Desmoplastic Small Round Cell Tumor

Baer A, Oehl-Huber K, Dahlum S, Fischer A, Gerstenmaier U, Seufferlein T, Buck A, Beer A, Thaiss W, Möller P, Döhner H, Siebert R, Marienfeld R, Barth TFE. Desmoplastic Small Round Cell Tumors: Clinical Presentation, Molecular Characterization, and Therapeutic Approach of Seven Patients

Desmoplastic small round blue cell tumor (DSRCT) is a highly aggressive fatal sarcoma without evidence-based therapeutic guidelines. We present here seven patients with DSRCT including immunohistochemistry combined with fluorescence in situ hybridization (FISH), next generation sequencing (NGS, n = 6) as well as OncoScan array (n = 3) analyses and show consecutive therapeutic approaches. All seven DSRCT patients presented with an extended abdominal mass; median age at diagnosis was 24.8 years. NGS analyses revealed five class 4 or 5 sequence variants. Remarkably, OncoScan and targeted analyses by FISH identified genomic gains of CCND1 in two cases. Cyclin D1 expression was present in all seven tumors as shown by immunohistochemical staining. Multimodal therapeutic concepts included systemic therapies, resection, and radiation. Six patients were treated as first-line therapy with conventional chemotherapy. All except one patient had a dismal therapy response. Subsequent therapy lines consisted of chemotherapeutic combinations followed by targeted therapies. Due to Cyclin D1 expression, the CDK4/6 inhibitor palbociclib was applied to four patients. The median therapy duration until disease progression in these patients was 4.5 months (range, 1.5-5 months). So, CCND1 genomic gain and Cyclin D1 expression are common features pointing to cell-cycle deregulation as a possible therapeutic target.

Abdominopelvic desmoplastic small round cell tumor with metastasis: A case report and literature review

RATIONALE

Desmoplastic small round cell tumor (DSRCT) is a rare and rapidly metastasizing soft tissue sarcoma, distinguished by its unique cell morphology and pleomorphic differentiation.

PATIENT CONCERNS

This report describes the case of an 18-year-old male diagnosed with abdominopelvic DSRCT exhibiting metastases to the peritoneum, liver, pleura, bone, and muscle. The patient primarily presented with symptoms of incomplete intestinal obstruction and an abdominal mass.

DIAGNOSES

Colonoscopy revealed lumen stenosis caused by external compression mass. Contrast-enhanced computed tomography and 18F-fluorodeoxyglucose positron emission tomography/computed tomography revealed multiple lesions in the abdominopelvic cavity. A needle biopsy of an abdominal wall lesion established it as a malignant tumor, origin unknown. Immunohistochemical staining post-surgery showed positive results for Cytokeratin (CK), CK7, Desmin, Vimentin, Caudal type homeobox 2 (CDX2), and Ki-67. Fluorescence in situ hybridization analysis revealed an Ewing sarcoma breakpoint region 1/EWS RNA binding protein 1 (EWSR1) rearrangement, and next-generation sequencing identified an EWSR1-Wilms tumor protein 1 (WT1) gene fusion.

INTERVENTIONS

The patient underwent laparoscopic exploratory surgery, which encompassed biopsy, ascites drainage, adhesion lysis, reinforcement of weakened sections of the small intestinal walls, and repositioning of twisted intestines. Postoperatively, the treatment protocol included fasting, rehydration, gastrointestinal decompression, and parenteral nutrition. However, the patient did not received chemotherapy.

OUTCOMES

The patient declined further treatment and deceased in early November.

LESSONS

This case highlights the nonspecific nature of DSRCT symptoms. In clinical practice, it is crucial to meticulously evaluate unexplained intestinal obstruction in young patients, considering DSRCT as a differential diagnosis to avoid delays in diagnosis.

Case report: An unusual presentation of intra-abdominal desmoplastic small round cell tumor

Background

Intra-abdominal desmoplastic small round cell tumor (IDSRCT) is a rare entity (0.2-0.74 cases per million people per year), which predominantly occurs in young men. It may present as an abdominal mass with pain, distention, and constipation. IDSRCT has a very poor prognosis, with 5-year overall survival estimated at 15%-30%. Diagnosis is made with tissue biopsy.

Case description

We present a case of a 28-year-old man with a history of schizophrenia and depression who presented to an emergency room (ER) in November 2022 with constipation and pelvic pain. The patient was sent home with a bowel regimen after radiography showed no obstruction. He re-presented for evaluation due to persistent pain. A computerized tomography scan of the abdomen and pelvis (CT A/P) revealed numerous pelvic masses with severe colitis, bilateral moderate hydronephrosis, and metastatic disease in the liver. A colonoscopy showed a mass extending 3 cm from the anus to 10 cm causing a partial obstruction. Biopsy was read as squamous cell carcinoma (SCC). The patient was subsequently admitted to our institution with pelvic pain, nausea, and vomiting. Colorectal surgery performed a colectomy with end-ileostomy due to colonic obstruction. He was evaluated by a medical oncologist, with previous slides requested for review. Initial review was concerning metastatic basaloid SCC with neuroendocrine features and a Ki67 of 70%. Given his recent abdominal surgeries, chemotherapy was delayed until February 2023 when he was started on reduced dose carboplatin and paclitaxel. Tumor specimen was sent for next generation sequencing (NGS) and programmed death-1 ligand 1 (PD-L1) testing. NGS results returned after the first dose of chemotherapy was given and showed a t(11;22) EWSR-WT1 translocation characteristic of desmoplastic small round cell tumor. The patient was supported in the hospital and discharged with oncology follow-up.

Discussion

As seen in this case, pathology review is essential to ensuring correct diagnosis and appropriate treatment plan. This is especially true when the clinical scenario does not match the listed pathology. Additional diagnostics such as NGS are invaluable in establishing correct diagnosis.

