Expanded molecular profiling of myxofibrosarcoma reveals potentially actionable targets

When Is It Important to Sequence Sarcomas and Other Mesenchymal Neoplasms? A Practical Guide to Molecular Testing

The increasingly widespread availability of next-generation sequencing has led to its incorporation as a diagnostic tool in pathology and a modality for identifying targetable alterations. However, sequencing is still a somewhat expensive and time-consuming. Here, we discuss tumor types for which (1) molecular testing is not generally indicated, (2) surrogate immunohistochemical markers have rendered molecular testing unnecessary, or (3) sequencing is important for diagnostic and therapeutic purposes. We also provide a practical framework to assist in decision-making for molecular testing of both classified and unclassified mesenchymal neoplasms, reflecting our practice in a tertiary sarcoma referral center.

Exploring the Potential of Optical Genome Mapping in the Diagnosis and Prognosis of Soft Tissue and Bone Tumors

Sarcomas are rare malignant tumors of mesenchymal origin with a high misdiagnosis rate due to their heterogeneity and low incidence. Conventional diagnostic techniques, such as Fluorescence In Situ Hybridization (FISH) and Next-Generation Sequencing (NGS), have limitations in detecting structural variations (SVs), copy number variations (CNVs), and predicting clinical behavior. Optical genome mapping (OGM) provides high-resolution genome-wide analysis, improving sarcoma diagnosis and prognosis assessment. This study analyzed 53 sarcoma samples using OGM. Ultra-high molecular weight (UHMW) DNA was extracted from core and resection biopsies, and data acquisition was performed with the Bionano Saphyr platform. Bioinformatic pipelines identified structural variations, comparing them with known alterations for each sarcoma subtype. OGM successfully analyzed 62.3% of samples. Diagnostic-defining alterations were found in 95.2% of cases, refining diagnoses and revealing novel oncogenic and tumor suppressor gene alterations. The challenges included DNA extraction and quality issues from some tissue samples. Despite these limitations, OGM proved to be a powerful diagnostic and predictive tool for bone and soft tissue sarcomas, surpassing conventional methods in resolution and scope, enhancing the understanding of sarcoma genetics, and enabling better patient stratification and personalized therapies.

SS18-SSX Expression and Clinicopathologic Profiles in a Contemporary Cohort of Primary Paratesticular Synovial Sarcoma: A Series of Fourteen Patients

Synovial sarcoma (SS) is a rare genitourinary malignancy with a specific SS18::SSX 1/2 gene fusion in majority of the instances. The paratesticular location of this neoplasm is extremely rare and only 4 cases are reported in the literature. Herein, we describe the clinicopathologic features and molecular profile of paratesticular SS in the largest case series to date and to the best of our knowledge, and the only series to use novel SS18-SSX antibody for immunohistochemistry. Clinicopathologic, immunohistochemical (IHC), molecular, treatment, and follow-up data of the patients were analyzed. There were 14 patients, ranging from 15 to 47 years (mean: 30 y). The tumor size ranged from 4​​​​​​ to 15 cm. The tumors were unilateral, solid, and homogeneous tan-white with monomorphic spindle cell histology. All 14 tumors expressed SS18-SSX and TLE1 IHC and harbored SS18 rearrangement. In addition, the tumor with multifocal SS18-SSX expression had lower break-apart signals in the FISH assay (38% of the tumor cells; range: 29% to 85%). Radical orchiectomy was performed in all 14 patients and adjuvant chemotherapy was administered in 9 patients. Follow-up was available in 9 patients. The follow-up duration ranged from 5 to 24 months (median=10 mo). Four patients died of metastatic disease (range: 5 to 16 mo) and 2 patients who are alive had metastatic disease at the last follow-up. Based on our experience with the largest series to date and aggregate of the published data, paratesticular SS has a poor prognosis despite aggressive therapy. Owing to its rarity, the differential diagnosis is wide and requires a systematic approach for ruling out key morphologic mimics aided with SS18-SSX IHC and molecular confirmation because this distinction carries important therapeutic and prognostic implications. Due to the excellent concordance of SS18-SSX IHC results with FISH results as observed in our study, we would like to suggest inclusion of SS18-SSX in the diagnostic immunohistochemistry panel of all spindle cell sarcomas where synovial sarcoma is considered as a morphologic differential. SS18-SSX-positive staining may be used as a surrogate for FISH assay in a resource-limited setting where molecular assay is not available. Furthermore, IHC has a fairly shorter turn-around-time, is less complex, and of low cost.

