Myxoid/round Cell Liposarcoma Research Articles

A retrospective analysis of antitumour activity with trabectedin in translocation-related sarcomas

AimsApproximately 20% of soft tissue sarcomas (STS) have subtype-specific chromosomal translocations; these generate chimeric oncoproteins which can act as abnormal transcription factors. Since trabectedin can bind to DNA and displace transcription factors, antitumour activity was explored in translocation-related sarcoma (TRS) subtypes. MethodsThe current retrospective pooled analysis includes data from 81 patients with TRS treated in 8 phase II trials. ResultsTRS subtypes were: synovial sarcoma (SS, n=45), myxoid-round cell liposarcoma (MRC-L-sarcoma, n=27), alveolar soft part sarcoma (ASPS, n=4), endometrial stromal sarcoma (ESS, n=3) and clear cell sarcoma (CCS, n=2). All but one patient had received prior chemotherapy (median of 2 lines). Patients received a median of 4 trabectedin cycles (range, 1–48; median dose intensity=0.40mg/m2/week). Partial responses according to Response Evaluation Criteria in Solid Tumours (RECIST) occurred in 8 patients (ORR=10%; 95% CI, 4–19%): four in MRC-L-sarcoma; three in SS and one in ESS. Tumour control rate (ORR plus stable disease) was 59% (95% CI, 48–70%). Median PFS was 4.1months (6-month PFS rate=40%). Median overall survival was 17.4months (survival rate at 12months=60%). Trabectedin had a manageable safety profile. ConclusionTrabectedin demonstrates encouraging disease control in TRS. Since these promising results were generally noted in patients following chemotherapy, a phase III randomised trial in first-line is ongoing to compare trabectedin with doxorubicin-based chemotherapy in patients with TRS.

Randomized multicenter phase III trial of trabectedin (T) versus doxorubicin-based chemotherapy as first-line therapy in patients with translocation-related sarcoma (TRS).

TPS10101 Background: One third of sarcoma histotypes have specific chromosomal translocations which result in abnormal transcription factors, integral to the change to a malignant phenotype. T is the first of a new class of anti-tumor agents with a transcription-targeted mechanism of action. In vitro evidence exists of the ability of T to interfere with the aberrant transcription factor’s binding to DNA promoters in TRS. Patients with TRS, such as myxoid/round cell liposarcomas (MRCL) have benefited from long-lasting tumor control in response to T. Methods: A randomized, phase III study of T (1.5 mg/m2 in 24-h intravenous infusion every 3 weeks [q3wk]) vs doxorubicin 75 mg/m2 q3wk, or doxorubicin 60 mg/m2 with ifosfamide 6-9 g/m2 q3wk) as first line treatment in patients with advanced TRS. Primary aim: to determine the efficacy of T vs doxorubicin-based therapy by comparing progression-free survival (PFS) in each arm. Secondary aims: comparison of PFS rates at six months, response rate (RR), PFS and RR by histological type (MRCL vs other subtypes), overall survival, safety, exploratory response evaluation by Choi criteria and pharmacogenomic analyses. Patients with confirmed TRS of the following subtypes: MRCL, alveolar soft part sarcoma,angiomatoid fibrous histiocytoma, clear cell sarcoma, desmoplastic small round cell tumor, low grade endometrial stromal sarcoma, low grade fibromyxoid sarcoma,myxoid chondrosarcoma and synovial sarcoma, are stratified by performance status (PS 0 vs 1-2) and sarcoma subtype (MRCL vs other subtypes) and randomized (1:1 ratio) to T or doxorubicin ± ifosfamide. Confirmation of the translocation by fluorescence in situ hybridization is compulsory for inclusion in the primary efficacy analysis. An adaptive design was chosen to test the reduction in relative risk of progression or death with T, an interim analysis will be conducted with 45 PFS events from 80 evaluable patients. To date 117 patients have been enrolled from six countries and 29 centers. An independent data monitoring committee met on 15 November 2011 and concluded that the trial should continue as planned.