Mesotheliomas in Children

Mesotheliomas are rare and aggressive tumors that originate from mesothelial cells. Although exceedingly rare, these tumors may occur in children. Different from adult mesotheliomas, however, environmental exposures particularly to asbestos do not appear to play a major role in mesotheliomas in children, in whom specific genetic rearrangements driving these tumors have been identified in recent years. These molecular alterations may increasingly offer opportunities for targeted therapies in the future, which may provide better outcomes for these highly aggressive malignant neoplasms.

Desmoplastic small round cell tumor: from state of the art to future clinical prospects

INTRODUCTION

Desmoplastic small round cell tumor (DSRCT) is an extremely rare and highly aggressive soft tissue sarcoma, presenting mainly in male adolescents and young adults with multiple nodules disseminated within the abdominopelvic cavity. Despite a multimodal approach including aggressive cytoreductive surgery, intensive multi-agent chemotherapy, and postoperative whole abdominopelvic radiotherapy, the prognosis for DSRCT remains dismal. Median progression-free survival ranges between 4 and 21 months, and overall survival between 17 and 60 months, with the 5-year overall survival rate in the range of 10-20%.

AREA COVERED

This review discusses the treatment strategies used for DSRCT over the years, the state of the art of current treatments, and future clinical prospects.

EXPERT OPINION

The unsatisfactory outcomes for patients with DSRCT warrant investigations into innovative treatment combinations. An international multidisciplinary and multi-stakeholder collaboration, involving both pediatric and adult sarcoma communities, is needed to propel preclinical model generation and drug development, and innovative clinical trial designs to enable the timely testing of treatments involving novel agents guided by biology to boost the chances of survival for patients with this devastating disease.

Highlighting the Diversity of Desmoplastic Small Round Cell Tumor: A Case Series

Desmoplastic small round cell tumor (DSRCT) is a rare malignant tumor that occurs mainly in the retroperitoneum of children and young adults. In its prototypical form, DSCRT displays characteristic morphology with nested primitive small round cells in a desmoplastic stroma and a distinctive immunophenotype with polyphenotypic differentiation. However, DSCRT can also exhibit a broader clinical, histologic and immunohistochemical spectrum and, therefore, cause diagnostic difficulties. Given that DSCRT is an aggressive and nearly universally fatal disease, making the correct diagnosis is critically important. Herein, we report three patients with DSRCT and unusual clinical, morphologic or immunohistochemical characteristics, in order to highlight its remarkable diversity and increase awareness of this unusual, distinctive neoplasm.

Molecular profiling in desmoplastic small round cell tumours

Desmoplastic small round cell tumour (DSRCT) is an ultra-rare soft tissue sarcoma that is characterised by aggressive disease and dismal patient outcomes. Despite multi-modal therapy, prognosis remains poor and there are currently no effective targeted therapies available for patients with this disease. Advances in comprehensive molecular profiling approaches including next generation sequencing and proteomics hold the promise of identifying new therapeutic targets and biomarkers. In this review, we provide an overview of the current status of molecular profiling studies in DSRCT patient specimens and cell lines, highlighting the key genomic, epigenetic and proteomic findings that have contributed to our biological knowledge base of this recalcitrant disease. In-depth analysis of these molecular profiles has led to the identification of promising novel and repurposed candidate therapies that are suitable for translation into clinical trials. We further provide a perspective on how future integrated studies including proteogenomics could further enrich our understanding of this ultra-rare entity and deliver progress that will ultimately impact the outcomes of patients with DSRCT.

Exploration of Flavonoids as Lead Compounds against Ewing Sarcoma through Molecular Docking, Pharmacogenomics Analysis, and Molecular Dynamics Simulations

Ewing sarcoma (ES) is a highly malignant carcinoma prevalent in children and most frequent in the second decade of life. It mostly occurs due to t(11;22) (q24;q12) translocation. This translocation encodes the oncogenic fusion protein EWS/FLI (Friend leukemia integration 1 transcription factor), which acts as an aberrant transcription factor to deregulate target genes essential for cancer. Traditionally, flavonoids from plants have been investigated against viral and cancerous diseases and have shown some promising results to combat these disorders. In the current study, representative flavonoid compounds from various subclasses are selected and used to disrupt the RNA-binding motif of EWS, which is required for EWS/FLI fusion. By blocking the RNA-binding motif of EWS, it might be possible to combat ES. Therefore, molecular docking experiments validated the binding interaction patterns and structural behaviors of screened flavonoid compounds within the active region of the Ewing sarcoma protein (EWS). Furthermore, pharmacogenomics analysis was used to investigate potential drug interactions with Ewing sarcoma-associated genes. Finally, molecular dynamics simulations were used to investigate the stability of the best selected docked complexes. Taken together, daidzein, kaempferol, and genistein exhibited a result comparable to ifosfamide in the proposed in silico study and can be further analyzed as possible candidate compounds in biological in vitro studies against ES.

Giant desmoplastic small round cell tumor of the abdomen: A case report

BACKGROUND

Desmoplastic small round cell tumor (DSRCT) is a rare, aggressive, mesenchymal malignancy of a separate clinicopathological entity. It has a predilection for young men, with no evidence of any ethnic predilection. The current diagnostic gold standard for DSRCT includes histopathologic, immunohistochemical, and cytogenetic studies in order to confirm the variable phenotypic expression and characteristic chromosomal translocation.

CASE SUMMARY

A 65-year-old man presented with a sensation of an abdominal mass and a presentation of an incomplete bowel obstruction. Initial lab tests were in the normal range except for carbohydrate antigen. Contrast-enhanced CT showed that a large, mass-confounding density was occupied in the omentum majus area of the middle and lower abdominal wall. A 3D reconstruction of the images was performed to clarify the relationship between the tumor and the colon and was confirmed by a colonoscopy. After surgery, immunohistochemistry and fluorescence in situ hybridization (FISH) revealed EWSR1-WT1 gene rearrangement at 22q12, confirming the diagnosis of desmoplastic small round cell tumor.

