Small Round Blue Cell Sarcomas Research Articles

Molecular and immunohistochemical testing of bone tumours: review and update.

Primary bone tumours can pose diagnostic problems due to their overlapping radiologic and histologic features. Given the recent advancement in our understanding of the biology of bone tumours, multiple immunohistochemical and molecular markers have been devised to aid in their diagnosis. This review provides brief updates on select bone tumours, including chondrosarcomas, benign chondrogenic tumours, osteosarcomas, benign osteogenic tumours, fibroosseous lesions, vascular tumours, osteoclastic giant cell-rich or cystic tumours, chordoma, adamantinoma, small round blue cell sarcomas, and others. We discuss their salient molecular features and novel immunohistochemical correlates, along with some tips to avoid common diagnostic pitfalls.

Mixed epithelial and stromal tumours of the kidney with malignant transformation: a clinicopathological study of four cases

Mixed epithelial and stromal tumour of the kidney is a complex benign neoplasm in which malignancy rarely arises. In this study, we report four mixed epithelial and stromal tumours in which sarcoma or carcinoma developed. In the first, a multifocal adenocarcinoma arose and areas of transition from benign to malignant epithelium were observed. Oestrogen and progesterone receptors were diffusely present in the nuclei of the spindle cell stroma of the benign component. The second was a sarcoma in which benign epithelial elements were intermixed. Outside the renal parenchyma, clusters of small benign glands surrounded by oestrogen receptor-positive benign stroma were present, supporting the diagnosis of mixed epithelial and stromal tumour. Fluorescence in situ hybridisation for SYT-SSX translocation and immunohistochemical results, specifically TLE1 -ativity, argued against primary renal synovial sarcoma. The patient died 24 months after surgery. The third tumour consisted of small blue round cells, positive for epithelial membrane antigen, BCL2, CD99, and FLI1. Throughout the tumour, the presence of benign appearing branching tubules in fibromuscular stroma, reactive for smooth muscle actin, desmin and progesterone receptor, supported the diagnosis of mixed epithelial and stromal tumour in which a small round blue cell sarcoma with EWSR1 rearrangement arose. In the fourth tumour, adenocarcinoma with papillary architecture arose in a typical mixed epithelial and stromal tumour. In summary, we present four cases of mixed epithelial and stromal tumour with malignant transformation, two showing carcinomatous and the other two with sarcomatous transformation. Identification of typical benign looking elements and the absence of SYT-SSX translocation are helpful in recognition of this entity.

Association Between Biologically Effective Dose and Local Control After Stereotactic Body Radiotherapy for Metastatic Sarcoma

<h3>Purpose/Objective(s)</h3> Stereotactic body radiation therapy (SBRT) is increasingly utilized for treatment of patients with recurrent and metastatic tumors. Considering the relative radioresistance of some sarcoma histologies, SBRT may allow for higher biological effectiveness compared to conventional radiotherapy. We report local control outcomes after SBRT based on radiation dose and histology. <h3>Materials/Methods</h3> From our IRB-approved single-institution registry, all patients treated with SBRT for metastatic sarcoma between 2014 and 2020 were identified. Kaplan-Meier analysis was used to estimate local control and overall survival at 1 year. Univariate and multivariable Cox proportional hazard model analyses were performed to determine association between SBRT dose, histology, and local control. Small round blue cell sarcomas were classified as more radiosensitive and others as radioresistant histologies. A receiver operating characteristic (ROC) curve was generated to determine optimal biologically effective dose (BED) using a/β of 3 Gy. Local control was compared by SBRT dose using the BED cut point and histology. <h3>Results</h3> Forty-two patients with a total of 138 lesions met inclusion criteria. Median follow up was 9.7 months (range 0.5-34.5). Patients were heavily pre-treated with systemic therapy. Median SBRT prescription was 30 Gy (range 15-60) in 4 fractions (range 1-5). Sixty-two lesions met criteria for radiosensitive histology while 75 lesions were considered radioresistant. Local control for all lesions was 66.7% (95% CI, 56.6-78.5) at 1 year and 50.2% (95% CI, 38.2-66.1) at 2 years. Stratifying by histology, 1-year local control was 65.3% for radiosensitive and 68.6% for radioresistant histologies (<b>P</b> = 0.49). The ROC cut point for BED was 95 Gy. Local control at 1-year was 75% for lesions receiving ≥ 95 Gy BED, and 46.2% for lesions receiving < 95 Gy BED (<b>P</b> = 0.01). On subgroup analysis, local control by BED ≥ 95 Gy remained significant for radiosensitive histologies (<b>P</b> = 0.013), but was not significant for radioresistant histologies (<b>P</b> = 0.25). Overall survival was 47.6% (95% CI, 34.3-66.1) at 1 year and 39.0% (95% CI, 26.2-58.1) at 2 years, and median survival was 10.8 months. <h3>Conclusion</h3> For patients undergoing stereotactic body radiotherapy for metastatic sarcoma, local control was significantly improved when BED was ≥ 95 Gy for radiosensitive histologies, but was not significant for radioresistant histologies. Further investigation into the dose-response relationship is warranted to maximize the therapeutic index.

