Pediatric atypical teratoid/rhabdoid tumor in the cauda equina with rapid tumor progression: illustrative case.

BACKGROUND: Atypical teratoid/rhabdoid tumor (AT/RT) is an uncommon malignant neoplasm and rarely occurs in the spinal space, especially in the cauda equina. Only 8 cases of pediatric AT/RT of the cauda equina have been reported. Therefore, its clinical behavior and optimal treatment remain unclear. OBSERVATIONS: The authors describe the case of a 9-year-old boy who presented with progressive back and left leg pain. Initial magnetic resonance imaging showed an intradural extramedullary lesion at the L3-4 level, which progressed rapidly to the L2-5 level within a month. He underwent partial resection of the tumor with an L2-5 laminectomy. The histopathological diagnosis was AT/RT. He received adjuvant chemotherapy and radiotherapy, and his gait disturbance improved postoperatively. At 6 months' follow-up, disease recurrence was not observed. LESSONS: Although extremely rare, AT/RT should be included in the differential diagnosis for prompt therapeutic intervention. Safe resection with minimal functional impairment, followed by postoperative chemoradiation, can lead to tumor control and improve neurological function. https://thejns.org/doi/10.3171/CASE24219.

Successful treatment of pediatric patients with high-grade gliomas featuring leptomeningeal metastases by targeting BRAF V600E mutations with dabrafenib plus trametinib: two illustrative cases.

A combination of BRAF and MEK inhibitors is reported to be effective for gliomas with the BRAF V600E mutation; however, its efficacy in gliomas with leptomeningeal metastases (LMM) is still unknown. In this report, we describe two pediatric patients with high-grade glioma featuring the BRAF V600E mutation who were treated with dabrafenib and trametinib for LMM. Both 2 cases underwent craniotomy for primary intracranial lesions and were diagnosed as a high-grade glioma with BRAF V600E mutation; one case was consistent with anaplastic pleomorphic xanthoastorocytoma, the other was epithelioid glioblastoma. They received standard treatment for the lesions but subsequently were found to have new lesions including multiple spinal dissemination. We started administering dabrafenib and trametinib. Within a few days of starting treatment, the symptoms improved dramatically and MRI performed one month after the prescription of the two drugs demonstrated remission of both brain and spinal lesions. This report shows that dabrafenib and trametinib are effective not only for recurrent lesions but also for LMM in pediatric patients.

Efficacy and safety of nivolumab monotherapy in patients with unresectable clear cell sarcoma and alveolar soft part sarcoma (OSCAR Trial/NCCH1510).

BACKGROUND: Clear cell sarcoma (CCS) and alveolar soft part sarcoma (ASPS) are rare, and standard systemic therapy is not established except for sunitinib in ASPS. It is known that CCS and ASPS have a common biological feature of melanoma and Xp11.2/TFE3 translocation renal cell carcinoma, and immune-checkpoint inhibitors (ICIs) are effective in these tumors. The authors conducted a phase 2 trial to evaluate the efficacy and safety of nivolumab for CCS and ASPS. METHODS: The number of patients expected to be enrolled was 15-25 and was determined based on the Bayesian design. The primary end point was the confirmed objective response rate (ORR) according to the central review and the secondary end points included ORR, progression-free survival (PFS), overall survival (OS), and safety. RESULTS: A total of 26 patients (CCS, 12; ASPS, 14) were enrolled. Efficacy and safety were analyzed on 25 and 26 patients, respectively. The minimum number of responses required for a positive conclusion regarding the efficacy was four. However, only one patient (4.0%) with ASPS had a partial response. Complete response, stable disease, progression disease, and not evaluable were 0%, 60%, 32%, and 4.0%, respectively. Adverse events of grade 3 or 4 occurred in 57.7% (15 of 26). The median PFS was 4.9 months (95% confidence interval [CI], 3.7-8.6 months) and the median OS was 15.8 months (95% CI, 8.2-not reached). CONCLUSIONS: The primary end point of the ORR was not met for CCS and ASPS on the central review. Further studies are needed to evaluate ICIs in patients with ASPS.

Fluorescence in situ hybridization-negative intra-articular myxoid liposarcoma with complex rearrangements involving EWSR1::DDIT3 detected using nanopore sequencing.

