Juxta-articular extraskeletal myxoid chondrosarcoma mistaken for a benign cyst presenting with multiple lung metastases

Extraskeletal myxoid chondrosarcoma (EMC) is a malignant cartilage neoplasm usually encountered in the proximal extremities. We report the case of a 58-year-old male who presented initially with a 3-month history of cough. Initial staging demonstrated a right upper lobe mass with bilateral pulmonary nodules and moderate tracer uptake in the right lung mass and right groin on positron emission tomography imaging. Endobronchial ultrasound biopsy confirmed a histological diagnosis of EMC for which the patient underwent right upper lobe wedge resection. Pelvic MRI revealed a peripherally enhancing juxta-articular lesion within the region of the right obturator externus bursa, which was thought initially to represent either a ganglion or paralabral cyst. However, ultrasound-guided biopsy yielded identical histology to the resected lung mass leading to the diagnosis of primary EMC in the right groin with pulmonary metastases. The patient underwent surgical excision of the right groin mass with no local recurrence on the surveillance computed tomography at 5, 12, and 18 months but eventual disease recurrence in the right groin and further progression of the pulmonary metastases at 29 months. We emphasize that the contrast enhancement pattern of EMC can mimic a benign cystic lesion, in particular, when in a juxta-articular location, which has the potential to mislead radiologists and delay diagnosis and definitive treatment.

Extraskeletal Myxoid Chondrosarcoma of Floor of Mouth-A Rare Case Report and Review of Literature

Introduction

Chondrosarcomas are rare malignancies of the cartilage and myxoid chondrosarcoma is its variant which commonly occurs in soft tissue of extremities. Extraskeletal chondrosarcoma is a rare malignant neoplasm of bone or soft tissue origin and is characterized by the presence of spindle cells admixed with well differentiated cartilage or chondroid stroma. They are mostly radioresistant tumours and surgical resections with adequate margins is considered as the ideal treatment modality with adjuvant radiotherapy in high grade tumours and add on chemotherapy, in case of presence of poor prognostic factors.

Case Report

A 51-year-old diabetic, hypertensive female patient presented to our outpatient department with difficulty in chewing food for a duration of 6 months. On clinical examination, she had an ulceroproliferative growth involving right lower alveolus and floor of mouth. MRI face and neck with contrast showed a 4.1 × 2.9 × 4.5 cm lesion involving right lower alveolus extending to floor of mouth. Biopsy showed features of extraskeletal myxoid chondrosarcoma. She was planned for upfront surgery (Right composite resection with modified radical neck dissection with free fibula flap). Patient was stable post-surgery and was discharged in stable condition. Final histopathology report was high grade myxoid chondrosarcoma. The case was presented in tumour board and the patient was planned for adjuvant radiotherapy. She has been on regular follow up for the past 2 years and shows no signs of recurrence.

Conclusion

Extraskeletal myxoid chondrosarcoma of oral cavity is a rare entity and very few cases are reported. It is a malignant neoplasm which is diagnosed with the help of immunohistochemistry. Surgery is the ideal modality of treatment accompanied by adjuvant radiotherapy in cases of high-grade tumours.

TAF15::NR4A3 gene fusion identifies a morphologically distinct subset of extraskeletal myxoid chondrosarcoma mimicking myoepithelial tumors

Extraskeletal myxoid chondrosarcoma (EMC) is a rare sarcoma of uncertain differentiation predominantly arising in deep soft tissue. Its conventional morphologic appearance manifests as a relatively well-circumscribed, multilobular tumor composed of uniform short spindle-to-ovoid primitive mesenchymal cells with deeply eosinophilic cytoplasm arranged in anastomosing cords within abundant myxoid matrix. The genetic hallmark of EMC has long been considered to be pathognomonic gene rearrangements involving NR4A3, which when fused to TAF15, often have high-grade morphology with increased cellularity, moderate to severe cytologic atypia, and rhabdoid cytomorphology. Herein, we describe two cases of EMC with TAF15::NR4A3 fusion that appear morphologically distinct from both conventional and high-grade EMC. Both cases had an unusual biphasic appearance and showed diffuse positivity for p63, mimicking myoepithelial tumors. DNA methylation profiling demonstrated that both cases clearly cluster with EMC, indicating that they most likely represent morphologically distinct variants of EMC. The clinical significance and prognostic impact of this morphologic variance remains to be determined. Molecular testing, including DNA methylation profiling, can help to confirm the diagnosis and avoid confusion with mimics; it adds another layer of data to support expanding the morphologic spectrum of EMC.

Extraskeletal myxoid chondrosarcoma of the gingival: a rare case report and review of the literature

BACKGROUND

Extraskeletal myxoid chondrosarcoma (EMC) is a rare malignant tumor described in the head and neck region, especially in the gingival. We present one case arising in the gingival of right mandible, and briefly reviewed the related literature.

