High amplification levels of MDM2 and CDK4 correlate with poor outcome in patients with dedifferentiated liposarcoma: A cytogenomic microarray analysis of 47 cases (2023)

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Article preview Cancer Genetics Introduction Section snippets Patient selection Clinical and pathologic review Summary of cytogenomic microarray findings Discussion Conflict of interest References (38) Am J Pathol Cell Signal Mol Cytogenet Cancer Lett Cancer Cell Subtype specific prognostic nomogram for patients with primary liposarcoma of the retroperitoneum, extremity, or trunk Ann Surg Dedifferentiated liposarcoma: a clinicopathological analysis of 155 cases with a proposal for an expanded definition of dedifferentiation Am J Surg Pathol Chromosome aberrations in solid tumors Nat Genet Structure of the supernumerary ring and giant rod chromosomes in adipose tissue tumors Genes Chromosomes Cancer Distinct mdm2/p53 expression patterns in liposarcoma subgroups: implications for different pathogenetic mechanisms J Pathol Clinical and biological significance of CDK4 amplification in well-differentiated and dedifferentiated liposarcomas Clin Cancer Res In vitro and in silico studies of MDM2/MDMX isoforms predict Nutlin-3A sensitivity in well/de-differentiated liposarcomas Lab Invest Regulation of p53 stability by Mdm2 Nature Potent and orally active small-molecule inhibitors of the MDM2-p53 interaction J Med Chem Direct binding of cyclin D to the retinoblastoma gene product (pRb) and pRb phosphorylation by the cyclin D-dependent kinase CDK4 Genes Dev Antiproliferative effects of CDK4/6 inhibition in CDK4-amplified human liposarcoma in vitro and in vivo Mol Cancer Ther MDM2 copy numbers in well-differentiated and dedifferentiated liposarcoma: characterizing progression to high-grade tumors Am J Clin Pathol Copy number losses define subgroups of dedifferentiated liposarcoma with poor prognosis and genomic instability Clin Cancer Res Prognostic relevance of federation nationale des centres de lutte contre le cancer grade and MDM2 amplification levels in dedifferentiated liposarcoma: a study of 50 cases Mod Pathol Cited by (35) Recommended articles (6) FAQs
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Cancer Genetics

Volumes 218–219,

December 2017

, Pages 69-80

Author links open overlay panelRobert W.RicciottiaAaron J.BaraffbGeorgeJourcMcKennaKyrissdYuWuaYuhuaLiuaShao-ChunLieBenjaminHochaPersonEnvelopeYajuan J.LiuaPersonEnvelope

Dedifferentiated liposarcoma (DDLS) is characterized at the molecular level by amplification of genes within 12q13-15 including MDM2 and CDK4. However, other than FNCLCC grade, prognostic markers are limited. We aim to identify molecular prognostic markers for DDLS to help risk stratify patients. To this end, we studied 49 cases of DDLS in our institutional archives and performed cytogenomic microarray analysis on 47 cases. Gene copy numbers for 12 loci were evaluated and correlated with outcome data retrieved from our institutional electronic medical records. Using cut point analysis and comparison of Kaplan-Meier survival curves by log rank tests, high amplification levels of MDM2 (>38 copies) and CDK4 (>30 copies) correlated with decreased disease free survival (DFS) (P = .0168 and 0.0169 respectively) and disease specific survival (DSS) (P = .0082 and 0.0140 respectively). Additionally, MDM2 and CDK4 showed evidence of a synergistic effect so that each additional copy of one enhances the effect on prognosis of each additional copy of the other for decreased DFS (P = .0227, 0.1% hazard). High amplification of JUN (>16 copies) also correlated with decreased DFS (P = .0217), but not DSS. The presence of copy number alteration at 3q29 correlated with decreased DSS (P = .0192). The presence of >10 mitoses per 10 high power fields and FNCLCC grade 3 also correlated with decreased DFS (P = .0310 and 0.0254 respectively). MDM2 and CDK4 gene amplification levels, along with JUN amplification and copy alterations at 3q29, can be utilized for predicting outcome in patients with DDLS.

