Mesenchymal Chondrosarcoma: a Review with Emphasis on its Fusion-Driven Biology

Primary orbital mesenchymal chondrosarcoma: clinicopathological characteristics and prognostic prediction

OBJECTIVE

This study aimed to analyze the clinicopathological characteristics of a rare malignant tumour, primary orbital mesenchymal chondrosarcoma (MCS), and identify the risk factors influencing its prognosis.

METHODS

A total of 15 patients with histologically confirmed primary orbital MCS were enrolled between April 2013 and October 2022. The relationships between clinicopathological features and outcomes, including recurrence and survival were analyzed.

RESULTS

During the follow-up period, 9 patients (60%) experienced disease relapse, and 7 patients (46.7%) succumbed to the disease. Immunohistochemical analysis showed positive rates for SMA, CD-99, S-100, vimentin, and Bcl-2 at 60%, 60%, 53.3%, 100%, and 93.3%, respectively. The Ki67 index was positively associated with the recurrence and mortality rates.

CONCLUSION

Our study suggested that the Ki67 index could be a vital prognostic factor for MCS. Further follow-up studies are required to assess the efficacy of chemotherapy and radiotherapy in improving patient outcomes.

Orbital mesenchymal chondrosarcoma and its specific fusion gene HEY1-NCOA2

BACKGROUND

Mesenchymal chondrosarcoma (MC) is an uncommon type of malignant soft tissue tumor. The skeleton is the most common site of MC. Extraosseous sarcoma is rare, especially that of the orbit. Fusion gene HEY1-NCOA2 has diagnostic significance for MC, but there is a lack of research on its related pathways. To analyze the characteristics of orbital mesenchymal chondrosarcoma (MC), and search for HEY1-NCOA2-related pathways in orbital MCs, four cases of orbital MC were included in the study.

METHODS

From January 2018 to December 2022, four MC patients hospitalized at Tianjin Medical University Eye Hospital were collected for a retrospective series of case studies. HEY1-NCOA2 of the assay specimens was detected by fluorescence in situ hybridization, and immunohistochemical staining was performed for representative proteins of the relevant pathways. For figure modification and statistical analysis, GraphPad Prism 8.0 (La Jolla, CA, USA) was utilized.

RESULTS

Four orbital MC were reported. Among the 4 ligible MC specimens, two were HEY1-NCOA2-positive and two were HEY1-NCOA2-negative. Immunohistochemistry showed stronger expression of COL2A1, APC, CD99, and Bcl2 in HEY1-NCOA2-positive samples than in HEY1-NCOA2-negative MCs.

CONCLUSION

We summarized the clinical features, treatments, and prognosis of orbital MC, including our cases and the literature. The expression of COL2A1 and Bcl2 is elevated in HEY1-NCOA2-positive tissues, and they promote tumor cell growth by regulating cell proliferation, apoptosis, epithelial-mesenchymal transition, and drug resistance. For HEY1-NCOA2-positive patients, given the high expression of CD99, drugs targeting the MAPK pathway may be an effective treatment.

Chondrosarcoma: New Molecular Insights, Challenges in Near-Patient Preclinical Modeling, and Therapeutic Approaches

Chondrosarcoma (CS), the second most common malignant bone tumor after osteosarcoma, accounts for 20-30% of all malignant bone tumors. It mainly affects adults, middle-aged, and elderly people. The CS family includes various entities displaying peculiar biological, genetic, and epigenetic characteristics and clinical behaviors. Conventional CS is the most common subtype. High-grade, dedifferentiated, and mesenchymal CS, as well as unresectable and metastatic CS, exhibit poor prognoses due to their intrinsic resistance to radiotherapy and chemotherapy, underscoring the urgent need for novel therapeutic strategies. CS research is dealing with several challenges. Experimental studies can rely on animal and patient-derived models, but the paucity of representative near-patient preclinical models has hampered predictive drug screening research. This review describes the main clinical and molecular features of CS subtypes, discussing recent data on the genetic alterations and molecular mechanisms involved in CS pathogenesis and progression. The review provides an overview of the current in vitro and in vivo CS models, discusses their advantages and limitations, and highlights the recent efforts in the development of new targeted therapies against CS dependencies, including IDH1/2 mutations, NAD+ dependency, and SIRT1-HIF-2α axis, or exploring DR5 targeting, antiangiogenic therapies, epigenetic drugs, and immunological approaches. All such strategies, in combination with advanced preclinical modeling and personalized multi-omic profiling, hold promise for improving the survival of patients with advanced CS.