Myxoid liposarcoma (MLPS) is a rare sarcoma, typically arising in deep soft tissues during the fourth to fifth decades of life. Histologically, MLPS is composed of uniform oval cells within a background of myxoid stroma and chicken-wire capillaries. Genetically, MLPS is characterized by the FUS/EWSR1::DDIT3 fusion gene, which generally results from balanced interchromosomal translocation and is detectable via DDIT3 break-apart fluorescence in situ hybridization (FISH). Here, we report an unusual intra-articular MLPS case, negative for DDIT3 break-apart FISH but positive for EWSR1::DDIT3. An 18-year-old female was referred to our hospital complaining of an intra-articular mass in the right knee joint. Histologically, the tumor was mainly composed of mature adipocytes, brown fat-like cells, and lipoblasts. Nanopore sequencing detected DNA rearrangements between EWSR1 and DDIT3 and clustered complex rearrangements involving multiple chromosomes, suggesting chromoplexy. Methylation classification using random forest, t-distributed stochastic neighbor embedding, and unsupervised hierarchical clustering correctly classified the tumor as MLPS. The copy number was almost flat. The TERT promoter C-124T was also detected. This report highlights, for the first time, the potential value of a fast and low-cost nanopore sequencer for diagnosing sarcomas.

MUC5AC immunoreactivity in scattered tumor cells is useful for diagnosing CIC-rearranged sarcoma.

CIC-rearranged sarcoma is an aggressive round cell sarcoma, and an alternative ATXN1/ATXN1L fusion has been reported. Diagnosis may be difficult, and molecular assays may suffer from imperfect sensitivity. Characteristic histology and ETV4 immunohistochemical positivity are diagnostically helpful. However, ETV4 staining is unavailable in most laboratories. Here, we explored the diagnostic utility of MUC5AC immunohistochemistry in CIC-rearranged sarcomas. All 30 cases, except one, of CIC-rearranged sarcomas and 2 ATXN1-rearranged sarcomas were positive for MUC5AC, although the number of immunopositive cells was generally low (< 5%) in most samples, representing a characteristic scattered pattern. The only MUC5AC-negative case had the lowest tumor volume. Among the 110 mimicking round cell malignancies, 12 tumors showed MUC5AC positivity, including occasional cases of synovial sarcoma and small cell carcinoma, whereas the remaining 98 samples were negative. Despite its lower specificity than that of ETV4 and sparse reactivity that requires careful interpretation, MUC5AC may serve as a useful marker for CIC/ATXN1-rearranged sarcoma because of its wider accessibility.

Resection and postoperative pazopanib for intraspinal recurrent solitary fibrous tumor: illustrative case.

BACKGROUND: Intracranial solitary fibrous tumors (SFTs) rarely recur in the spinal space. Only 4 cases of spinal recurrence from intracranial SFT have been reported; therefore, the optimal treatment of recurrent spinal SFT remains unclear. OBSERVATIONS: A 53-year-old woman with a history of resection of a right occipital anaplastic SFT presented with progressive back and side pain. She was diagnosed with an intradural extramedullary tumor ventral to the spinal cord at the T5-7 level. She underwent tumor resection with T5-6 laminectomy and T4 and T7 partial laminectomy. The tumor was completely removed in a piecemeal fashion using an ultrasonic aspirator with careful control of bleeding. Her symptoms quickly improved after the surgery, and she returned to normal life. The tumor was diagnosed as SFT. Pazopanib was administered postoperatively. Despite the recurrence of the intracranial tumor, the patient was alive without recurrence of the spinal tumor 14 months after resection. LESSONS: Although rare, intracranial SFTs have a risk of spinal recurrence. Complete resection of a recurrent spinal SFT can be achieved even in the ventral location. Pazopanib could be a possible therapeutic option for preventing local tumor recurrence in the management of recurrent spinal SFT. https://thejns.org/doi/10.3171/CASE24217.

Histological diagnostic discrepancy and its clinical impact in bone and soft tissue tumors referred to a sarcoma center.