CASE PRESENTATION

A 24-year-old male patient with a lesion of 3.5*2.0 cm in buccal gingival of right posterior mandible for 2 months. The tumor was composed of cartilaginous structures and myxoid matrix. Immunohistochemical(IHC) showed that the tumor cells to be positive for vimentin, focally positive for S-100, negative for calponin, SMA, SOX10. The Ki-67 labelling index was 80%. Fluorescent in situ Hybridization (FISH) was positive for NR4A3 rearrangement.

CONCLUSIONS

Due to its unusual site and low incidence in the oral region, a combination of histological findings, immunohistochemistry, and molecular pathology as well as differential diagnosis with other diseases should be taken into consideration in the process of clinical diagnosis and treatment.

Extraskeletal Myxoid Chondrosarcoma Identified in a Traumatic Fracture of the Toe: A Case Report

Introduction

Extraskeletal myxoid chondrosarcoma (EMC) is a rare soft-tissue sarcoma that typically presents in the proximal lower extremity and limb-girdle. It can be easily misdiagnosed, especially when located in atypical locations like the foot.

Case Report

We present the case of an 80-year-old Caucasian female with a left 3rd toe pain and swelling that was initially misdiagnosed as a traumatic fracture on radiographs but later determined to be an indolent EMC based on histology. She was successfully treated with amputation of the toe.

Conclusion

EMC should be considered in the differential of osseous and soft-tissue abnormalities on radiographic imaging of the extremities. As reported in the literature, it can present in atypical locations with minimal symptoms and successful treatments include resection. Future cases presenting similarly should be evaluated for EMC and, if present, reported along with their applied treatment protocols to allow for further assessment of current therapeutic guidelines.

Extraskeletal myxoid chondrosarcoma: a case report

Extraskeletal myxoid chondrosarcoma is a rare mesenchymal neoplasm of uncertain differentiation, characterized morphologically by abundant myxoid stroma, a multinodular growth pattern, and uniform cells arranged in strands, clusters, and reticular networks. It usually occurs in adults in the fifth decade, most often in the deep soft tissues of the proximal extremities. The molecular hallmark of this tumor, present in over 90% of cases, is the fusion of NR4A3 with EWSR1 at 22q12.2 or TAF15 at 17q12. Many other tumors with uniform tumor cells embedded in a myxoid matrix can mimic Extraskeletal myxoid chondrosarcoma, and the distinction can be difficult, often requiring immunohistochemistry and/or molecular testing. We herein report the case of an Extraskeletal myxoid chondrosarcoma that occurred in a 74-year-old woman who consulted for a slowly enlarging thigh mass, while highlighting the key morphologic, immunohistochemical, and molecular features of this rare type of soft tissue sarcoma, as well as a summary table gathering diagnostic features of relevance to the differential diagnosis.

Extraskeletal myxoid chondrosarcoma: p53 and Ki-67 offer prognostic value for clinical outcome - an immunohistochemical and molecular analysis of 31 cases

Extraskeletal myxoid chondrosarcoma (EMC) is a rare malignant soft tissue tumor of unpredictable clinical behavior. The morphological spectrum of EMC based on histology alone can be difficult. There is no precise immunohistochemical (IHC) profile that together with the clinical parameters is able to predict the clinical outcome. We studied 31 cases confirmed as EMC. Clinical and follow-up data were recorded. Histopathological, molecular, and IHC studies were performed. Association among histopathological parameters was assessed using a chi-square test to determine homogeneity or linear trend for ordinal variables. The Kaplan-Meier proportional risk test (log rank) was used to study the impact of the histological, IHC, and molecular factors on progression-free survival (PFS) and disease-specific survival (DSS). Most EMCs showed a typical architectural pattern. Only a few cases presented an atypical histology (higher cellularity and solid pattern). IHC positivity (focal or diffuse) was present for CDK4 (100%), STAT-6 (90%), CD117 (84%), HNK-1 (81%), SATB2 (68%), and S-100 (58%). Synaptophysin and INSM1 were expressed in 22.6% and 38.7% of cases respectively. The EWSR1::NR4A3 rearrangement was found in 19 cases and 7 tumors presented the TAF15::NR4A3 fusion. Positive surgical margins together with atypical histology and expression of p53 and Ki67 correlated with worse clinical prognosis. EMCs express several IHC markers which are also seen in other soft tissue sarcomas. The molecular detection of NR4A3 rearrangement supports the differential diagnosis. Positive surgical margins together with atypical histology and positive expression of p53 and Ki-67 seem to predict a poor clinical outcome with worse prognosis, increased rate of recurrence, metastasis, and poor overall survival.