A pictorial review of osseous and cartilaginous soft tissue tumours

Osseous and cartilaginous soft tissue tumours are a heterogenous group of neoplasms characterised by the presence of an osseous or cartilaginous component. Mineralisation of the osseous or cartilaginous component is a common finding amongst these lesions, presenting as calcification/ossification on radiological imaging. This pictorial review examines the key imaging findings and characteristics of osseous and cartilaginous soft tissue tumours with a focus on the distinguishing features which can help the radiologist to differentiate benign and malignant lesions. All examples provided are of histopathologically proven cases seen in our tertiary referral soft tissue sarcoma centre.

Primary Intraosseous Solitary Fibrous Tumor of the Mandible: Report of a Diagnostically Challenging Case with NAB2::STAT6 Fusion and Review of the Literature

INTRODUCTION

Solitary fibrous tumor (SFT) represents an uncommon mesenchymal neoplasm affecting primarily the extremities and deep soft tissues with, overall, benign but locally aggressive biologic behavior and an underlying pathognomonic NAB2::STAT6 fusion. Intraosseous SFTs are infrequent, and involvement of the jawbones is exceedingly rare.

CASE PRESENTATION

A 54-year-old woman presented with an asymptomatic, well-demarcated, multilocular radiolucency of the left posterior mandible featuring focally irregular borders, root resorption and lingual cortex perforation. The lesion had shown progressive growth over a 6-year period. Microscopically, a proliferation of predominantly ovoid and spindle-shaped cells with indistinct cell membrane borders, elongated, plump or tapered, hyperchromatic nuclei, and lightly eosinophilic cytoplasm was noted. Marked cytologic atypia, pleomorphism and mitoses were absent. A secondary population of epithelioid cells exhibiting ovoid or elongated vesicular nuclei, and abundant, pale eosinophilic or vacuolated cytoplasm was also present. The supporting stroma was densely fibrous with areas of marked hyalinization and variably-sized, ramifying, thin-walled vessels. By immunohistochemistry, lesional cells were strongly and diffusely positive for STAT6 and CD99, and focally immunoreactive for MDM2 and SATB2. Ki-67 was expressed in less than 5% of lesional cells, while most interspersed epithelioid cells were positive for the histiocyte marker, CD163. Molecular analysis disclosed a NAB2::STAT6 fusion confirming the diagnosis of SFT. The patient underwent segmental mandibulectomy.

CONCLUSIONS

Herein, we report the first case of primary intraosseous SFT of the mandible with complete documentation of its characteristic immunohistochemical and molecular features. Diagnosis of such unusual presentations may be further complicated by the challenging histomorphologic diversity of SFT.

Extra-skeletal intracranial mesenchymal chondrosarcoma: systematic-literature review

BACKGROUND

Intracranial mesenchymal chondrosarcoma (IMC) is a rare malignant tumor in pediatric population. IMC can present as extra- or intra-axial lesion in pediatric patients, though the former is commoner causing raised intracranial pressure (ICP). Radiological diagnosis is a challenge in these cases, as is it difficult to differentiate these from other extra-axial neoplasms due to the wide differential diagnosis in pediatric population. We aim to systematically review the literature and present a rare case of extraskeletal intracranial mesenchymal chondrosarcoma treated with safe maximal resection.

METHODS

A systematic review of literature was conducted in accordance with PRISMA guidelines. PubMed and Scopus databases were queried using the search terms, "primary intracranial chondrosarcoma", "extraskeletal mesenchymal chondrosarcoma", "mesenchymal chondrosarcoma" and "pediatric". Presentation, surgical management and outcome of a 15-year-old male with an extraskeletal IMC are also described.

