fusions in 2 PMMTI/UND. The remaining 7 cases lacking informative molecular data were analyzed by immunophenotyping and were included in the study as a training cohort, clearly separated from the main study group. These were 4 PMMTI, 1 HG-NET, and 1 CCSK in which poor RNA preservation precluded the confirmation of BCOR rearrangements and 1 CCSK in which no rearrangements were found. DNAm data were compared with those of brain tumor and/or sarcoma classifier. Differentially methylated regions (DMRs) were analyzed in the 3 groups. Twenty-two cases of the 24 molecularly confirmed PMMTI/UND and CCSK and 3 of 6 of those with only immunophenotyping were classified within the methylation class "BCOR-altered sarcoma family" with optimal calibrated scores. PMMTI/UND and CCSK showed similar methylation profiles, whereas thousands of DMRs and significantly enriched pathways were evident between soft tissue/kidney tumors and HG-NET. The CNV analysis showed an overall flat profile in 19 of the 31 evaluable tumors (8/10 CCSK; 9/18 PMMTI/UND; 2/4 HG-NET). The most frequent CNVs were 1q gain and 9p and 10q loss. Follow-up time data were available for 20 patients: ≥2 CNV significantly correlated with a worse overall survival rate. In conclusion, soft tissue and kidney BCOR sarcomas matched with BCOR-altered sarcoma methylation class, whereas those from the brain matched with the central nervous system tumor classifier HG-NET BCOR, supporting the notion that DNAm profiling is an informative diagnostic tool. CNV alterations were associated with a more aggressive clinical behavior.

BCOR-Rearranged Sarcoma of the Tonsil

A tonsillar mass in a young patient with no medical issues routinely presents as an infectious process. Practitioners must maintain a broad differential if diagnostic testing does not support an infection. Neoplasm must be excluded. Otolaryngologists must consider malignancies other than squamous cell carcinoma, the most common oropharyngeal malignancy, and lymphoma. Rare tumors, such as sarcomas, must also be considered. Otolaryngologists must be familiar with the proper management of rare oropharyngeal malignancies.

Small round cell sarcomas

Undifferentiated small round cell sarcomas (SRCSs) of bone and soft tissue comprise a heterogeneous group of highly aggressive tumours associated with a poor prognosis, especially in metastatic disease. SRCS entities mainly occur in the third decade of life and can exhibit striking disparities regarding preferentially affected sex and tumour localization. SRCSs comprise new entities defined by specific genetic abnormalities, namely EWSR1-non-ETS fusions, CIC-rearrangements or BCOR genetic alterations, as well as EWSR1-ETS fusions in the prototypic SRCS Ewing sarcoma. These gene fusions mainly encode aberrant oncogenic transcription factors that massively rewire the transcriptome and epigenome of the as yet unknown cell or cells of origin. Additional mutations or copy number variants are rare at diagnosis and, depending on the tumour entity, may involve TP53, CDKN2A and others. Histologically, these lesions consist of small round cells expressing variable levels of CD99 and specific marker proteins, including cyclin B3, ETV4, WT1, NKX3-1 and aggrecan, depending on the entity. Besides locoregional treatment that should follow standard protocols for sarcoma management, (neo)adjuvant treatment is as yet ill-defined but generally follows that of Ewing sarcoma and is associated with adverse effects that might compromise quality of life. Emerging studies on the molecular mechanisms of SRCSs and the development of genetically engineered animal models hold promise for improvements in early detection, disease monitoring, treatment-related toxicity, overall survival and quality of life.

Incidence and Demographic Profile of Ewings Sarcoma: Experience From a Tertiary Care Hospital

Introduction

Ewing sarcoma (ES) family of tumors (EFT) represents the second most common primary bone malignancy affecting children and adolescents after osteosarcoma. The tumor is characteristically associated with a chromosomal translocation resulting in a fusion transcript (EWSR1-FLI1). However, new molecular techniques have significantly transformed our understanding of this rare disease. The present study aims to analyze the incidence and demographic profile of Ewings sarcoma with an insight into the recent updates of the Ewing sarcoma (ES) family of tumors (EFT).

Materials and methods

All cases of Ewings sarcoma/peripheral neuroectodermal tumor (PNET) presented at a tertiary care center in South India from January 2010-December 2020 were included in this study. The demographic profile and patient details were obtained from the medical records section. Pathology reports of the included cases were retrieved, and associated factors were analyzed, including immunohistochemical studies and molecular workup.

