Myxoid chondrosarcoma with a translocation involving chromosomes 9 and 22

Clinical, imaging and pathological features of extraskeletal myxoid chondrosarcoma

OBJECTIVE

To evaluate clinical and radiological features of extraskeletal myxoid chondrosarcomas (EMC).

MATERIAL AND METHODS

Our pathology database was queried for cases of EMCs. Tumor location, size, imaging appearance, presence of metastases, disease recurrence, and clinical outcome were documented. Imaging studies were evaluated in consensus by a musculoskeletal radiologist and an orthopedic oncologist.

RESULTS

Thirty subjects met the inclusion criteria (mean age 52.7 ± 16.2 years; 19 male, 11 female), 17 (56.7%) of which had pre-operative imaging. Tumors occurred most often in the lower extremities (20/30; 66.7%). All cases presented as a soft-tissue mass without mineralization on XR or CT. On MRI, tumors were typically hyperintense on T2-weighted sequences (14/14; 100%) and had a chondroid matrix appearance (12/14; 85.7%). Tumor invasion was observed in 11 out of 16 (68.9%) patients and necrosis in 2 out of 11 subjects (18.2%). All subjects had their tumors examined by pathology, and 20 (66.7%) subjects also had descriptive information in addition to the diagnosis (tumor invasion, mitotic rate, and necrosis) noted in the pathology reports. The mean duration of follow-up was 9.4 ± 7.5 (1.0 - 29.6) years. At the last follow-up, 14 out of 28 (50%) subjects were disease-free, 6 out of 28 had persistent metastatic disease and 8 out of 28 had died.

CONCLUSIONS

EMC is a rare sarcoma that commonly presents as lower extremity soft tissue mass with chondroid appearance on MRI. Unlike conventional chondrosarcomas, EMC do not demonstrate mineralization on XR or CT.

Whole genome sequencing for metastatic mutational burden in extraskeletal myxoid chondrosarcoma

Extraskeletal myxoid chondrosarcoma (EMC) is an ultra-rare cancer that makes up less than 3% of all soft tissue sarcomas. It most often arises in the soft tissues of the proximal limbs and has a higher incidence in males. Though EMC has a good prognosis, it has an indolent course with high rates of local recurrence as well as metastasis to the lungs. EMC is characterized in 70% of cases by an EWS1-NR4A3 translocation, leading to constitutive expression of NR4A3. Structural variants (SVs) in EMC, especially large-scale genomic alterations, have not been well studied and studies are severely limited by sample size. In this study, we describe Whole Genome Sequencing (WGS) of a rare case of matched EMC primary tumor, lung metastasis, and pelvic metastasis to identify genomic alterations. We examined somatic variants, copy number variants (CNVs), and larger scale SVs such as translocations and breakend points. While the primary tumor and lung metastasis had similar somatic variations and CNVs, the pelvic metastasis had more unique SVs with especially increased mutational burden of SVs in chromosome 2. This suggests that different molecular drivers appear in more advanced, relapsing EMC compared with the primary tumor and early lung metastasis. Genomic studies such as ours may identify novel molecular complexities in rare cancers that may be leveraged for therapeutic strategies and precision medicine.

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.

Extraskeletal Myxoid Chondrosarcoma of the Vulva: A Case Report

Extraskeletal myxoid chondrosarcoma (EMC) of the vulva is extremely rare. We report our experience with a case of disease control by radiation therapy to a localized lesion of EMC. A 41-year-old woman presented to our clinic with a vulvar mass. Magnetic resonance imaging showed a 15 cm mass between the perineum and the medial thigh muscle. It was the "adductor magnus muscle." After the needle biopsy, a histopathological diagnosis of EMC was made. Tissue genomic analysis detected the EWSR1-NR4A3 fusion gene. A joint operation by the Department of Orthopedics, Gynecology, and Plastic Surgery was performed, which included a wide excision of the perineum, partial excision of the medial thigh muscle, and rectus abdominis valvuloplasty. Intraoperatively, pubic infiltration was detected. Postoperative pelvic radiotherapy was administered as adjuvant therapy. Recurrent common iliac lymph node metastases outside the irradiation field and multiple lung metastases were observed. Pazopanib was administered as adjuvant therapy. Pulmonary metastases were controlled, but the pelvic tumor had spread, so the patient underwent radiation therapy. After second-line chemotherapy with doxorubicin, left pleural effusion and mediastinal lymph node metastasis appeared, and third-line chemotherapy with eribulin mesylate was administered. The pleural effusion improved, but the patient developed cough again, and trabectedin was administered as the fourth chemotherapy. In this case, there was no local recurrence for three years after radiotherapy, suggesting the effectiveness of radiotherapy in local control.

Genomic Profiling of Sarcomas: A Promising Weapon in the Therapeutic Arsenal

Sarcomas are rare malignant mesenchymal neoplasms, and the knowledge of tumor biology and genomics is scarce. Chemotherapy is the standard of care in advanced disease, with poor outcomes. Identifying actionable genomic alterations may offer effective salvage therapeutic options when previous lines have failed. Here, we report a retrospective cohort study of sarcoma patients followed at our center and submitted to comprehensive genomic profiling between January 2020 and June 2021. Thirty patients were included, most (96.7%) with reportable genomic alterations. The most common alterations were linked to cell cycle regulation (TP53, CDKN2A/B, and RB1 deletions and CDK4, MDM2, and MYC amplifications). Most patients (96.7%) had microsatellite stability and low tumor mutational burden (≤10 muts/megabase (Mb); median 2 Muts/Mb). Two-thirds of patients had actionable mutations for targeted treatments, including five cases with alterations amenable to targeted therapies with clinical benefit within the patient's tumor type, ten cases with targetable alterations with clinical benefit in other tumor types, and five cases with alterations amenable to targeting with drugs under investigation in a clinical trial setting. A significant proportion of cases in this study had actionable genomic alterations with available targeted drugs. Next-generation sequencing is a feasible option for identifying molecular drivers that can provide therapeutic options for individual patients. Molecular Tumor Boards should be implemented in the clinical practice to discuss genomic findings and inform clinically relevant targeted therapies.