RESULTS

The search yielded 25 articles which met the inclusion criteria. These published records consisted of 33 IMC cases with mean age at presentation of 9.81 ± 5.2 years (range 2 months to 18 years). Frontal region was the commonest locations (11, 33.3%). Most common presentation was headache (14, 42.4%). All patients underwent surgical intervention: gross total resection (20, 60.6%), subtotal resection (9, 27.3%) and no extent mentioned (4, 12.1%). No adjuvant therapy was received in 15 patients (45.5%). On latest follow-up, 11 patients (33.3%) are on remission, 5 patients (15.2%) are symptom free, 3 patients (9.1%) had recurrence, 2 patients (6.1%) had metastasis and 9 patients (27.3%) expired.

CONCLUSION

IMC is a rare entity in pediatric population with imaging findings which are non-characteristic leading to its diagnostic challenge. It can masquerade as other extra-axial intracranial neoplasm (meningioma or hemangiopericytoma). Combination of clinico-radiological and pathological examination can help in accurate diagnosis.  Safe Maximal resection followed by radiotherapy is the preferred treatment strategy.

p160 nuclear receptor coactivator family members and their role in rare fusion‑driven neoplasms (Review)

Gene fusions with translocations involving nuclear receptor coactivators (NCoAs) are relatively common among fusion-driven malignancies. NCoAs are essential mediators of environmental cues and can modulate the transcription of downstream target genes upon binding to activated nuclear receptors. Therefore, fusion proteins containing NCoAs can become strong oncogenic drivers, affecting the cell transcriptional profile. These tumors show a strong dependency on the fusion oncogene; therefore, the direct pharmacological targeting of the fusion protein becomes an attractive strategy for therapy. Currently, different combinations of chemotherapy regimens are used to treat a variety of NCoA-fusion-driven tumors, but given the frequent tumor reoccurrence, more efficient treatment strategies are needed. Specific approaches directed towards inhibition or silencing of the fusion gene need to be developed while minimizing the interference with the original genes. This review highlights the relevant literature describing the normal function and structure of NCoAs and their oncogenic activity in NCoA-gene fusion-driven cancers, and explores potential strategies that could be effective in targeting these fusions.

Mesenchymal Chondrosarcoma from Diagnosis to Clinical Trials

Mesenchymal chondrosarcoma (MCS) is a rare subtype of chondrosarcoma with a poor prognosis. Although these tumors are sensitive to radiotherapy/chemotherapy, the standard treatment for localized MCS is only surgical resection, and there are no established treatment guidelines for patients with advanced and metastatic MCS. Due to the low incidence of MCS, the pathology of these tumors is still unknown, and other therapeutic options are lacking. Some studies show the potential role of the PDGF/PPI3K/AKT, PKC/RAF/MEK/ERK, and pRB pathways, and BCL2 overexpression in the pathogenesis of MCS. These findings provide an opportunity to use protein kinases and BCL2 inhibitors as potential therapy in MCS. In this review, we summarize the current knowledge about MCS diagnosis and treatment options. We show the immunological and molecular biomarkers used in the diagnosis of MCS. In addition, we discuss the known prognostic and predictive factors in MCS. Finally, we present the novel trends, including targeted therapies and ongoing clinical trials using protein kinase inhibitors and the death receptor 5 (DR5) agonist, which may be the focus of future MCS treatment studies.

Small biopsies in the head and neck: Bone and soft tissue

Bone and soft tissue lesions in the head and neck encompass not only a broad morphologic spectrum but also significant inherent clinicopathologic overlap. Epidemiology, radiology, and location - similar to the diagnostic assessment in other sites - are especially important considerations in the context of an established mesenchymal proliferation. Herein, the approach towards diagnosis is stratified by morphology (spindle, sarcomatoid, epithelioid, round cell), cellular lineage (fibroblastic, nerve sheath, rhabdomyogenic), and tumor grade (benign, low- to high-grade malignant) as the basis of further immunohistochemical or molecular investigation.

