Search

A novel histomolecular tumor, the "intracranial mesenchymal tumor (IMT), FET::CREB fusion-positive", has recently been identified and added to the 2021 World Health Organization Classification of Tumors of the Central Nervous System. One of the essential diagnostic criteria defined in this classification is the intracranial location of the tumor. Herein, we report a spinal case of IMT with a classical EWSR1::CREM fusion. We compare its clinical, histopathological, immunophenotypical, genetic and epigenetic features with those previously described in IMT, FET::CREB fusion-positive. The current case presented histopathological (epithelioid morphology with mucin-rich stroma, and expression of EMA and desmin), radiological (an extraparenchymal lobulated mass without dural tail), genetic (fusion implicating the EWSR1 and CREM genes), and epigenetic (DNA-methylation profiling) similarities to previously reported cases. This case constitutes the third "extracranial" observation of an IMT. Our results added data suggesting that the terminology "IMT, FET::CREB fusion-positive" is provisional and that further series of cases are needed to better characterize them.

Over the last decade, the development of next-generation sequencing techniques has led to the molecular dismantlement of adult and pediatric sarcoma, with the identification of multiple gene fusions associated with specific subtypes and currently integrated into diagnostic classifications. In this report, we describe and discuss the identification of a novel EWSR1-UBP1 gene fusion in an adult patient presenting with multi-metastatic sarcoma. Extensive pathological, transcriptomic, and genomic characterization of this tumor in comparison with a cohort of different subtypes of pediatric and adult sarcoma revealed that this fusion represents a novel variant of spindle cell rhabdomyosarcoma with features of TFCP2-rearranged subfamily.

A novel histomolecular tumor of the central nervous system, the “intracranial mesenchymal tumor (IMT), FET-CREB fusion-positive” has recently been identified in the literature and will be added to the 2021 World Health Organization Classification of Tumors of the Central Nervous System. However, our latest study using DNA-methylation analyses has revealed that intracranial FET-CREB fused tumors do not represent a single molecular tumor entity. Among them, the main subgroup presented classical features of angiomatoid fibrous histiocytoma, having ultrastructural features of arachnoidal cells, for. Another tumor type with clear cell component and histopathological signs of aggressivity clustered in close vicinity with clear cell sarcoma of soft tissue. Herein, we report one case of IMT with a novel SMARCA2-CREM fusion which has until now never been described in soft tissue or the central nervous system. We compare its clinical, histopathological, immunophenotypic, genetic and epigenetic features with those previously described in IMT, FET-CREB fusion-positive. Interestingly, the current case did not cluster with IMT, FET-CREB fusion-positive but rather presented histopathological (clear cell morphology with signs of malignancy), clinical (with a dismal course with several recurrences, metastases and finally the patient’s death), genetic (fusion implicating the CREM gene), and epigenetic (DNA-methylation profiling) similarities with our previously reported clear cell sarcoma-like tumor of the central nervous system. Our results added data suggesting that different clinical and histomolecular tumor subtypes or grades seem to be included within the terminology “IMT, FET-CREB fusion-positive”, and that further series of cases are needed to better characterize them.

Central nervous system (CNS) tumors with the BCOR (BCL6 Corepressor) internal tandem duplication (ITD) were recently isolated by a DNA-methylation profile from a series of primitive neuroectodermal tumors [1]. They are mainly characterized by a recurrent BCOR ITD and express BCOR by immunohistochemistry (IHC) [2]. In rare cases, they present an EP300-BCOR fusion inducing the absence of expression of BCOR by IHC [3]. In soft tissue and kidney tumors with different types of BCOR alterations, SATB2 has been considered a diagnostic hallmark and BCOR IHC is not highly specific in some other contexts (soft tissue and uterine tumors) [4]. In a recent paper, SATB2 immunoexpression has been evidenced in one CNS-tumor with proven BCOR ITD [5]. The aim of our study was to evaluate the sensitivity and specificity of the BCOR and SATB2 immunostainings in a large cohort of pediatric CNS tumors.