Results

Out of the 58 cases included in the study, 30 cases (52%) were children and adolescents (< 20 years) and the rest 28 cases (48%) were adults. The mean age was 22.56. Female preponderance was noted, with 32 cases (56%) being females and 26 cases (44%) were males. The location of the tumor was variable. Twenty-five (25) cases (44%) were found in bones such as the clavicle, tibia, and mandible. Seven cases were seen on the anterior chest wall. Other sites included the oropharynx, lungs, endobronchial, infrascapular region, retroperitoneum, and thighs. One case presented as metastatic Ewings sarcoma with divergent differentiation in lungs with the primary site of the tumor being the right humerus. Immunohistochemical (IHC) studies were done on 55 of the 58 tumors. Forty-six (46) cases (80.9%) were CD99 positive and 41 cases(71.4%) were FLI-1 positive. Eleven (11) cases were both CD 99 and FLI-1 positive. NKX2.2, a recent IHC marker, was positive in six cases.

Conclusion

Ewings sarcoma has a peak incidence in the second decade of life with a propensity toward the axial skeletal location. Understanding the pathobiology and molecular updates of ES is significant to differentiate them from aggressive round cell sarcomas. They not only aid in predicting the prognosis of these aggressive tumors but also guide in therapy.

A Rare Case of Breast Malignancy in an Adolescent Woman: Lessons Learned from Diagnosis and Management

Introduction

Primary breast malignancy in adolescent women is very rare and differs in several aspects from findings in adult women.

Case Presentation

A young woman aged 16 years presented with a locally aggressive breast tumor. The patient received cisplatin-based chemotherapy followed by tumor resection assuming a diagnosis of germ cell tumor. Four months later, she developed locally recurrent disease and underwent a mastectomy. No definite diagnosis was agreed upon despite intensive pathological workup. Subsequent management consisted of follow-up only and the patient remains in complete remission 9 years later.

Conclusion

This case demonstrates the difficulty of diagnosis and management of rare malignancies in adolescents, and highlights the importance of international and interdisciplinary collaboration in diagnosis and clinical decision-making.

Novel RGAG1-BCOR gene fusion revealed in a somatic soft tissue sarcoma with a long follow-up

BCOR-rearranged sarcomas are rare and belong to the Ewing-like sarcomas (ELS). Their morphology and histopathological features make the diagnosis challenging. We present a case, initially diagnosed as an unusual extraskeletal myxoid chondrosarcoma (EMC). A 54-year-old male patient developed an asymptomatic swelling of the lower leg. Imaging showed a 9.5-cm large intramuscular soft tissue mass. Due to its morphological and immunohistochemical profile on biopsy, it was initially diagnosed as an EMC. The patient was treated by complete resection and adjuvant radiotherapy and remained free of tumor at 7 years follow-up. Using next-generation sequencing (NGS), we retrospectively identified RGAG1-BCOR gene fusion (confirmed by RT-PCR), which has not been described in somatic soft tissue tumors so far. This finding broadens the spectrum of partner genes in the BCOR-rearranged sarcomas in a tumor with a well-documented, long clinical follow-up.

Molecular Approaches to Diagnosis in Ewing Sarcoma: Targeted RNA Sequencing

Molecular testing of pathognomonic gene fusions is mandatory for small round cell tumor diagnosis, including Ewing sarcoma which is indeed defined by a variety of chimeric genes. Reference laboratories are increasingly implementing NGS-based techniques to overcome several limitations of conventional singleplex determinations. We have been early adopters of a targeted-RNA sequencing method based on Anchored multiplex PCR, which allows assessing several fusion transcripts simultaneously with previous knowledge of only one partner gene. Here we describe in detail our protocol and tips for nucleic acid extraction, library preparation, sequencing, and reporting of gene fusions.

Current Status of Management and Outcome for Patients with Ewing Sarcoma

Ewing sarcoma is the second most common bone sarcoma in children after osteosarcoma. It is a very aggressive malignancy for which systemic treatment has greatly improved outcome for patients with localized disease, who now see survival rates of over 70%. However, for the quarter of patients presenting with metastatic disease, survival is still dismal with less than 30% of patients surviving past 5 years. Patients with disease relapse, local or distant, face an even poorer prognosis with an event-free 5-year survival rate of only 10%. Unfortunately, Ewing sarcoma patients have not yet seen the benefit of recent years' technical achievements such as next-generation sequencing, which have enabled researchers to study biological systems at a level never seen before. In spite of large multinational studies, treatment of Ewing sarcoma relies entirely on chemotherapeutic agents that have been largely unchanged for decades. As many promising modern therapies, including monoclonal antibodies, small molecules, and immunotherapy, have been disappointing to date, there is no clear candidate as to which drug should be investigated in the next large-scale clinical trial. However, the mechanisms driving tumor development in Ewing sarcoma are slowly unfolding. New entities of Ewing-like tumors, with fusion transcripts that are related to the oncogenic EWSR1-FLI1 fusion seen in the majority of Ewing tumors, are being mapped. These tumors, although sharing much of the same morphologic features as classic Ewing sarcoma, behave differently and may require a different treatment. There are also controversies regarding local treatment of Ewing sarcoma. The radiosensitive nature of the disease and the tendency for Ewing sarcoma to arise in the axial skeleton make local treatment very challenging. Surgical treatment and radiotherapy have their pros and cons, which may give rise to different treatment strategies in different centers around the world. This review article discusses some of these controversies and reproduces the highlights from recent publications with regard to diagnostics, systemic treatment, and surgical treatment of Ewing sarcoma.