HEY1-NCOA2 expression modulates chondrogenic differentiation and induces mesenchymal chondrosarcoma in mice

Mesenchymal chondrosarcoma affects adolescents and young adults, and most cases usually have the HEY1::NCOA2 fusion gene. However, the functional role of HEY1-NCOA2 in the development and progression of mesenchymal chondrosarcoma remains largely unknown. This study aimed to clarify the functional role of HEY1-NCOA2 in transformation of the cell of origin and induction of typical biphasic morphology of mesenchymal chondrosarcoma. We generated a mouse model for mesenchymal chondrosarcoma by introducing HEY1-NCOA2 into mouse embryonic superficial zone (eSZ) followed by subcutaneous transplantation into nude mice. HEY1-NCOA2 expression in eSZ cells successfully induced subcutaneous tumors in 68.9% of recipients, showing biphasic morphologies and expression of Sox9, a master regulator of chondrogenic differentiation. ChIP sequencing analyses indicated frequent interaction between HEY1-NCOA2 binding peaks and active enhancers. Runx2, which is important for differentiation and proliferation of the chondrocytic lineage, is invariably expressed in mouse mesenchymal chondrosarcoma, and interaction between HEY1-NCOA2 and Runx2 is observed using NCOA2 C-terminal domains. Although Runx2 knockout resulted in significant delay in tumor onset, it also induced aggressive growth of immature small round cells. Runx3, which is also expressed in mesenchymal chondrosarcoma and interacts with HEY1-NCOA2, replaced the DNA-binding property of Runx2 only in part. Treatment with the HDAC inhibitor panobinostat suppressed tumor growth both in vitro and in vivo, abrogating expression of genes downstream of HEY1-NCOA2 and Runx2. In conclusion, HEY1::NCOA2 expression modulates the transcriptional program in chondrogenic differentiation, affecting cartilage-specific transcription factor functions.

Metastatic mesenchymal chondrosarcoma showing a sustained response to cabozantinib: A case report

Mesenchymal chondrosarcoma is a rare and aggressive sarcoma subtype with high risk for distant metastases and poor prognosis. Currently NCCN- and ESMO-Guidelines recommend using Ewing sarcoma protocols as standard treatment. Nevertheless, in localized disease overall 5-year survival rates are below 50% whereas in metastatic spread median progression-free survival rates of only 5 months can be expected. Here we present a patient with metastatic osseous spread of mesenchymal chondrosarcoma that showed a sustained clinical improvement and a good partial response on imaging over a period of one year when treated with the multi-tyrosine kinase inhibitor cabozantinib. Although we cannot explain the exact mechanism underlying this treatment effect, tumors with similar genetic patterns might respond to the same therapy as well.

Mesenchymal chondrosarcoma of the head and neck with HEY1::NCOA2 fusion: A clinicopathologic and molecular study of 13 cases with emphasis on diagnostic pitfalls

BACKGROUND

Mesenchymal chondrosarcoma (MCS) is a rare translocation-associated sarcoma, driven by a canonical HEY1::NCOA2 fusion. The tumors typically have a biphasic phenotype of primitive small blue round cells intermixed with hyaline cartilage. The head and neck (HN) region is a common site for MCS, accounting for 12-45% of all cases reported.

AIMS

We assembled a relatively large cohort of 13 molecularly confirmed HN MCS for a detailed clinicopathologic analysis. The underlying fusion events were determined using fluorescence in situ hybridization and/or targeted RNA sequencing.

RESULTS

The median age of presentation was 19 years. Five MCSs (39%) had an intraosseous presentation (skull, maxilla, palate, and mandible), while the remaining eight cases occurred in the brain/meninges, orbit, and nasal cavity. Microscopically, HN MCSs were characterized by primitive round cells arranged in a distinctive nested architecture and a rich staghorn vasculature. A cartilaginous component of hyaline cartilage islands and/or single chondrocytes were present in 69% cases. A combined immunoprofile of CD99(+)/SATB2(+)/CD34(-)/STAT6(-) was typically noted. As this immunoprofile is non-specific, the referral diagnoses in cases lacking a cartilaginous component included Ewing sarcoma family and osteosarcoma. Among the seven patients with follow-up data, three developed distant metastasis and one died of disease.