NTRK gene fusions have been described in a wide variety of central nervous system (CNS) and soft tissue tumors, including the provisional tumor type "spindle cell neoplasm, NTRK-rearranged" (SCN-NTRK), added to the 2020 World Health Organization Classification of Soft Tissue Tumors. Because of histopathological and molecular overlaps with other soft tissue entities, controversy remains concerning the lineage and terminology of SCN-NTRK.This study included 16 mesenchymal tumors displaying kinase gene fusions (NTRK fusions and one MET fusion) initially diagnosed as infantile fibrosarcomas (IFS), SCN-NTRK, and adult-type fibrosarcomas from the soft tissue, viscera and CNS. We used immunohistochemistry, DNA methylation profiling, whole RNA-sequencing and ultrastructural analysis to characterize them. Unsupervised t-distributed stochastic neighbor embedding analysis showed that 11 cases (2 CNS tumors and 9 extra-CNS) formed a unique and new methylation cluster, while all tumors but one, initially diagnosed as IFS, clustered in a distinct methylation class. All the tumors except one formed a single cluster within the hierarchical clustering of whole RNA-sequencing data. Tumors from the novel methylation class co-expressed CD34 and S100, had variable histopathological grades and frequently displayed a CDKN2A deletion. Ultrastructural analyses evidenced a myofibroblastic differentiation.Our findings confirm that SCN-NTRK share similar features in adults and children and in all locations combine an infiltrative pattern, distinct epigenetic and transcriptomic profiles, and ultrastructural evidence of a myofibroblastic lineage. Further studies may support the use of new terminology to better describe their myofibroblastic nature.

Introduction: Meningeal solitary fibrous tumors (SFT), like all SFT, are defined by NAB2-STAT6 fusion and share clinicopathologic similarities with meningiomas, the most frequent meningeal tumors. Our aim is to establish the molecular identity of meningeal SFT and seek molecular prognostic factors. Methods: RNA sequencing and whole exome sequencing (WES) were performed in STAT6-positive SFT and grade 2–3 meningiomas, and data concerning other soft tissues tumors was obtained from the local database. Uniform manifold approximation and projection (UMAP), individual gene expression and Gene Set Enrichment Analysis (GSEA) were performed. Results: RNA clustering shows that SFT share a common molecular signature, different from any other type of tumoral tissue. Meningeal SFT aggregate with other SFT, with no clinical or histological subgroup. Comparison of genes expressions suggests significant over-expressions of ZIC2, ZIC3, ZIC5, GABBR2, TP53 in CNS-SFT. The pathogenic TP53 c.743G > T variant, previously undescribed in SFT, was found in one sample of meningeal SFT during malignant progression. Conclusions: Meningeal SFT are molecular counterparts of extra-meningeal SFT, completely separate from meningiomas. They might develop from the same tissues and benefit from the same treatments as SFT.

A previously healthy 12-year-old boy began experiencing intracranial hypertension symptoms. Cerebral magnetic resonance imaging (MRI) showed a pineal mass. Cerebrospinal fluid and blood tested negative for β-human chorionic gonadotrophin, α-foetoprotein, carcinoembryonic antigen, and placental alkaline phosphatase.

BCOR-ITD tumours form an emerging family of aggressive entities with an internal tandem duplication (ITD) in the last exon of the BCOR gene. The family includes cerebral tumours, termed central nervous system BCOR-ITD (CNS BCOR-ITD), and sarcomatous types described in the kidney as clear cell sarcoma of the kidney (CCSK), in the endometrium as high-grade endometrial stromal sarcoma, and in the bone and soft tissue as undifferentiated round cell sarcoma or primitive myxoid mesenchymal tumour of infancy. Based on a series of 33 retrospective cases, including 10 CNS BCOR-ITD and 23 BCOR-ITD sarcomas, we interrogated the homogeneity of the entity regarding clinical, radiological, and histopathological findings, and molecular signatures. Whole-transcriptomic sequencing and DNA methylation profiling were used for unsupervised clustering. BCOR-ITD tumours mostly affected young children with a median age at diagnosis of 2.1 years (range 0-62.4). Median overall survival was 3.9 years and progression-free survival was 1.4 years. This dismal prognosis is shared among tumours in all locations except CCSK. Histopathological review revealed marked differences between CNS BCOR-ITD and BCOR-ITD sarcomas. These two groups were consistently segregated by unsupervised clustering of expression (n = 22) and DNA methylation (n = 21) data. Proximity between the two groups may result from common somatic changes within key pathways directly related to the novel activity of the ITD itself. Conversely, comparison of gene signatures with single-cell RNA-Seq atlases suggests that the distinction between BCOR-ITD sarcomas and CNS BCOR-ITD may result from differences in cells of origin.

