Correlation of histological grade of dedifferentiation with clinical outcome in 55 patients with dedifferentiated liposarcomas

Use of Mitotic Activity and the Size of Any Dedifferentiated Component for Risk Assessment in MDM2-Amplified Liposarcoma

CONTEXT.—

The characteristic molecular signature for both atypical lipomatous tumor/well-differentiated liposarcoma and dedifferentiated liposarcoma is amplified sequences derived from chromosome 12q13-15, including MDM2 proto-oncogene (MDM2). As the progression of atypical lipomatous tumor/well-differentiated liposarcoma to the more aggressive dedifferentiated liposarcoma has the potential to adversely affect patient outcomes, the extent of the latter component might be important to evaluate.

OBJECTIVE.—

To investigate the correlation between clinicopathologic characteristics, including tumor size, modified Fédération Nationale des Centres de Lutte Contre le Cancer (FNCLCC) grade, molecular data, and outcomes in 123 surgically resected MDM2-amplified liposarcomas.

DESIGN.—

Pathology reports and clinical records were reviewed. A log-rank test was used to compare the survival trends, and univariate logistic regression was performed to identify variables associated with adverse events (distant metastasis and/or death), from which the P value was derived to construct a multivariate regression model.

RESULTS.—

In univariate analysis, the largest single dimension of the dedifferentiated component, the percentage of cells with gain of chromosome 12, mitotic count, and the presence of modified FNCLLC grade 3 were associated with adverse events. In multivariate analysis, the largest single dimension of the dedifferentiated component (odds ratio: 1.169; 95% CI: 1.053, 1.299; P = .003), and a higher mitotic count (odds ratio: 1.133; 95% CI: 1.037, 1.237; P = .006) were correlated with adverse events. There was no statistically significant association between current local recurrence status, overall largest tumor dimension, overall tumor volume, MDM2 copy number, or MDM2 to chromosome 12 centromere probe ratio and adverse outcomes.

CONCLUSIONS.—

Staging dedifferentiated liposarcoma based on the size of the dedifferentiated component better predicts the outcome.

"Enhancing Liposarcoma Prognosis - A New Predictive Scoring System Integrating Histopathological Insights"

Introduction

Liposarcomas are malignant soft tissue tumours with heterogeneous features and variable prognosis. Each entity comprised in this group displays distinct morphology and harbours specific genetic alterations, which correlate with clinical behaviour and therapy response. The aim of this study is to analyse the clinical and histopathological features that can influence the prognosis of liposarcoma. We also present a newly designed scoring system that could be useful for predicting the risk of disease progression and death in patients with different liposarcoma subtypes.

Materials and Methods

We carried out a retrospective multicentric study on 77 liposarcomas diagnosed between 2009 and 2023 that were followed up to assess the presence of metastases and survival of the patients. We evaluated the age, gender, tumour location and dimensions, histological subtype, mitotic index, presence and percentage of necrosis, and their association with disease progression and survival.

Results

In this respect, progression-free survival was positively associated with lower mitotic index, somatic soft-tissue localization, well-differentiated and myxoid subtypes and absence of necrosis. Overall survival was negatively influenced by older age, higher mitotic index, dedifferentiated and pleomorphic subtypes and the presence of necrosis. Therefore, several clinical and histopathological features of liposarcomas, such as tumour location, mitotic index, and tumour necrosis can strongly predict the disease evolution.

Discussion

This study focuses on developing a new scoring system that considers histologic subtype, mitotic index, and tumour necrosis as indicators that could predict the risk of disease progression and overall survival in patients with liposarcoma. The system classifies liposarcomas of any histological subtype into low-risk and high-risk tumours. Diagnosing liposarcomas using this two-tiered system could be useful for providing personalized therapy, in order to avoid relapses, metastases and improve the disease's prognosis.