Histological diagnosis of sarcomas (malignant bone and soft tissue tumors) is challenging due to their rarity, morphological diversity, and constantly evolving diagnostic criteria. In this study, we aimed to assess the concordance in histological diagnosis of bone and soft tissue tumors between referring hospitals and a tertiary sarcoma center and analyzed the clinical impact of the diagnostic alteration. We analyzed 628 consecutively accessioned specimens from 624 patients who visited a specialized sarcoma center for treatment. The diagnoses at referring hospitals and those at the sarcoma center were compared and classified into four categories: agreed, disagreed, specified, and de-specified. Of the 628 specimens, the diagnoses agreed in 403 (64.2%) specimens, whereas some changes were made in 225 (35.8%) specimens: disagreed in 153 (24.3%), specified in 52 (8.3%), and de-specified in 20 (3.2%) cases. The benign/intermediate/malignant judgment changed for 92 cases (14.6%). The diagnostic change resulted in patient management modification in 91 cases (14.5%), including surgical and medical treatment changes. The main inferred reason for the diagnostic discrepancies was a different interpretation of morphological findings of the tumor, which accounted for 48.9% of the cases. This was followed by the unavailability of specialized immunohistochemical antibodies and the unavailability of genetic analysis. In summary, our study clarified the actual clinical impact of diagnostic discrepancy in bone and soft tissue tumors. This may underscore the value of pathology consultation, facilitating access to specialized diagnostic tools, and continued education. These measures are expected to improve diagnostic precision and ultimately benefit patients.

Malignant perineurioma derived from the retroperitoneum with an aggressive clinical course: a case report.

BACKGROUND: Malignant perineurioma is a rare malignant counterpart of perineurioma derived from perineural cells. Resection is the primary option for the treatment of malignant perineuriomas; however, patients often develop recurrence after resection, and effective treatment for advanced or recurrent lesions needs to be established. This report describes a 51-year-old female with a rare malignant perineurioma in the retroperitoneum, which contributing valuable insights to the literature. CASE PRESENTATION: The patient presented with abdominal distension and the imaging work-up revealed a huge hemorrhagic tumor in the retroperitoneum and obstruction of inferior vena cava by the tumor. The patient underwent surgery retrieving the tumor combined with left hemiliver and retrohepatic vena cava, which confirmed the diagnosis of a malignant perineurioma based on histopathological and immunohistochemical examination. Cancer gene panel testing identified mutations in NF2. Radiotherapy was administered for peritoneal dissemination 2 months after surgery, and the patient died from disease progression 6 months after surgery. CONCLUSIONS: This rare case highlights the challenges in managing retroperitoneal malignant perineuriomas. The aggressive characteristics and limited treatment options for advanced malignant perineuriomas underscore the need for understanding the pathogenesis and developing effective systemic therapies. The identification of an NF2 mutation provides significant insights into potential therapeutic target.

Sarcoma of the Lung and Mediastinum.

Primary sarcoma of the lung and mediastinum is rare. The diagnosis requires careful exclusion of sarcomatoid carcinoma, sarcomatoid mesothelioma, and metastases from extra-thoracic sites. This review summarizes the key morphologic, immunohistochemical, and molecular characteristics of sarcomas that are encountered in the lung and mediastinum. The tumor types discussed are synovial sarcoma, well-differentiated/dedifferentiated liposarcoma, myxoid pleomorphic liposarcoma, intimal sarcoma of the pulmonary artery, inflammatory myofibroblastic tumor, epithelioid hemangioendothelioma, primary pulmonary myxoid sarcoma, malignant peripheral nerve sheath tumor, Ewing sarcoma, and CIC-rearranged sarcoma. Relevant differential diagnoses are also addressed.

FDG PET/CT and MRI Findings of Extraskeletal Myxoid Chondrosarcoma Showing a Nonmyxoid Cellular Variant.

ABSTRACT: We present a new, extremely rare nonmyxoid cellular variant of extraskeletal myxoid chondrosarcoma. Although diagnosis is radiologically and pathologically challenging, FDG PET/CT and MRI accurately showed the malignancy and high tumor density. A 52-year-old woman complained of a left dorsal mass, which presented inhomogeneous intermediate signals on T2-weighted images, with diffusion restriction, strong enhancement, and increased accumulation of FDG (SUV max , 5.2). Although biopsy was inconclusive, a highly malignant tumor was suspected radiologically. The resected specimen was histologically diagnosed as extraskeletal myxoid chondrosarcoma by detection of EWSR1::NR4A3 fusion using fluorescence in situ hybridization.