BCOR-ITD tumours form an emerging family of aggressive entities with an internal tandem duplication (ITD) in the last exon of the BCOR gene. The family includes cerebral tumours, termed central nervous system BCOR-ITD (CNS BCOR-ITD), and sarcomatous types described in the kidney as clear cell sarcoma of the kidney (CCSK), in the endometrium as high-grade endometrial stromal sarcoma (HG-ESS), in bone, and in soft tissue as undifferentiated round cell sarcoma (URCS) or primitive myxoid mesenchymal tumour of infancy (PMMTI). Based on a series of 33 retrospective cases, including 10 CNS BCOR-ITD and 23 BCOR-ITD sarcomas, we interrogated the homogeneity of the entity regarding clinical, radiological and histopathological findings, and molecular signatures. Whole transcriptomic sequencing and DNA methylation profiling were used for unsupervised clustering. Histopathological review revealed marked differences between CNS BCOR-ITD and BCOR-ITD sarcomas. These two groups were consistently segregated by unsupervised clustering of expression (n=22) and DNA methylation (n=21) data. Proximity between the two groups may result from common somatic changes within key pathways directly related to the novel activity of the ITD itself. Conversely, comparison of gene signatures with single-cell RNAseq atlases suggests that the distinction between BCOR-ITD sarcomas and CNS BCOR-ITD may result from differences in cells of origin.

International audience; Cancers of unknown primary (CUP) are metastatic cancers for which the primary tumor is not found despite thorough diagnostic investigations. Multiple molecular assays have been proposed to identify the tissue of origin (TOO) and inform clinical care; however, none has been able to combine accuracy, interpretability, and easy access for routine use. We developed a classifier tool based on the training of a variational autoencoder to predict tissue of origin based on RNA-sequencing data. We used as training data 20,918 samples corresponding to 94 different categories, including 39 cancer types and 55 normal tissues. The TransCUPtomics classifier was applied to a retrospective cohort of 37 CUP patients and 11 prospective patients. TransCUPtomics exhibited an overall accuracy of 96% on reference data for TOO prediction. The TOO could be identified in 38 (79%) of 48 CUP patients. Eight of 11 prospective CUP patients (73%) could receive first-line therapy guided by TransCUPtomics prediction, with responses observed in most patients. The variational autoencoder added further utility by enabling prediction interpretability, and diagnostic predictions could be matched to detection of gene fusions and expressed variants. TransCUPtomics confidently predicted TOO for CUP and enabled tailored treatments leading to significant clinical responses. The interpretability of our approach is a powerful addition to improve the management of CUP patients. Copyright