CONCLUSION

Being different from the predilection of DSRCT for young men, the patient in our case is a 65-year-old man with a huge mass involving the transverse colon and the bladder.

Selective Immunoreactivity for WT1 Carboxy-Terminus Distinguishes Desmoplastic Small Round Cell Tumor From its Histologic Mimics

Desmoplastic small round cell tumor (DSRCT) is an aggressive pediatric round cell sarcoma containing a characteristic EWSR1-WT1 gene fusion. In the absence of genetic data, distinguishing DSRCT from other small round cell tumors of childhood can be problematic due to overlapping histologic and immunohistochemical features. We studied the utility of immunohistochemistry with antibodies targeting both the amino-terminal and carboxy-terminal regions of the Wilms tumor-1 (WT1) protein in differentiating these groups of tumors. The study cohort included 33 cases of genetically confirmed pediatric round cell tumors (10 DSRCTs, 12 Wilms tumors, 10 Ewing sarcomas, and 1 CIC-rearranged sarcoma). Immunoreactivities and immunolocalization of both the WT1 amino-terminus and carboxy-terminus were scored and documented. All DSRCTs displayed selective reactivity for only the WT1 carboxy-terminus (10/10), while dual immunoreactivity for both the WT1 carboxy-terminus (12/12) and amino-terminus antibodies (12/12) were characteristic of Wilms tumors. CIC-rearranged sarcoma showed variable WT1 nuclear immunopositivity (1/1, 1/1) and Ewing sarcomas were consistently WT1-negative for both the WT1 amino-terminus (0/10) and carboxy-terminus (0/10). Dual WT1 amino-terminus and carboxy-terminus immunohistochemistry remains a helpful diagnostic tool in discriminating intraabdominal small round cell tumors, which serves as an adjunct to the genetic information in preventing misdiagnosis.

A Classic Presentation of Desmoplastic Small Round Cell Tumor

Desmoplastic small round cell tumor (DSRCT) is a rare malignancy, of uncertain differentiation, which more commonly affects adolescents and young adult males; it usually has an intra-abdominal location. We describe the case of a 35-year-old male who presented initially with occasional abdominal pain, and subsequently with abdominal mass sensation, without any other associated symptoms. Imaging studies reported an intra-abdominal mass located in mesogastrium, right hypochondrium, and right lumbar region, without clear evidence of infiltration to secondary structures, but with clear peritoneal spread to greater omentum and pelvis. Definitive diagnosis of DSRCT is based on histologic and immunohistochemical findings. Standard treatment includes intensive neoadjuvant chemotherapy, surgical cytoreduction, and radiotherapy. Despite this multidisciplinary approach, DSRCT has a poor prognosis and a high mortality rate at five years.

Overexpression of EWSR1 (Ewing sarcoma breakpoint region 1/EWS RNA binding protein 1) predicts poor survival in patients with hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the most prevalent malignant neoplasms with high relapse and mortality rate. It is of great importance to identify novel and effective molecular markers to predict prognosis for the treatment of HCC. The Ewing sarcoma breakpoint region 1 (EWSR1) gene is well known to fuse with various partner genes and involved in promoting the development of multiple sarcomas, especially the Ewing sarcoma family of tumors. Nevertheless, seldom studies have focused on the role of EWSR1 in cancers of epithelial origin, let alone in HCC. In the current study, the transcriptional and clinical data of EWSR1 in HCC patients were obtained from TCGA and GEO databases, as well as 124 cases from the department of Pathology of Sichuan Jianyang People's Hospital. Kaplan-Meier and Cox regression analysis were used to assess patient prognosis. EWSR1 mRNA levels were significantly upregulated in HCC tissues than in normal liver tissues (P < 0.001). The TCGA database analysis showed upregulation of EWSR1 was associated with histological grade, pathologic T stage and death, in addition to that, the T staging, N staging, TNM staging, Ki67, AFP expression were extremely higher in the EWSR1 over-expression group in our cohort. Univariate and multivariate Cox hazard regression analysis results revealed that EWSR1 was an independent prognostic factor for OS in HCC, and bioinformatics analysis showed RNA splicing process represented the major function and pathway. In conclusion, our data showed EWSR1 could serve as a novel promising prognostic biomarker for HCC patients.Abbreviations: AFP, Alpha-fetoprotein; CCL14, C-C motif chemokine ligand 14; CK19, Cytokeratin 19; CI, coefficient interval; COL1A1, Collagen 1A1; DFS, Disease-free Survival; EWSR1, Ewing Sarcoma breakpoint region 1/EWS RNA binding protein 1; FLI1, Friend leukemia virus integration 1; GEO, Gene Expression Omnibus; GO, Gene Ontology; HCC, Hepatocellular carcinoma; HR, Hazard ratio; KEGG, Kyoto Encyclopedia of Genes and Genomes; mRNA, messenger Ribonucleic Acid; N, nodule; OS, Overall survival; PPI, Protein-Protein Interaction analysis; RNA, Ribonucleic Acid; SD, Standard Deviation; TCGA, The Cancer Genome Atlas; T, tumor; TNM, tumor-nodule-metastasis.

Intra-Abdominal Desmoplastic Small Round Cell Tumor: Current Treatment Options and Perspectives

Intra-abdominal desmoplastic small round cell tumor (IDSRCT) is a rare and highly malignant soft tissue neoplasm, which is characterized by rapid progression and poor prognosis. The mechanism underlying the development of this neoplasm remains elusive, but all cases are characterized by the chromosomal translocation t (11;22) (p13; q12), which results in a formation of EWSR1-WT1 gene fusion. The diagnosis of IDSRCT is often made with core-needle tissue biopsy specimens or laparoscopy or laparotomy. Immunohistochemical analyses have shown the co-expression of epithelial, neuronal, myogenic, and mesenchymal differentiation markers. FISH or reverse transcription polymerase chain reaction detecting EWS-WT1 fusion can be performed to assist in molecular confirmation. There is no standard of care for patients with IDSRCT currently, and majority of newly diagnosed patients received the aggressive therapy, which includes >90% resection of surgical debulking, high-dose alkylator-based chemotherapy, and radiotherapy. More recently, targeted therapy has been increasingly administered to recurrent IDSRCT patients and has been associated with improved survival in clinical conditions. Immunotherapy as a possible therapeutic strategy is being explored in patients with IDSRCT. In this review, we summarize currently available knowledge regarding the epidemiology, potential mechanisms, clinical manifestations, diagnosis, treatment, and prognosis of IDSRCT to assist oncologists in comprehensively recognizing and accurately treating this malignancy.