CONCLUSION

HN MCS may arise at intra- or extra-osseous sites. The HN MCS appears to have a more prolonged survival compared other MCS sites. Testing for HEY1::NCOA2 fusion is recommended in HN tumors with nested round cell morphology and staghorn vasculature that lack a distinctive cartilaginous component.

Systemic treatment for primary malignant sarcomas arising in craniofacial bones

Introduction

Craniofacial bones may be the site of origin of various sarcomas. We review the various malignancies affecting this region of the body and attempt to put systemic treatment approaches into perspective.

Material and methods

Non-systematic literature review

Results

Conventional types of osteosarcoma, Ewing sarcoma, and chondrosarcoma are the most frequent bone sarcomas occurring in craniofacial region, but variants may occur. The tumors’ biologies and the resulting treatment strategies vary distinctly. As a general rule, local control remains paramount regardless of histology. The efficacy of antineoplastic chemotherapy varies by type of malignancy. It is clearly indicated in Ewing sarcoma and related tumors, potentially of benefit in high-grade osteosarcoma, undifferentiated pleomorphic sarcoma, dedifferentiated and mesenchymal chondrosarcoma, and of no proven benefit in the others.

Conclusions

Various histologies demand various and distinct treatment approaches, with local control remaining paramount in all. The efficacy of systemic treatments varies by type of tumor. Prospective trials would help in all of these to better define systemic treatment strategies.

Patient-derived xenografts and in vitro model show rationale for imatinib mesylate repurposing in HEY1-NCoA2-driven mesenchymal chondrosarcoma

Mesenchymal chondrosarcoma (MCS) is a high-grade malignancy that represents 2-9% of chondrosarcomas and mostly affects children and young adults. HEY1-NCoA2 gene fusion is considered to be a driver of tumorigenesis and it has been identified in 80% of MCS tumors. The shortage of MCS samples and biological models creates a challenge for the development of effective therapeutic strategies to improve the low survival rate of MCS patients. Previous molecular studies using immunohistochemical staining of patient samples suggest that activation of PDGFR signaling could be involved in MCS tumorigenesis. This work presents the development of two independent in vitro and in vivo models of HEY1-NCoA2-driven MCS and their application in a drug repurposing strategy. The in vitro model was characterized by RNA sequencing at the single-cell level and successfully recapitulated relevant MCS features. Imatinib, as well as specific inhibitors of ABL and PDGFR, demonstrated a highly selective cytotoxic effect targeting the HEY1-NCoA2 fusion-driven cellular model. In addition, patient-derived xenograft (PDX) models of MCS harboring the HEY1-NCoA2 fusion were developed from a primary tumor and its distant metastasis. In concordance with in vitro observations, imatinib was able to significantly reduce tumor growth in MCS-PDX models. The conclusions of this study serve as preclinical results to revisit the clinical efficacy of imatinib in the treatment of HEY1-NCoA2-driven MCS.

Effect of surgery and radiotherapy on overall survival in patients with chondrosarcoma: A SEER-based study

PURPOSE

Chondrosarcoma is an orthopedic malignancy, and the purpose of this study was to evaluate the effect of surgery and radiotherapy (RT) on the survival of patients with chondrosarcoma.

METHODS

Data were obtained from the SEER database for patients diagnosed with chondrosarcoma between 1988 and 2015. All patients were divided into surgery, RT, surgery + RT, and no surgery/no RT groups. Kaplan-Meier curves were used to analyze the overall survival and cancer-specific survival of patients in different treatment groups. The propensity score matching was used to balance baseline covariates between patients in the surgery and surgery + RT groups and in the RT and surgery + RT groups.

RESULTS

Data from 3756 patients with chondrosarcoma were included in this study. The number of patients who underwent surgery, RT, surgery + RT, and no surgery or RT was 2885 (76.8%), 112 (3.0%), 403 (10.7%), and 356 (9.5%), respectively. Multivariate Cox regression models showed that treatment modality was independent risk factor for OS and CSS. Before PSM, Kaplan-Meier curves showed that OS and CSS were highest in the surgery group and lowest in the RT group. After PSM, although there was no significant difference in OS (p = .13) and CSS (p = .22) between the surgery and surgery + RT group, OS was longer in the surgery group than in the surgery + RT group. Additionally, OS (p < .001) and CSS (p = .009) were longer in the surgery + RT group than in the RT group after PSM.