Mutation of KIT in cellular extraskeletal myxoid chondrosarcoma: a case report and literature review

BACKGROUND

Extraskeletal myxoid chondrosarcomas (EMCs) are solid tumors that have been genetically and biologically characterized. Only a few studies have discussed the role of the KIT gene or CD117 expression in EMCs, identified by immunohistochemical (IHC) staining. Herein, we present a novel case of cellular EMC exhibiting an EWSR1-NR4A3 fusion, KIT exon 13 mutations and strong diffuse expression of CD117.

CASE PRESENTATION

A 69-year-old man presented with a fist-sized tumor on his left shoulder. CT revealed a tumor in the left thoracic and dorsal muscle space. The tumor was completely resected. Histologically, the tumor cells had a nodular structure and infiltrated the peripheral fat and muscle tissues. The tumor cells were uniform in size with round nuclei, well-defined nucleoli and eosinophilic cytoplasm. Immunohistochemically, the tumor cells were positive for CD117, vimentin, CD56 and NSE and focally expressed desmin; the cells were negative for myogenin, S-100, SYN, INSM1, CD34, STAT6, INI-1, Brachyury, ERG, TLE1, AE1/AE3, WT-1, CD99 and SMA. NGS revealed an EWSR1-NR4A3 fusion and KIT exon 13 mutations. The patient had no further treatment after surgery, and no recurrence or metastasis occurred during the ~ 10 month follow-up period.

CONCLUSIONS

Molecular detection is an indispensable technique for diagnosing cellular EMCs. The KIT mutations noted in this case report may offer fresh insights into EMCs treatment options.

EWSR1-The Most Common Rearranged Gene in Soft Tissue Lesions, Which Also Occurs in Different Bone Lesions: An Updated Review

EWSR1 belongs to the FET family of RNA-binding proteins including also Fused in Sarcoma (FUS), and TATA-box binding protein Associated Factor 15 (TAF15). As consequence of the multifunctional role of EWSR1 leading to a high frequency of transcription of the chromosomal region where the gene is located, EWSR1 is exposed to aberrations such as rearrangements. Consecutive binding to other genes leads to chimeric proteins inducing oncogenesis. The other TET family members are homologous. With the advent of widely used modern molecular techniques during the last decades, it has become obvious that EWSR1 is involved in the development of diverse benign and malignant tumors with mesenchymal, neuroectodermal, and epithelial/myoepithelial features. As oncogenic transformation mediated by EWSR1-fusion proteins leads to such diverse tumor types, there must be a selection on the multipotent stem cell level. In this review, we will focus on the wide variety of soft tissue and bone entities, including benign and malignant lesions, harboring EWSR1 rearrangement. Fusion gene analysis is the diagnostic gold standard in most of these tumors. We present clinicopathologic, immunohistochemical, and molecular features and discuss differential diagnoses.

Extraskeletal Myxoid Chondrosarcoma: State of the Art and Current Research on Biology and Clinical Management

Simple Summary

The aim of this review is to provide an overview of the biological basis of pathogenesis and current research in extraskeletal myxoid chondrosarcoma (EMC), together with the state of the art of treatment for localized and advanced disease. EMC is an ultra-rare sarcoma sub-type, more often arising from the soft tissues, marked by specific molecular features consisting in rearrangement of the NR4A3 gene, identified in recent years and very useful to distinguish EMC from other mimics. Available pharmacological treatments in particular are discussed, with a focus on the most recent results and future perspectives.

Abstract

Extraskeletal myxoid chondrosarcoma (EMC) is an ultra-rare mesenchymal neoplasm with uncertain differentiation, which arises mostly in the deep soft tissue of proximal extremities and limb girdles. EMC is marked by a translocation involving the NR4A3 gene, which can be fused in-frame with different partners, most often EWSR1 or TAF1. Although EMC biology is still poorly defined, recent studies have started shedding light on the specific contribution of NR4A3 chimeric proteins to EMC pathogenesis and clinical outcome. Standard treatment for localized disease is surgery, plus or minus radiation therapy with an expected prolonged survival even though the risk of relapse is about 50%. In advanced cases, besides the standard chemotherapy currently used for soft tissue sarcoma, antiangiogenic agents have recently shown promising activity. The aim of this review is to provide the state of the art of treatment for localized and advanced disease, with a focus on pharmacological treatments available for EMC. The biological basis of current research and future perspectives will be also discussed.

Identification of an Actionable Mutation of KIT in a Case of Extraskeletal Myxoid Chondrosarcoma

Extraskeletal myxoid chondrosarcoma (EMC) is an extremely rare soft tissue sarcoma, marked by a translocation involving the NR4A3 gene. EMC is usually indolent and moderately sensitive to anthracycline-based chemotherapy. Recently, we reported on the therapeutic activity of sunitinib in a series of EMC cases, however the molecular target of sunitinib in EMC is unknown. Moreover, there is still the need to identify alternative therapeutic strategies. To better characterize this disease, we performed whole transcriptome sequencing in five EMC cases. Peculiarly, in one sample, an in-frame deletion (c.1735_1737delGAT p.D579del) was identified in exon 11 of KIT. The deletion was somatic and heterozygous and was validated both at DNA and mRNA level. This sample showed a marked high expression of KIT at the mRNA level and a mild phosphorylation of the receptor. Sanger sequencing of KIT in additional 15 Formalin Fixed Paraffin Embedded (FFPE) EMC did not show any other mutated cases. In conclusion, exon 11 KIT mutation was detected only in one out of 20 EMC cases analyzed, indicating that KIT alteration is not a recurrent event in these tumors and cannot explain the EMC sensitivity to sunitinib, although it is an actionable mutation in the individual case in which it has been identified.

Extraskeletal Myxoid Chondrosarcoma of the Foot Clinically Mimicking Plantar Fibromatosis

Extraskeletal myxoid chondrosarcoma (EMC) is a rare soft tissue sarcoma usually presenting in proximal extremities of middle-aged men. The authors discuss a unique case of EMC, localized in the plantar foot of a 76-year-old woman, clinically suspected as plantar fibromatosis. It is important to avoid misdiagnosis of EMC because of their propensity for late recurrence and their metastatic potential.

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.