NY‐ESO‐1 is a ubiquitous immunotherapeutic target antigen for patients with myxoid/round cell liposarcoma

Myxoid/round cell liposarcoma (MRCL) is the second most common liposarcoma subtype, accounting for >33% of liposarcomas and approximately 10% of all soft tissue sarcomas. Although MRCL is a chemosensitive subtype, patients with metastatic disease have a poor outcome. NY-ESO-1 is a cancer-testis antigen (also known as cancer germ cell antigen) that has been successfully targeted in vaccine trials and in adoptive T-cell therapy trials for the treatment of several solid tumors. The authors investigated the feasibility of targeting NY-ESO-1 in patients with MRCL by evaluating the prevalence of NY-ESO-1 expression in tumors using immunohistochemistry and quantitative reverse transcriptase-polymerase chain reaction analysis. NY-ESO-1-specific tumor recognition by NY-ESO-1-specific T-cells also was analyzed using a chromium release assay. A search of the University of Washington Sarcoma Tissue Bank identified paraffin-embedded tumor samples from 25 patients with MRCL. NY-ESO-1 expression was observed in every MRCL tumor assessed (100%); in 18 tumors (72%), staining was homogenous. In all but 2 tumors, staining was sufficiently robust (2+) that such patients would be eligible for clinical trials of NY-ESO-1-directed therapy. By using NY-ESO-1 specific, CD8-positive T-cells, the in vitro sensitivity of myxoid liposarcoma cell lines to antigen-specific lysis was demonstrated. The current results establish NY-ESO-1 as an important target antigen for the treatment of patients with MRCL.

PPARγ agonists enhance ET-743–induced adipogenic differentiation in a transgenic mouse model of myxoid round cell liposarcoma

Myxoid round cell liposarcoma (MRCLS) is a common liposarcoma subtype characterized by a translocation that results in the fusion protein TLS:CHOP as well as by mixed adipocytic histopathology. Both the etiology of MRCLS and the mechanism of action of TLS:CHOP remain poorly understood. It was previously shown that ET-743, an antitumor compound with an unclear mechanism of action, is highly effective in patients with MRCLS. To identify the cellular origin of MRCLS, we engineered a mouse model in which TLS:CHOP was expressed under the control of a mesodermally restricted promoter (Prx1) in a p53-depleted background. This model resembled MRCLS histologically as well as functionally in terms of its specific adipocytic differentiation-based response to ET-743. Specifically, endogenous mesenchymal stem cells (MSCs) expressing TLS:CHOP developed into MRCLS in vivo. Gene expression and microRNA analysis of these MSCs showed that they were committed to adipocytic differentiation, but unable to terminally differentiate. We also explored the method of action of ET-743. ET-743 downregulated TLS:CHOP expression, which correlated with CEBPα expression and adipocytic differentiation. Furthermore, PPARγ agonists enhanced the differentiation process initiated by ET-743. Our work highlights how clinical observations can lead to the generation of a mouse model that recapitulates human disease and may be used to develop rational treatment combinations, such as ET-743 plus PPARγ agonists, for the treatment of MRCLS.

Metastatic Patterns of Myxoid/Round Cell Liposarcoma: A Review of a 25-Year Experience

Myxoid/round cell liposarcoma (MRCL), unlike other soft tissue sarcomas, has been associated with unusual pattern of metastasis to extrapulmonary sites. In an attempt to elucidate the clinical features of MRCL with metastatic lesions, 58 cases, from the medical database of Keio University Hospital were used for the evaluation. 47 patients (81%) had no metastases, whereas 11 patients (11%) had metastases during their clinical course. Among the 11 patients with metastatic lesions, 8 patients (73%) had extrapulmonary metastases and 3 patients (27%) had pulmonary metastases. Patients were further divided into three groups; without metastasis, with extrapulmonary metastasis, and with pulmonary metastasis. When the metastatic patterns were stratified according to tumor size, there was statistical significance between the three groups (P = 0.028). The 8 cases with extrapulmonary metastases were all larger than 10 cm. Similarly, histological grading had a significant impact on metastatic patterns (P = 0.027). 3 cases with pulmonary metastatic lesions were all diagnosed as high grade. In conclusion, large size and low histological grade were significantly associated with extrapulmonary metastasis.