Introduction

Liposarcoma is the most common type of sarcoma in adults and accounts for about 20% of all adult sarcomas. It is divided into three main types which are morphologically, clinically, and genetically distinct from one another: (i) atypical lipomatous tumor/well-differentiated liposarcoma and dedifferentiated liposarcoma (ALT/WDLS and DDLS), (ii) myxoid/round cell liposarcoma, and (iii) pleomorphic liposarcoma. ALT/WDLS are by definition low-grade, non-metastasizing neoplasms characterized by lipogenic/lipoblastic neoplastic cells with intermixed areas of atypical spindle cells. DDLS occurs as transformation from ALT/WDLS into a higher grade sarcoma during which lipogenic differentiation is most often lost; however, in some instances DDLS may harbor homologous lipoblastic differentiation and morphologically resemble pleomorphic liposarcoma. DDLS is most commonly an intermediate- to high-grade sarcoma with metastatic potential and much poorer prognosis than ALT/WDLS (1). Other than simply the presence of dedifferentiation, anatomic site remains the main prognostic factor with retroperitoneal tumors having the worst outcome as compared to other sites (2).

Chromosome alterations including gene and/or regional copy number alterations (CNA) may affect gene expression and are common in various types of cancer (3). The vast majority of ALT/WDLS and DDLS are characterized by supernumerary ring and giant marker chromosomes containing amplified sequences from the 12q13-15 region. Included in these supernumerary chromosome regions are amplified MDM2 and HMGA2 genes and, usually, CDK4 at 12q14.1 4, 5, 6. MDM2, an oncoprotein recently recognized as a potential therapeutic target, is overexpressed and known to inactivate the tumor suppressor p53 by targeting it for proteasomal degradation 5, 7, 8, 9. CDK4, on the other hand, plays a role in cell cycle progression through phosphorylation of RB1 and has also become a recognized potential therapeutic target 10, 11. Amplification of MDM2 and HMGA2 is thought to be the main driver event in liposarcomagenesis with CDK4 often acting as an “MDM2-HMGA2 helper.” 5, 6 Although knowledge of these molecular genetic alterations is useful for diagnosis, molecular prognostic markers for DDLS remain limited.

Higher levels of MDM2 gene amplification as well as increasing genomic complexity have been demonstrated in DDLS as compared to WDLS 12, 13. These findings provide evidence that liposarcoma acquires additional genomic alterations as it progresses from low to higher grade sarcoma. Amplification levels of MDM2 and CDK4 in liposarcoma have been previously investigated as potential prognostic markers. MDM2 has so far shown modest prognostic value as measured by FISH, Q-PCR, and MLPA in both ALT/WDLS and DDLS 14, 15, 16. The presence of CDK4 amplification has been previously shown to be more common in tumors with dedifferentiation and higher amplification levels of CDK4 have been shown to correlate with higher rate of local recurrence in ALT/WDLS 15, 16, 17. None of the previous studies, however, have effectively stratified patients with DDLS into risk groups based upon MDM2 and/or CDK4 amplification levels. Furthermore, survival analyses in some of these studies have lumped patients with ALT/WDLS and DDLS together even though it is recognized that patients with dedifferentiated tumors fair worse than those without dedifferentiation.

Amplification of c-Jun, which effects C/EBPβ and PPARγ function, has been previously described in liposarcoma and thought to be oncogenic, but its role in dedifferentiation and disease progression remains unclear 18, 19. Amplification of MAP3K5 and GLI1 are common in DDLS and at least one study has shown amplification of these genes as well as JUN to be mutually exclusive 20, 21, 22. Other than MDM2 and CDK4, many other genes within the 12q13-15 amplicon, including DDIT3, YEATS4, and FRS2 have been found to be frequently amplified in DDLS and may play a role in liposarcomagenesis 22, 23, 24.

In this study, we investigate the relationship of CNAs at specific loci including levels of gene amplification in DDLS with prognosis. Given that prognostic tools are still lacking, we hope to identify prognostic markers to help risk stratify liposarcoma patients. Additionally, further investigation of the genetic events that contribute to liposarcomagenesis and effect tumor behavior will add to our overall understanding of the biology of these tumors and may help in the identification of novel therapeutic targets.

Section snippets

Patient selection

The institutional electronic pathology database was searched to retrospectively identify patients diagnosed with DDLS and treated at our institution between January 1999 and January 2015. The study protocol was reviewed and approved by the institutional review boards (University of Washington, Human Subjects Division). Cases that had sufficient material available for review were included and any material appropriate for cytogenomic microarray analysis was acquired.