Uncommon and peculiar soft tissue sarcomas: Multidisciplinary review and practical recommendations. Spanish Group for Sarcoma research (GEIS -GROUP). Part II

Among all Soft Tissue sarcomas there are some subtypes with low incidence and/or peculiar clinical behaviour, that need to be consider separately. Most of them are orphan diseases, whose biological characteristics imply a clearly different diagnostic and therapeutic approach from other more common sarcoma tumors. We present a brief and updated multidiciplinary review, focused on practical issues, aimed at helping clinicians in decision making. In this second part we review these subtypes: Alveolar Soft Part Sarcoma, Epithelioid Sarcoma, Clear Cell Sarcoma, Desmoplastic Small Round Cell Tumor, Rhabdoid Tumor, Phyllodes Tumor, Tenosynovial Giant Cell Tumors, Myoepithelial Tumor, Perivascular Epithelioid Cell Neoplasms (PEComas), Extraskeletal Myxoid Chondrosarcoma, NTRK-fusions Sarcomas. Most of them present their own radiological and histopathological feautures, that are essential to know in order to achieve early diagnosis. In some of them, molecular diagnosis is mandatory, not only in the diagnosis, but also to plan the treatment. On the other hand, and despite the low incidence, a great scientific research effort has been made to achieve new treatment opportunities for these patients even with approved indications. These include new treatments with targeted therapies and immunotherapy, which today represent possible therapeutic options. It is especially important to be attentive to new and potential avenues of research, and to promote the conduct of specific clinical trials for rare sarcomas.

Heterogeneous Circulating Tumor Cells in Sarcoma: Implication for Clinical Practice

Simple Summary

The present review is aimed to discuss the relevance of assaying for the presence and isolation of circulating tumor cells (CTCs) in patients with sarcoma. Just a few studies have been performed to detect and enumerate viable CTCs in sarcoma and a majority of them still represent proof-of-concept studies, while more frequently tumor cells have been detected in the circulation by using the PCR-based method. Nevertheless, recent advances in technologies allowed detection of epithelial–mesenchymal transitioned CTCs from patients with mesenchymal malignancies, despite results being mostly preliminary. The possibility to identify CTCs holds a great promise for both applications of liquid biopsy in sarcoma for precision medicine, and for research purposes to pinpoint the mechanism of the metastatic process through the characterization of tumor mesenchymal cells. Coherently, clinical trials in sarcoma have been designed accordingly to detect CTCs, for diagnosis, identification of novel therapeutic targets and resistance mechanisms of systemic therapies, and patient stratification.

Abstract

Bone and soft tissue sarcomas (STSs) represent a group of heterogeneous rare malignant tumors of mesenchymal origin, with a poor prognosis. Due to their low incidence, only a few studies have been reported addressing circulating tumor cells (CTCs) in sarcoma, despite the well-documented relevance for applications of liquid biopsy in precision medicine. In the present review, the most recent data relative to the detection and isolation of viable and intact CTCs in these tumors will be reviewed, and the heterogeneity in CTCs will be discussed. The relevance of epithelial–mesenchymal plasticity and stemness in defining the phenotypic and functional properties of these rare cells in sarcoma will be highlighted. Of note, the existence of dynamic epithelial–mesenchymal transition (EMT)-related processes in sarcoma tumors has only recently been related to their clinical aggressiveness. Also, the presence of epithelial cell adhesion molecule (EpCAM)-positive CTC in sarcoma has been weakly correlated with poor outcome and disease progression, thus proving the existence of both epithelial and mesenchymal CTC in sarcoma. The advancement in technologies for capturing and enumerating all diverse CTCs phenotype originating from these mesenchymal tumors are presented, and results provide a promising basis for clinical application of CTC detection in sarcoma.

EWSR1-PATZ1-rearranged sarcoma: a report of nine cases of spindle and round cell neoplasms with predilection for thoracoabdominal soft tissues and frequent expression of neural and skeletal muscle markers

The knowledge of clinical features and, particularly, histopathological spectrum of EWSR1-PATZ1-rearranged spindle and round cell sarcomas (EPS) remains limited. For this reason, we report the largest clinicopathological study of EPS to date. Nine cases were collected, consisting of four males and five females ranging in age from 10 to 81 years (average: 49 years). Five tumors occurred in abdominal wall soft tissues, three in the thorax, and one in the back of the neck. Tumor sizes ranged from 2.5 to 18 cm (average 6.6 cm). Five patients had follow-up with an average of 38 months (range: 18-60 months). Two patients had no recurrence or metastasis 19 months after diagnosis. Four patients developed multifocal pleural or pulmonary metastasis and were treated variably by surgery, radiotherapy, and chemotherapy. The latter seemed to have little to no clinical benefit. One of the four patients was free of disease 60 months after diagnosis, two patients were alive with disease at 18 and 60 months, respectively. Morphologically, low, intermediate, and high-grade sarcomas composed of a variable mixture of spindled, ovoid, epithelioid, and round cells were seen. The architectural and stromal features also varied, resulting in a broad morphologic spectrum. Immunohistochemically, the following markers were most consistently expressed: S100-protein (7/9 cases), GFAP (7/8), MyoD1 (8/9), Pax-7 (4/5), desmin (7/9), and AE1/3 (4/9). By next-generation sequencing, all cases revealed EWSR1-PATZ1 gene fusion. In addition, 3/6 cases tested harbored CDKN2A deletion, while CDKN2B deletion and TP53 mutation were detected in one case each. Our findings confirm that EPS is a clinicopathologic entity, albeit with a broad morphologic spectrum. The uneventful outcome in some of our cases indicates that a subset of EPS might follow a more indolent clinical course than previously appreciated. Additional studies are needed to validate whether any morphological and/or molecular attributes have a prognostic impact.