Myxoid\Round Cell Liposarcoma (MRCLS) Revisited: An Analysis of 418 Primarily Managed Cases

Objectives of this study were to evaluate oncologic outcomes and to provide guidelines for the management of primary myxoid (MLS) and round cell liposarcoma (RCLS). A multicenter, retrospective study of 418 cases of MRCLS primarily managed by Canadian multidisciplinary sarcoma teams. Study included 418 cases (MLS: 311 patients and RCLS: 107; >5% round cell) with a median age of 45 years and a median follow-up of 5.2 years. Median tumor size was 10 cm, and 81% were deep and 90% were in lower limb. The majority of patients underwent surgical resection and radiotherapy, with a small percentage (6%) receiving chemotherapy. The overall 10-year local control rate was 93% with no differences between MLS and RCLS. Radiotherapy was significant in preventing local relapse and reducing tumor diameter (median=18%) and improving microscopic margin status, but did not impact survival. Radiotherapy and the margin status were independent predictors of local recurrence. The 5- and 10-year metastatic-free survivals were 84 and 77% respectively for MLS and 69 and 46% for RCLS. The initial site of metastasis was found in multiple locations (34%) and bone involvement was frequent (40%) with predilection for spine (79%). Round cell percent (>5%) and tumor diameter (>10 cm) correlated with increased risk for metastasis and death. MLS and RCLS showed different metastatic risk but equally good local control. Radiotherapy was effective in preventing local recurrence and should be delivered as neoadjuvant. New staging strategies are to be defined to account for the unusual metastatic pattern.

Sensitivity of well-differentiated/dedifferentiated liposarcoma (WD/DD) and myxoid round cell/liposarcoma (MRCL) to high-dose ifosfamide: Combined analysis from two European referral institutions.

10023 Background: Liposarcomas are the most common histological type of soft-tissue sarcomas (STS). Its main subgroups, WD/DD and MRCL, are distinct diseases with divergent morphology, genetics, an...

Prognostic Factors and Metastatic Patterns in Primary Myxoid/Round-Cell Liposarcoma

Background. This study aimed to investigate prognostic factors for patients with myxoid/round-cell liposarcoma (MRCLS), in particular the significance of the round cell component, and to identify metastatic patterns as well as possibly suggest a suitable strategy for followup. Methods. Clinical, morphologic, and follow-up data from 160 patients with MRCLS was reviewed and statistically analysed. Results. Of 130 tumours with the round cell component evaluated, 61 had no round cell component, 27 had <5% round cell component, and 42 had >5%. All patients underwent surgical excision, 15 requiring amputation. 107 patients received adjuvant radiotherapy. Local recurrence occurred in 19 patients (12%), predominantly in patients with marginal or intralesional margins and a round cell component. Overall disease specific survival was 75% at 5 years and 56% at 10 years and was related to the proportion of round cell component. Of 52 patients who developed metastases, 38 (73%) had purely extrapulmonary metastases. We could not identify any factors predicting the site of metastases developing. Conclusions. The occurrence of any round cell component is the most important adverse prognostic factor for patients with MRCLS; patients with >5% round cell component are at higher risk of local recurrence, metastasis and tumour-related death and should be considered for adjuvant radiotherapy and possibly chemotherapy. The best method of monitoring extrapulmonary metastases remains to be established.

Efficacy of neoadjuvant doxorubicin and ifosfamide (AI) in myxoid/round cell liposarcoma (MRCL): The M. D. Anderson Cancer Center experience (MDACC).