CONCLUSION

Surgical resection was the key approach for the treatment of chondrosarcoma, while RT confers no significant advantage in improving patient survival time.

Molecular Markers of Pediatric Solid Tumors—Diagnosis, Optimizing Treatments, and Determining Susceptibility: Current State and Future Directions

Advances in molecular technologies, from genomics and transcriptomics to epigenetics, are providing unprecedented insight into the molecular landscape of pediatric tumors. Multi-omics approaches provide an opportunity to identify a wide spectrum of molecular alterations that account for the initiation of the neoplastic process in children, response to treatment and disease progression. The detection of molecular markers is crucial to assist clinicians in accurate tumor diagnosis, risk stratification, disease subtyping, prediction of treatment response, and surveillance, allowing also for personalized cancer management. This review summarizes the most recent developments in genomics research and their relevance to the field of pediatric oncology with the aim of generating an overview of the most important, from the clinical perspective, molecular markers for pediatric solid tumors. We present an overview of the molecular markers selected based on therapeutic protocols, guidelines from international committees and scientific societies, and published data.

Clofarabine induces ERK/MSK/CREB activation through inhibiting CD99 on Ewing sarcoma cells

Clofarabine, an FDA approved purine analog, is used in the treatment of relapsed or refractory acute lymphoblastic leukemia. Clofarabine acts by inhibiting DNA synthesis. We demonstrated that clofarabine may have a novel function though inhibiting CD99, a transmembrane protein highly expressed on Ewing Sarcoma (ES) cells. CD99 is a validated target in ES whose inhibition may lead to a high therapeutic index for patients. Here we present additional data to support the hypothesis that clofarabine acts on CD99 and regulates key signaling pathways in ES. Cellular thermal shift assay indicated a direct interaction between clofarabine and CD99 in ES cell lysates. Clofarabine induced ES cell death does not require clofarabine's conversion to its active form by deoxycytidine kinase. A phosphokinase array screen with clofarabine and a CD99 blocking antibody identified alterations in signaling pathways. CD99 inhibition with clofarabine in ES cells caused rapid and sustained phosphorylation of ERK, MSK, and CREB. However, activation of this pathway did not correlate with clofarabine induced ES cell death. In summary, we demonstrated that clofarabine may activate ERK, MSK, and CREB phosphorylation through CD99 within minutes, however this paradoxical activation and subsequent ES cell death requires additional investigation.

OLIG2 Immunolabeling of Mesenchymal Chondrosarcoma: Report of 14 Cases

Mesenchymal chondrosarcoma (MC) is a rare aggressive mesenchymal sarcoma. Specific markers for the differential diagnosis of MCs remain to be developed. OLIG2 expression has been reported only in neuroepithelial tumors. Recently, OLIG2 expression was found to be involved in the development of NCOA2 fusion-positive alveolar rhabdomyosarcomas. Therefore, we investigated whether OLIG2 expression could be used as a diagnostic marker for MC. We report the clinical pathological and immunohistochemical features of 14 MCs. All tumors showed typical pathological features including biphasic patterns with sheets of primitive round mesenchymal cells and interspersed islands of cartilage. These tumors expressed BCL2, SOX9, and CD99. OLIG2 was robustly expressed in 12/14 of MCs. NCOA2 rearrangement was found in 12 cases. OLIG2 expression was not found in the NCOA2 rearrangement-negative MCs. Notably, OLIG2 expression was not detected in 52 neoplasms (8 Ewing sarcomas, 23 hemangiopericytomas, and 21 chondrosarcomas) that are frequently misdiagnosed as MC. Our findings provide convincing evidence that OLIG2 can serve as a reliable marker in the differential diagnosis of MC and may be a unique neurodevelopmental gene expression signature for the NCOA2 rearranged MCs.