The role of molecular pathology in mediastinal sarcomas.

Mediastinal sarcomas represent rare neoplasms of mesenchymal origin. Most published data on mediastinal sarcomas is primarily derived from small series and case reports. Although rare, primary mediastinal sarcomas have a clinically aggressive course with worse 10-year survival rates than other types of mediastinal tumors, highlighting the importance of adequate diagnosis of these lesions. The diagnosis of mediastinal sarcomas is complicated by the varied histologic subtypes of tumors that can occur and which can sometimes display overlapping clinical, morphological, imaging, and immunohistochemical features. Cytogenetic analysis and more recently, molecular techniques, have provided new methods by which these tumors can be differentiated. Sarcomas occurring within the mediastinum are an extremely heterogenous group of tumors, although the specific incidence of the different subtypes of mediastinal sarcomas varies among studies, there is a subset of lesions that appear to occur more commonly across most published studies. These tumors include synovial sarcoma, liposarcoma, malignant peripheral nerve sheath tumor (MPNST), small round blue cell sarcomas (including Ewing sarcoma) and leiomyosarcoma (LMS). Other rare sarcoma subtypes may also less commonly occur within the mediastinum. Many of these sarcomas have specific, recurrent genetic abnormalities that can be identified through cytogenetic and molecular testing allowing for accurate diagnosis. This review aims to cover the role of molecular pathology, specifically with regards to diagnosis, as well as discuss the salient molecular genetic features of the various types of sarcoma that occur within the mediastinum. In addition, the various types of cytogenetic and molecular diagnostic tests available for the diagnosis of different types of sarcomas will be reviewed.

Small Round Blue Cell Sarcoma Other Than Ewing Sarcoma: What Should an Oncologist Know?

The diagnosis of round cell sarcomas has changed rapidly over the last decade, causing much diagnostic confusion for pathologists and oncologists. The advances in diagnosis are largely due to the advent of next-generation sequencing techniques, which allowed the recognition of novel gene fusions in round cell sarcomas. The new 5th edition of the WHO Classification of Tumors of Soft Tissue and Bone recognizes four subgroups of undifferentiated round cell sarcomas: Ewing sarcoma, CIC-rearranged sarcomas, BCOR-altered sarcomas, and sarcomas with EWSR1-non-ETS fusions, in addition to desmoplastic small round cell tumor. This classification is based on a variety of publications showing that each of these molecular subtypes has unique clinical and prognostic characteristics distinct from Ewing sarcoma, therefore supporting the validity of recognizing these as discrete diagnostic entities. Despite our improved ability to diagnose these new round cell sarcomas, there remains confusion on how best to identify and treat these tumors. However, several key clinicopathologic features can point the physician toward the correct diagnosis. The goal of the following article is to emphasize the key clinical, pathologic, molecular, and prognostic differences between Ewing sarcoma and these non-Ewing round cell malignancies to improve recognition of these rare diseases.