10080 Background: Myxoid/round cell liposarcomas (MRCLs) represent a subgroup of soft tissue sarcomas (STSs) with a multinodular gelatinous macroscopic appearance and a unique chimeric FUS-CHOP gene expression. Doxorubicin and ifosfamide (AI), in combination, is an often-used first-line regimen for MRCLs. However, this standard combination is administrated at a wide dosing range with variable efficacy. With the emerging benefit from trabectidin, (ET-743, Yondelis), a marine-derived alkaloid, in MRCLs, we present the response to neoadjuvant AI, as administrated in MRCL patients (pts) at our institute as a historical benchmark. Methods: We reviewed the clinical records and imaging, focusing on treatment and outcome of all pts with MRCL at our institute from Jan. 2000 to Dec 2009. Pts were treated for 4 - 6 cycles with neoadjuvant doxorubicin (75-90 mg/m2 continuous infusion over 72h q3wk), and ifosfamide (2.5 g/m2 daily × 4 q3wk) with mesna. Main endpoints were: objective response rate by RECIST and Choi criteria (defining response as a decrease in tumor size of ≥10%), time to maximal response and disease free survival (DFS). Results: Clinical data and imaging were available for 24 pts. Median age was 42y (14-72), female:male ratio was 1:1.4, median tumor largest diameter prior to AI was 14.9 cm (6-23.3). Twenty-two tumors were located in the lower extremity, one in the neck and one in the perineum. Partial response rate was 41.6% (n=10) by RECIST and 83.3% (n=20) according to Choi criteria. Tumor diameter decreased by an average of 26.5% (6.2-56.1) and average time to maximum response was 4.2 months. No disease progression or fatalities occurred. Radiotherapy was used in 19/24 pts and all pts underwent surgery with an R0 intent; however, 5 were found to have positive margins. During a median follow up of 54.1 months (95% CI 34 to 78.1) 6 pts developed distant recurrences (2 with positive margins) diagnosed at a median of 23 months (14-50) following surgery of whom two died. The estimated lower limit of 95% CI for median DFS time was 50 months with a 5 year DFS rate of 0.68 (95% CI 0.49 to 0.95). Conclusions: These results confirm the high activity of neoadjuvant AI in MRCL pts. No significant financial relationships to disclose.

Imaging of Skeletal Metastases in Myxoid Liposarcoma

Unlike other soft tissue sarcomas, myxoid/round cell liposarcoma (MRCL) has a tendency to spread to extrapulmonary sites but bone metastases are thought to be uncommon. In case reports, negative bone scintigraphy has been noted in patients with myxoid/round cell liposarcoma and bone metastases but the prevalence and optimal method of diagnosis of bone metastases in this common subtype of liposarcoma are unclear. In an attempt to answer these questions, data were obtained from a prospective database of patients with sarcoma, including MRCL, and the diagnostic imaging used was examined. A variety of imaging tools were used including plain X-rays, bone scintigraphy, computed tomography (CT), and magnetic resonance imaging (MRI). Eight patients (4.3%) developed skeletal metastases all of which were positive on MRI. Bone scintigraphy was negative in two out of four cases, CT was negative in six out of seven, and X-rays were negative in four. Radiography and CT measure mainly cortical bone involvement, whereas MRI examines bone marrow. When investigating patients with MRCL for bone pain, negative X-rays and bone scans do not rule out bone metastases. In our experience, MRI provides the most sensitive technique for the diagnosis of bone metastases in MRCL.

