Dedifferentiated Liposarcoma Research Articles

Primary dedifferentiated liposarcoma of the gallbladder: a case report and literature review

BackgroundLiposarcoma (LPS) is a kind of malignancy of soft tissue usually found in the retroperitoneal, limb, or neck region, and some may be detected with delayed symptoms (pain or palpable mass), and less frequently occurs in organs of the digestive system. In contrast, Dedifferentiated liposarcoma (DDLPS) is a common histological subtype of LPS. The present study reported a case of dedifferentiated liposarcoma originating in the gallbladder. Differentiated liposarcoma originating from the gallbladder is rarely reported.Case descriptionA 64-year-old female patient presented to our hospital with a painless abdominal mass. Abdominal computed tomography (CT) showed that the gallbladder had lost its normal shape, and a 9.1 cm × 7.1 cm × 12.1 cm mass was seen in the area of the gallbladder fossa and the right upper abdomen below it, which had an irregular morphology, inhomogeneous density, and nodular calcification, with marked inhomogeneous enhancement on enhancement scan. Preoperative tumor markers and liver function indicators were not abnormal. With suspicion of a giant malignant tumor of the gallbladder, she underwent a cholecystectomy combined with abdominal mass resection. After surgery, the tumor and gallbladder, were completely resected, and postoperative pathological results confirmed the diagnosis of dedifferentiated liposarcoma deriving from gallbladder. After surgery, the patient and his family refused to continue treatment. After 15 months follow-up, the patient remains asymptomatic and does not show any signs of recurrence. And she is now under continued follow - up.ConclusionsTreatment of dedifferentiated liposarcoma is still at exploratory stage, and a lack of clinical evidence for this condition might hinder access to clinical trials and studies. Currently, the treatment of choice for dedifferentiated liposarcoma remains radical resection. In the available clinical studies, there are no robust data to support clinical use of neoadjuvant and adjuvant radiochemotherapy. As with other diseases, the use of radiotherapy and chemotherapy before and after surgery may be a potential future treatment.

Case report: a rare clinical presentation of a difficult diagnosis of dedifferentiated liposarcoma showing leiomyosarcoma phenotype in the ileocecal region

Dedifferentiated liposarcoma is a malignant lipomatous tumor that rarely occurs in the gastrointestinal tract, including the ileocecal region. In this case, computed tomography and magnetic resonance imaging showed no fatty mass located in the mesenteric or submucosal lesion, and positron emission tomography–computed tomography showed a high maximum standardized uptake value, collectively indicating the gastrointestinal stroma tumor and lymphoma. The pathological findings resemble leiomyosarcoma; the immunohistochemistry findings including mouse double minute 2 homolog and cyclin D-dependent kinase-4 and amplification of mouse double minute 2 homolog in fluorescence in situ hybridization just favored the diagnosis of dedifferentiated liposarcoma with leiomyosarcoma phenotype and not leiomyosarcoma. Recently, a new inhibitor for mouse double minute 2 homolog and cyclin D-dependent kinase-4 has been developed, and clinical trials for dedifferentiated liposarcoma are currently ongoing. This could change the treatment strategy drastically compared with other soft tissue sarcomas. Hence, a correct diagnosis of dedifferentiated liposarcoma is required.