Imaging features and clinical course of undifferentiated round cell sarcomas with CIC-DUX4 and BCOR-CCNB3 translocations

OBJECTIVE

To describe the pre-treatment imaging features and clinical course of undifferentiated round cell sarcomas with CIC-DUX4 and BCOR-CCNB3 translocations.

MATERIALS AND METHODS

In this retrospective study, several pre-treatment imaging features (tumor location, size, enhancement pattern, necrosis, flow voids, calcification, and FDG avidity) and the clinical course of patients were evaluated.

RESULTS

In 12 patients with CIC-DUX4 sarcomas (median age, 24 years; range, 12-75), sarcomas were located in the soft tissue (n = 10), bone (n = 1), and lungs (n = 1). On MRI, all 10 CIC-DUX4 sarcomas presented as a large necrotic mass (mean size 6.7 cm, range 2.3-11.3) with 100% demonstrating contrast enhancement, 60% showing flow voids, and 20% demonstrating fluid-fluid levels. On PET, the mean SUVmax was 13.2 (range, 8.5-18.1). Among 12 patients with follow-up, 3 died within a year of diagnosis. The most common site of metastases was the lungs (5/12). In 5 patients with BCOR-CCNB3 sarcomas (median age, 14 years; range, 2-17), sarcomas were located in the spine (n = 2), femur (n = 1), tibia (n = 1), and pelvis (n = 1). On radiograph or CT, 2 were lytic, 3 were sclerotic. Soft tissue calcifications occurred in 40% of BCOR-CCNB3 sarcomas. On MRI, all 3 BCOR-CCNB3 tumors enhanced with 33% demonstrating flow voids and 66% exhibiting necrosis. On PET, the mean SUVmax was 6.3 (range 5.7-6.9).

CONCLUSION

CIC-DUX4 sarcomas often present as necrotic and hypermetabolic soft tissue masses while sarcomas with BCOR-CCNB3 translocations are vascular bone lesions with necrosis at imaging. CIC-DUX4 sarcomas are clinically more aggressive than BCOR-CCNB3 sarcomas.

CIC-rearranged round cell (Ewing-like) sarcoma of the uterus: Review of the literature

CIC-rearranged round cell sarcoma (CRS) is a rare entity that presents in various anatomical locations and involves deep soft-tissue structures and skin. Although commonly confused with and clinically similar to Ewing sarcoma (ES), investigators have recently shown that this unique condition maintains morphologic and pathologic features that are distinct from ES. In this report, we present and discuss a case of CRS of the uterus, the first of its kind to be reported in the English-language literature. We urge the scientific community to continue its investigations in elucidating the features of this entity, as young women who suffer from this condition have dismal prognoses and currently do not have access to therapeutic options for cure.

Pancreaticoduodenectomy for a primary duodenal capicua transcriptional repressor (CIC) -rearranged sarcoma with severe bleeding: a case report

BACKGROUND

Capicua transcriptional repressor (CIC) -rearranged sarcoma is characterized by small round cells, histologically similar to Ewing sarcoma. However, CIC-rearranged sarcoma has different clinical, histological, and immunohistochemical features from Ewing sarcoma. It is important to differentiate between these tumors.

CASE PRESENTATION

The patient is a 44-year-old man with a duodenal tumor diagnosed in another hospital who presented with a history of melena. Laboratory studies showed anemia with a serum hemoglobin of 6.0 g/dL. He was hospitalized and gastrointestinal bleeding was controlled successfully with endoscopy. However, he suffered from appetite loss and vomiting and progression of anemia a few weeks after presentation. Upper gastrointestinal endoscopy showed a circumferential soft tumor in the second portion of the duodenum and the endoscope could not pass distally. Computed tomography scan showed a greater than 10 cm tumor in the duodenum, with compression of the inferior vena cava and infiltrating the ascending colon. A definitive pathologic diagnosis could not be established despite four biopsies from the tumor edge. Due to gastrointestinal obstruction and progression of anemia, a pylorus-preserving pancreaticoduodenectomy with partial resection of the inferior vena cava and right hemicolectomy was performed as a complete tumor resection. The tumor was diagnosed as a CIC-rearranged sarcoma, but 2 months postoperatively local recurrence and distant metastases to the liver and lung were found. The patient died 3 months after surgery.