Establishment and characterization of the novel myxofibrosarcoma cell line, SMU-MFS

Myxofibrosarcoma (MFS) is one of the most common soft-tissue sarcomas in elderly patients. Owing to the limited efficacy of chemotherapy and radiotherapy, complete resection is the only available curative treatment. Therefore, developing novel therapies for MFS is important to improve clinical outcomes. Herein, a novel MFS cell line, namely SMU-MFS, was established to better understand the biologic characteristics of MFS and develop new therapies. A tissue sample from the surgically resected tumor tissue of a 56-year-old patient with a tumor was subjected to primary culture. The cell line was established and authenticated by assessing the short tandem repeats of DNA microsatellites. The monolayer cultures of SMU-MFS cells exhibited constant growth, spheroid formation, and invasive capacity. Furthermore, the cells exhibited low chemosensitivity to doxorubicin, eribulin, and pazopanib, which are used to inhibit metastatic progression. In addition, of the four mice inoculated with SMU-MFS cells, tumors developed in two mice after 8 weeks. Altogether, the findings of this study suggest that the SMU-MFS cell line can be a useful tool for investigating MFS development and evaluating novel therapeutic agents.

Establishment and characterization of two novel patient-derived cell lines from myxofibrosarcoma: NCC-MFS7-C1 and NCC-MFS8-C1

Myxofibrosarcoma (MFS), an aggressive soft tissue sarcoma, presents a significant challenge because of its high recurrence rate, distal metastasis, and complex genetic background. Although surgical resection is the standard treatment for MFS, the outcomes are unsatisfactory and effective non-surgical treatment strategies, including drug therapy, are urgently warranted. MFS is a rare tumor that requires comprehensive preclinical research to develop promising drug therapies; however, only two MFS cell lines are publicly available worldwide. The present study reports two novel patient-derived MFS cell lines, NCC-MFS7-C1 and NCC-MFS8-C1. These cell lines have been extensively characterized for their genetic profile, proliferation, spheroid-forming capacity, and invasive behavior, confirming that they retain MFS hallmarks. Furthermore, we conducted comprehensive drug screening against these cell lines and six others previously established in our laboratory to identify potential therapeutic candidates for MFS. Among the screened agents, actinomycin D, bortezomib, and romidepsin demonstrated considerable antiproliferative effects that were superior to those of doxorubicin, a standard drug, highlighting their potential as novel drugs. In conclusion, NCC-MFS7-C1 and NCC-MFS8-C1 are valuable research resources that contribute to the understanding of the pathogenesis and development of novel therapies for MFS.

p53 as a Potential Actionable Target in Myxofibrosarcoma: A Molecular and Pathologic Review of a Single-Institute Series

Myxofibrosarcoma (MFS) is a common adult soft tissue sarcoma characterized by high-local recurrence rate, poorly understood molecular pathogenesis, lack of specific prognostic markers, and effective targeted therapies. To gain further insights into the disease, we analyzed a well-defined group of 133 primary MFS cases. Immunohistochemical (IHC) staining for p53, MET, RET, and RB was performed. Twenty-five cases were analyzed by targeted resequencing of known cancer driver hotspot mutations, whereas 66 and 64 MFSs were examined for the presence of genetic variants in TP53 and MET gene, respectively. All clinical, histologic, immunostaining, and genetic variables were analyzed for their impact on 5-years overall survival (OS) and 5-years event-free survival (EFS). In our series, no grade I tumors relapsed and high grade are related to a positive MET immunostaining (P = .034). Both local recurrence (P = .038) and distal metastases (P = .016) correlated to the presence of "single nucleotide variant (SNV) plus copy number variation (CNV)" in TP53. Multivariate analysis revealed that age (>60 years), metastasis at presentation, and positive IHC-p53 signal are risk factors for a poor OS (P = .003, P = .000, and P = .002), whereas age (>60 years), synchronous metastasis, and tumor size (>10 cm) predict an unfavorable 5-years EFS (P = .011, P = .000, and P = .023). Considering the smaller series (n = 66) that underwent molecular screening, the presence of "SNV+CNV" in TP53 represents a risk factor for a worse 5-years EFS (hazard ratio, 2.5; P = .017). The present series confirms that TP53 is frequently altered in MFS (86.4% of cases), appearing to play an important role in MFS tumorigenesis and being a potentially drugable target. A positive p53 immunostainings is related to a poor diagnosis, and it is the presence of a single nucleotide genetic alterations in TP53 that is essential in conferring MFS an aggressive phenotype, thus supporting the use of molecular profiling in MFS to better define the role of p53 as a prognostic factor.

Pan-cancer Genomic Analysis of AXL Mutations Reveals a Novel, Recurrent, Functionally Activating AXL W451C Alteration Specific to Myxofibrosarcoma