Clinical and pathologic review

All archived slides for cases

Summary of cytogenomic microarray findings

Adequate material for cytogenomic microarray analysis was available for 47 cases. Copy number gains and losses of chromosomal material were common in DDLS. Although single copy losses were common, losses of both copies (homozygous or bi-allelic loss) for any of the genes investigated were not observed. The copy number evaluations for 12 loci are summarized in Table2.

Amplification of genes within the 12q13-15 region was most common and found in 44 of 47 DDLS cases. Amplified genes included MDM2

Discussion

Potential prognostic markers for DDLS have been previously investigated. While grading of DDLS has historically been subjective and somewhat vague, a recent study by Jour etal. (14) found that FNCLCC grading of DDLS may predict a greater risk of local recurrence in grade 3 tumors. In that study, DDLS with high MDM2 gene amplification, defined as 20 or more gene copies as measured by fluorescence in-situ hybridization (FISH), showed a higher recurrence rate on univariate analysis; however,

Conflict of interest

All authors have no financial conflicts of interest to declare.

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      2022, Pathology Research and Practice

      Sarcomas are mesenchymal-derived cancers with overlapping clinical and pathologic features and a remarkable histological heterogeneity. While a precise diagnosis is often challenging to achieve, systemic treatment of sarcomas is still quite uniform. In this scenario, next generation sequencing (NGS) may be exploited to assist diagnosis and to identify specific targetable alterations. However, the precise role of genomic characterization in these diseases is still debated. In the present study, we analyzed 18 samples from 11 low-incidence sarcomas using NGS technology. We also used an in-silico prediction tool to reclassify variants of unknown significance and then looked for potentially druggable alterations to match with targeted therapies. Our cohort presented several predictable findings (e.g. MYC amplification in radio-induced angio-sarcoma, COL1A1-PDGFB rearrangements in dermatofibrosarcoma protuberans) along with unexpected results (e.g. the reciprocal WT1-EWSR1 fusion in a desmoplastic small round cell tumor). One third of patients (6/18) displayed at least one actionable molecular alterations. Our experience confirms the potential role of NGS in the management of rare sarcomas. This tool may support the diagnostic process, but also detect targets for personalized therapies.

    • The utility of fluorescence in situ hybridization (FISH) in determining DNA damage-inducible transcript 3 (DDIT3) amplification in dedifferentiated liposarcomas – an important diagnostic pitfall

      2021, Pathology Research and Practice

      Dedifferentiated liposarcoma (DDLPS) is characterized by non-lipogenic sarcoma fields coexisting with adipocyte-rich well-differentiated areas. Amplification of the 12q13–15 region includes the MDM2 and DDIT3 genes. MDM2 amplification is considered a genetic hallmark of DDLPS, while DDIT3 is typically rearranged in myxoid liposarcoma. Recent studies showed that DDIT3 amplification is associated with myxoid liposarcoma-like (LPS-like) morphology in DDLPS. Our study aimed to evaluate the status of MDM2 and DDIT3 by FISH in DDLPS and correlate it with MLPS-like features.

      Six patients with MLPS-like morphology DDLPS were investigated pathologically, immunohistochemically, and genetically. The control groups of patients with classical DDLPS morphology and well-differentiated liposarcoma (WDLPS) were established and molecularly assessed as well. Fluorescence in situ hybridization (FISH) used in routine diagnostics was performed to determine the status of MDM2 and DDIT3 genes.

      The patient's mean age was 64 (range from 43 to 85 years) with a 5:4 male to female ratio. Tumors were localized retroperitoneally (15) and extra-retroperitoneally (3). All cases demonstrated amplification of the 12q15 region containing MDM2 gene and co-amplification of the 5′ DDIT3 FISH Probe representing DDIT3 telomeric tag. However, we did not find the relation of myxoid LPS-like morphology with DDIT3 amplification as previously reported.

      The biopsy material from DDLPS with myxoid areas can be misclassified as myxoid liposarcoma. Indeed, according to the histological image, DDIT3 status may be evaluated first. In these cases, we show that the DDIT3 telomeric tag amplification assessed by FISH, is a common, nonspecific feature, which is also found in classical DDLPS and WDLPS. Therefore, we believe that co-amplification of DDIT3 and MDM2 may be considered a spectrum of the 12q13–15 region amplification due to the specification of FISH methodology.