10540 Background: NTRK ( Neurotrophic receptor tyrosine kinase) fusion transcript was initially described in infantile fibrosarcoma (IFS) and is now known to be present in many other rare types of tumor with a lower incidence. The main objective of the study is to describe the presentation and outcome of unselected tumors with NTRK fusion transcript (NTRK-FTT) to better consider the role of TRK inhibitors (TRKi) in such entities. Methods: We selected patients (pts) from the Institut Curie biobank (adults and children) with NTRK-FTT and which were assessed by RT-qPCR then RNA sequencing in a prospective or retrospective process, between 2001 and 2019. Results: We identified 62 NTRK-FTT among 2119 screened tumors (2.2 cases/year with RT-qPCR and 6.9 cases/year with RNA seq after 2016), NTRK3 (44 cases) (including 41 NTRK3-ETV6), NTRK2 (9) or NTRK1 (9). Most of pts had under 2 years (y) (74%) and only 7 pts were adults. We report preliminary analysis of clinical observation for the first 27 pts. Median age was 0.4 y [0-60.2]. Pathologic diagnosis was IFS (12 cases), various CNS tumors (4), atypical teratoid rhabdoid tumor (1), myofibroblastic inflammatory tumor (2), benign tumors (3), cellular congenital mesoblastic nephroma (2), lipofibromatosis like neural tumor, myxoïd liposarcoma, unclassifiable sarcoma (1 each). Two pts had metastatic tumors. Among all, 22 had surgery (1 mutilating), 15 chemotherapy, 4 radiotherapy, and 5 received TRKi, as second line treatment (2 pts) or ≥ third line (3 pts). After a median follow-up of 50 months [range, 1-155], 20/27 pts remained in complete remission, 3 had stable residue, and 4 had progressive disease (associated to 1 disease-related and 1 toxic deaths). Five-year OS is 88% [95%CI, 73.5-100] and 5y-EFS 59.5% [95%CI, 41.7-84.9]. Conclusions: This descriptive study showed that NTRK-FTT is rare (2.9%), encompasses a variety of different histotypes (n = 14). Systematic RNA sequencing allowed to depict 3.5 times more NTRK-FTT than targeted RT-qPCR. Overall outcome is favorable despite frequent tumor events. According to tumor type and the uncertainties regarding the long-term side effects of TRKi, the benefit/risk ratio must be carefully evaluated before using these drugs in first line.

Sarcoma represents a highly heterogeneous group of tumours. We report here the first unbiased and systematic search for gene fusions combined with unsupervised expression analysis of a series of 184 small round cell sarcomas. Fusion genes were detected in 59% of samples, with half of them being observed recurrently. We identified biologically homogeneous groups of tumours such as the CIC-fused (to DUX4, FOXO4 or NUTM1) and BCOR-rearranged (BCOR-CCNB3, BCOR-MAML3, ZC3H7B-BCOR, and BCOR internal duplication) tumour groups. VGLL2-fused tumours represented a more biologically and pathologically heterogeneous group. This study also refined the characteristics of some entities such as EWSR1-PATZ1 spindle cell sarcoma or FUS-NFATC2 bone tumours that are different from EWSR1-NFATC2 tumours and transcriptionally resemble CIC-fused tumour entities. We also describe a completely novel group of epithelioid and spindle-cell rhabdomyosarcomas characterized by EWSR1- or FUS-TFCP2 fusions. Finally, expression data identified some potentially new therapeutic targets or pathways. Copyright © 2018 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Background Fanconi anemia (FA) predisposes to hematologic disorders and myeloid neoplasia in childhood and to solid cancers, mainly oral carcinomas, in early adulthood. Few cases of solid cancers have been reported in childhood. Procedures We conducted a national retrospective study of solid tumors occurring in patients registered with or determined to have FA during childhood in France. Phenotypic features, tumor type, cancer treatment, and outcome were analyzed. Whenever available, fresh-frozen tumors were analyzed by microarray-based comparative genomics hybridization. Results We identified eight patients with FA with solid tumor from 1986 to 2012. For two patients, the diagnosis of FA was unknown at the time of cancer diagnosis. Moreover, we identified one fetus with a brain tumor. All patients showed failure to thrive and had dysmorphic features and abnormal skin pigmentation. Seven patients had BRCA2/FANCD1 mutations; five of these featured more than one malignancy and the median age at the time of cancer diagnosis was 11 months (range 0.4–3 years). Solid tumor types included five nephroblastomas, two rhabdomyosarcomas, two neuroblastomas, and three brain tumors. Two children died from the toxic effects of chemotherapy, two patients from the cancer, and one patient from secondary leukemia. Only one BRCA2 patient was alive more than 3 years after diagnosis, after tailored chemotherapy. Conclusion Solid tumors are rare in FA during childhood, except in patients with BRCA2/FANCD1 mutations. The proper genetic diagnosis is mandatory to tailor the treatment. Pediatr Blood Cancer 2015;62:463–470. © 2014 Wiley Periodicals, Inc.