Myxofibrosarcoma (MFS) is a common soft tissue sarcoma of the elderly that typically shows low tumor mutational burden, with mutations in TP53 and in genes associated with cell cycle checkpoints ( RB1 , CDKN2A ). Unfortunately, no alterations or markers specific to MFS have been identified and, as a consequence, there are no effective targeted therapies. The receptor tyrosine kinase AXL, which drives cellular proliferation, is targetable by new antibody-based therapeutics. Expression of AXL messenger RNA is elevated in a variety of sarcoma types, with the highest levels reported in MFS, but the pathogenic significance of this finding remains unknown. To assess a role for AXL abnormalities in MFS, we undertook a search for AXL genomic alterations in a comprehensive genomic profiling database of 463,546 unique tumors (including 19,879 sarcomas, of which 315 were MFS) interrogated by targeted next-generation DNA and/or RNA sequencing. Notably, the only genomic alterations recurrent in a specific sarcoma subtype were AXL W451C (n = 8) and AXL W450C (n = 2) mutations. The tumors involved predominantly older adults (age: 44 to 81 [median: 72] y) and histologically showed epithelioid and spindle-shaped cells in a variably myxoid stroma, with 6 cases diagnosed as MFS, 3 as undifferentiated pleomorphic sarcoma (UPS), and 1 as low-grade sarcoma. The AXL W451C mutation was not identified in any non-sarcoma malignancy. A review of publicly available data sets revealed a single AXL W451C-mutant case of UPS that clustered with MFS/UPS by methylation profiling. Functional studies revealed a novel activation mechanism: the W451C mutation causes abnormal unregulated dimerization of the AXL receptor tyrosine kinase through disulfide bond formation between pairs of mutant proteins expressing ectopic cysteine residues. This dimerization triggers AXL autophosphorylation and activation of downstream ERK signaling. We further report sarcomas of diverse histologic subtypes with AXL gene amplifications, with the highest frequency of amplification identified in MFS cases without the W451C mutation. In summary, the activating AXL W451C mutation appears highly specific to MFS, with a novel mechanism to drive unregulated signaling. Moreover, AXL gene amplifications and messenger RNA overexpression are far more frequent in MFS than in other sarcoma subtypes. We conclude that these aberrations in AXL are distinct features of MFS and may aid diagnosis, as well as the selection of available targeted therapies.

The Role of Methylation Analysis in Distinguishing Cellular Myxoma from Low-Grade Myxofibrosarcoma

Cellular myxoma is a benign soft tissue tumor frequently associated with GNAS mutation that may morphologically resemble low-grade myxofibrosarcoma. This study aimed to identify the undescribed methylation profile of cellular myxoma and compare it to myxofibrosarcoma. We performed molecular analysis on twenty cellular myxomas and nine myxofibrosarcomas and analyzed the results using the methylation-based DKFZ sarcoma classifier. A total of 90% of the cellular myxomas had GNAS mutations (four loci had not been previously described). Copy number variations were found in all myxofibrosarcomas but in none of the cellular myxomas. In the classifier, none of the cellular myxomas reached the 0.9 threshold. Unsupervised t-SNE analysis demonstrated that cellular myxomas form their own clusters, distinct from myxofibrosarcomas. Our study shows the diagnostic potential and the limitations of molecular analysis in cases where morphology and immunohistochemistry are not sufficient to distinguish cellular myxoma from myxofibrosarcoma, particularly regarding GNAS wild-type tumors. The DKFZ sarcoma classifier only provided a valid prediction for one myxofibrosarcoma case; this limitation could be improved by training the tool with a more considerable number of cases. Additionally, the classifier should be introduced to a broader spectrum of mesenchymal neoplasms, including benign tumors like cellular myxoma, whose distinct methylation pattern we demonstrated.

MDM2 Amplification Status in a Cohort of Well-Characterized Myxofibrosarcoma: A Clinicopathologic Analysis of 22 Tumors

Myxofibrosarcomas (MFS) present as slowly enlarging superficial masses in elderly patients. Even though these tumors fail to exhibit a distinct immunophenotype, diagnosis is straightforward when they present in subcutaneous tissue. Intramuscular MFS, however, are more challenging to diagnose as the differential also includes dedifferentiated liposarcoma with myxoid features. The vast majority of dedifferentiated liposarcomas show MDM2 amplification, whereas limited data exists as to the MDM2 status of MFS. We sought to explore the rate of MDM2 amplification in cases of classic MFS. Our archives were searched for MFS; only subcutaneous well-sampled resections were included. FISH for MDM2 amplification was performed on each tumor. A cohort of myxoid dedifferentiated liposarcoma resections was studied for comparison. Twenty-two MFS arose in patients aged 44 to 85 years. All tumors contained an infiltrative population of atypical cells embedded in a myxoid stroma with curvilinear blood vessels. MDM2 amplification by FISH was identified in 3 (of 22; 14%) tumors. Available follow up on 17 patients (range 1-96 months; median 13 months) revealed 6 patients with local recurrence and 1 with distant metastasis. Of 3 patients with MDM2- amplified MFS, 1 experienced recurrence and died of unrelated causes, while the second was alive without disease 12 months after diagnosis. Even though the rate of MDM2 amplification by FISH in MFS appears to be low, a subset of cases may show this genetic alteration, which pathologists should be aware of to avoid misclassification as myxoid dedifferentiated liposarcomas. Further studies are necessary to determine if amplification status adds prognostic value.

A novel patient-derived immortalised cell line of myxofibrosarcoma: a tool for preclinical drugs testing and the generation of near-patient models

BACKGROUND

Myxofibrosarcoma is a rare malignant soft tissue sarcoma characterised by multiple local recurrence and can become of higher grade with each recurrence. Consequently, myxofibrosarcoma represents a burden for patients, a challenge for clinicians, and an interesting disease to study tumour progression. Currently, few myxofibrosarcoma preclinical models are available.