Establishment, characterization and functional testing of two novel ex vivo extraskeletal myxoid chondrosarcoma (EMC) cell models

Extraskeletal myxoid chondrosarcoma (EMC) is a malignant mesenchymal neoplasm of uncertain differentiation as classified by the WHO Classification of Tumours 2020. Although often associated with pronlonged survival, EMC has high rates of distant recurrences and disease-associated death. EMCs are translocation sarcomas and harbor in > 90% of the cases an NR4A3 rearrangement. The molecular consequences of the NR4A3 gene fusions are not yet fully elucidated as well-characterized ex vivo cell models for EMC are lacking. Patient-derived ex vivo models are important and essential tools for investigating disease mechanisms associated with diseases that are rare, that exhibit poor prognosis and for the identification of potential novel treatment options. We established two novel EMC ex vivo models (USZ20-EMC1 and USZ22-EMC2) for functional testing and research purposes. USZ20-EMC1 and USZ22-EMC2 were established and maintained as sarco-sphere cell models for several months in culture. The cells were molecularly characterized using DNA sequencing and methylation profiling. Both cell models represent their native tumor tissue as confirmed by histomorphology and their molecular profiles, suggesting that native tumor cell function can be recapitulated in the ex vivo models. Using a functional screening approach, novel anti-cancer drug sensitivities including potential synergistic combinations were identified. In conclusion, two novel EMC ex vivo cell models (USZ20-EMC1 and USZ22-EMC2) were successfully established and characterized from native tumor tissues. Both cell models will be useful tools for further investigating disease mechanisms and for answering basic and translational research questions.

Extraskeletal myxoid chondrosarcoma: A study of 17 cases focusing on the diagnostic utility of INSM1 expression and presenting rare morphological variants associated with non-EWSR1::NR4A3 fusions

Extraskeletal myxoid chondrosarcoma (EMC) is a rare sarcoma of uncertain lineage. Insulinoma-associated protein 1 (INSM1) has recently been described as a highly specific and sensitive immunohistochemical marker for EMC. The goal of this study was to evaluate the diagnostic significance of INSM1 immunohistochemistry in EMC. Furthermore, correlations between molecular and morphological findings were performed. Sixteen of 17 EMC cases were stained with the INSM1 antibody. Tumors with at least 5% INSM1-positive cells and any staining intensity were considered positive. Molecular testing was successfully performed in 12/17 cases. The immunohistochemical analysis detected 13 INSM1-positive (81%) and 3 INSM1-negative tumors (19%). The extent of the staining was classified as 1+ in 7 cases (44%), 2+ in 2 cases (13%), 3+ in 2 cases (13%) and 4+ in 2 cases (13%). Intensity of immunostaining was weak in 5 cases (31%), moderate in 2 cases (13%) and strong in 6 cases (38%). Molecular assays revealed 8 EWSR1::NR4A3 positive tumors (67%), 2 TAF15::NR4A3 positive tumors (17%), 1 TCF12::NR4A3 positive tumor (8%) and 1 NR4A3 positive tumor (8%) in which no other gene alteration was identified. Two of them, namely TCF12 positive and one TAF15 positive tumors, were highly cellular and partially associated with pseudopapillary architecture. Our study found that moderate/strong expression of INSM1 in more than 25% of tumor cells was present in only 31% of cases. Thus, the diagnostic utility of INSM1 is rather low. Two morphologically unique cases of non-EWSR1 rearranged EMC with an extremely rare pseudopapillary growth pattern are also reported.

Intra-muscular extraskeletal myxoid chondrosarcoma of the thigh: a case report

Soft tissue sarcomas are mesenchymal tumors that account for about 1% of all malignancies. We retrospectively analyzed a rare case of a painful intra-muscular extraskeletal myxoid chondrosarcoma in the thigh of a 35-year-old man, that had undergone excision. Histological and immunohistochemical analysis of the mass revealed extraskeletal myxoid chondrosarcoma. The patient proceeded to radiotherapy and chemotherapy after curative surgery and had a good outcome.

Primary intracranial extraskeletal myxoid chondrosarcoma: A case report and review of literature

BACKGROUND

Primary intracranial extraskeletal myxoid chondrosarcoma (EMC) is an extremely rare low- to intermediate-grade malignant soft tissue sarcoma, and only 15 cases have been reported in the literature. Due to its rarity, clinical data and research on this tumor type are extremely limited, the pathogenesis and histological origin are still unclear, and the diagnostic and standard clinical treatment strategies for intracranial EMC remain controversial and undefined.

CASE SUMMARY

We reported a case of a 52-year-old male who was admitted to the hospital with headache and dizziness for 1 mo, and his health status deteriorated during the last week. CT of the head showed a well-defined low-density lesion situated in the left cavernous sinus. Brain magnetic resonance imaging (MRI) showed a 3.4 cm × 3.0 cm sized, well-defined, round-shaped and heterogeneously enhanced lesion located in the left cavernous sinus. The entire lesion was removed via supratentorial craniotomy and microsurgery. Postoperative pathological diagnosis indicated primary intracranial EMC. Subsequently, the patient underwent 45 Gy/15 F stereotactic radiotherapy after discharge. At present, it is 12 mo after surgery, with regular postoperative follow-up and regular MRI examinations, that there are no clinical symptoms and radiographic evidence indicating the recurrence of the tumor, and the patient has returned to normal life.

CONCLUSION

Currently, the most beneficial treatment for primary intracranial EMC is gross total resection combined with postoperative radiotherapy. Long-term follow-up is also necessary for patients.