Cellular origin and clonal evolution of human dedifferentiated liposarcoma

Dedifferentiated liposarcoma (DDLPS) is the most frequent high-grade soft tissue sarcoma subtype. It is characterized by a component of undifferentiated tumor cells coexisting with a component of well-differentiated adipocytic tumor cells. Both dedifferentiated (DD) and well-differentiated (WD) components exhibit MDM2 amplification, however their cellular origin remains elusive. Using single-cell RNA sequencing, DNA sequencing, in situ multiplex immunofluorescence and functional assays in paired WD and DD components from primary DDLPS tumors, we characterize the cellular heterogeneity of DDLPS tumor and micro-environment. We identify a population of tumor adipocyte stem cells (ASC) showing striking similarities with adipocyte stromal progenitors found in white adipose tissue. We show that tumor ASC harbor the ancestral genomic alterations of WD and DD components, suggesting that both derive from these progenitors following clonal evolution. Last, we show that DD tumor cells keep important biological properties of ASC including pluripotency and that their adipogenic properties are inhibited by a TGF-β-high immunosuppressive tumor micro-environment.

Dedifferentiation in bone and soft tissue sarcomas: How do we define it? What is prognostically relevant?

Dedifferentiation traditionally is defined by descriptive criteria as a tumor showing an abrupt change in histology from a conventional, classic, low-grade appearing neoplasm to a tumor that is more cellular, pleomorphic and "high grade", with grading typically being performed by subjective criteria. The dedifferentiated areas range from areas with recognizable histologic differentiation which differs from the primary tumor (such as an osteosarcoma arising from a low-grade chondrosarcoma) to areas containing sarcomas without specific histologic differentiation (such as pleomorphic or spindle cell sarcoma). Many, but not all, dedifferentiated tumors are aggressive and associated with significantly shorter survival than their conventional counterparts, even grade 3 conventional tumors. As a result, dedifferentiated tumors are generally considered to be clinically aggressive and as a result, more aggressive surgery or the addition of (neo)adjuvant chemotherapy is often considered. However, long-term (greater than 20 year) survivors are reported in the most common dedifferentiated bone and soft tissue sarcomas. Moreover, use of mitotic criterion for defining dedifferentiation in dedifferentiated liposarcoma as well as grading (by the French system) have been found to be associated with survival. This paper reviews the literature on dedifferentiated chondrosarcoma, dedifferentiated liposarcoma, dedifferentiated chordoma and dedifferentiated parosteal osteosarcoma. As a result of that review, recommendations are advocated to identify evidence-based, objective diagnostic and grading criteria for dedifferentiation that are appropriate for each tumor type. Adding such criteria will improve consistency in diagnosis worldwide, allow easier comparison of clinical research performed on dedifferentiated tumors and help communicate (to patients and clinicians) the tumors with highest risk of clinically aggressive behavior, to allow appropriate and personalized treatment planning.

Case Report: Primary low-grade dedifferentiated liposarcoma of the urinary bladder with molecular confirmation

Liposarcomas originating in the urinary bladder are extremely rare. Only six cases of bladder liposarcoma have been reported, and all have been described as myxoid liposarcomas. Notably, none of the patients underwent molecular testing. Here, we report a dedifferentiated liposarcoma (DDL) that occurred in the urinary bladder, primarily in a 69-year-old Chinese woman, with infrequent low-grade dedifferentiation. Computed tomography (CT) revealed an ill-defined solid mass in the anterior bladder wall. The patient underwent a partial bladder resection. Histologically, the tumor cells with mild-to-moderate nuclear atypia were arranged in fascicular and storiform patterns, mimicking a low-grade fibroblastic tumor. In addition, scattered small foci of typical lipoma-like well-differentiated components were identified. Immunohistochemically, the tumor tested positivity for MDM2, CDK4, and p16. Fluorescence in situ hybridization revealed MDM2 gene amplification in the neoplastic cells. Whole-exome sequencing showed that this tumor also harbored CDK4, TSPAN31, and JUN amplification. At the latest follow-up (85 months after surgery), the patient was alive, with no evidence of disease. To the best of our knowledge, this is the first example of a molecularly confirmed primary bladder liposarcoma and the first case of DDL at this site.