Dedifferentiated Chondrosarcoma

We describe the clinicopathologic and cytogenetic findings of an unusual dedifferentiated chondrosarcoma with a rhabdomyosarcomatous component in a case report and review the relevance of these findings with respect to seven previously reported cases. Cytogenetic studies of dedifferentiated chondrosarcoma are limited to 2 previously described cases, both with dedifferentiated components distinct from this case. In this study, cytogenetic analysis of 3 separate specimens, biopsy with chondrosarcoma, definitive surgical, and lung metastasis with rhabdomyosarcomatous component, revealed clonal karyotypic aberrations in each. A structural abnormality involving the short arm of chromosome 17 and extra copies of chromosomes 5, 7, 12, and 20 were common to all three specimens. These findings reveal multiple shared chromosomal anomalies between the primary chondrosarcoma and the dedifferentiated components, which suggests a clonal evolution. Int J Surg Pathol 2(4):319-328, 1995

Extraskeletal myxoid chondrosarcoma presenting as an intradural spinal mass: report of a rare clinical presentation with an emphasis on differential diagnostic considerations

Extraskeletal myxoid chondrosarcoma is a rare soft tissue neoplasm that occurs predominantly in the soft tissues of the lower extremities. Herein we present a case of a 29 year old male who presented with bilateral femoral numbness believed to be the result of prior injury to his back. A magnetic resonance imaging revealed a mass in the T4-T5 epidural space compressing the spinal cord. Laminectomy was performed and the lesion removed piecemeal. The pathology specimen consisted of multiple fragments of dura involved by a myxoid neoplasm with a nodular growth pattern. The tumor cells were arranged in anastomosing cords and strands. Individual tumor cells were small, of uniform size and shape, with small hyperchromatic nuclei and scant eosinophilic cytoplasm. Immunohistochemical stains were performed which showed the tumor cells were diffusely positive for vimentin and focally positive for EMA, S-100 protein and cytokeratin, whereas they were negative for CD34 and CD99. Fluorescence in situ hybridization (FISH) studies showed a clonal population of cells with re-arrangement of the EWSR1 locus, confirming the histologic impression of extraskeletal myxoid chondrosarcoma. This is the first report of a case of an extraskeletal myxoid chondrosarcoma arising from the dura, confirmed to have rearrangement of the EWSR1 gene by FISH. There have only been two other cases of dural based extraskeletal myxoid chondrosarcoma reported prior to our case. We also briefly review the published literature and discuss differential diagnostic considerations for this rare tumor.

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.

Anthracycline-based chemotherapy in extraskeletal myxoid chondrosarcoma: a retrospective study

BACKGROUND

Extraskeletal myxoid chondrosarcoma (EMC) is a rare subgroup within soft tissue sarcomas. Its sensitivity to chemotherapy is reported to be low.

METHODS

We retrospectively reviewed a series of 11 EMC patients treated as from 2001 within the Italian Rare Cancer Network (RCN) with anthracycline-based chemotherapy. Pathologic diagnosis was centrally reviewed in all cases and confirmed by the presence of the specific chromosomal rearrangements, involving the NR4A3 gene locus on chromosome 9.

RESULTS

Eleven patients treated with anthracycline-based chemotherapy were included (M/F: 9/2 - mean age: 52 years - site of primary: lower limb/other = 9/2 - metastatic = 11 - front line/ further line = 10/1 - anthracycline as single agent/ combined with ifosfamide = 1/10). Ten patients are evaluable for response. Overall, best response according to RECIST was: partial response (PR) = 4 (40 %), stable disease (SD) = 3, progressive disease (PD) = 3 cases. Median PFS was 8 (range 2-10) months.

CONCLUSIONS

By contrast to what reported so far, anthracycline-based chemotherapy is active in a distinct proportion of EMC patients.

Extraskeletal myxoid chondrosarcoma of the thigh with a t(9;17) translocation

Extraskeletal myxoid chondrosarcomas (EMC) are relatively rare. We report a case of EMC of the thigh. A 41-year-old man presented with a tumor history of more than 4 months. Following open biopsy, wide resection of the tumor was performed. Histopathologically, the tumor had a multinodular architecture consisting of myxomatous areas demarcated by fibrous septa. Proliferation of uniform, round tumor cells with oval nuclei was observed. Well-formed hyaline cartilage and rhabdoid-like cells were not visible. Immunohistochemically, the tumor cells were positive for vimentin and S-100. The composite karyotype was 46,XY,t(9;17)(q22;q11),t(9;21)(q21;p13), and the diagnosis of EMC was made. No recurrence of the mass or metastasis was observed during a follow-up period of 4 years and 7 months. Only 50 cytogenetic cases of EMC, including our case, have been reported in the English literature thus far. Clinical presentation, radiological features and histopathological and cytogenetic findings are described, and the relevant literature is reviewed.

Distinguishing chordoid meningiomas from their histologic mimics: an immunohistochemical evaluation

Chordoid meningioma, World Health Organization grade II, is an uncommon variant of meningioma with a propensity for aggressive behavior and increased likelihood of recurrence. As such, recognition of this entity is important in cases that show similar morphologic overlap with other chondroid/myxoid neoplasms that can arise within or near the central nervous system. A formal comparison of the immunohistochemical features of chordoid meningioma versus tumors with significant histologic overlap has not been previously reported. In this study, immunohistochemical staining was performed with antibodies against D2-40, S100, pankeratin, epithelial membrane antigen (EMA), brachyury, and glial fibrillary acidic protein (GFAP) in 4 cases of chordoid glioma, 6 skeletal myxoid chondrosarcomas, 10 chordoid meningiomas, 16 extraskeletal myxoid chondrosarcoma, 18 chordomas, 22 low-grade chondrosarcomas, and 27 enchondromas. Staining extent and intensity were evaluated semiquantitatively and mean values for each parameter were calculated. Immunostaining with D2-40 showed positivity in 100% of skeletal myxoid chondrosarcomas, 96% of enchondromas, 95% of low-grade chondrosarcomas, 80% of chordoid meningiomas, and 75% of chordoid gliomas. Staining with S100 demonstrated diffuse, strong positivity in all (100%) chordoid gliomas, skeletal myxoid chondrosarcomas, low-grade chondrosarcomas, and enchondromas, 94% of chordomas, and 81% of extraskeletal myxoid chondrosarcomas, with focal, moderate staining in 40% of chordoid meningiomas. Pankeratin highlighted 100% of chordoid gliomas and chordomas, 38% of extraskeletal myxoid chondrosarcomas, and 20% of chordoid meningiomas. EMA staining was positive in 100% of chordoid gliomas, 94% of chordomas, 90% of chordoid meningiomas, and 25% of extraskeletal myxoid chondrosarcomas. Brachyury was positive only in the chordomas (100%), whereas GFAP was positive only in the chordoid gliomas (100%). EMA was the most effective antibody for differentiating chordoid meningioma from skeletal myxoid chondrosarcoma, low-grade chondrosarcoma, and enchondroma, whereas D2-40 was the most effective antibody for differentiating chordoid meningioma from extraskeletal myxoid chondrosarcoma and chordoma. Our findings demonstrate that in conjunction with clinical and radiographic findings, immunohistochemical evaluation with a panel of D2-40, EMA, brachyury, and GFAP is most useful in distinguishing chordoid meningioma from chordoid glioma, skeletal myxoid chondrosarcoma, extraskeletal myxoid chondrosarcoma, chordoma, low-grade chondrosarcoma, and enchondroma. A lack of strong, diffuse S100 reactivity may also be useful in excluding chordoid meningioma. Among the neoplasms evaluated, brachyury and GFAP proved to be both sensitive and specific markers for chordoma and chordoid glioma, respectively. Of note, this study is the first to characterize the D2-40 immunoprofile in extraskeletal myxoid chondrosarcoma, results that could be of utility in differential diagnostic assessment.