Periosteal Myxoid Leiomyosarcoma Histologically Mimicking Extraskeletal Myxoid Chondrosarcoma: Report of a Case with Histopathological and Cytopathological Comparison with Extraskeletal Myxoid Chondrosarcoma

Myxoid leiomyosarcoma (MLS) is a rare variant of leiomyosarcoma, with most cases occurring in the uterus. A case of MLS arising in the periosteal region of the tibia, mimicking extraskeletal myxoid chondrosarcoma (EMC), is described. The evaluation included histological and cytological comparison with EMC. The patient was a 77-year-old man with a palpable mass at the anterior aspect of the right lower leg. After diagnosis by cytopathology and biopsy examination, a wide resection was performed. The resulting cytological smears were composed primarily of spindle-shaped tumor cells in a myxoid and hemorrhagic background. Histologically, the tumor showed abundant myxoid matrix and tumor cells proliferating in a cord-like to reticular pattern, exhibiting a lace-like arrangement that mimicked EMC. Although immunohistochemical findings suggested leiomyosarcoma, a diagnosis of EMC eventually was excluded by the lack of a split signal when assessed for a rearrangement of NR4A3 by chromogenic in situ hybridization. Despite histological similarity to EMC, characteristic cytological findings of EMC such as epithelioid structures with a cord-like pattern and chondroblast-like lacunar structures were not observed in the smears of this patient's MLS. We propose that cytopathological examination of bone and soft tissue lesions is useful as a diagnostic tool in similar cases. A total diagnostic workup, including clinical, radiographic, cytopathological, histopathological, and molecular findings, is needed to ensure an accurate final diagnosis and to reduce diagnostic error.

Wide en bloc resection of an extraskeletal myxoid chondrosarcoma about the knee with single-stage knee extensor mechanism reconstruction: A case report

Soft tissue sarcomas about the patellar tendon necessitate wide resection and thus present a significant reconstructive challenge. This article describes the novel use of a synthetic mesh graft to reconstruct the knee extensor mechanism as a single stage procedure after wide en bloc resection of an extraskeletal myxoid chondrosarcoma (EMC) in a patient with an invasive mass that was intimately associated with her patellar tendon.

Extraskeletal myxoid chondrosarcoma: combining cytopathology with molecular testing to achieve diagnostic accuracy

INTRODUCTION

Advances in the genetics of soft tissue neoplasia have allowed for the diagnostic recognition of specific tumor types from small biopsy specimens, including those procured using the fine needle aspiration (FNA) biopsy technique. Extraskeletal myxoid chondrosarcoma (EMC) is a malignant mesenchymal neoplasm characterized by NR4A3 and, less specifically, by EWSR1 gene rearrangements. A series of EMC cytologic specimens was examined to demonstrate the diagnostic value of incorporating fluorescence in situ hybridization (FISH) testing in cytologic cases of suspected EMC.

MATERIALS AND METHODS

A search was made of our cytopathology and surgical pathology databases for cases diagnosed as EMC. FNA biopsy cytology, exfoliative cytology, imprint cytology, and FISH analysis were performed and examined using standard techniques.

RESULTS

A total of 16 cases of EMC were retrieved from 15 patients (male/female ratio, 2.8:1; mean age, 62 years). Of the 15 patients, 10 were new patients with primary tumors, 2 had locally recurrent tumors, and 4 had metastases. The sites included the extremities in 10 cases, the trunk in 4, serous effusion in 1, and a mediastinal lymph node in 1 case. The specific cytologic diagnoses were EMC (14 cases; 88%), suspicious for EMC (n = 1), and malignant cells (n = 1). All cases for which FISH testing was successfully used were specifically recognized as EMC. Aspirates and imprint smears consisted of uniformly rounded cells set in an opaque myxoid/chondromyxoid stroma (less abundant and more diaphanous in the effusion sample), sometimes arranged in short anastomosing cords. FNA of 1 case of an EMC cellular variant mimicked a malignant small rounded cell tumor.

CONCLUSION

EMC can be added to the growing list of soft tissue neoplasms that are specifically recognizable using cytopathology, coupled with judicious application of ancillary molecular testing.

SWI/SNF Complex-Deficient Soft Tissue Neoplasms: A Pattern-Based Approach to Diagnosis and Differential Diagnosis

Loss of different components of the Switch/sucrose nonfermentable (SWI/SNF) chromatin remodeling complex has been increasingly recognized as a central molecular event driving the initiation and/or dedifferentiation of mostly lethal but histogenetically diverse neoplasms in different body organs. This review summarizes and discusses the morphologic and phenotypic diversity of primary soft tissue neoplasms characterized by SWI/SNF complex deficiency with an emphasis on convergent and divergent cytoarchitectural patterns.

Extraskeletal myxoid chondrosarcoma with massive pulmonary metastases

Background

Extraskeletal myxoid chondrosarcoma (EMC) is a rare malignant mesenchymal neoplasm of uncertain differentiation characterized by rearrangements of the NR4A3 gene. EMC often affects adults around the age of 50 and arise in the deep tissues of the proximal extremities and limb girdles. EMC is characterized by indolent growth rate but strong tendency to local recurrence and metastatic spread. No systemic treatment is specifically approved by the FDA for this disease and surgery has been traditionally the only potentially curative strategy.