A “Double-Hit” Translocation Sarcoma—First Report of the Co-occurrence of EWSR1-FLI1 and MTMR2-NTRK2 Fusion in a Small Round Blue Cell Sarcoma

Abstract We report a case of a 51-year-old man with primary diagnosis of Ewing sarcoma confined to the soft tissue, associated with EWSR1-FLI1 gene fusion demonstrated by fluorescence in situ hybridization (FISH). Six years after the diagnosis, immunohistochemistry for NTRK (neurotrophic receptor tyrosine kinase 1–3) was performed on this tumor using 2 Pan-Trk rabbit monoclonal antibodies, A7H6R (Cell Signaling Technology, Danvers, Mass) and EPR17341 (Abcam, Cambridge, Mass). Both clones showed diffuse moderate to strong cytoplasmic expression including presence of nuclear stain. RNA sequencing demonstrated the co-occurrence of MTMR2-NTRK2, a novel gene fusion, in the same tumor block used for EWSR1 FISH testing. While FISH for NRK2 did not confirm gene rearrangement, an atypical signal pattern was identified. This case challenges the concept that NTRK fusions are mutually exclusive with other oncogenic drivers. The clinical course of this patient has also been unusual as the tumor has followed an indolent course with no evidence of recurrent or metastatic disease.

BCOR involvement in cancer.

BCOR is a gene that encodes for an epigenetic regulator involved in the specification of cell differentiation and body structure development and takes part in the noncanonical polycomb repressive complex 1. This review provides a comprehensive summary of BCOR’s involvement in oncology, illustrating that various BCOR aberrations, such as the internal tandem duplications of the PCGF Ub-like fold discriminator domain and different gene fusions (mainly BCOR–CCNB3, BCOR–MAML3 and ZC3H7B–BCOR), represent driver elements of various sarcomas such as clear cell sarcoma of the kidney, primitive mesenchymal myxoid tumor of infancy, small round blue cell sarcoma, endometrial stromal sarcoma and histologically heterogeneous CNS neoplasms group with similar genomic methylation patterns known as CNS-HGNET-BCOR. Furthermore, other BCOR alterations (often loss of function mutations) recur in a large variety of mesenchymal, epithelial, neural and hematological tumors, suggesting a central role in cancer evolution.

Ewing-like sarcoma: An emerging family of round cell sarcomas.

Ewing-like sarcomas are an emerging subgroup of small round blue cell sarcomas that share various degrees of morphological, immunohistochemical, molecular, and clinical similarity with Ewing sarcoma. Despite these similarities, Ewing-like sarcomas lack the pathognomonic molecular hallmark of Ewing sarcoma: A translocation between a gene of the RNA-binding TET family (EWSR1 or FUS) with a gene of the ETS-transcription family ( FLI1, ERG, ETV1, ETV4, or FEV). Recently, increased use of modern molecular methods based on next-generation sequencing have enabled the identification of distinct subgroups within this previously uncharacterized group of Ewing-like sarcomas based on the discovery of novel molecular driving events. The focus of this review is to provide an update on the main subcategories of Ewing-like sarcomas discovered to date: CIC-rearranged sarcomas, BCOR-rearranged sarcomas, sarcomas with a rearrangement between EWSR1 and a non-ETS family gene, and the substantial fraction of tumors which remain uncharacterized by molecular methods. There is increasing evidence that these tumors represent stand-alone entities with unique characteristics rather than simply a subgroup of Ewing sarcoma; thus, the question of the best therapeutic approach for these often aggressive sarcomas remains of primary importance. Ultimately, large collaborative efforts will be necessary to better determine the characteristics of this rare, heterogeneous family of tumors.