The utility of fluorescence in situ hybridization (FISH) in the diagnosis of myxoid soft tissue neoplasms

Diagnosing myxoid soft tissue neoplasms can be challenging because of overlapping histologic features. Distinct chromosomal translocations have been identified in several myxoid sarcomas, including t(12;16)(q13;p11) FUS-DDIT3 in myxoid liposarcoma, t(7;16)(q34;p11) FUS-CREB3L2 in low-grade fibromyxoid sarcoma, and t(9;22)(q31;q12) EWSR1-NR4A3 in extraskeletal myxoid chondrosarcoma. These recurrent chromosomal alterations are attractive targets for diagnostic studies. To that end, dual-color, break-apart fluorescence in situ hybridization (FISH) probes spanning the genomic regions of EWSR1 (22q12), DDIT3 (12q13), and FUS (16p11) (Vysis, Downer's Grove, IL) were evaluated in formalin-fixed, paraffin-embedded tissues from myxoid neoplasms, including intramuscular myxoma (n=10), myxoid liposarcoma (n=18), low-grade fibromyxoid sarcoma (n=10), extraskeletal myxoid chondrosarcoma (n=13), and myxofibrosarcoma (n=8). Of the myxoid liposarcomas, 18/18 cases had a rearrangement of the DDIT3 gene, with 17/18 (94.4%) showing both DDIT3 and FUS gene rearrangements. A FUS gene rearrangement was identified in 7/10 (70%) of low-grade fibromyxoid sarcomas, with no changes involving EWSR1 or DDIT3. An EWSR1 translocation was seen in 6/13 (46.2%) of extraskeletal myxoid chondrosarcomas, without changes in DDIT3 or FUS genes. The remaining neoplasms studied showed no rearrangements involving DDIT3, FUS, or EWSR1 genes. In conclusion, interphase FISH using DDIT3 and FUS probes identifies the characteristic translocation in myxoid liposarcoma. FUS and EWSR1 probes are useful in confirming the diagnosis of low-grade fibromyxoid sarcoma and extraskeletal myxoid chondrosarcoma, respectively. The specificity of the probes is documented as none of the non-translocation-associated myxoid tumors showed genomic abnormalities with the probes tested. FISH is capable of providing specific ancillary information useful in this often difficult differential diagnosis.

Chondromyxoid fibroma of rib with a novel chromosomal translocation: a report of four additional cases at unusual sites

BACKGROUND

Chondromyxoid fibromas (CMFs) are rare benign chondroid/myxoid matrix-producing tumors that occur in metaphyses of long tubular bones, and very rarely in small bones of hands and feet. Flat bone involvement is even more uncommon. Prior cytogenetic analyses have identified complex abnormalities involving chromosome 6 in the majority of cases.

METHODS

A search for CMF over an 8-year period (1999-2006) from the surgical pathology files of our institution yielded 16 cases. Four cases occurred in relatively unusual regions, three from the small bones of distal extremities and one from the rib. The rib lesion was submitted for routine cytogenetic analysis.

RESULTS

Radiographic studies revealed that all four lesions were well-defined expansile radiolucent lesions which expanded the bony cortices with lobulated margins, sclerotic rim, septation, and no calcification. Morphologically, all four lesions showed typical features of CMF and had low proliferative index with Ki-67. Cytogenetic analysis on the rib lesion revealed a novel chromosomal translocation, t(1;5)(p13;p13). None of the four patients had a recurrence after a mean duration of follow-up of 24 months.

CONCLUSION

CMF originating in unusual locations should be distinguished from chondrosarcomas, especially on small biopsies, and should be included in the differential diagnosis. As previously noted in the literature, the cells can be positive for actin but unlike conventional chondroid neoplasms can be negative for S-100. To our knowledge, this is the first report describing a novel chromosomal translocation, t(1;5)(p13;p13) in CMF.

Skeletal recurrences and metastases of extraskeletal myxoid chondrosarcoma

OBJECTIVE

The objective was to elucidate clinical and imaging features of skeletal involvement, recurrences, and metastases of extraskeletal myxoid chondrosarcoma.

MATERIALS AND METHODS

Included in this series are 4 patients, aged 44 to 65 years, 3 of whom were men and 1 a woman.

RESULTS

The primary lesions were in the thigh (n = 3) and the upper arm (n = 1). Three patients with multiple metastases died of the disease, 2 were considered to have local recurrence in the adjacent bone. Skeletal metastases occurred after lung metastases in 2 cases, and before lung metastases in 1 case. Typical imaging findings are well-defined lesions with no sclerotic margin or matrix mineralization. A slow, but persistent growth is noted on the imaging features.

CONCLUSION

Although skeletal metastases of chondrosarcoma of bone and soft tissue are rare, myxoid chondrosarcomas, currently classified tumors of uncertain differentiation, rarely metastasize and/or recur in the bones. The imaging features are typically of a localized lesion with cortical disruption or expansion.