Radiomic features of primary retroperitoneal sarcomas: a prognostic study

BackgroundRisk-stratification of patients with retroperitoneal sarcomas (RPS) relies on validated nomograms, such as Sarculator. This retrospective study investigated whether radiomic features extracted from computed tomography (CT) imaging could i) enhance the performance of Sarculator and ii) identify G3 dedifferentiated liposarcoma (DDLPS) or leiomyosarcoma (LMS), which are currently consider in a randomized clinical trial testing neoadjuvant chemotherapy. MethodsPatients with primary localized RPS treated with curative-intent surgery (2011-2015) and available pre-operative CT imaging were included. Regions of interest (ROIs) were manually annotated on both unenhanced and portal venous phase acquisitions. Top performing radiomic features were selected with outcome-specific random forest models, through generation of replicative experiments (contexts) where patients were split into training and testing sets. Endpoints were overall and disease-free survival (OS, DFS).Prognostic models for DFS and OS included the top five selected radiomic features and the Sarculator nomogram score.Models accuracy was assessed with Harrell’s Concordance (C-)index. ResultsThe study included 112 patients, with a median follow-up of 77 months (IQR 65-92 months).Sarculator alone achieved a C-index of 0.622 and 0.686 for DFS and OS, respectively. Radiomic features only marginally enhanced the prediction accuracy of Sarculator for OS (C-index=0.726, C-index gain: 0.04) or DFS (C-index=0.639, C-index gain: 0.017). Finally, radiomic features identified patients with G3 DDLPS or LMS with an accuracy of 0.806. ConclusionRadiomic features marginally improved the performance of Sarculator in RPS.However, they accurately identified G3 DDLPS or LMS at diagnosis, potentially improving patients selection for neoadjuvant treatments.

Safety and efficacy of pembrolizumab, radiation therapy, and surgery versus radiation therapy and surgery for stage III soft tissue sarcoma of the extremity (SU2C-SARC032): an open-label, randomised clinical trial.

Approximately half of patients with localised, high-risk soft tissue sarcoma of the extremity develop metastases. We aimed to assess whether the addition of pembrolizumab to preoperative radiotherapy and surgery would improve disease-free survival. We completed an open-label, randomised clinical trial in patients with grade 2 or 3, stage III undifferentiated pleomorphic sarcoma or dedifferentiated or pleomorphic liposarcoma of the extremity and limb girdle. Patients were enrolled at 20 academic institutions in Australia, Canada, Italy, and the USA. Patients were randomly assigned to preoperative radiotherapy then surgery (control group) or preoperative pembrolizumab with radiotherapy (initiated 1-14 days after the first dose of pembrolizumab) then surgery and postoperative pembrolizumab (experimental group). Pembrolizumab (200 mg intravenously every 3 weeks) was administered as three neoadjuvant cycles (before, during, and after radiotherapy) and 14 or less adjuvant cycles. Primary endpoint was disease-free survival. This study is registered with ClincialTrials.gov (NCT03092323). Between Nov 18, 2017, and Nov 14, 2023, 143 participants were randomly assigned to treatment. A modified intention-to-treat analysis of 127 patients with median follow-up of 43 months showed that the experimental group (n=64) had significantly longer disease-free survival than the control group (n=63; log-rank one-sided p=0·035; hazard ratio [HR] 0·61; 90% CI 0·39-0·96). The 2-year disease-free survival increased by 15% with addition of pembrolizumab: 52% (90% CI 42-64) and 67% (90% CI 58-78) for the control and experimental groups, respectively. Disease-free survival was similarly improved with pembrolizumab for the intention-to-treat patient population (HR 0·61 [90% CI 0·39-0·95]). Grade 3 or higher adverse events occurred more frequently in the experimental group (56%) than the control group (31%). Addition of pembrolizumab to preoperative radiotherapy and surgery improves disease-free survival for patients with stage III undifferentiated pleomorphic sarcoma and pleomorphic or dedifferentiated liposarcoma of the extremity, which establishes a promising new treatment option for these patients. Stand Up to Cancer and Merck Sharp & Dohme.

Identification of the First Case of Dedifferentiated Liposarcoma in Amphibians: Insights from Maculopaa medogensis

Dedifferentiated liposarcoma (DDLPS) is a rare and aggressive type of cancer primarily reported in humans, with no documented cases in animals. In this study, we present the first case of DDLPS in a wild amphibian species, Maculopaa medogensis. The tumor was discovered during a routine examination and diagnosed through a combination of advanced diagnostic methods, including micro-CT imaging, gross anatomical inspection, histological analysis, and immunohistochemistry. The tumor exhibited both well-differentiated and dedifferentiated components, characteristic of DDLPS, with evidence of tissue invasion and multiple metastases. Immunohistochemical analysis revealed the strong positive expression of markers such as S100A4, CDK4, MDM2, and CD34, while Leptin expression was negative, further confirming the diagnosis. This is the first reported case of DDLPS in a non-human species, expanding our understanding of cancer in wildlife and underscoring the significance of amphibians as environmental indicators. These findings provide valuable insights for veterinary medicine and wildlife conservation, particularly regarding the role of environmental stressors in cancer development. This study highlights the need for comprehensive diagnostic approaches in wildlife pathology.