Predicting Trabectedin Efficacy in Soft Tissue Sarcoma: Inflammatory Biomarker Analysis.

BACKGROUND/AIM: Trabectedin is used as a treatment for advanced-stage soft tissue sarcomas (STSs), particularly liposarcoma and leiomyosarcoma. Aside from its direct effect on tumor cells, trabectedin can affect the immune system in the tumor microenvironment. This study aimed to evaluate whether inflammatory biomarkers predict trabectedin efficacy in STSs. PATIENTS AND METHODS: We retrospectively reviewed the clinical features and outcomes of patients with STS treated with trabectedin at our institution between 2016 and 2020. The neutrophil-to-lymphocyte ratio (NLR), lymphocyte-to-monocyte ratio (LMR), platelet-to-lymphocyte ratio (PLR), and systemic inflammation response index (SIRI=neutrophil × monocyte/lymphocyte) were calculated based on the blood samples obtained prior to trabectedin treatment initiation. Analyses of overall survival (OS) and progression-free survival (PFS) were performed according to various factors. RESULTS: Of the 101 patients identified, 54 had L-sarcoma (leiomyosarcoma: 30; liposarcoma: 24), and 47 had other types of STSs. Elevated SIRI, NLR, PLR, LMR, and C-reactive protein (CRP) were associated with worse PFS (p<0.001, p=0.008, p=0.027, p=0.013, and p<0.001, respectively) according to the results of the univariate analysis. Multivariate analysis showed that elevated SIRI, other histology, and CRP were associated with poor PFS (p=0.007, p=0.008, and p=0.029, respectively). In addition, the multivariate analysis of OS showed that SIRI was an independent prognostic factor (hazard ratio=2.16, p=0.006). CONCLUSION: Pretreatment SIRI can be considered a biomarker for the prognostic prediction of patients with STS treated with trabectedin.

Incidence of skeletal-related events in patients with Ewing sarcoma: An observational retrospective study in Japan.

BACKGROUND: Skeletal-related events (SREs), including the pathological fracture, surgical treatment or radiation of bone lesions, malignant spinal cord compression, hypercalcemia, are important considerations when managing metastatic bone tumors; however, owing to their rarity, the incidence of SREs in patients with Ewing sarcoma remains unknown. METHODS: We retrospectively reviewed the clinical data from 146 patients with Ewing sarcoma treated at a single institution from 2005 to 2019. The median age at diagnosis was 22.7 years. Fifty patients (34.2%) had metastatic disease at diagnosis. The primary outcome was the SRE-free rate among patients with Ewing sarcoma. Moreover, we identified the risk factors for SREs using univariate or multivariate analyses. RESULTS: During the observational period (median, 2.6 years), SREs occurred in 23 patients. Radiation to the bone, malignant spinal cord compression, and hypercalcemia were documented as the initial SREs in 12 patients (52.2%), 10 patients (43.5%), and one patient (4.3%), respectively. The SRE-free rate was 94.2 ± 2.0, 87.3 ± 3.0, and 79.6 ± 3.8% at 1, 2, and 3 years after the initial visit, respectively. Multivariate analysis revealed bone metastasis at diagnosis (hazard ratio [HR] = 4.41, p = 0.007), bone marrow invasion (HR = 34.08, p < 0.001), and local progression or recurrence after definitive treatment (HR = 3.98, p = 0.012) as independent risk factors for SREs. CONCLUSIONS: SREs are non-rare events that can occur during the treatment course for Ewing sarcoma, with an especially high incidence of malignant spinal cord compression. Patients with metastatic disease at diagnosis, especially in the bone or bone marrow, or with local progression or recurrence after definitive treatment, should be carefully monitored for the occurrence of SREs. The most effective methods to monitor the occurrence of SREs and new preventative therapies for SREs should be investigated in the future.

Establishment and characterization of two novel patient-derived cell lines from giant cell tumor of bone: NCC-GCTB8-C1 and NCC-GCTB9-C1.