Case presentation

A 41-year-old Caucasian woman originally presented with a 14.8 cm left thigh mass. She was managed with wide local resection but after 2 years she developed recurrent disease in the pelvis and in the lungs; the lung involvement was characterized by innumerable nodules without any significant respiratory symptoms. After failing three clinical trials, she experienced prolonged disease control while on treatment with the tyrosine kinase inhibitor (TKI) pazopanib and radiation therapy delivered to the pelvic lesion. Dose reduction of pazopanib due to severe diarrhea was followed by rapid disease progression in the pelvis requiring vascular stenting; increase in tumor growth after discontinuation of a TKI has been described in other malignancies and is a possibility in this specific patient.

Conclusion

While surgical management of EMC with or without radiation therapy is still the preferable approach when feasible, small series support the use of tyrosine kinase inhibitors and possible new immunotherapies in selected patients. Basket trials focusing on diseases with unique genomic features such as EMC will hopefully provide a better understanding of new options for care.

Extraskeletal myxoid chondrosarcoma with massive pulmonary metastases

Background

Extraskeletal myxoid chondrosarcoma (EMC) is a rare malignant mesenchymal neoplasm of uncertain differentiation characterized by rearrangements of the NR4A3 gene. EMC often affects adults around the age of 50 and arise in the deep tissues of the proximal extremities and limb girdles. EMC is characterized by indolent growth rate but strong tendency to local recurrence and metastatic spread. No systemic treatment is specifically approved by the FDA for this disease and surgery has been traditionally the only potentially curative strategy.

Case presentation

A 41-year-old Caucasian woman originally presented with a 14.8 cm left thigh mass. She was managed with wide local resection but after 2 years she developed recurrent disease in the pelvis and in the lungs; the lung involvement was characterized by innumerable nodules without any significant respiratory symptoms. After failing three clinical trials, she experienced prolonged disease control while on treatment with the tyrosine kinase inhibitor (TKI) pazopanib and radiation therapy delivered to the pelvic lesion. Dose reduction of pazopanib due to severe diarrhea was followed by rapid disease progression in the pelvis requiring vascular stenting; increase in tumor growth after discontinuation of a TKI has been described in other malignancies and is a possibility in this specific patient.

Conclusion

While surgical management of EMC with or without radiation therapy is still the preferable approach when feasible, small series support the use of tyrosine kinase inhibitors and possible new immunotherapies in selected patients. Basket trials focusing on diseases with unique genomic features such as EMC will hopefully provide a better understanding of new options for care.

Systemic manifestations of extraskeletal myxoid chondrosarcoma associated with a novel t(2;22)(q34;q12) EWS translocation in a child and a review of the literature

Extraskeletal myxoid chondrosarcoma (EMC), a soft-tissue sarcoma with unique clinicopathologic features and characteristic chromosomal translocations, is extremely rare in the pediatric population. We, herein, present the case of a 7-year-old boy with profound microcytic hypochromic anemia, poor weight gain and a mid-thoracic paraspinal mass that was identified as EMC. Systemic manifestations of localized, nonmetastatic EMC have never been described in the pediatric population, yet our patient's anemia and poor weight gain resolved after successful surgical resection of the tumor, suggesting that localized EMC can present with systemic manifestations. The tumor also contained a novel t(2;22)(q34;q12) translocation involving the EWSR1 gene, which is consistent with additional reports suggesting that a growing list of translocations can drive formation of, and potential new management strategies for, EMC.

Primary extraskeletal myxoid chondrosarcoma of bone: Report of three cases and review of the literature

Extraskeletal myxoid chondrosarcoma is a rare neoplasm of soft tissue. The usual location is in deep parts of the proximal extremities and limb girdles in middle-aged adults. The bone location as primary location is extremely rare and few cases are reported. We present three cases arising in bone with molecular confirmation using both RT-PCR and FISH analysis. Patients include two men and one woman with an age of 62, 69 and 73 years old. The mean size of the lesion was 13cm (range 8-18cm). Tumors arose in the iliac bone in two cases and in the proximal humerus in the other case. At time of diagnosis the three cases show bone cortex and soft tissue involvement. On imaging, lesions have a lobular pattern, are purely lytic, but take up contrast medium after injection. Two patients are alive with disease (local recurrence and lung metastasis) after five years and five years and six months, respectively and one patient died of disease two years after the diagnosis. The primary extraskeletal myxoid chondrosarcoma of bone seems to have a more aggressive behavior than the soft tissue counterpart. The molecular confirmation of diagnosis using RT-PCR is necessary to do the differential diagnosis with other entities, in particular with myoepithelioma that shows similar morphological features and EWSR1 and FUS genes rearrangement.