Abstract PR06: Functional genomics of CIC-DUX4 fusions in zebrafish recapitulates the spectrum of human CIC-rearranged cancers

Abstract CIC-DUX4 sarcomas are aggressive soft-tissue malignancies characterized by frequent metastases and poor survival. Histologically, CIC-DUX4 sarcomas resemble Ewing sarcomas but do not express EWS-FLI1 or other FET-ETS fusion genes typical of Ewing sarcoma. The tumors arise from chromosomal translocations that fuse the transcriptional repressor CIC with the homeodomain-containing protein DUX4, creating an aberrant transcription factor. However, the critical targets of CIC-DUX4 have been only partly described, the cell of origin and mechanism of transformation are unknown, and animal models of the disease are lacking. Owing to this poor biologic understanding, patients with CIC-DUX4 sarcomas are treated with the same regimens used for classical Ewing sarcoma, despite generally poor outcomes. To comprehensively address these problems, we are taking a cross-species comparative oncology approach via analysis of human CIC-DUX4 sarcomas and genetically engineered in vivo zebrafish models. Human CIC-DUX4 transgenes exerted strong effects on zebrafish embryonic development. Beginning at 5 weeks of age, almost 40% of injected animals developed invasive, rapidly growing tumors. Strikingly, two classes of tumors emerged: small round blue cell sarcomas developed in soft tissues including the trunk musculature and the ventral abdomen, and CNS-PNETs arose in the head. This recapitulates the spectrum of human tumors with CIC gene rearrangements. To further understand the molecular mechanisms of tumorigenesis, we performed RNASeq on zebrafish CIC-DUX4 sarcoma and zebrafish EWS-FLI1 sarcomas alongside human tumors and nonmalignant tissues. This analysis revealed pathways conserved between fish and human, including RAS-MAPK signaling, and highlighted the central importance of ETV4 in this disease. Further studies established ETV4 as a valuable new marker of the human disease. Taken together these findings demonstrate that CIC-DUX4 expression is sufficient to promote the development of tumors, give insight into the cellular origins of CIC-DUX4 tumors, and provide a valuable new animal model for translational research. Citation Format: Sarah Watson, Genevieve C. Kendall, Whitney A. Murchison, Olivier Delattre, Franck Tirode, James F. Amatruda. Functional genomics of CIC-DUX4 fusions in zebrafish recapitulates the spectrum of human CIC-rearranged cancers [abstract]. In: Proceedings of the AACR Conference on Advances in Sarcomas: From Basic Science to Clinical Translation; May 16-19, 2017; Philadelphia, PA. Philadelphia (PA): AACR; Clin Cancer Res 2018;24(2_Suppl):Abstract nr PR06.

PC3 - 129 Primary Intracranial Round Cell Sarcoma in an HIV Patient: A Case Report and a Review of Literature

Primary intracranial sarcoma among patients diagnosed with HIV is rare. Case reports published have shown that there is an increasing number of cases of leiomyosarcoma, hemangiopericytoma and rhabdomyosarcoma among these patients. Further, there are also few reports that sarcomas may present atypically, sometimes mimicking a brain abscess. We report a case of a 26 year old male, newly diagnosed HIV, who presented with bilateral chronic suppurative otitis media associated fever, headache and vomiting. Neuroimaging showed with multiple rim enhancing masses on the left temporal, parietal and occipital areas and bilaterally sclerosed mastoid air cells. Initial impression was an otogenic abscess. Burrhole craniotomy and evacuation of the cystic masses was done. Histopathologic examination revealed a small round blue cell sarcoma. Different immunostains were done to differentiate the various subtypes of sarcomas possible. Patient was discharged improved but did not consent to chemotherapy or radiotherapy.