    • Rational drug design, synthesis, and biological evaluation of novel chiral tetrahydronaphthalene-fused spirooxindole as MDM2-CDK4 dual inhibitor against glioblastoma

      2020, Acta Pharmaceutica Sinica B

      Simultaneous inhibition of MDM2 and CDK4 may be an effective treatment against glioblastoma. A collection of chiral spirocyclic tetrahydronaphthalene (THN)-oxindole hybrids for this purpose have been developed. Appropriate stereochemistry in THN-fused spirooxindole compounds is key to their inhibitory activity: selectivity differed by over 40-fold between the least and most potent stereoisomers in time-resolved FRET and KINOMEscan® in vitro assays. Studies in glioblastoma cell lines showed that the most active compound ent-4g induced apoptosis and cell cycle arrest by interfering with MDM2 -P53 interaction and CDK4 activation. Cells treated with ent-4g showed up-regulation of proteins involved in P53 and cell cycle pathways. The compound showed good anti-tumor efficacy against glioblastoma xenografts in mice. These results suggested that rational design, asymmetric synthesis and biological evaluation of novel tetrahydronaphthalene fused spirooxindoles could generate promising MDM2-CDK4 dual inhibitors in glioblastoma therapy.

    • A review of retroperitoneal liposarcoma genomics

      2020, Cancer Treatment Reviews

      Retroperitoneal liposarcomas are rare tumours that carry a poorer prognosis than their extremity counterparts. Within their subtypes – well differentiated (WDL), dedifferentiated (DDL), myxoid (MLS) and pleomorphic (PLS) - they exhibit a diverse genomic landscape. With recent advances in next generation sequencing, the number of studies exploring this have greatly increased. The recent literature has deepened our understanding of the hallmark MDM2/CDK4 amplification in WDL/DDL and addressed concerns about toxicity and resistance when targeting this. The FUS-DDIT3 fusion gene remains the primary focus of interest in MLS with additional potential targets described. Whole genome sequencing has driven identification of novel genes and pathways implicated in WDL/DDL outside of the classic 12q13-15 amplicon. Due to their rarity; anatomical location and histologic subtype are infrequently mentioned when reporting the results of these studies. Reports can include non-adipogenic or extremity tumours, making it difficult to draw specific retroperitoneal conclusions. This narrative review aims to provide a summary of retroperitoneal liposarcoma genomics and the implications for therapeutic targeting.

    • The combination of gemcitabine and docetaxel arrests a doxorubicin-resistant dedifferentiated liposarcoma in a patient-derived orthotopic xenograft model

      2019, Biomedicine and Pharmacotherapy

      Citation Excerpt :

      LS can be divided in four groups: well-differentiated liposarcoma (WDLPS), dedifferentiated liposarcoma (DDLS), myxoid/round cell liposarcoma (MLPS), and pleomorphic liposarcoma (PLPS) [3]. DDLS is characterized by the overexpression of DDIT3 (DNA-damage-inducible transcript 3), CDK4 (cyclin dependent kinase 4) and MDM2 (mouse double minute 2 homolog) [4–7]. Peng et al. [8] reported overexpression of several receptors in DDLS.

      Liposarcoma (LS) is a chemotherapy-resistant disease. The aim of the present study was to find precise therapy for a recurrent dedifferentiated liposarcoma (DDLS) in a patient-derived orthotopic xenograft (PDOX) model. The DDLS PDOX models were established orthotopically in the right inguinal area of nude mice. The DDLS PDOX models were randomized into five groups: untreated; doxorubicin (DOX); gemcitabine (GEM) combined with docetaxel (DOC); pazopanib (PAZ); and yondelis (YON). On day 15, all mice were sacrificed. Measurement of tumor volume and body weight were done two times a week. The DDLS PDOX was resistant to DOX (P > 0.184). YON suppressed tumor growth significantly compared to control group (P < 0.027). However, only GEM combined with DOC arrested the tumor growth (P < 0.001). These findings suggest that GEM combined with DOC has clinical potential for this and possibly other DDLS patients.