Analysis of CHOP rearrangement in pleomorphic liposarcomas using fluorescence in situ hybridization

Pleomorphic liposarcoma (PLS) is an aggressive subtype of liposarcoma composed of high-grade sarcoma with pleomorphic lipoblasts. PLS usually exhibits a heterogeneous histology and sometimes has a myxoid or round cell area similar to myxoid/round cell liposarcomas (MLS/RCs). Using fluorescence in situ hybridization (FISH) analysis, we investigated the existence of CHOP split signals in various histological areas of PLS including the MLS/RC-like feature and also estimated the distribution of various signals with polyploidy and amplification. Moreover, to detect CHOP fusion transcripts we performed nested reverse transcription-polymerase chain reaction (RT-PCR). Seven PLSs and three MLS/RCs were selected for FISH analysis using the locus-specific indicator CHOP (12q13) dual color, break apart probe (Vysis, USA). The FISH analysis was applied to formalin-fixed, paraffin-embedded tissue sections of representative areas in all cases. Six of seven PLS cases showed the CHOP split signal ranging from 0.5% to 3% of counted nuclei, while all cases of MLS/RC exhibited CHOP rearrangement in more than 50% of counted nuclei. All cases of PLS showed a varied distribution of extra signals with polyploidy and amplification in each histological area. No CHOP fusion transcript was found in any case of PLS by nested RT-PCR. A CHOP rearrangement in PLS should be recognized only as a representative part of complex karyotypes, because the number of cells with split signals was minute compared with that of MLS/RC, and the signals were found in any area despite their histological differences. The cytogenetic background of PLS and that of MLS/RC are obviously different despite histological similarity.

Primary retroperitoneal myxoid liposarcoma&amp;em;a non existing disease? An immunohistochemical and molecular biologic analysis

10569 Background: Almost all primary retroperitoneal liposarcomas are well- or de-differentiated tumors. However, occasionally primary retroperitoneal liposarcomas are diagnosed as myxoid or roundcell liposarcoma (PRMRLS), a classification based on the histologic presence of myxoid areas and a vascular crow-feet pattern, morphologically specific for myxoid/roundcell liposarcoma (MRLS). Genetically, there is a difference between MRLS and well- or de-differentiated liposarcoma. MRLS have a classical translocation causing FUS-CHOP or EWS-CHOP fusion while well- or de-differentiated liposarcomas are characterized by amplification of the 12q13–15 region, which among many other genes includes MDM2 and CDK4. Since in particular all MRLS are highly radio- and chemo-sensitive, differentiation between subtypes is important to indicate prognosis and optimize treatment. We studied whether PRMRLS are related to true MRLS or should be classified as well- or de-differentiated liposarcomas with focal MRLS-like changes. Methods: Patients classified as PRMRLS (n=16) were reviewed. Results were compared to a group diagnosed with primary extremity MRLS (n=20). In both groups, histopathologic, immunohistochemical and molecular biologic analysis was performed. Results: In PRMRLS, MDM2 and CDK4 stained slides were positive in 65% and 80% respectively and both tests were negative in all extremity MRLS. Translocation analysis showed FUS-CHOP or EWS-CHOP fusion to be present in all extremity MRLS, but absent in all sixteen investigated PRMRLS. Multiplex Ligation-Dependant Probe Amplification showed amplification of region 12q13–15 in 94% of PRMLS and in 5% of primary extremity MRLS patients. Conclusions: Classic MRLS, characterized by a FUS-CHOP or EWS- CHOP fusion oncogen was not found in PRMRLS, while MDM2 and CDK4 amplification was present in most specimens. In PRMRLS, the probability of focal MRLS-like changes in well- or de-differentiated liposarcoma is a more presumable explanation for the histologic appearance. In these cases most likely treatment should be designed as for well- or de-differentiated liposarcoma. No significant financial relationships to disclose.