Extraskeletal myxoid chondrosarcoma: updated clinicopathological and molecular genetic characteristics

Extraskeletal myxoid chondrosarcoma (EMC) is a rare soft-tissue sarcoma characterized by distinctive morphological and cytogenetical features. As its name implies, EMC was believed to represent a variant of soft-tissue chondrosarcoma owing to its histological resemblance to chondroblastic tissue in the early stages of cartilage development or chondroid tumors such as skeletal chondrosarcoma. However, the chondroid nature has been a subject of controversy, and its line of differentiation remains to be determined. Consequently, the tumor is provisionally classified into a group of tumors of uncertain differentiation in the revised World Health Organization classification of tumors of soft tissue and bone. Moreover, immunohistochemical and ultrastructural features of neural or neuroendocrine differentiation have been recently reported in a subset of EMC, providing a new insight into their histogenetic nature. Chromosomal rearrangements involving 9q22, such as t(9;22)(q22;q12), and resultant NR4A3 fusion genes are tumor-type specific or pathognomotic for this entity and are assumed to play an important role in the development of EMC. Although the biological mechanisms and functions are largely unknown, the NR4A3-related pathway is considered a potential molecular target for future therapeutic intervention. Because of its protracted but resilient nature, a tenacious and long-term follow up is necessary for any patient.

Genetics of chondrosarcoma and related tumors

PURPOSE OF REVIEW

The burgeoning body of information on the genetic changes present in and underlying the development and biology of human cancers has carried implications regarding the possible genetic events that are responsible for not only the genesis of these cancers but also the hope of the cure for these cancers. Chondrosarcomas are a group of tumors that fall into this category. The purpose of this review is to summarize the genetic findings in these tumors.

RECENT FINDINGS

The histopathologic variability of chondrosarcomas is reflected in the complexity and lack of specificity of their cytogenetic and molecular genetic findings, except for extraskeletal myxoid chondrosarcomas. These are characterized in the preponderant number of cases by a translocation, t(9;22)(q22;q12), and in a small number of cases by variant translocations t(9;17)(q22;q11) and t(9;15)(q22;q21). These translocations lead to the formation of abnormal fusion genes and gene products (proteins). In each of these translocations, the CHN gene is involved, resulting in the chimeric fusion genes EWS/CHN, RBP56/CHN, and TCF12/CHN, respectively. The specific translocations and their associated molecular genetic changes are diagnostic of extraskeletal myxoid chondrosarcomas. The abnormal proteins resulting from these fusion genes aberrantly affect gene transcription and cellular signaling pathways thought to be responsible for initiating sarcoma formation. In skeletal (central) chondrosarcomas of varying histopathologic types, the cytogenetic and molecular genetic findings are variable, complex, and apparently lacking in specificity. These changes may reflect a stepwise process (or processes) of oncogenesis involving an array of genes.

SUMMARY

Although some cartilaginous tumors are characterized by specific or recurrent chromosome alterations and molecular genetic changes, much is yet to be learned about the nature and sequence of these genetics events and about their unique role in the stepwise process involved in the development and biology of each tumor type, both malignant and nonmalignant. Until such time, some of the genetic changes, particularly the presence of specific translocations, can be of definite diagnostic value.

Studies on the molecular pathogenesis of extraskeletal myxoid chondrosarcoma-cytogenetic, molecular genetic, and cDNA microarray analyses

Extraskeletal myxoid chondrosarcomas (EMCs) are characterized by recurrent chromosome translocations resulting in fusions of the nuclear receptor TEC to various NH(2)-terminal partners. Here we describe the phenotypic, cytogenetic, and molecular genetic characteristics of a series of 10 EMCs. Using spectral karyotyping and fluorescence in situ hybridization, clonal chromosome abnormalities were detected in all but one tumor. A t(9;22)(q22;q12) translocation was found in three cases; a del(22)(q12-13)in one case; and variant translocations, including t(9;17)(q22;q11-12), t(7;9;17)(q32;q22;q11), and t(9;15)(q22;q21), were detected in one case each. Recurrent, secondary abnormalities, including trisomy 1q, 7, 8, 12, and 19, were found in seven tumors. All tumors contained translocation-generated or cryptic gene fusions, including EWS-TEC (five cases, of which one was a novel fusion), TAF2N-TEC (four cases), and TCF12-TEC (one case). cDNA microarray analysis of the gene expression patterns of two EMCs and a myxoid liposarcoma reference tumor revealed a remarkably distinct and uniform expression profile in both EMCs despite the fact that they had different histologies and expressed different fusion transcripts. The most differentially expressed gene in both tumors was CHI3L1, which encodes a secreted glycoprotein (YKL-40) previously implicated in various pathological conditions of extracellular matrix degradation as well as in cancer. Our findings suggests that EMC exhibits a tumor-specific gene expression profile, including overexpression of several cancer-related genes as well as genes implicated in chondrogenesis and neural-neuroendocrine differentiation, thus distinguishing it from other soft tissue sarcomas.

Translocation der(13;21)(q10;q10) in skeletal and extraskeletal mesenchymal chondrosarcoma

Cytogenetic studies of mesenchymal chondrosarcoma are few and to date, no specific or recurrent aberrations have been found. In this investigation, the cytogenetic and molecular cytogenetic (spectral karyotypic and fluorescence in situ hybridization) findings for two mesenchymal chondrosarcomas, one arising skeletally and the other extraskeletally, are reported. An identical Robertsonian translocation involving chromosomes 13 and 21 [der(13;21)(q10;q10)] was detected in both cases, possibly representing a characteristic rearrangement for this histopathologic entity. Both cases also exhibited loss of all or a portion of chromosomes 8 and 20 and gain of all or a portion of chromosome 12. The observation of similar chromosomal abnormalities in both skeletal and extraskeletal mesenchymal chondrosarcoma supports a genetic as well as histopathologic relationship between these anatomically distinct neoplasms.

Novel translocation (9;12)(q22;q24) in secondary chondrosarcoma arising from hereditary multiple exostosis

We report a new translocation in a patient with a history of hereditary multiple exostosis (HME) who developed a recurrent grade I chondrosarcoma involving the sacrum and retroperitoneum. Karyotypic analysis of the tumor revealed a sole chromosome abnormality t(9;12)(q22;q24.3). To our knowledge, this translocation has not been previously identified in either chondrosarcoma, HME, or related tumor types. Our novel translocation may be related to the sarcomatous degeneration of the pre-existing exostosis.