Developmental tumors in children and young adults carry few genetic alterations, yet they have diverse clinical presentation. Focusing on Ewing sarcoma, we sought to establish the prevalence and characteristics of epigenetic heterogeneity in genetically homogeneous cancers. We performed genome-scale DNA methylation sequencing for a large cohort of Ewing sarcoma tumors and analyzed epigenetic heterogeneity on three levels: between cancers, between tumors, and within tumors. We observed consistent DNA hypomethylation at enhancers regulated by the disease-defining EWS-FLI1 fusion protein, thus establishing epigenomic enhancer reprogramming as a ubiquitous and characteristic feature of Ewing sarcoma. DNA methylation differences between tumors identified a continuous disease spectrum underlying Ewing sarcoma, which reflected the strength of an EWS-FLI1 regulatory signature and a continuum between mesenchymal and stem cell signatures. There was substantial epigenetic heterogeneity within tumors, particularly in patients with metastatic disease. In summary, our study provides a comprehensive assessment of epigenetic heterogeneity in Ewing sarcoma and thereby highlights the importance of considering nongenetic aspects of tumor heterogeneity in the context of cancer biology and personalized medicine., The following associations supported this work: Courir pour Mathieu, Dans les pas du Géant, Olivier Chape, Les Bagouzamanon, Enfants et Santé, and les Amis de Claire. The study was performed in the context of the following European Union consortia: Euro Ewing (grant agreement no. 602856), BLUEPRINT (grant agreement no. 282510), PROVABES (grant agreement no. 01KT1310), ASSET (grant agreement no. 259348), and TECHNOBEAT (grant agreement no. 668724). N.C.S. was supported by a long-term fellowship of the Human Frontier Science Program (LT000211/2014). J.K. was supported by a DOC Fellowship of the Austrian Academy of Sciences. D. Surdez was supported by the Institut Curie-SIRIC (Site de Recherche Intégrée en Cancérologie) program. E.d.A. was supported by Ministry of Economy and Competitiveness of Spain-FEDER grants (CIBERONC, RD12/0036/0017, PI14/01466), María García-Estrada, CRIS contra el Cáncer Foundations, and Pablo Ugarte Association. C.B. was supported by a New Frontiers Group award of the Austrian Academy of Sciences and by a European Research Council (ERC) Starting Grant (European Union's Horizon 2020 research and innovation program; grant 679146). E.M.T. was supported by fellowships of the Austrian Science Fund (FWF, Lise Meitner Fellowship M1448-B13; and Elise Richter Fellowship V506-B28).

Rhabdoid tumours (RTs) are highly aggressive tumours of infancy, frequently localized in the central nervous system (CNS) where they are termed atypical teratoid/rhabdoid tumours (AT/RTs) and characterized by bi-allelic inactivation of the SMARCB1 tumour suppressor gene. In this study, by temporal control of tamoxifen injection in Smarcb1flox/flox;Rosa26-CreERT2 mice, we explore the phenotypes associated with Smarcb1 inactivation at different developmental stages. Injection before E6, at birth or at 2 months of age recapitulates previously described phenotypes including embryonic lethality, hepatic toxicity or development of T-cell lymphomas, respectively. Injection between E6 and E10 leads to high penetrance tumours, mainly intra-cranial, with short delays (median: 3 months). These tumours demonstrate anatomical, morphological and gene expression profiles consistent with those of human AT/RTs. Moreover, intra- and inter-species comparisons of tumours reveal that human and mouse RTs can be split into different entities that may underline the variety of RT cells of origin., SMARCB1 inactivation is prevalent in human atypical teratoid/rhabdoid tumours but a mouse model that accurately phenocopies the human disease is lacking. Here, the authors show that inactivation of SMARCB1 between E6 and E10 in mice results in tumours that better recapitulate the human phenotype, compared to previously reported models.