METHODS

In this paper, we present a spontaneously immortalised myxofibrosarcoma patient-derived cell line (MF-R 3). We performed phenotypic characterization through multiple biological assays and analyses: proliferation, clonogenic potential, anchorage-independent growth and colony formation, migration, invasion, AgNOR staining, and ultrastructural evaluation.

RESULTS

MF-R 3 cells match morphologic and phenotypic characteristics of the original tumour as 2D cultures, 3D aggregates, and on the chorioallantoic membrane of chick embryos. Overall results show a clear neoplastic potential of this cell line. Finally, we tested MF-R 3 sensitivity to anthracyclines in 2D and 3D conditions finding a good response to these drugs.

CONCLUSIONS

In conclusion, we established a novel patient-derived myxofibrosarcoma cell line that, together with the few others available, could serve as an important model for studying the molecular pathogenesis of myxofibrosarcoma and for testing new drugs and therapeutic strategies in diverse experimental settings.

Modeling Myxofibrosarcoma: Where Do We Stand and What Is Missing?

Myxofibrosarcoma (MFS) is a malignant soft tissue sarcoma (STS) that originates in the body's connective tissues. It is characterized by the presence of myxoid (gel-like) and fibrous components and typically affects patients after the fifth decade of life. Considering the ongoing trend of increasing lifespans across many nations, MFS is likely to become the most common musculoskeletal sarcoma in the future. Although MFS patients have a lower risk of developing distant metastases compared with other STS cases, MFS is characterized by a high frequency of local recurrence. Notably, in 40-60% of the patients where the tumor recurs, it does so multiple times. Consequently, patients may undergo multiple local surgeries, removing the risk of potential amputation. Furthermore, because the tumor relapses generally have a higher grade, they exhibit a decreased response to radio and chemotherapy and an increased tendency to form metastases. Thus, a better understanding of MFS is required, and improved therapeutic options must be developed. Historically, preclinical models for other types of tumors have been instrumental in obtaining a better understanding of tumor development and in testing new therapeutic approaches. However, few MFS models are currently available. In this review, we will describe the MFS models available and will provide insights into the advantages and constraints of each model.

Superficial CD34-Positive Fibroblastic Tumor: A Newly Recognized Entity With Overlapping Features of PRDM10-Rearranged Soft Tissue Tumors

Superficial CD34-positive fibroblastic tumor (SCPFT) is a recently identified, infrequent, low-grade mesenchymal neoplasm, first identified in 2014. Although it is relatively new to the field, SCPFT has been gaining prominence in surgical pathology practice because of its distinctive features. As of now, there are limited reported cases of SCPFT, with fewer than 100 instances documented in scientific literature. This distinctive blend of rarity and intriguing variability in presentation emphasizes the significance of identifying and understanding this uncommon entity, facilitating precise diagnosis and optimal management. In this article, we aimed to present a notable case of SCPFT in a male in his 20s who presented with a distinct subcutaneous mass measuring 2.4 × 1.8 cm at the medial aspect of the knee joint. The patient reported no significant medical history or trauma to the affected area. MRI of the knee showed a well-defined 2.4 × 1.8 cm subcutaneous mass with no definite communication with the underlying ligament or meniscus. The histopathological examination revealed spindle cell neoplasm arranged in intersecting fascicles, accompanied by arborizing blood vessels. Neoplastic spindle cells exhibited marked nuclear pleomorphism, and abundant and eosinophilic cytoplasm, with focal areas of granular, glassy, and lipidized cytoplasm. Nuclear pseudo inclusions and a few mitotic figures (1-2 per high-power field) were noted. Inflammatory infiltrates were identified within the neoplasm, comprising eosinophils and lymphocytes, highlighting an immune response within the tumor microenvironment. The surgical margin exhibited involvement with the tumor infiltrates, with the neoplastic cells extending into the adjacent fat tissue. This finding indicates local tumor spread and potential challenges in achieving complete resection. Immunohistochemical staining showed positive staining for CD34, corroborating the diagnosis of a CD34-positive fibroblastic tumor. Focal positive staining for pan-CK was noted. Staining for CD31, smooth muscle actin (SMA), desmin, S100, and anaplastic lymphoma kinase (ALK) was negative, supporting the diagnosis. The Ki67 proliferation index was low.

Biology and Management of High-Grade Myxofibrosarcoma: State of the Art and Future Perspectives

Myxofibrosarcoma (MFS) is one of the most common adult soft tissue sarcomas, typically arising in the extremities. Histologically, MFS is classified into three grades: low, intermediate, and high. Histological grades correlate with distant metastases and tumor-associated mortality. The diagnosis of MFS is challenging due to a lack of well-characterized immunohistochemical markers. High-grade MFS displays highly complex karyotypes with multiple copy number alterations. Recent integrated genomic studies have shown the predominance of somatic copy number aberrations. However, the molecular pathogenesis of high-grade MFS remains poorly understood. The standard treatment for localized MFS is surgical resection. The systemic treatment options for advanced disease are limited. This review provides an updated overview of the clinical and imaging features, pathogenesis, histopathology, and treatment of high-grade MFS.