Relevance of translocation type in myxoid liposarcoma and identification of a novel EWSR1‐DDIT3 fusion

The clinical course of myxoid/round cell liposarcoma (MRCL) is characterized by frequent local recurrences and metastases at unusual sites. MRCLs carry specific translocations, t(12;16) or rarely t(12;22), linking the FUS or the EWSR1 gene with the DDIT3 gene, respectively. Nine FUS/DDIT3 and three EWSR1/DDIT3 variants of fusion transcripts have been described thus far. In search of prognostic markers for MRCL, we analyzed the translocation types of 31 patients and related them to the event free and overall survival. Using break-apart FISH and RT-PCR combined with DNA sequencing, we detected FUS/DDIT3 fusions in 30 sarcomas, while an EWSR1/DDIT3 translocation was identified in one tumor. FUS/DDIT3 type II (exons 5-2) was most commonly detected (20 cases), followed by type I (7-2) (7 cases) and type III (8-2) (3 cases). A single tumor carrying a t(12;22) translocation expressed a hitherto unknown EWSR1-DDIT3 fusion transcript (13-3) linking the complete RNA-binding domain of EWSR1 with a short piece of the 5'-UTR and the entire open reading frame of the DDIT3 gene. Interestingly, five of six patients with type I (7-2) FUS/DDIT3 fusions displayed local recurrences and/or metastatic spread within the first 3 years, generally requiring chemotherapeutical treatment (median disease-free survival 17 months). In contrast, 9 of 13 patients with type II FUS/DDIT3 translocations remained at 3 years disease-free (median disease-free survival 75 months). Since the total number of patients is still limited, further studies are required to verify a putative association of type I FUS/DDIT3-fusion transcripts with a prognosis of MRCL.

A Monoclonal Antibody for Molecular Diagnosis of Myxoid-Round Cell Liposarcoma

Advances in Anatomic Pathology: July 2007 - Volume 14 - Issue 4 - p 297 doi: 10.1097/PAP.0b013e3180ca8ac0

Localized myxoid/round cell liposarcoma in adult patients. IL6 protein expression analysis

10075 Background: Myxoid/round cell liposarcoma (MLPS) is an uncommon soft tissue sarcoma with a relatively favorable prognosis and is considered a low grade malignancy. Methods: Retrospective analysis of 123 localized MLPS adult patients (pts) treated at our institution from 1987 to 2005 was performed. Paraffin embedded tissue was analyzed for IL6, IL6 receptor, NFkB and bcl-2 protein expression (positive (+) or negative) by tissue microarray immunostaining. Results: The median age of the 77 males and 46 females was 42 years (yr) (range 15–70). Lower extremity (LE) was the site more affected (77 pts). Median tumor size was 11 cm (range 2.5–40 cm), 87 were deep tumors and 63 were grade 1 tumors. Preoperative biopsy was carried on 38 pts. All but 2 pts underwent surgery (R0 24%, R1/R2 76%); 44 pts had a second surgery. Chemotherapy (CT) and radiation therapy were given to 30% and 52% of pts respectively. Complete remission was achieved in 98% of pts. After a median follow up of 6 yr (range 0.1–19 yr) 53 pts relapsed (43%); 37 locally, 11 distant and 5 both. Metastases occurred in 26 pts, 17 solitary and 9 multiple. The 5-yr, 10-yr and 15-yr DFS were 56%, 48% and 44% respectively. Median time to first relapse was 6.5 yr (range 0.1–16 yr). The 5-yr, 10-yr and 15-yr OS are 90%, 79% and 64% respectively. Tumor site, pre-surgical biopsy, R0 surgery and second surgery correlates with a better DFS in the multivariate analysis. So far 19 tumors have been studied for, NFkB (+) 57%, IL6 (+) 47% and Bcl2 (+) 30%, positivity. All tumors (+) for IL6 were also (+) for IL6 receptor. None of the proteins correlated to DFS and/or OS. Conclusions: Pts with localized resected MLPS require a prolonged follow-up since relapses occur after 10 yrs. PFS and OS correlate with an optimal loco-regional treatment. Half of MLPS expressed IL6, probably involving an autocrine phenomenon; whether this cytokine is involved in tumor aggressiveness, remains to be established. No significant financial relationships to disclose.