NKX3.1 immunohistochemistry is highly specific for the diagnosis of mesenchymal chondrosarcomas: experience in the Australian population

Mesenchymal chondrosarcoma (MC) is a rare sarcoma that typically arises in adolescents and young adults and characteristically harbours a HEY1-NCOA2 gene fusion. A recent study has shown that NKX3.1 immunohistochemistry (IHC) is highly specific and sensitive in MCs. NKX3.1 is a nuclear marker expressed in prostatic tissue and is widely used in most laboratories to determine prostatic origin of metastatic tumours. In the current study we investigated whether this stain can be used in the diagnostic workup of MC, as it may assist in triaging cases for further molecular testing, by assessing its expression in a cohort of MCs and in a wide spectrum of sarcoma types. Furthermore, we aimed to elucidate if expression of NKX3.1 by MCs is related to androgen receptor (AR) expression. We identified NKX3.1 positive nuclear staining in 9 of 12 individual patients of MC (n=20 of 25 samples when taking into account separate episodes). Four of the five negative specimens had been previously subjected to acid-based decalcification. NKX3.1 was negative in 536 samples from 16 non-MC sarcomas derived from largely tissue microarrays (TMAs). Overall, we identified 80% sensitivity and 100% specificity for NKX3.1 IHC in MCs. The sensitivity increased to 95.2% when acid-based decalcified specimens were excluded from the analysis. No correlation between NKX3.1 expression and AR IHC was identified. In summary, our findings indicate that NKX3.1 nuclear positivity is highly sensitive and specific for MC, provided that ethylenediaminetetraacetic acid (EDTA)-based rather than acid-based decalcification is used for sample processing. NKX3.1 IHC in the right clinical and histopathological setting can potentially be sufficient for the diagnosis of MC, reserving molecular confirmation only for equivocal cases.

Intracranial extra-axial mesenchymal chondrosarcoma in a 16-month-old patient with a literature review of pediatric patients

Mesenchymal chondrosarcoma is a rare high-grade malignant subtype of chondrosarcoma that is characterized by undifferentiated, round, or spindled mesenchymal cells, interspersed with islands of hyaline cartilage. We report a primary intracranial extra-axial mesenchymal chondrosarcoma in a 16-month-old patient with a review of the literature focusing on intracranial extra-axial MCs with or without skull involvement in pediatric patients, including differential diagnosis. The patient was admitted with a swelling in the right temporooccipital region. There was intracranial extra-dural extension of the mass, which abuts the neural parenchyma without any invasion. A complete tumor resection was performed. Pathological diagnosis was mesenchymal chondrosarcoma. The patient was free of symptoms after surgery.

Mesenchymal chondrosarcoma of the orbit masquerading as a hemophilic pseudotumor

An 11-year-old boy presented with a lesion of the right orbit that was thought to be a hemophilic pseudotumor. Excisional biopsy revealed an unexpected diagnosis of mesenchymal chondrosarcoma. Both mesenchymal chondrosarcoma and hemophilic pseudotumor of the orbit are exceedingly rare. To the best of our knowledge, this is the first reported case of orbital mesenchymal chondrosarcoma masquerading as hemophilic pseudotumor.

Intracranial Mesenchymal Chondrosarcoma Lacking the Typical Histopathological Features Diagnosed by HEY1-NCOA2 Gene Fusion

Intracranial mesenchymal chondrosarcoma (MCS) is a rare neoplasm. The diagnosis of MCS is confirmed by the presence of a biphasic pattern on histological examination, comprising undifferentiated small round cells admixed with islands of well-differentiated hyaline cartilage; however, a differential diagnosis may be challenging in some cases. A 28-year-old woman with a 2-month history of headache was referred to our hospital. Radiologic studies showed an extra-axial lobulated mass composed of calcified and uncalcified areas occupying the left middle fossa. Surgical resection was planned, but her headache suddenly worsened before her planned hospital admission and she was admitted as an emergency. Radiologic studies showed an acute hemorrhage in the uncalcified part of the mass. The mass was resected via the left zygomatic approach after embolization of the feeder vessels. The most likely histopathological diagnosis was MCS. However, the typical bimorphic pattern was not identified in our surgical samples; each undifferentiated area and well-differentiated area was observed separately in different tissue specimens, and no islands of well-differentiated hyaline cartilage were identified within the undifferentiated areas in the same specimen. Molecular assays confirmed the presence of HEY1-NCOA2 fusion. IRF2BP2-CDX1 fusion and IDH1/2 mutations were negative. The final diagnosis of MCS was made based on the presence of HEY1-NCOA2 gene fusion. MCS should be included in the differential diagnosis when radiologic studies show an extra-axial lobulated mass with calcification. Furthermore, molecular demonstration of HEY1-NCOA2 gene fusion may help make a precise diagnosis of MCS, especially in surgical samples lacking the typical histopathological features.