Giant cell tumor of bone (GCTB) is a rare osteolytic bone tumor consisting of mononuclear stromal cells, macrophages, and osteoclast-like giant cells. Although GCTB predominantly exhibits benign behavior, the tumor carries a significant risk of high local recurrence. Furthermore, GCTB can occasionally undergo malignant transformation and distal metastasis, making it potentially fatal. The standard treatment is complete surgical resection; nonetheless, an optimal treatment strategy for advanced GCTB remains unestablished, necessitating expanded preclinical research to identify appropriate therapeutic options. However, only one GCTB cell line is publicly available from a cell bank for research use worldwide. The present study reports the establishment of two novel cell lines, NCC-GCTB8-C1 and NCC-GCTB9-C1, derived from the primary tumor tissues of two patients with GCTB. Both cell lines maintained the hallmark mutation in the H3-3A gene, which is associated with tumor formation and development in GCTB. Characterization of these cell lines revealed their steady growth, spheroid-formation capability, and invasive traits. Potential therapeutic agents were identified via extensive drug screening of the two cell lines and seven previously established GCTB cell lines. Among the 214 antitumor agents tested, romidepsin, a histone deacetylase inhibitor, and mitoxantrone, a topoisomerase inhibitor, were identified as potential therapeutic agents against GCTB. Conclusively, the establishment of NCC-GCTB8-C1 and NCC-GCTB9-C1 provides novel and crucial resources that are expected to advance GCTB research and potentially revolutionize treatment strategies.

Establishment and characterization of NCC-ASPS2-C1: a novel patient-derived cell line of alveolar soft part sarcoma.

Alveolar soft part sarcoma (ASPS) is a rare mesenchymal tumor characterized by rearrangement of the ASPSCR1 and TFE3 genes and a histologically distinctive pseudoalveolar pattern. ASPS progresses slowly, but is prone to late metastasis. As ASPS is refractory to conventional chemotherapy, the only curative treatment is complete surgical resection. The prognosis of advanced and metastatic cases is poor, highlighting the need for preclinical research to develop appropriate treatment options. However, ASPS is extremely rare, accounting for < 1% of all soft tissue sarcomas, and only one patient-derived ASPS cell line is available from public cell banks worldwide for research. This study reports the establishment of a novel ASPS cell line derived from the primary tumor tissue of an ASPS patient, named NCC-ASPS2-C1. This cell line retains the ASPSCR1-TFE3 fusion gene, which is characteristic of ASPS. The characterization of this cell line revealed stable growth, spheroid formation, and invasive properties. By screening a drug library using NCC-ASPS2-C1, we identified several drugs that inhibited the proliferation of ASPS cells. In conclusion, the establishment of NCC-ASPS2-C1 provides a valuable resource for advancing ASPS research and developing novel treatments for this challenging disease.

Ozonated Olive Oil Intake Attenuates Hepatic Steatosis in Obese db/db Mice.

Chronic inflammation and insulin resistance lead to metabolic syndrome and there is an urgent need to establish effective treatments and prevention methods. Our previous study reported that obese model Zucker (fa/fa) rats fed with ozonated olive oil alleviated fatty liver and liver damage by suppressing inflammatory factors. However, differences among animal species related to the safety and efficacy of ozonated olive oil administration remain unclear. Therefore, this study investigated the effects of oral intake of ozonated olive oil on lipid metabolism in normal mice and mice in the obesity model. C57BL/6J and db/db mice were fed the following AIN-76 diets for four weeks: the mice were either fed a 0.5% olive oil diet (Control diet) or 0.5% ozonated olive oil diet (Oz-Olive diet) in addition to 6.5% corn oil. The results indicated that four weeks of Oz-Olive intake did not adversely affect growth parameters, hepatic lipids or serum parameters in normal C57BL/6J mice. Subsequent treatment of db/db mice with Oz-Olive for four weeks reduced the levels of hepatic triglycerides, serum alkaline phosphatase, and serum insulin. These effects of Oz-Olive administration might be due to suppression of fatty acid synthesis activity and expression of lipogenic genes, as well as suppression of inflammatory gene expression. In conclusion, this study confirmed the safety of Oz-Olive administration in normal mice and its ability to alleviate hepatic steatosis by inhibiting fatty acid synthesis and inflammation in obese mice.