Exceptional Response to MEK Inhibition in a Patient With RAF1-Mutant Myxofibrosarcoma: Case Report and Mechanistic Overview

Complete response to Trametinib in a heavily-pretreated sarcoma: RAF1 as a predictor of MEKi Response

Primary sclerosing liposarcoma of the ovary: Case report and a review of the literature

INTRODUCTION

Primary soft tissue sarcoma of the ovary is uncommon, with most literature reports being in the format of a single case report or small case series.

PRESENTATION OF CASE

We report a case of a primary sclerosing liposarcoma of the ovary in a 67-year-old lady. She presented with a rapidly growing ovarian mass, which was surgically excised. Histologically, the lesion appeared nodular with alternating hypercellular and low-cellularity areas, with areas of necrosis. It comprised atypical spindled, oval and stellate cells set in abundant myxoid and fibrous hyalinised stroma. Immunohistochemistry showed expression of p16, CDK4, CD34, S-100 and MDM2. The case was sent to a referral centre where MDM2 gene amplification was detected by interphase fluorescent in-situ hybridisation (FISH) analysis, rendering a diagnosis of well-differentiated sclerosing liposarcoma with focal low-grade dedifferentiation.

DISCUSSION

To the best of our knowledge, this is the first reported example of a sclerosing variant of liposarcoma in the ovary. Differential diagnosis includes microcystic stromal tumour (MST), sclerosing stromal tumour (SST), atypical spindle cell lipoma, myxoid liposarcoma, myxofibosarcoma, solitary fibrous tumour and low grade fibromyxoid sarcoma.

CONCLUSION

Ovarian sarcomas are characterised by a rapid and aggressive clinical course, requiring multidisciplinary team input for ongoing management. Complete surgical resection with clear margins is the mainstay of treatment.

Molecular and clinicopathological analysis revealed an immuno-checkpoint inhibitor as a potential therapeutic target in a subset of high-grade myxofibrosarcoma

This study aimed to identify differences in genetic alterations between low- and high-grade lesions in myxofibrosarcoma (MFS) and to examine the efficacy of immune checkpoint inhibitors in 45 patients with MFS. First, genetic differences between low- and high-grade components within the same tumor were analyzed in 11 cases using next-generation sequencing. Based on the obtained data, Sanger sequencing was performed for TP53 mutations in the remaining 34 patients. Loss of heterozygosity (LOH) analysis was performed at the TP53 and RB1 loci. Immunohistochemistry was performed for FGFR3, KIT, MET, programmed death receptor ligand 1 (PD-L1), CD8, FOXP3, and mismatch repair proteins. The microsatellite instability status was also evaluated in all cases. TP53 deleterious mutations and LOH at TP53 and RB1 loci were detected significantly more frequently in high-grade than in low-grade MFS (P = 0.0423, 0.0455, and 0.0455, respectively). LOH at the RB1 locus was significantly associated with shorter recurrence-free survival in both univariate and multivariate analyses. TP53 alterations, such as mutation and LOH, were more frequently observed in low-grade areas within high-grade MFS than in pure low-grade MFS. The positive PD-L1 expression rate was 35.6% (16/45), and all these 16 cases were high-grade. A high density of both CD8+ and FOXP3+ tumor-infiltrating lymphocytes was associated with PD-L1 positivity. LOH at the RB1 locus was identified an independent adverse prognostic factor for recurrence-free survival in patients with MFS. Immune checkpoint inhibitors may be a therapeutic option for a subset of high-grade MFS.

The landscape of genetic aberrations in myxofibrosarcoma

Myxofibrosarcoma (MFS) is a rare subtype of sarcoma, whose genetic basis is poorly understood. We analyzed 69 MFS cases using whole-genome (WGS), whole-exome (WES), and/or targeted-sequencing (TS). Newly sequenced genomic data were combined with additional deposited 116 MFS samples. WGS identified a high number of structural variations (SVs) per tumor most frequently affecting the TP53 and RB1 loci, 40% of tumors showed a BRCAness-associated mutation signature, and evidence of chromothripsis was found in all cases. Most frequently mutated /copy number altered genes affected known disease drivers such as TP53 (56.2%), CDKN2A/B (29.7%), RB1 (27.0%), ATRX (19.5%), and HDLBP (18.9%). Several previously unappreciated genetic aberrations including MUC17, FLG, and ZNF780A were identified in more than 20% of patients. Longitudinal analysis of paired diagnosis and relapse time points revealed a 1.2-fold mutation number increase accompanied with substantial changes in clonal composition over time. This study highlights the genetic complexity underlying sarcomagenesis of MFS. This article is protected by copyright. All rights reserved.