The Conundrum of Dedifferentiation in a Liposarcoma at a Peculiar Location: A Case Report and Literature Review

Dedifferentiated liposarcoma of the deep soft tissue of the lower extremities is an infrequent finding. Myxoid liposarcoma is considered the most common soft tissue neoplasia arising in this anatomic region. Divergent differentiation usually occurs within well-differentiated liposarcoma and is exceedingly rare in a myxoid liposarcoma. We report a 32-year-old man who developed a dedifferentiated liposarcoma of the thigh on the background of a pre-existing myxoid liposarcoma. The gross examination of the surgical specimen showed a 11/7/2 cm tumour mass with solid tan-grey areas and focal myxoid degeneration. The microscopic examination revealed a malignant lipogenic proliferation, containing round cells with hyperchromatic nuclei and atypical lipoblasts, confined to the basophilic stroma with a myxoid aspect. Abrupt transition towards a hypercellular, non-lipogenic area consisting of highly pleomorphic spindle cells with atypical mitotic figures was also noted. Immunohistochemical staining was performed. Tumour cells in the lipogenic area were intensely positive for S100 and p16, and CD34 staining highlighted an arborizing capillary network. The dedifferentiated tumour areas showed positive MDM2 and CDK4 staining within neoplastic cells, with the Ki 67 proliferation marker expressed in approximately 10% of the cells. Wild-type TP53 protein expression pattern was documented. Thus, the diagnosis of a dedifferentiated liposarcoma was established. This paper aims to provide further knowledge about liposarcomas with divergent differentiation at peculiar locations, emphasizing the importance of histopathologic examination and immunohistochemical analysis for establishing the diagnosis and assessing the therapeutic response and prognosis of this condition.

Dedifferentiated liposarcoma in the extremity and trunk wall: A multi-institutional study of 132 cases by the Japanese Musculoskeletal Oncology Group (JMOG)

BACKGROUND

Dedifferentiated liposarcoma occurs predominantly in the retroperitoneum. Given the paucity of cases, information on the clinical characteristics of this entity in the extremities and trunk wall is quite limited. In particular, the significance of preoperative evaluation and principles of intraoperative management of the different components, i.e., well-differentiated and dedifferentiated areas, are still to be defined.

METHODS

Clinical characteristics, treatment outcomes, and risk factors for poor oncological outcomes in cases of dedifferentiated liposarcoma in the extremity or trunk wall were analyzed by a retrospective, multicentric study.

RESULTS

A total of 132 patients were included. The mean duration from the initial presentation to dedifferentiation was 101 months in dedifferentiation-type cases. The 5-year local recurrence-free survival, metastasis-free survival, and disease-specific survival rates were 71.6%, 75.7%, and 84.7%, respectively. Among 32 patients with metastasis, 15 presented with extrapulmonary metastasis. A percentage of dedifferentiated area over 87.5%, marginal/intralesional margin, and R1/2 resection in the dedifferentiated area were independent risk factors for local recurrence. Dedifferentiated areas over 36 cm², French Federation of Cancer Centers Sarcoma Group grade III, and intralesional or marginal resection were independent risk factors for metastasis. A dedifferentiated area over 77 cm² and lung metastasis were independent risk factors for disease-specific mortality.

CONCLUSIONS

The typical clinical characteristics of dedifferentiated liposarcoma in the extremity and trunk wall were reconfirmed in the largest cohort ever. The evaluation of the dedifferentiated area in terms of grade, extension, and pathological margin, together with securing adequate surgical margins, was critical in the management of this entity.

Silver In Situ Hybridization for the Rapid Assessment of MDM2 Amplification in Soft Tissue and Bone Tumors. Validation Based on an Audit of 192 Consecutive Cases Evaluated by Silver In Situ Hybridization and Fluorescence In Situ Hybridization