    • Molecular updates in adipocytic neoplasms <sup>✰</sup>

      2019, Seminars in Diagnostic Pathology

      Citation Excerpt :

      YEATS4, amplified in 81–86% of ALT/WDL/DDLPS,2,3,49,50 is thought to cooperate with MDM2 in the repression of p53,51 while amplification of TERT, located on 5p, and amplified along with NKD2, IRX2, TRIO, AMACR, SKP2, and RICTOR,51 may prevent cellular senescence in some cases. Amplified genes on 12q involved in adipogenic differentiation include HMGA2, amplified in 75–100% of ALT/WDL/DDLPS, usually with truncation of the 3′ end,1–3 DDIT3, amplified in up to 32%,1,4,50 and PTPRQ, on 12q21, in 46%.4,52 Amplified genes on other chromosomes associated with the inhibition of adipocytic differentiation include YAP1 (11q22.1) and CEBPA (19q13.11).4,53,54

      Adipocytic neoplasms include a diversity of both benign tumors (lipomas) and malignancies (liposarcomas), and each tumor type is characterized by its own unique molecular alterations driving tumorigenesis. Work over the past 30 years has established the diagnostic utility of several of these characteristic molecular alterations (e.g. MDM2 amplification in well- and dedifferentiated liposarcoma, FUS/EWSR1-DDIT3 gene fusions in myxoid liposarcoma, RB1 loss in spindle cell/pleomorphic lipoma). More recent studies have focused on additional molecular alterations which may have therapeutic or prognostic impact. This review will summarize several of the important molecular findings in adipocytic tumors that have been described over the past 10 years.

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    FAQs

    What does positive for MDM2 mean? ›

    A positive result is consistent with amplification of the MDM2 gene locus (12q15) and supports the diagnosis of parosteal osteosarcoma or low-grade central osteosarcoma. A negative result indicates an absence of amplification of the MDM2 gene locus (12q15).

    What does MDM2 amplification mean? ›

    MDM2 amplification by FISH is designed to detect amplification of the MDM2 gene to aid in patient diagnosis of soft tissue and bone tumors. In soft tissue tumors, MDM2 amplification is a frequent and specific finding in well differentiated liposarcoma/atypical lipomatous tumor (ref.

    What is dedifferentiated liposarcoma? ›

    Dedifferentiated liposarcoma is a high-grade nonlipogenic sarcoma that arises in a background of a preexisting well-differentiated liposarcoma. The phenomenon of dedifferentiation is time dependent, and primary or de novo tumors exceed secondary neoplasms in a ratio of 9:1.

    What causes MDM2 amplification? ›

    MDM2 amplification was most commonly associated with liposarcoma. Concomitant alterations in additional genes such as CDK4 amplification and TP53 mutations, along with variable responses to targeted therapies including MDM2 inhibitors, suggest that further combinational studies are needed to target this population.

    What is MDM2 and CDK4? ›

    Atypical lipomatous tumor/well-differentiated liposarcoma (ALT/WDL) and dedifferentiated liposarcoma (DDL) are reported to have murine double-minute type 2 (MDM2) and cyclin-dependent kinase 4 (CDK4) amplification as a characteristic genetic alteration.

    What is CDK4 amplification? ›

    CDK4 Amplification is a predictive biomarker for use of palbociclib in patients. Of the therapies with CDK4 Amplification as a predictive biomarker, 1 has NCCN guidelines in at least one clinical setting. Liposarcoma has the most therapies targeted against CDK4 Amplification or its related pathways [5].

    How can you tell the difference between lipoma and liposarcoma? ›

    The biggest distinction is that lipoma is noncancerous (benign) and liposarcoma is cancerous (malignant). Lipoma tumors form just under the skin, usually in the shoulders, neck, trunk, or arms. The mass tends to feel soft or rubbery and moves when you push with your fingers.

    How long can you live with dedifferentiated liposarcoma? ›

    Around 90 out of 100 people (around 90%) with well differentiated liposarcomas in the connective tissue of the trunk of the body survive their cancer for 5 years or more after they are diagnosed.

    Can you survive dedifferentiated liposarcoma? ›

    Patients with a low grade and well differentiated sarcoma have a relatively good prognosis with a five-year survival rate of 85%. Conversely, patients with a high grade tumor (e.g. dedifferentiated sarcoma) have a poor prognosis with a five-year survival rate of 18-21%.

    How do you treat dedifferentiated liposarcoma? ›

    The standard treatment for localized DDL is surgery, with or without radiotherapy. In advanced disease, the standard first-line therapy is an anthracycline-based regimen, with either single-agent anthracycline or anthracycline in combination with the alkylating agent ifosfamide.