When is a lipoma not a lipoma? Case report presenting a lipoblastoma-like tumor of the gluteal cleft in an older gentleman with literature review

Introduction and importance

Lipoblastoma-like tumors are rare tumors that can be confused with lipoblastomas and liposarcomas but have distinct characteristics. This tumor has previously been identified in the vulva of females, and recently in isolated cases of young males. Given its rarity, we present an instance of this tumor in an older man, demonstrating that this pathology is not limited to a specific age or sex, and surgeons and pathologists must be aware of it in their differential.

Case presentation

A 58-year-old male presented for evaluation of an enlarging mass in his right gluteal cleft. Prior to referral for surgical evaluation, the patient underwent an ultrasound-guided biopsy of the mass. Histologically, the tumor was a low-grade cellular spindle cell neoplasm in a fibrous to myxoid stroma. Immunohistochemical and molecular workup ruled out several malignant mesenchymal neoplasms, including myxoid liposarcoma, dedifferentiated liposarcoma, melanoma, low-grade fibromyxoid sarcoma, and sarcomatoid carcinoma. The patient initially declined surgery, but the mass continued to grow, and excision was chosen given the uncertain pathology. The tumor was resected with negative margins and histologically characterized as a “lipoblastoma-like lesion”, with features of a myxoid liposarcoma and spindle cell lipoma. Seven months post-resection, there were no signs of recurrence or metastasis.

Clinical discussion

Despite radiologic and pathologic similarities to malignant lipomatous tumors, lipoblastoma-like tumors are benign and have a good prognosis.

Conclusions

Clinicians should be aware of this entity despite its rarity as resection with negative margins is curative and may be needed to rule out more aggressive tumors.

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Lipoblastoma-like tumors (LLTs) are rare soft tissue tumors.

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LLTs can easily be confused clinically and pathologically for benign lipomas but also malignant liposarcomas.

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Pathologic evaluation is able to distinguish these tumors from their more aggressive counterparts.

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Because of their rare nature, clinicians may over or under-treat these tumors which require surgical excision.

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Local recurrence is rare but is predicated on negative surgical margins.

Establishment and Characterization of NCC-MFS5-C1: A Novel Patient-Derived Cell Line of Myxofibrosarcoma

Myxofibrosarcoma (MFS) is a highly aggressive malignancy with complex karyotypes and a postoperative recurrence tendency, owing to its strong invasiveness. Although systemic chemotherapy is considered in patients with unresectable MFS, the efficacy of conventional chemotherapy is hitherto unclear. Recently, drug screening analysis using a large number of tumor cell lines has been attempted to discover novel therapeutic candidate drugs for common cancers. However, the number of MFS cell lines is extremely small because of its low incidence-this hinders the conduction of screening studies and slows down the development of therapeutic drugs. To overcome this problem, we established a novel MFS cell line, NCC-MFS5-C1, which was shown to harbor typical MFS genetic abnormalities and thus had useful properties for in vitro studies. We conducted the largest integrated screening analysis of 210 drugs using NCC-MFS5-C1 cells along with four MFS cell lines, which we previously reported. Bortezomib (a proteasome inhibitor) and romidepsin (a histone deacetylase inhibitor) showed stronger antitumor effects than the standard drug, doxorubicin. Therefore, the NCC-MFS5-C1 cell line can potentially contribute to elucidating MFS pathogenesis and developing a novel MFS treatment.

T-regulatory cells predict clinical outcome in soft tissue sarcoma patients: a clinico-pathological study

BACKGROUND

Soft tissue sarcomas (STS) are generally considered non-immunogenic, although specific subtypes respond to immunotherapy. Antitumour response within the tumour microenvironment relies on a balance between inhibitory and activating signals for tumour-infiltrating lymphocytes (TILs). This study analysed TILs and immune checkpoint molecules in STS, and assessed their prognostic impact regarding local recurrence (LR), distant metastasis (DM), and overall survival (OS).

METHODS

One-hundred and ninety-two surgically treated STS patients (median age: 63.5 years; 103 males [53.6%]) were retrospectively included. Tissue microarrays were constructed, immunohistochemistry for PD-1, PD-L1, FOXP3, CD3, CD4, and CD8 performed, and staining assessed with multispectral imaging. TIL phenotype abundance and immune checkpoint markers were correlated with clinical and outcome parameters (LR, DM, and OS).

RESULTS

Significant differences between histology and all immune checkpoint markers except for FOXP3+ and CD3-PD-L1+ cell subpopulations were found. Higher levels of PD-L1, PD-1, and any TIL phenotype were found in myxofibrosarcoma as compared to leiomyosarcoma (all p < 0.05). The presence of regulatory T cells (Tregs) was associated with increased LR risk (p = 0.006), irrespective of margins. Other TILs or immune checkpoint markers had no significant impact on outcome parameters.

CONCLUSIONS

TIL and immune checkpoint marker levels are most abundant in myxofibrosarcoma. High Treg levels are independently associated with increased LR risk, irrespective of margins.