Extraskeletal myxoid chondrosarcoma: a clinicopathologic, immunohistochemical, and molecular analysis of 18 cases

Extraskeletal myxoid chondrosarcoma (EMCS) is an uncommon clinicopathologically well-defined tumor, but its pathogenesis and biologic behavior are poorly understood. We reviewed 18 cases of EMCS to verify clinicopathologic features and immunohistochemical profiles together with molecular detection of the tumor-specific fusion genes. The tumors were located mainly in the proximal extremities and limb girdles (72%). Two tumors arose at unusual anatomic sites: the finger and the hip joint. Nine of the 17 followed-up patients were alive and disease free, 4 were alive with recurrences and/or metastases, and 4 died of the tumor. Fifteen tumors showed typical features of EMCS, and 3 had hypercellular areas in addition to conventional EMCS areas. The tumors were variably immunoreactive for S-100 protein (50%), NSE (89%), peripherin (60%), and synaptophysin (22%). Chromogranin A and some epithelial markers (AE1/AE3, CAM5.2, and epithelial membrane antigen) were entirely negative. Frequent expressions of the neural/neuroendocrine markers suggest possible neural/neuroendocrine differentiation in at least some EMCSs, in addition to chondroid differentiation. In a reverse-transcription polymerase chain reaction (RT-PCR) assay using paraffin-embedded specimens, EWS-CHN or TAF2N-CHN fusion gene transcripts characteristic of EMCS could be detected in 15 (83%) of the 18 cases: EWS-CHN type 1 in 11 cases, EWS-CHN type 2 in 1, and TAF2N-CHN in 3. Three fusion-negative cases included 2 conventional EMCSs and 1 considered a "cellular" variant of the tumor. None of 30 other soft tissue and bone tumors with myxoid or chondroid morphology that we examined contained these fusion genes. Thus, RT-PCR detection of EWS-CHN or TAF2N-CHN fusion gene using archival paraffin-embedded tissue is a feasible and useful ancillary technique for the diagnosis of EMCS.

Chondroblastoma-like chondroma of soft tissue: an underrecognized variant and its differential diagnosis

Soft-tissue chondromas are usually composed entirely of mature hyaline cartilage. Infrequently, however, they may exhibit morphologic features that result in diagnostic difficulty. The authors report a series of eight hypercellular soft-tissue chondromas composed of enlarged chondrocytes within a variable amount of chondroid matrix that often demonstrated delicate calcifications and contained numerous osteoclast-like multinucleated giant cells. This histologic appearance closely resembles that of chondroblastoma of bone. However, its extraosseous location, dense cellularity, and poorly formed cartilage can cause confusion with more aggressive chondroid neoplasms of soft tissue. The clinicopathologic features of these chondroblastoma-like chondromas are discussed, emphasizing the characteristics that facilitate their accurate identification.

The cytogenetic and molecular characterization of benign and malignant soft tissue tumors

Cytogenetic analyses of benign and malignant soft tissue tumors have led to the description of recurrent, specific, and even pathognomonic chromosomal translocations and/or other rearrangements in most types of soft tissue tumors. The consistent karyotypic rearrangements have provided critical diagnostic information in this group of neoplasms that often presents significant diagnostic challenges to the clinician and the pathologist. These findings have also been instrumental in the characterization of the abnormalities at the molecular level. Novel genes have been isolated from the translocation junctions and the mechanisms of their deregulation identified. This has increased our understanding of the histogenesis of these tumors, paved the way for the molecular diagnosis of many sarcomas, aided in directing therapy, and also provided important prognostic information.

Extraskeletal myxoid chondrosarcoma: a clinicopathologic, immunohistochemical, and ploidy analysis of 23 cases

Twenty-three cases of extraskeletal myxoid chondrosarcoma, evaluated at the Mayo Clinic between 1968 and 1996, were studied for clinicopathologic features, immunohistochemical profile, Ki-67 activity, and ploidy status to identify adverse prognostic factors. Females and males were equally affected, and the median age at diagnosis was 50 years. The tumors were located mainly in the lower extremities (83%), and the median tumor size was 9.5 cm. Sixteen tumors showed low cellularity (70%), and eight tumors had high mitotic activity (more than two per 10 high-power fields). The tumors were immunoreactive for vimentin (89%), synaptophysin (72%), epithelial membrane antigen (28%), and S-100 protein (17%). Nine tumors were diploid, three aneuploid, and one tetraploid. Mean Ki-67 activity was 11% (range, 1 to 45%). The 10-year overall survival rate was 78%. On univariate analysis, tumor size > or = 10 cm, high cellularity, presence of anaplasia or rhabdoid features, mitotic activity more than two per 10 high-power fields, Ki-67 > or = 10%, and Ki-67 "hot spot" > or = 25% were associated with decreased metastasis-free or overall survival. Ploidy status was not associated with any adverse outcome. The presence of any of these adverse prognostic factors can indicate the possibility of a more aggressive behavior in extraskeletal myxoid chondrosarcoma, and a closer follow-up is suggested.

Clonal chromosome abnormalities in enchondromas and chondrosarcomas

We report cytogenetic findings in short-term cell cultures from five enchondromas and four chondrosarcomas. Clonal chromosome aberrations were found in one case of enchondroma, and in all cases of chondrosarcoma. The only enchondroma with nonrandom abnormalities had a reciprocal t(8;17)(q23;p13), and monosomies 9, 19, and/or 22. In contrast to the few karyotypic findings in one of five enchondromas, the four chondrosarcomas were commonly characterized by cytogenetic heterogeneity, with a tendency for increasing karyotypic complexity in higher grade tumors. Two cases, one grade III and one metastasizing grade II chondrosarcoma, revealed hypodiploid stem- and sidelines with loss of chromosomes 6, 10, 13, 14, and 22, as common chromosomal abnormalities, suggesting a distinct karyotypic pattern in a subset of biologically aggressive chondrosarcomas.