Sensitivity of myxoid-round cell liposarcoma (MRCL) to trabectedin (T) may be related to a direct effect on the fusion transcript

10000 Background: Myxoid-round cell liposarcomas (MRCL) is a variant of liposarcoma, associated with t(12;16)(q13;p11) and the rarer t(12;22)(q13;q12) chromosomal translocation, resulting in the FUS-CHOP and EWS-CHOP fusion proteins, supposed to act as aberrant transcription factors. We reported the exceedingly high clinical efficacy of T against MRCL, which is a magnitude higher in comparison to other liposarcomas and sarcomas. Reasons thereof remain unknown, but a distinct mechanism of action of T in MRCL is suspected on clinical grounds. Methods: Tumor biopsies were taken from 9 MRCL patients (pts) before starting T, and the tumor was fully characterized by cytogenetic and molecular analysis. Primary cultures were set up, and tumor fragments were transplanted in scid mice, to develop an experimental model aimed at investigating the mechanism of action of T. Chromatin immunoprecipitation (ChIP) analysis on the 402–91 myxoid liposarcoma cell line was performed, to characterize the DNA binding capability of FUS-CHOP. Finally, in vivo ChIP analyses are currently ongoing, using tumor samples obtained before and after therapy with T. Tumor samples from 3 patients have been processed so far. Results: All patients had t(12–16) by FISH. Molecular characterization showed that 7 pts had the type II transcript, 1 had the type III, and 1 both type II and III. Primary cultures evaluated after the first 3 passages were morphologically, cytogenetically and molecularly consistent with the original tumor, as well as the 4 tumours grown in mice so far. In the myxoid liposarcoma cell line carrying the type I transcript, selective binding of FUS-CHOP to some promoters was seen. Impairment of this binding activity was observed after treatment with T at concentration 1–4 nM. Conclusions: There is in vitro evidence of a direct effect of T on the fusion protein's ability to bind to promoters. In vivo studies on the experimental model are ongoing, and results will be presented. No significant financial relationships to disclose.

Significance of necrosis and gene expression profiling in high-grade myxoid/round cell liposarcoma (MRLS) of the extremity

9015 Background: Myxoid liposarcoma represents a morphologic continuum, with histologic grade determined by the extent of the round cell (RC) component. For this study, MRLS was defined as having a...

Detection of FUS-CHOP fusion gene in paraffin-embedded tissues and its clinicopathologic significance for myxoid/round cell liposarcomas

To explore the feasibility of detecting FUS-CHOP fusion gene in formalin-fixed, paraffin-embedded tissue and its application in the diagnosis and differential diagnosis of myxoid/round cell liposarcomas (MRCLs). Forty-four formalin-fixed, paraffin-embedded MRCL samples and 60 control cases (atypical/well-differentiated liposarcoma, pleomorphic liposarcoma, low-grade myofibrosarcoma, etc.) retrieved from the archival files were studied. Nested reverse transcription-polymerase chain reaction (RT-PCR) technique was employed to detect the FUS-CHOP mRNA expression, followed by DNA sequencing confirmation of the PCR product. Housekeeping gene PGK was used to assess the quality of the mRNA templates. PGK mRNA was detected in 93 of 104 tumor cases (89.4%), including 39 MRCLs cases (39/44, 88.6%) and 90% of the negative control cases. Type II FUS-CHOP fusion transcript was successfully detected in 20 out of 39 (51.3%) MRCL cases. Type I FUS-CHOP fusion transcript was not detected in any MRCLs in this study. All 60 negative control cases were negative for the FUS-CHOP fusion gene transcripts. (1) Nested RT-PCR can be used to detect FUS-CHOP mRNA in formalin-fixed, paraffin-embedded tissues. (2) FUS-CHOP is considered a specific molecular and genetic hallmark for MRCLs. Nested RT-PCR is a sensitive and specific technique in detecting FUS-CHOP gene, and can be used in the diagnosis and differential diagnosis of MRCLs.