Diagnosis of extraskeletal myxoid chondrosarcoma in the thigh using EWSR1-NR4A3 gene fusion: a case report

BACKGROUND

Extraskeletal myxoid chondrosarcoma is a rare soft tissue sarcoma that has unusual ultrastructural and molecular features. However, unlike other soft tissue sarcomas, it does not have specific clinical symptoms or radiological features, which can make its diagnosis difficult. Nevertheless, extraskeletal myxoid chondrosarcoma has a rare gene fusion (EWSR1-NR4A3) that is useful for making a differential diagnosis.

CASE PRESENTATION

A 43-year-old Japanese man presented with a soft tissue mass in his right thigh. A physical examination and radiography revealed a large soft tissue mass. During magnetic resonance imaging, the mass exhibited isointensity on T1-weighted images and high intensity on T2-weighted images, as well as gadolinium enhancement at the side edge of the partition structure. Thus, we considered a possible diagnosis of a malignant myxoid soft tissue tumor, such as myxoid liposarcoma, myxofibrosarcoma, or metastatic carcinomas, including myoepithelial tumor and neuroendocrine tumor, and performed an incisional biopsy to make a definitive diagnosis. The pathological findings revealed a lobulated tumor with a myxoid structure and atypical spindle-shaped cells that created eosinophilic cord-like forms. Immunohistochemistry revealed that the tumor was positive for S-100 and negative for synaptophysin, chromogranin A, and pan keratin (AE1/AE3). The percentage of Ki-67 was 10 % in the hot spot area. Based on these clinicopathological findings, we initially considered the possibility of a myxoid liposarcoma, although we did not observe any lipoblasts. Therefore, we considered the possibility of an extraskeletal myxoid chondrosarcoma. As this tumor is very rare, we searched for the EWSR1-NR4A3 gene fusion using fluorescence in situ hybridization, which confirmed the diagnosis of extraskeletal myxoid chondrosarcoma. Positron emission tomography-computed tomography did not identify any obvious metastases, and we performed radical resection of our patient's vastus medialis and femur with a 3 cm margin. After the resection, we treated his resected femur using liquid nitrogen, and reconstructed his femur using autogenous fibula and plate fixation. No local recurrence or metastasis was observed at the 1-year follow-up.

CONCLUSION

Genetic testing is useful for diagnosing extraskeletal myxoid chondrosarcoma based on the presence of the EWSR1-NR4A3 gene fusion.

Pulmonary extraskeletal myxoid chondrosarcoma: A case report and literature review

•

Extraskeletal myxoid chondrosarcoma (EMC) is a rare tumor characterized by the multinodular growth of primitive chondroid cells in an abundant myxoid matrix.

•

EMC is categorized as a tumor of uncertain differentiation by the 2002 WHO classification.

•

EMC has shown to have the recurrent balanced chromosomal translocation t(9;22) (q22;q12.2), which leads to the oncogenic fusion gene EWSR1-NR4A3.

•

EMC usually presents in male patients beyond their fifth decade as a slow growing, palpable mass in the extremities.

•

Pulmonary extraskeletal myxoid chondrosarcomas are extremely rare with only isolated case reports found in the literature.

Background

Extraskeletal myxoid chondrosarcoma (EMC) accounts for the 3% of all soft tissue sarcomas and it's categorized as a tumour of uncertain differentiation. This entity has shown to have the recurrent balanced chromosomal translocation t(9;22) (q22;q12.2), which leads to the oncogenic fusion gene EWSR1-NR4A3. This sarcoma usually presents as a slow growing, palpable mass in the extremities. EMC arising from the lung is extremely infrequent. We report one case of pulmonary extraskeletal mixoid chondrosarcoma and a review of the world literature.

Case report

A 69-year-old male patient presented with intermittent hemoptysis for the last 6 months. A PET/CT scan showed a hypermetabolic solid mass with lobulated borders of approximately 29 × 26 mm in the inferior right lobe. We performed a right thoracotomy with inferior lobectomy and lymphadenectomy of levels VII, VIII, X, and XI levels. The neoplasm was constituted by cords of small cells with small round nucleus and scarce cytoplasm immerse in an abundant myxoid matrix. The immunophenotype was positive for MUM-1, CDK4, MDM2, and showed focal expression for S-100 protein and CD56. The final pathology report revealed a pulmonary extraskeletal mixoid chondrosarcoma. No further surgical interventions or adjuvant therapies were needed.

Conclusion

EMC is an intermediate-grade neoplasm, characterized by a long clinical course with high potential for local recurrence and distant metastasis. Treatment for EMC is surgical and non-surgical treatment is reserved for recurrence or metastatic disease. Pulmonary extraskeletal myxoid chondrosarcoma is a rare neoplasm with only isolated case reports found in the literature.