The discovery of almost invariable mouse double minute 2 (MDM2) amplification among atypical lipomatous tumors (ALT)/well-differentiated liposarcoma and dedifferentiated liposarcoma is incorporated into the contemporary diagnostic workup of fatty lesions. MDM2 amplifications are also found frequently in intimal sarcomas and in low-grade osteogenic sarcoma. At present, fluorescence in situ hybridization (FISH) is the reference test for MDM2 assessment. We are interested in evaluating silver in situ hybridization (SISH) for this purpose. Between October 2016 and May 2020, in 192 consecutive cases requiring MDM2 FISH, SISH was also performed concurrently, including 77 (40.1%) core biopsies and 115 (58.9%) surgical specimens. The mean patient age was 61.0 years. SISH results were available overnight or within 48 hours if repeat testing was required. FISH results were available within 2 to 5 weeks. The cost of SISH was one third of FISH. FISH demonstrated MDM2 amplification in 44 cases (23.6%), was negative in 144 cases (74.4%) and nondiagnostic in 4 decalcified cases (2.0%). SISH showed MDM2 amplification in 33 cases (17.2%), no amplification in 119 cases (62.0%), and indeterminate results because of poor signal in 40 (20.8%) cases. All 33 (100%) SISH-amplified tumors and 113 of 119 (95.0%) nonamplified results were confirmed by FISH. There were no clear differences in the performance of SISH on NCB versus surgical specimens. The overall performance indices of SISH are sensitivity 75%, specificity 78.5%, positive predictive value 100%, and negative predictive value 95.8%. FISH is not required when SISH is clearly amplified. This is clinically useful and improves efficiency. Nonamplified SISH results provide early indications of the likely FISH findings, but there is a 4.2% chance of FISH being positive. At present, the main drawback of SISH is the high rate of nondiagnostic tests. Optimization of SISH signal detection to reduce the proportion of indeterminate results is our current focus.

A Rare Case of Low-Grade Dedifferentiated Liposarcoma Presenting as a Pharyngeal Polyp: Avoiding a Pitfall With Significant Repercussions

Dedifferentiated liposarcoma is a nonlipogenic sarcoma of variable histological grade that frequently arises in association with a well-differentiated liposarcoma. Dedifferentiation occurs in approximately 10% of well-differentiated liposarcomas and is most commonly encountered in the retroperitoneum. Dedifferentiated liposarcoma of the upper respiratory tract is an extremely rare occurrence. Herein, we report a very rare case of low-grade dedifferentiated liposarcoma of the pharynx that presented as a polyp mimicking a benign process clinically and microscopically. We discuss the relevant molecular findings and review the current literature.

Clinicopathological and Histopathological Review of Dedifferentiated Liposarcoma: A Comprehensive Study of 123 Primary Tumours

AIMS

Dedifferentiated liposarcoma (DDLS) exhibits varying histopathological features, but their significance for the biological behaviour of this disease has not been fully clarified. This study aimed at elucidating the prognostic factors of DDLS by clinicopathologically reviewing a large case series.

METHODS AND RESULTS

We clinicopathologically reviewed 123 cases of primary de novo DDLS without preoperative treatment, including 81 in the internal trunk (internal DDLS) and 42 in peripheral sites (peripheral DDLS). Univariate and multivariate analyses of their features were also performed for all cases, the internal DDLS group, and the peripheral DDLS group. The results showed that, in all three groups, distant metastasis was significantly associated with shorter overall survival (OS) (univariate analysis, P<0.0001, =0.0011, and 0.0101, respectively), whereas local recurrence showed no significant effect on prognosis. Histopathologically, high mitotic count and the presence of round tumour cells were significantly associated with shorter OS in multivariate analysis of the internal DDLS group (P=0.0022, HR=4.39, 95% CI 1.71-11.28; P=0.0014, HR=7.19, 95% CI 2.14-24.16, respectively). Meanwhile, in the peripheral DDLS group, necrosis and high-grade histological components were significantly associated with shorter OS (univariate analysis, P=0.0068 and 0.0174, respectively).

CONCLUSIONS

The presence of round tumour cells may be one of the histological factors associated with a worse prognosis in DDLS, as previous studies indicated. This work also suggested that distant metastasis may be predictive of prognosis in both internal and peripheral DDLS, instead of local recurrence.

What Are the Results of Resection of Localized Dedifferentiated Liposarcomas in the Extremities?

BACKGROUND

Dedifferentiated liposarcoma (DDLPS) is a rare malignancy that transitions from an atypical lipomatous tumor to a sarcoma with a variable morphologic appearance. The behavior of this tumor in the retroperitoneum is aggressive, but the behavior of DDLPS in the extremities is less well-defined because it is rare. Few reports have assessed the imaging features and clinical outcomes of primary DDLPS in the extremities.

QUESTIONS/PURPOSES

In patients with primary DDLPS of the extremity, we asked the following questions: (1) How frequently do additional primary malignancies occur in patients with DDLPS? (2) What is the rate of overall survival, metastases, and local recurrence in DDLPS? (3) What factors are associated with metastasis-free survival and local recurrence in DDLPS?