Undifferentiated Small Round Cell Sarcomas with Rare EWS Gene Fusions : Identification of a Novel EWS-SP3 Fusion and of Additional Cases with the EWS-ETV1 and EWS-FEV Fusions

Ewing family tumors (EFTs) are prototypical primitive small round blue cell sarcomas arising in bone or extraskeletal soft tissues in children or adolescents. EFTs show fusions of EWS with a gene of the ETS family of transcription factors, either EWS-FLI1 (90 to 95%) or EWS-ERG (5 to 10%). Rare cases with fusions of EWS to other ETS family genes, such as ETV1, E1AF, and FEV, have been identified, but their clinicopathological similarity to classic EFTs remains unclear. We report four new cases of EFT-like tumors with rare EWS fusions, including two with EWS-ETV1, one with EWS-FEV, and a fourth case in which we cloned a novel EWS-SP3 fusion, the first known cancer gene fusion involving a gene of the Sp zinc finger family. Analysis of these three new cases along with data on nine previously reported cases with fusions of EWS to ETV1, E1AF, or FEV suggest a strong predilection for extraskeletal primary sites. EFT-like cases with fusions of EWS to non-ETS translocation partners are also uncommon but involve the same amino-terminal portion of EWS, which in our novel EWS-SP3 fusion is joined to the SP3 zinc-finger DNA-binding domain. As these data further support, these types of EWS fusions are associated with primitive extraskeletal small round cell sarcomas of uncertain lineage arising mainly in the pediatric population.

Differential expression of beta 1, beta 3 and beta 4 integrins in sarcomas of the small, round, blue cell category.

Integrins are a large and complex family of membrane spanning alpha beta heterodimeric cell surface glycoproteins mediating cell/cell and cell/matrix interactions. Small, round, blue cell sarcomas (SRBCS) are a group of poorly differentiated tumours of various and in part uncertain histogenesis displaying similar cytomorphology. Among them are rhabdomyosarcomas (RMS), ganglioneuroblastomas [(G)NB], primitive peripheral neuroectodermal tumours (pPNET) and Ewing's sarcomas (ES). Thirty-two SRBCS were studied immunohistochemically for the distribution of beta 1, beta 3 and beta 4 integrins in situ. We found complex and to some extent differential patterns of beta 1, beta 3 and beta 4 integrin subunit expression in different types of SRBCS: all of the sarcomas studied were consistently beta 1+, beta 4-, alpha 2-. Four of nine RMS were completely negative for all other integrin subunits studied while one RMS was alpha 5+ throughout and three RMS were focally alpha 5+. Three RMS expressed the alpha 6 and alpha v chains. In contrast to RMS, pPNET and ES, all of which were alpha 1-, alpha 3-, (G)NB were alpha 3+ and frequently co-expressed alpha 1. The eight pPNET and seven ES studied showed a similarly restricted integrin profile that was limited to the expression of beta 1 and alpha 5 in nearly all cases. In summary, RMS were beta 1+, alpha 1-, alpha 3- and heterogeneously expressed alpha 5 and alpha 6. (G)NB were generally beta 1+, alpha 1+, alpha 3+, alpha 5-, alpha 6-. pPNET and ES were beta 1+, alpha 1-, alpha 3-, alpha 5+, alpha 6-. The data illustrate a complex expression pattern of various integrins in SRBCS, a differential expression pattern of some of the integrin subunits among different types of SRBCS and almost identical integrin profiles in pPNET and ES.

Differential expression of leukocyte differentiation antigens in small round blue cell sarcomas