Results of sub-analysis of a phase 2 study on trabectedin treatment for extraskeletal myxoid chondrosarcoma and mesenchymal chondrosarcoma

Background

Trabectedin is reported to be particularly effective against translocation-related sarcoma. Recently, a randomized phase 2 study in patients with translocation-related sarcomas unresponsive or intolerable to standard chemotherapy was conducted, which showed clinical benefit of trabectedin compared with best supportive care (BSC). Extraskeletal myxoid chondrosarcoma (EMCS) and Mesenchymal chondrosarcoma (MCS) are very rare malignant soft tissue sarcomas, and are associated with translocations resulting in fusion genes. In addition, the previous in vivo data showed that trabectedin affect tumor necrosis and reduction in vascularization in a xenograft model of a human high-grade chondrosarcoma. The aim of the present analysis was to clarify the efficacy of trabectedin for EMCS and MCS subjects in the randomized phase 2 study.

Methods

Five subjects with EMCS and MCS received trabectedin treatment in the randomized phase 2 study. Three MCS subjects were allocated to the BSC group. Objective response and progression-free survival (PFS) were assessed according to the Response Evaluation Criteria in Solid Tumors (RECIST) version 1.1 by central radiology imaging review.

Results

The median follow-up time of the randomized phase 2 study was 22.7 months, and one subject with MCS was still receiving trabectedin treatment at the final data cutoff. The median PFS was 12.5 months (95 % CI: 7.4–not reached) in the trabectedin group, while 1.0 months (95 % CI: 0.3–1.0 months) in MCS subjects of the BSC group. The six-month progression-free rate was 100 % in the trabectedin group. One subject with MCS showed partial response, and the others in the trabectedin group showed stable disease. Overall survival of EMCS and MCS subjects was 26.4 months (range, 10.4–26.4 months) in the trabectedin group. At the final data cutoff, two of five subjects were still alive.

Conclusions

This sub-analysis shows that trabectedin is effective for patients with EMCS and MCS compared with BSC. The efficacy results were better than previously reported data of TRS. These facts suggest that trabectedin become an important choice of treatment for patients with advanced EMCS or MCS who failed or were intolerable to standard chemotherapy.

Trial registration

The randomized phase 2 study is registered with the Japan Pharmaceutical Information Center, number JapicCTI-121850 (May 31, 2012).

Clinicopathologic and radiologic features of extraskeletal myxoid chondrosarcoma: a retrospective study of 40 Chinese cases with literature review

The aim of this study is to describe the clinicopathologic and radiologic features of 40 cases of extraskeletal myxoid chondrosarcoma (EMC) from China. There were 25 males and 15 females (sex ratio, 1.7:1). Apart from an adolescent, all patients were adults with a median age of 49years. Twenty-four tumors (60%) occurred in the lower limb and limb girdles, especially the thigh, followed by the upper limb and limb girdles (20%) and trunk (10%). Other less commonly involved locations included the head and neck, sacrococcygeal region, and perineum. Tumors ranged in size from 1.5 to 19cm (mean, 7cm). By radiology, they appeared as hypoattenuated or isoattenuated masses on computed tomography with hyperintense signal on T2-weighted magnetic resonance imaging. Intralesional hypointense septa were present in most cases. Of the 40 tumors, 30 belonged to the classic subtype, whereas 9 cases were cellular, and 1 case had a rhabdoid phenotype. Tumor cells showed variable expression of synaptophysin (36%), S-100 protein (29%), epithelial membrane antigen (11%), and neuron-specific enolase (7%). Ki-67 index was remarkably higher in the cellular variant (mean, 30%). EWSR1-related rearrangement was detected in 12 of 14 cases tested by fluorescence in situ hybridization using break-apart probes. The overall 5- and 7-year survival was 71% and 60%, respectively. Awareness of the imaging features may help pathologists in the diagnosis of EMC. Fluorescence in situ hybridization also serves as a useful diagnostic tool for EMC, especially in the distinction from its mimics.

Extraskeletal Myxoid Chondrosarcoma Presenting as a Plantar Fibroma: Case Report and Review of the Literature

BACKGROUND

Extraskeletal myxoid chondrosarcoma is a rare tumor with an indolent course, high propensity for local recurrence, metastases, and propensity for the proximal extremities of middle-aged males.

CASE REPORT

We present the case of a 44-year-old man with an extraskeletal myxoid chondrosarcoma in the plantar fascia of the medial arch initially thought to be a plantar fibroma. Magnetic resonance imaging of the lesion demonstrated a lobulated subcutaneous mass plantar to the tarsal bones and inseparable from the fascia. Microscopic examination revealed a lobulated lesion composed of cords and nests of round to spindled malignant cells in a blue-gray myxoid matrix surrounded by fibrous septae. The malignant cells displayed variable positivity for S-100.

CONCLUSION

Plantar extraskeletal myxoid chondrosarcoma is a rare occurrence. It should always be considered in the differential diagnosis of masses arising in the plantar fascia of the foot.