CONCLUSIONS

Although the only definitive treatment for CIC-rearranged sarcoma is surgical resection, the CIC-rearranged sarcoma is highly malignant with a poor prognosis even after radical resection. More research is needed to establish optimal treatment strategies.

Capicua Transcriptional Repressor-Rearranged Undifferentiated Round Cell Sarcoma Metastatic to the Brain Treated with Surgery and Stereotactic Radiosurgery

BACKGROUND

Ewing-like sarcoma with capicua transcriptional repressor (CIC) rearrangement is a unique class of undifferentiated round cell sarcomas characterized by CIC-double homeobox 4 gene fusion. Despite showing great histologic resemblance to Ewing sarcomas, they have proved to be a distinct pathological entity from the immunohistochemistry and genetic examinations and the response to treatment. We have presented a case of CIC-rearranged Ewing-like sarcoma with cerebral metastasis managed with operative resection and gamma knife radiosurgery.

CASE DESCRIPTION

A 56-year-old woman had initially presented with an ulcerating lesion of the right fifth toe. The histological and immunohistochemical analysis revealed features consistent with CIC-rearranged Ewing-like sarcoma, which was confirmed with genetic analysis. Despite aggressive local control and a multidrug chemotherapy regimen, the patient developed multifocal metastases involving the lungs, femur, and cerebrum. The cerebral lesions were managed with surgery and gamma knife radiosurgery, with mixed results.

CONCLUSION

CIC-rearranged Ewing-like sarcomas have recently been recognized as a distinct disease entity with a highly aggressive course. Treatment paradigms have yet to be defined to properly manage such an aggressive pathological process.

[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.

High Specificity of BCL11B and GLG1 for EWSR1-FLI1 and EWSR1-ERG Positive Ewing Sarcoma

Ewing sarcoma (EwS) is an aggressive cancer displaying an undifferentiated small-round-cell histomorphology that can be easily confused with a broad spectrum of differential diagnoses. Using comparative transcriptomics and immunohistochemistry (IHC), we previously identified BCL11B and GLG1 as potential specific auxiliary IHC markers for EWSR1-FLI1-positive EwS. Herein, we aimed at validating the specificity of both markers in a far larger and independent cohort of EwS (including EWSR1-ERG-positive cases) and differential diagnoses. Furthermore, we evaluated their intra-tumoral expression heterogeneity. Thus, we stained tissue microarrays from 133 molecularly confirmed EwS cases and 320 samples from morphological mimics, as well as a series of patient-derived xenograft (PDX) models for BCL11B, GLG1, and CD99, and systematically assessed the immunoreactivity and optimal cut-offs for each marker. These analyses demonstrated that high BCL11B and/or GLG1 immunoreactivity in CD99-positive cases had a specificity of 97.5% and an accuracy of 87.4% for diagnosing EwS solely by IHC, and that the markers were expressed by EWSR1-ERG-positive EwS. Only little intra-tumoral heterogeneity in immunoreactivity was observed for differential diagnoses. These results indicate that BCL11B and GLG1 may help as specific auxiliary IHC markers in diagnosing EwS in conjunction with CD99, especially if confirmatory molecular diagnostics are not available.

DNA Methylation Profiling for Diagnosing Undifferentiated Sarcoma with Capicua Transcriptional Receptor (CIC) Alterations

Undifferentiated soft tissue sarcomas are a group of diagnostically challenging tumors in the pediatric population. Molecular techniques are instrumental for the categorization and differential diagnosis of these tumors. A subgroup of recently identified soft tissue sarcomas with undifferentiated round cell morphology was characterized by Capicua transcriptional receptor (CIC) rearrangements. Recently, an array-based DNA methylation analysis of undifferentiated tumors with small blue round cell histology was shown to provide a highly robust and reproducible approach for precisely classifying this diagnostically challenging group of tumors. We describe the case of an undifferentiated sarcoma of the abdominal wall in a 12-year-old girl. The patient presented with a voluminous mass of the abdominal wall, and multiple micro-nodules in the right lung. The tumor was unclassifiable with current immunohistochemical and molecular approaches. However, DNA methylation profiling allowed us to classify this neoplasia as small blue round cell tumor with CIC alterations. The patient was treated with neoadjuvant chemotherapy followed by complete surgical resection and adjuvant chemotherapy. After 22 months, the patient is disease-free and in good clinical condition. To put our experience in context, we conducted a literature review, analyzing current knowledge and state-of-the-art diagnosis, prognosis, and clinical management of CIC rearranged sarcomas. Our findings further support the use of DNA methylation profiling as an important tool to improve diagnosis of non-Ewing small round cell tumors.