Primary mesenchymal chondrosarcoma of the kidney without HEY1-NCOA2 and IRF2BP2-CDX1 fusion: A case report and review

Mesenchymal chondrosarcoma (MC) of the kidney is rare. To the best of our knowledge, the current report is the first case of a giant extraskeletal MC that arose primarily from the right kidney and mimicked renal cell carcinoma at the locally advanced stage (cT3bN0) with vena cava thrombus and multiple pulmonary arterial tumor emboli. Additionally, the literature on renal EMC is reviewed and the possibilities of oncogenic heterogeneity are discussed. A 64-year-old woman was admitted to Yamagata University Hospital for sudden onset of asymptomatic gross hematuria. CT revealed a 90 mm renal mass without calcification in the right kidney and tumor thrombus extending to the inferior vena cava. Radical nephrectomy with thrombectomy was performed. Lung metastasis was detected 2 months later. The patient received systemic chemotherapy, which was only marginally effective. She died of the malignancy 8 months after surgery. Microscopic examination of the tumor revealed typical histology of MC and a lack of HEY1-NCOA2 and IRF2BP2-CDX1 gene fusions in the tumor tissues. Not all MC patients may exhibit chromosomal alterations in the tumor, suggesting the presence of genetically heterogeneous pathways of MC oncogenesis. Further studies are required to confirm the present findings and reinforce the molecular diagnosis of MC.

Prognostic Factors and Treatment Options for Patients with High-Grade Chondrosarcoma

Background

The goal of this study was to determine the prognostic factors exclusive for high-grade chondrosarcoma and whether adjuvant radiotherapy could achieve better overall survival (OS) or cancer-specific survival (CSS) for patients with high-grade chondrosarcoma.

Material/Methods

Surveillance, Epidemiology, and End Results (SEER) cancer registry database was utilized to extract the chondrosarcoma cases diagnosed between 1973 and 2014. Among these cases, the histological grades of poorly differentiated (grade 3) and undifferentiated (grade 4) were categorized as high-grade and included in this study. Chondrosarcoma OS and CSS were the primary outcomes in the present study. The log-rank test was performed for univariate analysis, and the Cox regression model was conducted for multivariate analysis.

Results

A total of 743 patients with high-grade chondrosarcoma were identified in this study (430 cases were poorly differentiated tumors, and 313 cases were undifferentiated tumors). Age at diagnosis, pathological grade, histo-type, SEER stage, tumor size and surgical resection were identified as independent predictors in both OS and CSS analysis of high-grade chondrosarcoma. When stratified by histological grade, surgical resection remained the effective treatment. Strikingly, radiotherapy was determined as an independent protective factor in both OS and CSS analysis of undifferentiated (grade 4) dedifferentiated chondrosarcoma, and adjuvant radiotherapy combined surgical resection could improve both the OS and CSS of patients with undifferentiated myxoid and dedifferentiated chondrosarcoma compared with other treatment regimens.

Conclusions

Our study first demonstrated that adjuvant radiotherapy combined surgery could improve the survival of patients with undifferentiated myxoid and dedifferentiated chondrosarcoma. These results encourage the application of adjuvant radiotherapy for patients with high-grade chondrosarcoma and maximize the patients’ outcome.

Robot-assisted radical nephrectomy for primary renal mesenchymal chondrosarcoma: case report and literature review

As an extremely rare malignant neoplasm, only 12 mesenchymal chondrosarcoma (MC) arising in kidney have been reported to date. Herein, we reported a case of primary renal MC resected with robot assistance, which has not been reported before. According to the cases reported in English literature, we analyzed the characteristics of this rare malignancy and systematically review its treatment.