Small round blue cell sarcomas (SRBCS) comprise a group of cytomorphologically poorly differentiated neoplasms that are characterized by different histogenesis and biologic behavior. Twenty-seven well-characterized SRBCS were examined immunohistochemically to detect the expression of a panel of leukocyte differentiation (CD) antigens and class I (HLA-A,B,C) and class II (HLA-DR) major histocompatibility complex antigen. Although various cell surface antigens were detectable in SRBCS, the pan-leukocytic-histiocytic CD53 antigen was absent in the neoplastic population of all tumors studied; this finding allowed the authors to discriminate these lesions from lymphomas and leukemias. Some antigens had a differential pattern of expression in the SRBCS group, in particular in the undifferentiated tumor cell populations. In most instances, neuroblastomas (NB) and ganglioneuroblastomas (GNB) were CD9+/CD24+/CD56+ but CD40-/HLA-A,B,C-. Rhabdomyosarcomas (RMS) were CD56+ in all specimens and CD9+ in many samples; generally, they showed CD24-/CD40-/HLA-A,B,C-. Ewing sarcomas (ES) and peripheral primitive neuroectodermal tumors (pPNET) were HLA-A,B,C+/CD40+ but CD9-/CD24-/CD56- in most instances. Thus, with few exceptions, the expression of CD9 and CD56 and the simultaneous absence of HLA-A,B,C and CD40 differentiated GNB, NB, and RMS from ES and pPNET. GNB, NB, and RMS differed in regard to their CD24 expression. These data show that various types of SRBCS have different patterns of cell surface antigens. Therefore, these antigens are considered to be helpful in the immunophenotypic subclassification of SRBCS: The immunophenotypic similarities between ES and pPNET, however, might be an additional argument for a close relationship between these two lesions.

Value of Nude Mice Xenografts in the Expression of Cell Heterogeneity of Human Sarcomas of Bone and Soft Tissue

Nude mice xenotransplants have been performed on human primary sarcomas of bone and soft tissues in order to delve into the cell heterogeneity of these neoplasms. Particular emphasis has been given to the group of small round blue cell sarcomas (Ewing's sarcomas and peripheral neuroectodermal tumors). Out of 31 xenotransplanted sarcomas, 16 cases have grown positively, and many of them continue to be transferred into nude mice on a regular time basis, being presently considered as fully established nude lines. Here we report the results of such a system, which has been followed with optical, electron microscopical, immunohistochemical and cytogenetic techniques. Osteosarcomas make up the group with the highest number of positivities taken (6 out of 9 transplanted cases). Diversity in growth rate, positive tumors and morphology are taken into consideration. Epithelial foci were seen in one of the transplanted neoplasms. Malignant fibrous histiocytoma and other mesenchymal sarcomas of bone and soft tissues are reviewed. Changes in immunohistochemical reactivity (alpha-1AT and alpha-1AQT) were observed in the transplanted neoplasms. Cytogenetic analysis performed on an undifferentiated (primitive) soft-tissue sarcoma provided clues to its synovial origin. Analysis of Ewing's sarcoma performed on nude mice transplanted tumors shows heterogeneous immunohistochemical response, with enhancement of cytokeratin positive cells, not previously seen in the primary neoplasms.

Small round blue cell sarcoma of bone mimicking atypical Ewing's sarcoma with neuroectodermal features. An analysis of five cases with immunohistochemical and electron microscopic support

Ewing's sarcoma (ES) of bone may occasionally display rosette-like textures mimicking Homer-Wright ones, as seen in neuroectodermic neoplasms (neuroblastoma, peripheral neuroepithelioma). Of a group of 39 cases of ES, reviewed with electron microscopic study, the authors have isolated five atypical ES, which histologically also possessed neuroectodermic traces. These tumors were composed of small round blue cells with rosette-like figures and cytoplasmic glycogen. The immunohistochemical analysis showed positivity for neuron-specific enolase (NSE) as well as for HNK-1 (leu-7) monoclonal antibody. Electron microscopic examination confirmed the tumor cell as being of small round type, with a dense chromatine pattern and the presence of isolated dendritic processes, as well as synaptic-like buttons; intermediate filaments, neurotubuli, and dense-core neurosecretory granules also were seen. Moreover, in two cases basement-like condensations surrounded some cells. Scanning electron microscopic study in one case confirmed the presence of rosette-like figures and cell elongations with short dendritic projections of the cytoplasm. Clinically and radiologically these cases showed features similar to ES of bone; one case, located in the chest wall, had a local relapse after treatment, with the histologic features of a pleomorphic neuroblastoma. The authors conclude that these tumors resemble closely immature neuroepithelioma of soft tissue but, being primary to bone, are superimposable on those described as "neuroectodermal tumors of bone."