METHODS

We defined DDLPS as a biphasic neoplasm that transitions from an atypical lipomatous tumor (ALT) to a sarcoma of variable morphologic appearance and histologic grades. We retrospectively evaluated the medical records of patients with DDLPS of the extremities who underwent surgery in our institution between 2003 and 2017. During that time, 16 patients were treated for this diagnosis; one was excluded from this study because the patient did not have an MRI, leaving 15 patients (nine men, six women; their median [range] age was 67 years [42 to 87]) for evaluation. All had a minimum of 2 years follow-up (median [range] 54 months [25 to 136]); 14 of 15 have been seen in the last 5 years (one patient, who was doing well at the time, was lost after 9 years of follow-up). In 11 patients, MRI demonstrated two components: an ALT component with high intensity on both T1-weighed and T2-weighted sequences and a dedifferentiated component low-to-intermediate intensity on T1-weighed and heterogeneous hyperintensity on T2-weighted sequence. Nine patients were evaluated using 2-deoxy-2-18F-fluoro-D-glucose positron emission tomography (FDG-PET) combined with CT (PET/CT). PET/CT showed a biphasic pattern with a close relationship to MRI findings. The dedifferentiated component presented with high FDG uptake (median [range] maximum standardized uptake value 5.1 [1.9 to 22.6]), while the atypical lipomatous tumor component showed almost no FDG uptake. In all patients, immunohistochemical studies of p16 and cyclin-dependent kinase-4 (CDK4) were investigated. Positive staining for both p16 and CDK4 were seen in 13 of 15 patients.We retrospectively evaluated the electronic medical records of all patients in our institution for the presence of additional primary malignancies, local recurrence-free survival, metastasis-free survival, and overall survival. The survival rate was estimated using the Kaplan-Meier method. The Wilcoxon exact test was used to determine the prognostic importance of the following survival variables: age, sex, maximum tumor size, radiotherapy, and surgical margin.

RESULTS

Seven additional primary malignancies developed in five of 15 patients (two lung cancers, two sarcomas, one renal cell cancer, one uterine cancer, and one non-Hodgkin lymphoma). The 3- and 5-year metastasis-free survival rates were 86% (95% CI 0.67 to 1.00) and 75% (95% CI 0.49 to 1.00), respectively. With the numbers available, we found no factors associated with metastasis-free survival. The 3- and 5-year overall survival rates were 100% (95% CI 1.00 to 1.00) and 88% (95% CI 0.65 to 1.00), respectively. Three of 15 patients had local recurrence. The 3- and 5-year local recurrence-free survival rates were 86% (95% CI 0.67 to 1.00) and 75% (95% CI 0.49 to 1.00), respectively. Large (> 15 cm) tumors were more likely to have a local recurrence (p = 0.04).

CONCLUSIONS

In this small series, we found that the extremities are a favorable site for DDLPS compared with the retroperitoneum, although we did not directly compare the two sites. This rare tumor has a relatively high likelihood of being associated with other malignancies. We believe patients should be assessed and monitored carefully for this possibility. In the future, larger studies are needed to better define predictors of local recurrence, although the tumor's size may be associated with a greater propensity for local recurrence.

LEVEL OF EVIDENCE

Level II, prognostic study.

Epidemiology and survival of liposarcoma and its subtypes: A dual database analysis

PURPOSE

Liposarcoma (LPS) is a one of the most commonly diagnosed soft tissue sarcomas. Little is known about the epidemiology and prognosis of each subtype. We present an analysis of epidemiology and survival of the subtypes of LPS using a national database.

METHODS

We queried the Survival Epidemiology, and End Results (SEER) and the Canadian Institute for Clinical Evaluative Sciences (ICES) databases for data on 7 types of LPS. Pearson's chi square was used to determine associations between variables and subtypes. Kaplan-Meier and Cox Regression analyses were performed for two tests: one using SEER data and the other using variables common to both SEER and ICES.

RESULTS

The well-differentiated subtype was the most common subtype identified. Metastatic disease was associated with decreased survival across all subtypes and age >35 was associated with decreased survival in well-differentiated and myxoid subtypes. Tumor grade was associated with decreased survival in the well-differentiated, myxoid, mixed, and round cell subtypes. In the secondary analysis, age >35 was associated with decreased survival in the myxoid subtype.