Desmoplastic Small Round Cell Tumor with "Pure" Spindle Cell Morphology and Novel EWS-WT1 Fusion Transcript: Expanding the Morphological and Molecular Spectrum of This Rare Entity

Background: Desmoplastic small round cell tumor (DSRCT) is a rare pediatric soft tissue neoplasm composed of small round tumor cells with prominent stromal desmoplasia, polyphenotypic differentiation and EWSR1-WT1 gene fusion. We, herein, present a unique case of DSRCT, exhibiting a pure spindle cell morphology, absence of desmoplastic stroma and showing a novel EWS-WT1 fusion transcript. Methods: A 12-year-old boy presented multiple intra-abdominal, confluent and mass-forming nodules that affected the entire abdominal and pelvic cavities. Results: Histologically, the nodules were composed of spindle cells with scant cytoplasm and oval nuclei arranged into short, intersecting fascicles and set in a scant, non-desmoplastic, stroma. Immunohistochemically, neoplastic cells were stained with vimentin, desmin, WT-1 (C-terminus antibodies) and EMA. Reverse-transcriptase polymerase chain reaction (RT-PCR) analysis showed the presence of an unusual chimeric transcript, composed of an in-frame junction of exon 9 of EWS to exon 7 of WT1, confirming the histological diagnosis of DSRCT. Conclusions: The present case contributes to widen the morphological spectrum of this entity; notably, the additional presence of a novel chimeric fusion transcript contributes to making the present case even more unique. Whether the detection of the above-mentioned fusion transcripts could explain the unusual morphology of the tumor remains to be established.

Desmoplastic Small Round Cell Tumor: A Review of Main Molecular Abnormalities and Emerging Therapy

Simple Summary

Desmoplastic small round cell tumor is a rare neoplasm with extremely aggressive behavior. Despite the multimodal treatment for newly diagnosed patients with chemotherapy, cytoreductive surgery and radiation, the cure rate is still low. For relapsed or progressive disease, there is limited data regarding second and third-line therapies. Novel agents have shown only modest activity. Recent molecular changes have been identified in this disease and this opens opportunities to be explored in future clinical trials.

Abstract

Desmoplastic small round cell tumor (DSRCT) is an extremely rare, aggressive sarcoma affecting adolescents and young adults with male predominance. Generally, it originates from the serosal surface of the abdominal cavity. The hallmark characteristic of DSRCT is the EWSR1–WT1 gene fusion. This translocation up-regulates the expression of PDGFRα, VEGF and other proteins related to tumor and vascular cell proliferation. Current management of DSRCT includes a combination of chemotherapy, radiation and aggressive cytoreductive surgery plus intra-peritoneal hyperthermic chemotherapy (HIPEC). Despite advances in multimodal therapy, outcomes remain poor since the majority of patients present disease recurrence and die within three years. The dismal survival makes DSRCT an orphan disease with an urgent need for new drugs. The treatment of advanced and recurrent disease with tyrosine kinase inhibitors, such as pazopanib, sunitinib, and mTOR inhibitors was evaluated by small trials. Recent studies using comprehensive molecular profiling of DSRCT identified potential therapeutic targets. In this review, we aim to describe the current studies conducted to better understand DSRCT biology and to explore the new therapeutic strategies under investigation in preclinical models and in early phase clinical trials.

Desmoplastic Small Round Cell Tumors: A review with focus on clinical management and therapeutic options

Desmoplastic Small Round Cell Tumors (DSRCTs) are an entity of rare, aggressive soft tissue sarcomas described by Gerald and Rosai in 1989. It predominantly affects male adolescents and young adults, with a peak incidence between an age of 20 and 30 years. Typically, DSRCT demonstrate as multiple small tumor nodules within the abdominal cave, retroperitoneum and pelvis. In more than 50% of the cases, the neoplasm presents metastatic at the timepoint of diagnosis. Histologically, DSRCTs have a characteristic morphology with sharply demarcated islands of uniform small round cells in abundant desmoplastic stroma organized in loose extracellular matrix. Immunohistochemistry reveals a polyphenotypic differentiation with co-expression of epithelial, myogenic, mesenchymal and neural markers. The morphology is highly variable and can hinder diagnosis. The most consistent molecular characteristic of DSRCT is the reciprocal t(11;22)(p13q12) translocation. This mutation leads to a formation of the EWSR1-WT1 fusion oncogene, which encodes for a chimeric protein with transcriptional regulatory activity and is regarded as driving source of the disease. To date, there is no standardized concept for clinical management, staging and treatment. Patients receive an aggressive multimodal therapeutic approach consisting of chemotherapy, radical surgical procedures, hyperthermic, intraperitoneal chemotherapy (HIPEC) and radiation. New targeted therapies are used in experimental settings as salvage therapy. So far, none of these therapies showed significant long-term success. This review gives an overview of diagnostic difficulties and pitfalls, discusses therapeutic strategies and highlights options for clinical management.