    What does negative for MDM2 amplification mean? ›

    A negative result indicates an absence of amplification of the MDM2 gene locus (12q15). However, negative results do not exclude the diagnosis of low-grade central osteosarcoma or parosteal osteosarcoma.

    What are the two roles of MDM2? ›

    In this classic model, MDM2 directed p53 ubiquitination and degradation play the central role. However, emerging evidence suggests dual roles of MDM2 as a repressor of p53 activity. Ubiquitination dependent and ubiquitination independent mechanisms are jointly present to control p53 activity.

    Why is MDM2 important in cells? ›

    Mdm2 (murine double minute 2 homolog) is best known for its role as a negative regulator of the tumor-suppressor p53. Due to the ability of p53 to induce cell-cycle arrest and apoptosis, tight regulation of this protein is necessary for normal cellular growth and development.

    Is MDM2 a tumor suppressor? ›

    MDM2 is an oncogene that mainly functions to modulate p53 tumor suppressor activity. In normal cells the MDM2 protein binds to the p53 protein and maintains p53 at low levels by increasing its susceptibility to proteolysis by the 26S proteosome.

    What happens when MDM2 is mutated? ›

    We report that mutations in MDM2 can impair its p53 degrading ability by various mechanisms, including disrupting the MDM2–p53 interaction and inhibiting its ubiquitin ligase activity. Our results indicate that MDM2 can be functionally inactivated with respect to its presumed primary function of degrading p53.

    Is MDM2 a gene or protein? ›

    Mouse double minute 2 homolog (MDM2) also known as E3 ubiquitin-protein ligase Mdm2 is a protein that in humans is encoded by the MDM2 gene. Mdm2 is an important negative regulator of the p53 tumor suppressor.

    What is the relationship between p53 and MDM2? ›

    p53 and MDM2 form an auto-regulatory feedback loop. p53 stimulates the expression of MDM2; MDM2 inhibits p53 activity because it blocks its transcriptional activity, favours its nuclear export and stimulates its degradation. Different cellular signals, such as DNA-damage or oncogene activation, induce p53 activation.

    What inhibits MDM2? ›

    Similar to Nutlin-3a, RG7112 is a cis-imidazoline nongenotoxic inhibitor that by binding to the p53 pocket on MDM2 and mimicking the interaction of Phe19, Trp23, and Leu26, effectively inhibits the p53–MDM2 interaction [13, 17].

    Where is MDM2 found? ›

    In humans, the MDM2 gene (also known as HDM2) is located on chromosome 12q14. 3-q15 and most frequently expresses a 491 amino acid residue protein. MDM2 is amplified at an overall frequency of 7% in human cancers and at a higher frequency within soft tissue sarcomas, osteosarcomas, and esophageal carcinomas (4, 5).

    How is MDM2 activated? ›

    A major p53-dependent gene is the cyclin-dependent kinase inhibitor, p21, which plays a critical role in cell cycle arrest. Importantly, p53 activation induces mdm2, serving to terminate p53-dependent programming when DNA repair is complete. The regulation of p53 is a complex and complicated network.

    What is CDK4 gene? ›

    Cyclin-dependent kinase 4 (CDK4) is a gene that encodes a protein that is a member of the serine/threonine kinase family. The protein functions in the progression of the cell cycle at from G1 to S phase and the activation of RB1.

    What happens to p53 and MDM2 upon DNA damage? ›

    Upon DNA damage or other stressors, however, p53 is released from MDM2 inhibition and allowed to accumulate, inducing gene expression that triggers cell cycle arrest and apoptosis. It should be noted that prior to p53 activation, MDM2 must be inhibited.

    What is a liposarcoma? ›

    Liposarcoma is a type of cancer that occurs in fat cells in the body, most often in the muscles of the limbs or the abdomen. Liposarcoma is a rare type of cancer that begins in the fat cells. Liposarcoma is considered a type of soft tissue sarcoma.

    What is atypical Lipomatous tumor? ›

    What is an atypical lipomatous tumour? Atypical lipomatous tumours are rare tumours which can develop in the soft tissues of the body. This could be in any part of the body, but they are more common in the thigh and arm. They are benign (non-cancerous) tumours but can have a tendency to recur.

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