CONCLUSIONS

The prognosis of liposarcoma differs greatly by subtype. Clinicians should account for patient factors at the time of diagnosis to best navigate treatment of their patients.

Primary anatomical site, adjuvant therapy, and other prognostic variables for dedifferentiated liposarcoma

BACKGROUND

Dedifferentiated liposarcoma (DDLPS) is a high-grade, clinically aggressive tumor associated with low survival probabilities. Prognostic variables for DDLPS have not been previously reported in a large patient population.

METHODS

A total of 3573 patients with primary DDLPS were analyzed from the National Cancer Data Base (NCDB). The 5- and 10-year survival probabilities were calculated, and the groups were compared using log-rank comparisons and multivariable Cox hazard regression analysis. Median survival was also calculated.

RESULTS

Males comprised 65% of the cohort, the median age at diagnosis was 64 years of age, and 65.4% of the patients were between 51 and 75 years of age. The most common site for primary tumors is the retroperitoneum or abdomen (59.5%). Head or neck tumors had the best 5-year outcomes (86.4%) followed by extremities (67.1%), pelvis (65.8%), thorax or trunk (58.9%), and finally retroperitoneum or abdomen (42.6%). Best outcomes were noted in the 26- to 50-year-old age group (5-year survival:66.8%), < 10 cm size (5-year survival:66.1%), FNCLCC grade 1 (5-year survival:69.2%), and stage II disease (5-year survival:66.7%). Radiation therapy yielded the best 5-year and 10-year survival probabilities of 59% and 39.3%, respectively. Out of all the adjuvant therapies, the use of radiation resulted in the best 5-year survival of 63.4%.

CONCLUSION

In the largest and most comprehensive study to date on DDLPS, major findings include primary site as a significant prognostic variable with age at presentation, sex, tumor stage, and type of adjuvant therapy significantly impacting overall survival.

Mesenchymal Neoplasms of the Genitourinary System: A Selected Review with Recent Advances in Clinical, Diagnostic, and Molecular Findings

Mesenchymal neoplasms of the genitourinary (GU) tract often pose considerable diagnostic challenges due to their wide morphologic spectrum, relative rarity, and unexpected incidence at GU sites. Soft tissue tumors arise throughout the GU tract, whether from adventitia surrounding or connective tissues within the kidneys, urinary bladder, and male and female genital organs. This selected article focuses on a subset of these lesions, ranging from benign to malignant and encompassing a range of patterns of mesenchymal differentiation, where recent scholarship has lent greater insight into their clinical, molecular, or diagnostic features.

Subclassification of pleomorphic sarcomas: How and why should we care?

Pleomorphic sarcomas are a heterogeneous group of mesenchymal neoplasms with widely varied clinical behavior but overlapping histologic appearances. The following guidelines are helpful when approaching the diagnosis of a pleomorphic sarcoma. (1) Be aware of the relative incidence of the various sarcoma types: several pleomorphic sarcomas are relatively common (e.g., dedifferentiated liposarcoma and undifferentiated pleomorphic sarcoma), whereas others are exceptionally rare. (2) Pay attention to anatomic location: some pleomorphic sarcomas have a predilection for somatic soft tissues, especially the thigh (e.g., undifferentiated pleomorphic sarcoma, pleomorphic liposarcoma, pleomorphic rhabdomyosarcoma), whereas other pleomorphic sarcomas most often arise in the retroperitoneum (e.g., dedifferentiated liposarcoma). (3) Carefully sample the resection specimen, paying particular attention to areas with differences in gross appearances (e.g., fleshy, fibrous, mucoid, or gritty). (4) Search for histologic clues (i.e., myxoid stroma, lipoblasts, and osteoid matrix, in order to diagnose myxofibrosarcoma, pleomorphic liposarcoma, and extraskeletal osteosarcoma, respectively); these critical diagnostic features may be limited in extent. (5) Apply immunohistochemistry judiciously, after generating a differential diagnosis; always exclude metastatic sarcomatoid carcinoma and melanoma before diagnosing a pleomorphic sarcoma. This review will present an approach to the diagnosis of pleomorphic sarcomas, emphasizing differential diagnosis and the application of ancillary studies (immunohistochemistry and FISH), when relevant.