[Myxoid tumors of deep soft tissues]

Myxoid soft tissue tumors form a heterogeneous group. Their biological potential encompasses the whole spectrum from benign to highly malignant. The present article focuses on myxoid tumors of the deep soft tissues: myxofibrosarcoma, low-grade fibromyxoid sarcoma, myxoma, myxoid liposarcoma, extraskeletal myxoid chondrosarcoma and nodular fasciitis. The last two decades have brought into practice multiple powerful tools that support pathologists in making precise diagnoses, even on small incisional biopsies: detection of fusion transcripts by rt-PCR, detection of chromosomal fusion or breakpoint by FISH, detection of point mutations by PCR and expression of specific markers by immunohistochemistry. Conventional morphology remains the mainstay of diagnosis, and it is essential to obtain adequate clinical and radiological information before interpreting small incisional biopsies. The present article is a summary of morphologic features used to diagnose the most common tumors of the deep soft tissues.

Activity of sunitinib in extraskeletal myxoid chondrosarcoma

BACKGROUND

Extraskeletal myxoid chondrosarcoma (EMC) is a rare soft tissue sarcoma, marked by NR4A3 rearrangement. Herein we report on the activity of sunitinib in a series of 10 patients, strengthening what initially observed in two cases.

PATIENTS AND METHODS

From July 2011, 10 patients with progressive metastatic translocated EMC have been consecutively treated with sunitinib 37.5mg/day, on a named-use basis. In an attempt to interpret the activity of sunitinib in EMC, genotype/phenotype correlations were carried out by fluorescence in situ hybridization (FISH) analyses. Moreover, transcriptome, immunohistochemical and biochemical analyses of a limited set of samples were performed focusing on some putative targets of sunitinib.

RESULTS

Eight of 10 patients are still on therapy. Six patients had a Response Evaluation Criteria in Solid Tumours (RECIST) partial response (PR), two were stable, two progressed. Positron emission tomography (PET) was consistent in 6/6 evaluable cases. One patient underwent surgery after sunitinib, with evidence of a pathologic response. At a median follow-up of 8.5 months (range 2-28), no secondary resistance was detected. Median progression free survival (PFS) has not been reached. Interestingly, all responsive cases turned out to express the typical EWSR1-NR4A3 fusion, while refractory cases carried the alternative TAF15-NR4A3 fusion. Among putative sunitinib targets, only RET was expressed and activated in analysed samples.

CONCLUSIONS

This report confirms the therapeutic activity of sunitinib in EMC. Genotype/phenotype analyses support a correlation between response and EWSR1-NR4A3 fusion. Involvement of RET deserves further investigation.

Extraskeletal myxoid chondrosarcoma with non-EWSR1-NR4A3 variant fusions correlate with rhabdoid phenotype and high-grade morphology

Extraskeletal myxoid chondrosarcomas (EMC) are rare soft tissue sarcomas with distinctive histology and uncertain histogenesis, characterized by Ewing sarcoma breakpoint region 1-nuclear receptor subfamily 4, group A, member 3 (EWSR1-NR4A3) fusion in 75% of the cases. A smaller proportion of cases show NR4A3 fused to other gene partners including TATA binding protein-associated factor 15 (TAF15), transcription factor 12 (TCF12), and TRK-fused gene (TFG). The impact of various gene fusions on morphology and outcome has not been previously evaluated. We investigated 26 consecutive EMCs and correlated the genetic findings with morphology and clinical outcome. There were 5 females and 21 males (median age, 49.5 years). Mean size of the tumors was 11 cm. Fluorescence in situ hybridization analysis showed EWSR1-NR4A3 gene fusion in 16 cases (62%), TAF15-NR4A3 gene fusion in 7 cases (27%), and TCF12-NR4A3 gene fusion in 1 case (4%). Two cases showed only NR4A3 gene rearrangements. Morphologically, most EWSR1-rearranged tumors (10/16) showed low cellularity, minimal cytologic atypia, and low mitotic counts. In contrast, 80% of EMCs with variant (non-EWSR1) NR4A3 gene fusions (TAF15, TCF12) had high-grade morphology with increased cellularity, proliferation, and cytologic atypia, showing a plasmacytoid/rhabdoid morphology in half the cases. Follow-up showed that only 1 of 16 patients with EWSR1-rearranged tumors died of disease, in contrast to 3 (43%) of 7 TAF15-rearranged tumors. In conclusion, EMCs with variant NR4A3 gene fusions show a higher incidence of rhabdoid phenotype, high-grade morphology, and a more aggressive outcome compared with the EWSR1-NR4A3 positive tumors. Furthermore, fluorescence in situ hybridization assay for NR4A3, along with EWSR1, may be an additional ancillary test to confirm diagnosis of EMCs.

A case of highly aggressive extraskeletal myxoid chondrosarcoma

Extraskeletal myxoid chondrosarcoma (EMC) is a soft tissue malignancy characterized by specific chromosomal abnormalities involving the TEC gene. This disease has historically been considered largely indolent both histologically and clinically. Rarer subsets of EMC exist that demonstrate aggressive histopathologic features and clinical behavior, though it remains unclear whether or not aggressive histopathology is predictive of outcome. Herein we present a case of EMC with aggressive histopathologic features that underwent rapid clinical progression despite initial treatment with curative intent. This case provides the context for a discussion of the existing literature regarding treatment, prognosis, pathology, and genetic/molecular features of EMC in general and aggressive EMC specifically.