Prognostic significance of MRI findings in patients with myxoid-round cell liposarcoma.

The aims of this study were to determine the prognostic significance of MRI findings in patients with myxoid-round cell liposarcomas and to clarify which MRI features best indicate tumors with adverse clinical behavior. The initial MRI studies of 36 pathologically confirmed myxoid-round cell liposarcomas were retrospectively reviewed, and observations from this review were correlated with the histopathologic features. MR images were evaluated by two radiologists with agreement by consensus, and both univariate and multivariate analyses were conducted to evaluate survival with a median clinical follow-up of 33 months (range, 9-276 months). Statistically significant MRI findings that favored a diagnosis of intermediate- or high-grade tumor were large tumor size (> 10 cm), deeply situated tumor, tumor possessing irregular contours, absence of lobulation, absence of thin septa, presence of thick septa, absence of tumor capsule, high-intensity signal pattern, pronounced enhancement, and globular or nodular enhancement. Of these MRI findings, thin septa (p < 0.05), a tumor capsule (p < 0.01), and pronounced enhancement (p < 0.01) were associated significantly, according to univariate analysis, with overall survival. Multivariate analysis indicated that pronounced enhancement was associated significantly with overall survival (p < 0.05). Contrast-enhanced MRI findings can indicate a good or adverse prognosis in patients with myxoid-round cell liposarcomas.

Molecular Variability of TLS - CHOP Structure Shows No Significant Impact on the Level of Adipogenesis: A Comparative Ultrastructural and RT-PCR Analysis of 14 Cases of Myxoid/Round Cell Liposarcomas

A specific TLS-CHOP fusion gene derived from the t(12;16) is present in at least 95% of myxoid/round cell liposarcomas (MLS). Rare cases of MLS show a variant t(12;22) translocation, resulting in EWS-CHOP fusion gene. The CHOP gene encodes a leucine-zipper transcription factor, which is implicated in both oncogenic transformation and inhibition of adipogenesis. To examine whether the molecular variability of TLS-CHOP or EWS-CHOP fusion transcript structure is associated with the degree of inhibition of adipogenesis, a comparative ultrastructural and RT-PCR-based analysis of 14 MLS was performed. The specimens consisted of 9 primary, 2 locally recurrent tumors, and one representative sample each from 3 patients with multifocal soft tissue metastases. Histologically, there were 8 high-grade and 6 low-grade MLS using 5% round cell (RC) component as the cutoff point. By RT-PCR assay there were 13 cases with TLS-CHOP fusion transcripts: 7 cases of type 5-2 (known as type II), 4 cases of type 7-2 (known as type I),1 case of type 8-2 (known as type III), and 1 unique case of type 6-2.The remaining 1 case showed an EWS-CHOP fusion transcript. Ultrastructural examination revealed that tumor cells were composed of a moderate-to-predominant proportion of well-formed lipoblasts in 4 cases, while in 6 cases such lipoblasts were very scant.The remaining 4 tumors were arrested in the stage of transitional cells. The heterogeneity of TLS-CHOP fusion transcript showed no apparent impact on adipogenesis, since both TLS-CHOP type I and II cases could randomly display various levels of lipoblastic differentiation. Furthermore, the 4 cases without definite lipoblasts showed no preference for any specific fusion variants and consisted of one each of TLS-CHOP subtypes. In addition, the fusion transcript variants did not correlate with other ultrastructural features, such as the presence and amount of glycogen, mitochondria, rough endoplasmic reticulum, vimentin-like intermediate filaments, and external lamina. However, there appeared to have a trend suggesting the predilections of glycogen particles and vimentin-like intermediate filaments in primitive mesenchymal cells and/or transitional cells. These findings cannot substantiate the hypothesis that the molecular variability of fusion transcripts has a biological impact on adipogenesis of MLS, and other factors might be implicated in their level of differentiation.