Clinical Characteristics, Management, and Outcomes of 19 Nonpediatric Patients with Desmoplastic Small Round Cell Tumor: A Cohort of Brazilian Patients

Desmoplastic small round cell tumor (DSRCT) is a rare and aggressive mesenchymal malignancy, usually affecting young males. There is no consensus on the best therapeutic approach. We seek to characterize a cohort of nonpediatric patients with DSRCT treated at a large Brazilian cancer center. We performed a retrospective analysis of patients with histologically confirmed DSRCT referred to our institution (2007–2020). Clinical and imaging data were extracted and summarized with descriptive statistics. Survival analyses were conducted by the Kaplan–Meier method and compared with the log-rank test. We included 19 patients with DSRCT, the median age at diagnosis was 26 years (range: 15–41 years), and 68% were male. Ninety percent presented with abdominopelvic masses, and 32% had extra-abdominal metastasis at diagnosis. Eleven patients (58%) underwent surgery, four patients (21%) received whole abdominal adjuvant radiotherapy, and five patients (26%) had hyperthermic intraperitoneal chemotherapy. Median OS was 27 months (interquartile range: 18–51 m). The five-year OS rate was 12%. Our data confirm the aggressiveness of DSRCT despite intense multimodality treatment. Outcomes of patients treated in a reference cancer center in a developing country are similar to cancer centers in developed nations. Multicenter cooperation is urgent to the development of clinical trials and to improve diagnosis and treatment efficacy.

Retroperitoneal Sarcomas: An Update on the Diagnostic Pathology Approach

Retroperitoneal sarcomas are a heterogenous group of rare tumors arising in the retroperitoneum. Retroperitoneal sarcomas comprise approximately 10% of all soft tissue sarcomas. Though any soft tissue sarcoma histologic types may arise in the retroperitoneal space, liposarcoma (especially well-differentiated and dedifferentiated types) and leiomyosarcoma do so most commonly. Retroperitoneal sarcomas are diagnostically challenging, owing to their diversity and morphological overlap with other tumors arising in the retroperitoneum. An accurate diagnosis is necessary for correct management and prognostication. Herein, we provide an update on the diagnostic approach to retroperitoneal sarcomas and review their key histologic findings and differential diagnoses.

Pediatric sarcomas display a variable EpCAM expression in a histology-dependent manner

EpCAM is a transmembrane glycoprotein typically overexpressed in cancer of epithelial origin and mainly involved in the epithelial-to–mesenchymal transition (EMT) of tumor cells that spread and disseminate. Strategies for the targeting and capture of EpCAM-expressing tumor cells are showing promise in cancers prone to metastatize, both as diagnostic tools and potential therapies. Sarcomas are among the most aggressive tumors in children, with a common mesenchymal origin that comprises both soft tissue sarcomas (STS) and bone sarcomas. The aim of this study was to assess EpCAM expression in pediatric sarcomas and correlate its expression with disease progression. To do so, we analyzed a set of cell lines and primary tumor tissues from rhabdomyosarcoma (RMS), Ewing sarcoma (ES), synovial sarcoma (SS) and desmoplastic small round cell tumor (DSRCT) STS, or osteosarcoma (OS) bone cancer. We demonstrated that EpCAM was variably expressed in pediatric sarcomas, with DSRCT, a rare, aggressive and almost fatal tumor type, characterized by the highest EpCAM expression levels. Interestingly, although EpCAM expression was lower in RMS tumors, high levels at diagnosis correlated with reduced patients' overall survival (p < 0.05). Indeed, membrane-bound EpCAM was detected in circulating sarcoma tumor cells, revealing its potential to be used as dissemination biomarker in this type of childhood cancers. This reinforces the concept that pediatric sarcomas do express both epithelial and mesenchymal markers and reside in an intermediate condition that most likely contributes to their aggressive phenotype and low survival rate.

Mini-Review on Targeted Treatment of Desmoplastic Small Round Cell Tumor

Desmoplastic small round cell tumor (DSRCT) is a devastating disease which most commonly affects adolescents, with a male predominance. Despite the best multimodality treatment efforts, most patients will ultimately not survive more than 3-5 years after diagnosis. Some research trials in soft-tissue sarcoma and Ewing sarcoma include DSRCT patients but few studies have been tailored to the specific clinical needs and underlying cytogenetic abnormalities characterizing this disease such as the typical EWSR1-WT1 gene fusion. Downstream activation of EWSR1-WT1 gene fusion includes signaling pathways of platelet-derived growth factor (PDGF), vascular endothelial growth factor (VEGF), and insulin growth factor (IGF)-1. Other biological pathways that are activated and expressed in DSRCT cells include endothelial growth factor receptor (EGFR), androgen receptor pathway, c-KIT, MET, and transforming growth factor (TGF) beta. Investigation of somatic mutations, copy number alterations (CNA), and chromosomes in DSRCT samples suggests that deregulation of mesenchymal-epithelial reverse transition (MErT)/epithelial-mesenchymal transition (EMT) and DNA damage repair (DDR) may be important in DSRCT. This mini review looks at known druggable targets in DSRCT and existing clinical evidence for targeted treatments, particularly multityrosine kinase inhibitors such as pazopanib, imatinib, and sorafenib alone or in combination with other agents such as mTOR (mammalian target of rapamycin) inhibitors. The aim is to increase shared knowledge about current available treatments and identify gaps in research to further efforts toward clinical development of targeted agents.

Primary desmoplastic small-round-cell tumor of the ovary

BACKGROUND

Desmoplastic small-round-cell tumor (DSRCT) is an extremely rare and highly aggressive malignancy. It is of yet unclear origin, but it is assumed to be of a mesothelial origin based on its tendency for widespread metastasis in serosal linings.

CASE PRESENTATION

In this report, we describe a young female who presented with bilateral ovarian masses that mimicked the classic clinical picture of ovarian cancer. The patient had a cytoreductive surgery done in the form of total abdominal hysterectomy, bilateral salpingo-oophorectomy, omentectomy, pelvic peritonectomy, low para-aortic and bilateral iliac lymphadenectomy. Postoperative course was smooth with no adverse events. The final pathology report revealed desmoplastic small-round-cell tumor. Afterwards, the patient was referred to medical oncologist to receive her adjuvant therapy.