Toward a Personalized Therapy in Soft-Tissue Sarcomas: State of the Art and Future Directions

Soft-tissue sarcomas are rare tumors characterized by pathogenetic, morphological, and clinical intrinsic variability. Median survival of patients with advanced tumors are usually chemo- and radio-resistant, and standard treatments yield low response rates and poor survival results. The identification of defined genomic alterations in sarcoma could represent the premise for targeted treatments. Summarizing, soft-tissue sarcomas can be differentiated into histotypes with reciprocal chromosomal translocations, with defined oncogenic mutations and complex karyotypes. If the latter are improbably approached with targeted treatments, many suggest that innovative therapies interfering with the identified fusion oncoproteins and altered pathways could be potentially resolutive. In most cases, the characteristic genetic signature is discouragingly defined as "undruggable", which poses a challenge for the development of novel pharmacological approaches. In this review, a summary of genomic alterations recognized in most common soft-tissue sarcoma is reported together with current and future therapeutic opportunities.

OSmfs: An Online Interactive Tool to Evaluate Prognostic Markers for Myxofibrosarcoma

Myxofibrosarcoma is a complex genetic disease with poor prognosis. However, more effective biomarkers that forebode poor prognosis in Myxofibrosarcoma remain to be determined. Herein, utilizing gene expression profiling data and clinical follow-up data of Myxofibrosarcoma cases in three independent cohorts with a total of 128 Myxofibrosarcoma samples from The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) databases, we constructed an easy-to-use web tool, named Online consensus Survival analysis for Myxofibrosarcoma (OSmfs) to analyze the prognostic value of certain genes. Through retrieving the database, users generate a Kaplan–Meier plot with log-rank test and hazard ratio (HR) to assess prognostic-related genes or discover novel Myxofibrosarcoma prognostic biomarkers. The effectiveness and availability of OSmfs were validated using genes in ever reports predicting the prognosis of Myxofibrosarcoma patients. Furthermore, utilizing the cox analysis data and transcriptome data establishing OSmfs, seven genes were selected and considered as more potentially prognostic biomarkers through overlapping and ROC analysis. In conclusion, OSmfs is a promising web tool to evaluate the prognostic potency and reliability of genes in Myxofibrosarcoma, which may significantly contribute to the enrichment of novelly potential prognostic biomarkers and therapeutic targets for Myxofibrosarcoma.

The Biology of Myxofibrosarcoma: State of the Art and Future Perspectives

BACKGROUND

Myxofibrosarcoma (MFS) is among the most highly complex sarcoma types. Molecular cytogenetic studies have identified a high level of genomic complexity.

SUMMARY

This review provides an update of the current research related to MFS, with particular emphasis on emerging mechanisms of tumorigenesis and their potential therapeutic impact. Many novel possible molecular markers have been identified, not only for prognostication in MFS, but also to serve as possible therapeutic targets, and thereby improve clinical outcomes. However, the molecular pathogenesis of MFS remains incompletely understood. Key Messages: Patients suffering from advanced MFS might benefit from expanded molecular evaluation in order to detect specific expression profiles and identify drug-able targets. Moreover, immunotherapy represents an intriguingly perspective due to the presence of "T-cell inflamed" tumor microenvironment.

Genetic aberrations and molecular biology of cardiac sarcoma

Cardiac tumors are rare and complex entities. Early assessment and differentiation between non-neoplastic and neoplastic masses, be they benign or malignant, is essential for guiding diagnosis, determining prognosis, and planning therapy. Cardiac sarcomas represent the most frequent primary malignant histotype. They could have manifold presentations so that the diagnosis is often belated. Moreover, considering their rarity and the limitation due to the cardiac location itself, the optimal multimodal management of patients affected by primary cardiac sarcomas still remains highly difficult and outcome dismal. Therefore, there is an urgent need to improve these results mainly focusing on more adequate tools for prompt diagnosis and exploring new and more effective therapies. Knowledge about the molecular landscape and pathogenesis of cardiac sarcoma is even more limited due to the rarity of this disease. In this sense, the molecular characterization of heart tumors could unfold potentially novel, druggable targets. In this review, we focused on genetic aberrations and molecular biology of cardiac sarcomas, collecting the scarce information available and resuming all the molecular findings discovered in each tumor subtype, with the aim to get further insights on mechanisms involved in tumor growth and to possibly highlight specific molecular profiles that can be used as diagnostic tests and unveil new clinically actionable targets in this tricky and challenging disease.