The development of a custom RNA-sequencing panel for the identification of predictive and diagnostic biomarkers in glioma.

PURPOSE: Various molecular profiles are needed to classify malignant brain tumors, including gliomas, based on the latest classification criteria of the World Health Organization, and their poor prognosis necessitates new therapeutic targets. The Todai OncoPanel 2 RNA Panel (TOP2-RNA) is a custom-target RNA-sequencing (RNA-seq) using the junction capture method to maximize the sensitivity of detecting 455 fusion gene transcripts and analyze the expression profiles of 1,390 genes. This study aimed to classify gliomas and identify their molecular targets using TOP2-RNA. METHODS: A total of 124 frozen samples of malignant gliomas were subjected to TOP2-RNA for classification based on their molecular profiles and the identification of molecular targets. RESULTS: Among 55 glioblastoma cases, gene fusions were detected in 11 cases (20%), including novel MET fusions. Seven tyrosine kinase genes were found to be overexpressed in 15 cases (27.3%). In contrast to isocitrate dehydrogenase (IDH) wild-type glioblastoma, IDH-mutant tumors, including astrocytomas and oligodendrogliomas, barely harbor fusion genes or gene overexpression. Of the 34 overexpressed tyrosine kinase genes, MDM2 and CDK4 in glioblastoma, 22 copy number amplifications (64.7%) were observed. When comparing astrocytomas and oligodendrogliomas in gene set enrichment analysis, the gene sets related to 1p36 and 19q were highly enriched in astrocytomas, suggesting that regional genomic DNA copy number alterations can be evaluated by gene expression analysis. CONCLUSIONS: TOP2-RNA is a highly sensitive assay for detecting fusion genes, exon skipping, and aberrant gene expression. Alterations in targetable driver genes were identified in more than 50% of glioblastoma. Molecular profiling by TOP2-RNA provides ample predictive, prognostic, and diagnostic biomarkers that may not be identified by conventional assays and, therefore, is expected to increase treatment options for individual patients with glioma.

Establishment and characterization of NCC-DFSP5-C1: a novel patient-derived dermatofibrosarcoma protuberans cell line.

Dermatofibrosarcoma protuberans (DFSP) is the most prevalent dermal sarcoma, characterized by the presence of the fusion of the collagen type I alpha 1 (COL1A1) gene with the platelet-derived growth factor beta chain (PDGFB) gene. Although PDGF receptor inhibitor imatinib mesylate was approved for the treating patients with unresectable or metastatic DFSP, disease progression was shown in 9.2% of the patients. Therefore, developing novel therapeutic strategies is crucial for improving the prognosis of DFSP. Patient-derived cell lines play a vital role in preclinical studies; however, only a limited number of DFSP cell lines are currently available in public cell banks. Here, we successfully established a novel DFSP cell line (NCC-DFSP5-C1) using surgically resected tumor tissue from a patient with DFSP. NCC-DFSP5-C1 cells were confirmed to carry the COL1A1-PDGFB translocation and maintain the same mutation as the original tumor tissue. They exhibited consistent growth, formed spheroids, and were invasive. By screening a drug library using NCC-DFSP5-C1 and four previously established DFSP cell lines, we identified anti-cancer drugs that inhibit DFSP cell proliferation. Our observations suggest that the NCC-DFSP5-C1 cell line holds promise as a valuable tool for conducting fundamental and preclinical studies for DFSP.

CIC-Rearranged Sarcoma.

CIC-rearranged sarcoma is a rare type of small round cell sarcoma. The tumors often affect the deep soft tissues of patients in a wide age range. They are highly aggressive, respond poorly to chemotherapy, and have a worse outcome than Ewing sarcoma. CIC-rearranged sarcoma has characteristic and recognizable histology, including lobulated growth, focal myxoid changes, round to epithelioid cells, and minimal variation of nuclear size and shape. Nuclear ETV4 and WT1 expression are useful immunohistochemical findings. CIC fusion can be demonstrated using various methods; however, even next-generation sequencing suffers from imperfect sensitivity, especially for CIC::DUX4.