Myxoid leiomyosarcoma of soft tissue, an underrecognized variant

Myxoid leiomyosarcoma is an uncommon tumor which, although previously well described in the uterus, is recognized to a lesser extent at other sites. We describe 18 cases of soft tissue leiomyosarcoma in which myxoid stroma occupied >50% of the tissue examined. Patients ranged in age from 22 to 84 years old (median, 57.5 yrs) and female patients outnumbered male patients 14 to 4. Tumor locations included the limbs (6 cases), female external genitalia (4 cases), head and neck region (3 cases), chest (2 cases), nipple, paratesticular soft tissue, and perineum (one case each). The tumors had a grossly gelatinous appearance and adopted three major histologic architectures: fascicular, reticular/microcystic, and "myxofibrosarcoma-like." The tumor cells were predominantly spindled in all cases with typical features of smooth muscle differentiation; there was a mixture of spindle and epithelioid cells in one case. No cases with pure epithelioid cytology were seen. All tumors displayed immunoreactivity for smooth muscle markers (smooth muscle actin 16/17, desmin 8/18) and, in addition, four cases were positive for keratin CAM 5.2 and three for epithelial membrane antigen. The tumors had a tendency to be morphologically lower grade (9 tumors were grade I, 8 were grade II, and only 1 was grade III). Follow up was available in 13 patients with a duration of 8 months to 41 years (median, 39 mos), and revealed local recurrences (often repeated) in five cases and metastases in two cases. There were three tumor-related deaths, of which two were the result of uncontrolled local disease. The differential diagnosis of myxoid leiomyosarcoma is broad and encompasses both benign and malignant lesions. Accurate diagnosis is critical because therapies may differ widely for entities in the differential diagnosis of myxoid leiomyosarcoma.

Skeletal and extraskeletal myxoid chondrosarcoma: a comparative clinicopathologic, ultrastructural, and molecular study

BACKGROUND

Skeletal myxoid chondrosarcoma (SMC) is considered to be either a typical chondrosarcoma with prominent myxoid alterations or an altogether unique malignant cartilage tumor. Extraskeletal myxoid chondrosarcoma (EMC) is a relatively rare but well-recognized neoplasm. It was initially thought to be a low grade sarcoma of cartilage derivation and was recently found, in most cases, to contain a reciprocal t(9;22), resulting in a fusion of the EWS and CHN genes. Are SMC and EMC the same entity arising in two different locations, or are they two separate entities? To the authors' knowledge, this study represents the first systematic attempt to answer this question.

METHODS

Forty consecutive cases of EMC (20 cases) and SMC (20 cases) were compared by light and electron microscopy, immunohistochemistry, and molecular analysis. The mean clinical follow-up for both groups was 55 months. Histologic criteria for SMC consisted of 95% myxoid matrix, with only minimal hyaline cartilage formation.

RESULTS

The gender distribution was identical in both groups (13 males and 7 females). The mean age was 55 years for EMC patients and 45 years for SMC patients. The EMC tumors were predominantly located in the deep soft tissues of the lower extremity (60%) and buttock (20%), and the mean tumor size was 13 cm. SMC was most commonly located in the bones around the hip joint (pelvis 35%; proximal femur 20%) and shoulder (20%); the mean size was 9 cm. Histologic grade in the EMC group correlated with survival (82% of the high grade tumors metastasized). Electron microscopy performed in 8 EMC cases revealed intracisternal microtubules in 3 cases and prominent mitochondria in 5, whereas in 5 SMC cases it revealed only inconspicuous organelles. Molecular analysis for the EWS-CHN fusion RNA resulting from the t(9;22) was performed in 15 cases (9 EMC and 6 SMC) and was detected in 7 of 9 EMC cases and 0 of 6 SMC cases. In one case, the molecular structure of the EWS-CHN fusion RNA was novel. The probability of metastasis was significantly higher (P=0.004) for the EMC group than for the SMC group.

CONCLUSIONS

Although similar light microscopic features are noted in EMC and SMC, fundamental differences are noted at the ultrastructural and molecular levels, suggesting that EMC and SMC represent two distinct entities in the chondrosarcoma family of tumors.

Deletion 1p in a low-grade chondrosarcoma in a patient with Ollier disease

Ollier disease is an uncommon, nonhereditary developmental disorder affecting enchondral ossification. Cytogenetic analysis of low-grade chondrosarcoma in a patient with Ollier disease (multiple enchondromatosis) revealed an interstitial deletion, del(1)(p11p31.2), as the only chromosome abnormality. This is the first cytogenetic study of a chondrosarcoma in a patient with Ollier disease. Such patients are at risk of developing chondrosarcoma and, because del(1p) is frequent in chondrosarcoma, it is suggested that this cytogenetic finding is associated with early chondrosarcomatous transformation.

Allelic loss on chromosome 22q in epithelioid sarcomas

Epithelioid sarcomas are soft tissue tumors with an indolent, but potentially aggressive, clinical behavior. Distinction from other benign and malignant entities may be a diagnostic dilemma. In this study, we evaluate the presence of loss of heterozygosity (LOH) of chromosome 22q in tumor DNA from 13 epithelioid sarcomas, four epithelioid angiosarcomas, and two epithelioid hemangioendotheliomas, and investigate its possible role in diagnosis. LOH was detected in 6 of 10 (60%) of the informative epithelioid sarcomas. No allele loss was detected in the informative vascular tumors, three angiosarcomas, and two hemangioendotheliomas. Chromosome 22q carries the locus of a tumor suppressor gene, the neurofibromatosis 2 (NF2) gene, which has been shown to be lost or mutated in some NF2-related tumors, sporadic meningiomas, and vestibular schwannomas, as well as a few other tumors. Our data suggest that a region of chromosome 22q may be the locus of a tumor suppressor gene involved in the tumorigenesis of these neoplasms. Genetic alterations of yet-unknown tumor suppressor genes in this region, or even the NF2 tumor suppressor gene, may play a role in epithelioid sarcomas tumorigenesis. The fact that LOH was only detected in epithelioid sarcomas and not in the vascular tumors studied suggests a possible role for this marker in diagnosis.

Chromosomal abnormalities in low grade chondrosarcoma and a review of the literature

In this study, cytogenetic analysis of two low-grade chondrosarcomas revealed relatively simple chromosomal complements with structural rearrangements involving chromosomes 1, 6, and 12 [46,XY,add(16)(q24)[3]/46,XY,t(1;20)(q21;q11),t(6;17)(q23;q23)[3]/46,XY, t(4;14)(q12;q24),t(5;6)(q12;p21) [2] and 45,XY,t(12;16)(q13;q24),-14[17]/44,idem,add(4)(p16),-17,[2] respectively]. Previously published reports of chondrosarcoma have revealed structural abnormalities of chromosomes 1, 6, 9, 12, and 15 as common. Also, a correlation between the simplicity or complexity of the abnormalities seen and histologic grade has been suggested. The findings of the current study support these earlier observations.