CONCLUSIONS

DSRCT is still an unknown disease to us given the limited number of cases and poor survival. Given the lack of clear guidelines, treatment is offered based on the best available evidence and the collaborative effort of a multi-disciplinary team.

Exosomal MiRNAs in Pediatric Cancers

MicroRNAs (miRNAs) have generated great attention in oncology as they play a fundamental role in the regulation of gene expression and their aberrant expression is present in almost all types of tumors including pediatric ones. The discovery that miRNAs can be transported by exosomes, which are vesicles of 40–120 nm involved in cellular communication, that are produced by different cell types, and that are present in different biological fluids, has opened the possibility of using exosomal miRNAs as biomarkers. The possibility to diagnose and monitor the progression and response to drugs through molecules that can be easily isolated from biological fluids represents a particularly important aspect in the pediatric context where invasive techniques are often used. In recent years, the idea of liquid biopsy as well as studies on the possible role of exosomal miRNAs as biomarkers have developed greatly. In this review, we report an overview of all the evidences acquired in recent years on the identification of exosomal microRNAs with biomarker potential in pediatric cancers. We discuss the following herein: neuroblastoma, hepatoblastoma, sarcomas (osteosarcoma, Ewing’s sarcoma and rhabdoid tumors, and non-rhabdomyosarcoma soft tissue sarcoma), brain tumors, lymphomas, and leukemias.

Important Recently Characterized Non-Ewing Small Round Cell Tumors

Round cell sarcomas morphologically similar to Ewing sarcoma, but lacking the classic immunohistochemical features, EWSR-ETS family fusions, and other signs of differentiation, are classified as Ewing-like sarcomas. Recent molecular advances led to the discovery and characterization of two recurrent oncogenic fusion rearrangements, CIC-DUX4 and BCOR-CCNB3, in a significant subset of Ewing-like sarcomas. Uncovered alternate fusion partners broadened the proposed classification of these tumors to CIC-rearranged sarcomas and BCOR-rearranged sarcomas. This article summarizes the clinicopathologic and molecular features of these entities, with particular attention paid to those features that overlap with and distinguish these sarcomas from other round cell sarcomas.

Desmoplastic Small Round Cell Tumors With Atypical Presentations: A Report of 34 Cases

Objectives. Desmoplastic small round cell tumor (DSRCT) is an aggressive round cell sarcoma that arises in the abdominal cavity/pelvis of young males. We sought to expand its clinicopathologic spectrum. Methods. Cases of DSRCT presenting in patients >30 years of age or tumors arising outside of the abdominal cavity/pelvis were retrieved. Results. Thirty-four cases were identified. Sixteen tumors arose at atypical sites (head/neck, intracranial, thigh, axilla/shoulder, inguinal/paratesticular, intraosseous, and uterine corpus). The remaining 18 patients were older than 30 years, and their tumors involved the abdomen or pelvis. The majority of cases showed areas with classic histology, while 6 cases exhibited solid growth and 5 showed macronodular architecture. Cytologic appearance included round cell, rhabdoid, epithelioid, and small cell. Conclusion. DSRCT may arise at nonabdominal locations in both pediatric and adult populations, as well as intra-abdominally in older adults, and these tumors exhibit high rates of metastasis and morbidity.

Immune profiles of desmoplastic small round cell tumor and synovial sarcoma suggest different immunotherapeutic susceptibility upfront compared to relapse specimens

BACKGROUND

Desmoplastic small round cell tumor (DSRCT) and synovial sarcoma are rare tumors with dismal outcomes requiring new therapeutic strategies. Immunotherapies have shown promise in several cancer types, but have not been evaluated in DSRCT and synovial sarcoma. Because the immune microenvironment can provide indications of the inflammatory nature of tumors, immunohistochemical staining is able to assess the tumor immune infiltrates in both tumor types.

PROCEDURE

Using tissue microarrays of DSRCT and synovial sarcoma tumor samples, we detected tumoral HLA-A/B/C, beta-2-microglobulin(B2M), and PD-L1 expression, and quantified tumor-infiltrating lymphocytes expressing CD4, CD8, CD56, CD45RO, or FOXP3 by immunohistochemistry. We used staining intensity on a scale of 0-3 and percentage of tumor stained to determine HLA, B2M, and PD-L1 scores. We calculated the cytotoxic T lymphocyte (CTL) target score as HLA score × B2M score/100.

RESULTS

In diagnostic samples, we found high HLA and CTL target scores and low PD-L1 expression with decreased scores in recurrence for both tumor types. We found an increase in CD56⁺ natural killer cells in DSRCT samples from diagnosis to recurrence.

CONCLUSIONS

We found similar immunostimulatory profiles in DSRCT and synovial sarcoma. Our findings suggest that DSRCT and synovial sarcoma may be amenable to immunotherapies, albeit there was significant heterogeneity. Interestingly, HLA and CTL target scores decreased at recurrence, possibly reflecting immunoevasion. Our findings suggest both tumor types may be amendable to CTL-based therapies at diagnosis but less so at relapse. Our results support further investigation into the prognostic and predictive value of these findings in a larger dataset.

Clinical management of a unique case of PNET of the uterus during pregnancy, and review of the literature

RATIONALE

PNETs (primitive neuroectodermal tumors) are a family of highly malignant neoplasms characterized by small round cells of neuroepithelial origin. They usually involve bone and soft tissues, and have a higher incidence in childhood.

PATIENT CONCERNS

In this case report, we describe the obstetric and oncological outcome of a huge mass diagnosed as a leiomyoma in a 39-year-old pregnant woman who complained of low back pain, dysuria, and urinary frequency at 22 weeks of gestation.

DIAGNOSES

During the 25th week of pregnancy, the patient was referred to our hospital at night with severe anemia and suspected hemoperitoneum. She underwent an emergency caesarean section, delivering a female fetus weighing 400 g, with an Apgar score of 7 at 1 minute and 9 at 5 minutes.