Immunohistochemical selection of biomarkers for tumor-targeted image-guided surgery of myxofibrosarcoma

Myxofibrosarcoma(MFS) is the most common soft tissue sarcoma(STS) in elderly patients. Surgical resection remains the main treatment modality but tumor borders can be difficult to delineate with conventional clinical methods. Incomplete resections are a common problem and local recurrence remains a clinical issue. A technique that has shown great potential in improving surgical treatment of solid tumors is tumor targeted imaging and image-guided surgery with near-infrared fluorescence. To facilitate this technique, it is essential to identify a biomarker that is highly and homogenously expressed on tumor cells, while being absent on healthy non-malignant tissue. The purpose of this study was to identify suitable molecular targets for tumor-targeted imaging of myxofibrosarcoma. Ten potential molecular targets for tumor targeted imaging were investigated with immunohistochemical analysis in myxofibrosarcoma tissue (n = 34). Results were quantified according to the immunoreactive score(IRS). Moderate expression rates were found for uPAR, PDGFRa and EMA/MUC1. High expression rates of VEGF and TEM1 were seen. Strong expression was most common for TEM1 (88.2%). These results confirms that TEM1 is a suitable target for tumor-targeted imaging of myxofibrosarcoma. Keywords Image-guided surgery; Immunohistochemistry; Molecular imaging; Myxofibrosarcoma; Soft tissue sarcoma; Tumor endothelial marker 1(TEM1), Vascular endothelial growth factor (VEGF).

Fine needle aspiration of malignant melanoma with myxoid features: A case report with molecular analysis

Malignant melanoma with myxoid features (MMM) is a rare melanoma variant in which tumor cells are embedded within a basophilic myxoid stroma. The stromal matrix is composed of acidic mucopolysaccharides, which are thought to be produced by mesenchymal stromal cells in response to melanoma invasion. Interestingly, this myxoid matrix is more often seen in metastasis from a primary tumor that does not have a myxoid stroma. The diagnosis of MMM on fine needle aspiration (FNA) can be confused with other myxoid tumors. Herein, we present a case of MMM diagnosed by FNA of a peri-auricular lymph node in an 89-year-old man with a history of resected malignant melanoma. We describe the clinical, cytohistological, and immunohistochemical findings, and present the unique molecular alterations that were identified. We also discuss the differential diagnosis and potential diagnostic pitfalls associated with MMM.

Successful multidisciplinary clinical approach and molecular characterization by whole transcriptome sequencing of a cardiac myxofibrosarcoma: A case report

BACKGROUND

Cardiac tumors are rare and complex entities. Surgery represents the cornerstone of therapy, while the role of adjuvant treatment remains unclear and, in case of relapse or metastatic disease, the prognosis is very poor. Lack of prospective, randomized clinical trials hinders the generation of high level evidence for the optimal diagnostic workup and multimodal treatment of cardiac sarcomas. Herein, we describe the multidisciplinary clinical management and molecular characterization of a rare case of cardiac myxofibrosarcoma in an elderly woman.

CASE SUMMARY

A 73-year-old woman presented signs and symptoms of acute left-sided heart failure. Imaging examination revealed a large, left atrial mass. With suspicion of a myxoma, she underwent surgery, and symptoms were promptly relieved. Histology showed a cardiac myxofibrosarcoma, a rare histotype of cardiac sarcoma. Eight months later, disease unfortunately relapsed, and after a multidisciplinary discussion, a chemotherapy with doxorubicin and then gemcitabine was started, achieving partial radiologic and complete metabolic response, which was maintained up to 2 years and is still present. This report is focused on the entire clinical path of our patient from diagnosis to follow-up, through surgery and strategies adopted at relapse. Moreover, due to their rarity, very little is known about the molecular landscape of myxofibrosarcomas. Thus, we also performed and described preliminary genome analysis of the tumor tissue to get further insight on mechanisms involved in tumor growth, and to possibly unveil new clinically actionable targets.

CONCLUSION

We report a case of cardiac myxofibrosarcoma that achieved a very good prognosis due to an integrated surgical, cardiac and oncologic treatment strategy.

Detection of GNAS mutations in intramuscular / cellular myxomas as diagnostic tool in the classification of myxoid soft tissue tumors

BACKGROUND

Intramuscular / cellular myxomas and low-grade myxofibrosarcomas are two different tumor entities with a significant histological overlap, especially if dealing with small biopsies. Despite the morphological similarities, they differ considerably in their biological behaviour. Intramuscular / cellular myxoma rarely shows signs of recurrence and never metastasizes, in contrast to myxofibrosarcoma that tends to recur more aggressively and to metastasize haematologically. Therefore, it is of great importance to distinguish these lesions - evaluation of GNAS mutation status could be of tremendous help.

METHODS

We reviewed 13 cases with intramuscular / cellular myxomas. The 13 cases included 5 men and 8 women, aged from 33 to 71 years (mean age 55.5 years). Immunohistochemistry was performed as well as next generation sequencing. Ten cases were located in the lower extremities and three cases were located in the upper extremities. Two lesions were initially misdiagnosed as a low-grade myxofibrosarcoma.

RESULTS

Performing next generation sequencing 12 out of 13 specimens showed a GNAS mutation.

CONCLUSIONS

Our findings demonstrate that GNAS mutations are more common in intramuscular / cellular myxomas, than had been reported in literature in the past. Next generation sequencing for determining GNAS mutation status on small biopsies or diagnostically challenging cases facilitates the diagnosis of intramuscular / cellular myxoma and separates this tumor entity from its mimics.