Characterization of a human myxoid malignant fibrous histiocytoma cell line, OH931

Malignant fibrous histiocytoma (MFH), the most common soft-tissue sarcoma of late adult life, includes several histopathologic subtypes. The myxoid MFH subtype is characterized by the presence of abundant mucopolysaccharide within a loose connective tissue stroma. Although the myxoid variant is typically distinguished clinically by its better prognosis, we report a case of myxoid MFH that exhibited an aggressive phenotype with early metastases and death. A cell line, OH931, was established from this myxoid MFH. The primary tumor, OH931 cell line, and cells recovered from tumors generated in nude mice shared similar morphologic features, including the continued production of abundant mucopolysaccharide. Cytogenetic analysis of the primary tumor and a subsequently established cell line (OH931) revealed a complex hypertriploid mainline. Chromosomal breakpoints involved in all three specimens analyzed (diagnostic biopsy, definitive surgical, and cell line) included 1p33, 1q21, 2p14, 4p15, 5q13, 12q13, 14p13, 15p13, 19q13 and 20q13.1. The OH931 cell line, which appears to maintain its peculiar characteristics in vitro, should be useful in studies investigating the role of mucopolysaccharide production in the process of neoplasia.

Chromosome 9 related aberrations and deletions of the CDKN2 and MTS2 putative tumor suppressor genes in human chondrosarcomas

Deletions on the short arm of chromosome 9 (9p21 region) have been reported in a number of hematopoietic and solid tumors. These aberrations on 9p have been previously associated with the loss of the interferon gene cluster and the gene for methylthioadenosine phosphorylase (MTAP), localized to the 9p21-22 region. Recently, two putative tumor suppressor gene(s) CDKN2 and MTS2 have been mapped to the 9p21 region, and shown to be deleted in a large number of tumors including leukemias, melanomas, bladder cancers and brain tumors. We have previously reported a similar 9p21 abnormality and deletions of the CDKN2 and MTS2 genes in a myxoid chondrosarcoma cell line and its subclones. In this study we report consistent abnormalities of chromosome 9 in additional chondrosarcomas examined by a detailed cytogenetic and molecular analysis. Seven chondrosarcoma cell lines, one primary chondrosarcoma, and a benign chondroma were examined. Four of the seven tumor cell lines examined showed grossly visible aberrations of chromosome 9. Molecular analysis of these chondrosarcoma cell lines revealed hemizygous deletions of the interferon genes, and the absence of the MTAP gene, protein or activity. In addition, four of the seven chondrosarcoma cell lines also showed deletions of the CDKN2 and/or MTS2 putative tumor suppressor genes, or the absence of the CDKN2 protein product. No such chromosome 9 related aberrations were detected in the benign chondroma. These data suggest that chromosome 9p21 abnormality, and deletions of the CDKN2 and MTS2 tumor suppressor genes may be a significant event in the development of chondrosarcomas.

Partial deletions of the CDKN2 and MTS2 putative tumor suppressor genes in a myxoid chondrosarcoma

Cytogenetic abnormalities of chromosome 9 (9p21) have been reported in a large number of tumors that include malignant melanomas, gliomas, lung cancers and leukemias. These aberrations on 9p have been previously shown to involve the loss of the interferon gene cluster and the gene for methylthioadenosine phosphorylase (MTAP), both of which have been mapped to the 9p21 region. Recently, two putative tumor suppressor gene(s) CDKN2 and MTS2, have been mapped to the 9p21 region, and have been shown to be deleted in a large number of hematopoietic and solid malignancies. In this study we report a cytogenetic and a detailed molecular analysis of a myxoid chondrosarcoma cell line 105KC and its clonal derivatives 105AJ, 105AJ1.1, 105AJ3.1, and 105AJ5.1. Specifically, we have demonstrated chromosome 9p21 related abnormalities by cytogenetic analysis, the associated loss of the interferon gene cluster, and the loss of the immunoreactive MTAP protein and activity. In addition, we have also shown the presence of deletions involving the CDKN2 and the MTS2 putative tumor suppressor genes in these chondrosarcoma cell lines. The above studies were extended to other chondrosarcoma cell lines and primary tumors, where similar deletions of the CDKN2 and MTS2 genes were found to be present (unpublished data). This suggests a potential role for the involvement of the CDKN2 and MTS2 putative tumor suppressor genes in the development of chondrosarcomas.

Frequent loss of heterozygosity for markers on chromosome arm 10q in chondrosarcomas

Many tumors exhibit loss of heterozygosity (LOH) for polymorphic markers in regions of the genome that contain genes whose normal function can suppress tumor growth. Mapping of regions of LOH can help identify putative tumor suppressor loci that play a role in the pathogenesis of a disease. We evaluated 18 chondrosarcomas for LOH at 17 short tandem-repeat polymorphism loci on chromosome 10. Sixty-seven percent of the tumors (12/18) showed LOH for at least one marker and in most of these tumors the region of loss spanned all or large portions of the chromosome. By determining the smallest segment consistently involved, we identified a 7-12 cM critical region for LOH in the proximal long arm. This genomic region contains the RET oncogene, which has been implicated in the pathogenesis of multiple endocrine neoplasia types 2A and 2B, Hirschsprung disease, and medullary and papillary thyroid carcinomas. LOH on chromosome arm 10q was found in early-stage chondrosarcomas and did not correlate with grade or prognosis. Inactivation or alteration of a gene located at this site may be an early event in the development of these tumors.

Cytogenetic study of extraskeletal mesenchymal chondrosarcoma. A case report

Extraskeletal mesenchymal chondrosarcoma (EMC) is a rare and highly malignant type of chondrosarcoma of soft tissue origin. We performed a cytogenetic study on a patient with EMC. Cytogenetic analysis revealed the tumor karyotype: 48-49,XX, t(4;9)(q23;q22), add(10)(q?26), +16, ?del(19)(p13), +1-2mar[cp12] / 48-50,idem, t(1;20)(q21;q13), +mar[cp6] / 46,XX [7].