INTERVENTION

During surgery, we found a huge uterine sarcoma-like metastatic tumor, invading the pelvic peritoneum and parametria bilaterally; the adnexae seemed disease-free. We performed a type B radical hysterectomy, bilateral salpingo-oophorectomy, pelvic peritonectomy, omentectomy, appendectomy, and excision of a bulky lymph node. Seven days after delivery, staging computed tomography (CT) scan demonstrated a large lombo-aortic lymph node compressing the left renal vein and we completed debulking with a second surgery, including diaphragmatic peritonectomy and excision of a huge lymph node by lombo-aortic lymphadenectomy, requiring partial reconstruction of an infiltrated renal vein.

OUTCOME

Ten days after the second surgery, echo-color Doppler showed a regular microcirculation in the left kidney. The patient was discharged after 10 days, and the baby after 1 month, both in good health.Histological examination revealed a uterine body cPNET (central primitive neuroectodermal tumor) orienting the clinical management toward chemotherapy with cisplatin and etoposide.

LESSONS

PNETs are aggressive neoplasms, usually diagnosed at an advanced stage. Due to their low incidence, universally accepted guidelines are still unavailable. Radical surgery leaving no macroscopic residual disease is mandatory in advanced stages. A good fertility-sparing procedure can be performed only in young women at early stages of disease, when the wish for childbearing is not yet fulfilled.

Clinical activity of eribulin in advanced desmoplastic small round-cell tumor

Desmoplastic small round-cell tumor is a rare but highly aggressive tumor occurring mainly in adolescents and young adults. Prolonged progression-free survival has been documented in patients who have undergone aggressive multimodality therapy - that is, multiagent intensive chemotherapy, debulking surgery, and radiation therapy. Eribulin is a microtubule-dynamics inhibitor, and it has recently been shown to be active in liposarcomas. In preclinical models, eribulin activities have also been shown to occur in Ewing's sarcoma cell lines, rhabdomyosarcomas and osteosarcomas. In this study, we report three cases of male patients suffering from desmoplastic small round-cell tumor and the clinical response to eribulin in two of them.

Cytoreductive surgery and hyperthermic intraperitoneal chemotherapy combined with two-stage hepatectomy for multiple and bilobar desmoplastic small round cell tumor liver metastases

Desmoplastic small round cell tumor (DSRCT) is a rare mesenchymal tumor usually affecting young patients. Local dissemination is common, and liver is the most common site for extraperitoneal metastases. Multimodal management has been shown to be the most effective treatment. Some authors consider liver metastases especially bi-lobar disease as a contraindication for surgical resection. We present a case of a DSRCT with bi-lobar metastases in an adult patient who underwent multi-modal management along with hepatectomy. A 51-year-old man was found to have a large intraperitoneal mass with bi-lobar liver metastases during work up for new onset reflux and abdominal pain. Biopsy confirmed it as DSRCT. The patient was treated with multi-modal therapy including cytoreductive surgery (CRS), hyperthermic intraperitoneal chemotherapy (HIPEC), two-stage hepatectomy (TSHP) combined with (⁹⁰Y) Yittrium-90 radioembolization of the right hepatic lobe and systemic chemotherapy. The patient had a right-sided pleural empyema one month after the surgery for which he required right-sided video-assisted thoracoscopy and decortication. He remains disease free at 2 years follow-up. DSRCT with bi-lobar liver metastases are best managed with multimodal therapy. TSHP seems to be a feasible and safe option in selected cases, with a potentially good outcome.

Expression and clinical association of programmed cell death-1, programmed death-ligand-1 and CD8+ lymphocytes in primary sarcomas is subtype dependent

In order to explore the potential of immune checkpoint blockade in sarcoma, we investigated expression and clinical relevance of programmed cell death-1 (PD-1), programmed death ligand-1 (PD-L1) and CD8 in tumors of 208 sarcoma patients. Primary untreated osteosarcoma (n = 46), Ewing sarcoma (n = 32), alveolar rhabdomyosarcoma (n = 20), embryonal rhabdomyosarcoma (n = 77), synovial sarcoma (n = 22) and desmoplastic small round cell tumors (DSRCT) (n = 11) were examined immunohistochemically. PD-L1 expression was predominantly detected in alveolar and embryonal rhabdomyosarcomas (15% and 16%, respectively). In the alveolar subtype PD-L1 expression was associated with better overall, event-free and metastases-free survival. PD-1 expression on lymphocytes was predominantly seen in synovial sarcomas (18%). High levels of CD8+ lymphocytes were predominantly detected in osteosarcomas (35%) and associated with worse event-free survival in synovial sarcomas. Ewing sarcoma and DSRCTs showed PD-1 on tumor cells instead of on tumor infiltrating lymphocytes. Overall, expression and clinical associations were found to be subtype dependent. For the first time PD-1 expression on Ewing sarcoma (19%) and DSRCT (82%) tumor cells was described.

Molecular Changes Associated With Tumor Initiation and Progression of Soft Tissue Sarcomas: Targeting the Genome and Epigenome

Soft tissue sarcomas are rare, but generally aggressive tumors which disproportionately affect children and young adults. They represent less than 10% of all cancers, but are one of the most frequently diagnosed cancers in pediatric patients. These cancers have a high rate of morbidity and mortality, and their overall incidence has been increasing at an estimated rate of 26% over the last 2 decades. The cause of this increased incidence is unknown but various environmental factors have been implicated. Establishing standard therapeutic strategies is challenging for soft tissue sarcomas as more than 50 different histological subtypes exist, each with their own molecular alterations and clinical characteristics, and this combination of tumor heterogeneity and a limited number of clinical cases make detailed omics level molecular studies particularly challenging. This chapter will focus on the unique genetic and epigenetic changes which characterize these cancers, with an emphasis on translocation-associated sarcomas involving primary gene fusions with the RNA chaperone protein EWSR1. We will highlight current therapeutic approaches and discuss opportunities for targeted molecular therapeutics.