Left inguinal dedifferentiated liposarcoma and primary unclassified sarcoma of the left lung as synchronous multiple sarcomas: a case report

BackgroundPulmonary nodules in patients with soft tissue sarcomas are likely pulmonary metastases, whereas synchronous primary pulmonary sarcomas are rare. Without surgery, determining whether a solitary pulmonary nodule is a primary or metastatic nodule is difficult. Herein, we report a rare case of a primary pulmonary sarcoma that presented synchronously with a primary dedifferentiated liposarcoma.Case presentationA 77-year-old man presented to another hospital with left inguinal swelling and a suspected recurrent inguinal hernia. Computed tomography revealed a left inguinal mass and pure-solid nodule in the left lung and the patient was referred to our hospital for detailed examination and treatment. The inguinal mass was pathologically diagnosed as a dedifferentiated liposarcoma using needle biopsy, whereas bronchoscopic biopsy revealed histological findings suggestive of a sarcoma; however, the primary site could not be determined. Positron emission tomography–computed tomography revealed no high-accumulation lesions except for the two sarcomas. We decided to perform surgery on both sarcomas for diagnostic and curative purposes. The surgical specimens showed that the two sarcomas were different. Based on the immunohistochemical staining findings of MDM2, a left inguinal dedifferentiated liposarcoma and primary pulmonary unclassified sarcoma were diagnosed. The patient displayed no evidence of recurrence 1 year after surgery.ConclusionsWe encountered a rare case of synchronous multiple primary sarcomas, one presenting in the lung and the other in the soft tissue. Surgery was required to achieve a definitive diagnosis for the patient, who achieved disease-free survival at 1 year. This case suggests that proactive resection of pulmonary nodules in patients with soft tissue sarcomas may be feasible as a diagnostic treatment if complete resection is achieved.

Evaluation of morphological patterns and immunohistochemical characteristics of well-differentiated and dedifferentiated liposarcomas

Evaluation of morphological patterns and immunohistochemical characteristics of well-differentiated and dedifferentiated liposarcomas

MDM2 Testing In Lipomatous Tumors: An Institutional Experience with 1,161 Neoplasms

Abstract Introduction/Objective Amplifications of the MDM2 gene is a well-recognized central molecular event in atypical lipomatous tumors, well-differentiated liposarcomas, and dedifferentiated liposarcomas. However, given the fact that most adipocytic neoplasms are benign, the specific testing approaches that will maximize the detection of MDM2 amplified tumors in an accurate and cost-efficient manner remains unclear. The purpose of this study is to present our experience with MDM2 testing by FISH in a large cohort of lipomatous neoplasms. Methods/Case Report The pathologic database of an academic medical center was queried for all lipomatous tumors as well as all tumors for which MDM2 testing was performed during a three-year period. At our center, MDM2 testing for well differentiated adipocytic neoplasms is triggered by the so-called “traditional criteria”: a deep tumor and/or tumor size >10 cm and/or recurrence. We also take an expanded approach for a variety of indications that may include equivocal atypia or clinical/imaging concern, among others. Testing is also performed on overt malignancies for which dedifferentiated liposarcoma is a plausible consideration after review of morphologic features. Clinicopathologic data, including patient age of diagnosis, tumor size, depth of tumor, results from MDM2 testing [when performed], anatomic location(s) and recurrence [where applicable], were collected for each patient. Results (if a Case Study enter NA) 1161 cases were assessed, 456 of whom underwent MDM2 testing, and 108 of which were ultimately classified as MDM2 amplified. Standardized bivariable comparisons found that a deep tumor location (p=0.0014) and older age (p=0.0002), but not tumor size at the >10 cm cut off were associated with MDM2 positivity. However, a logistic regression model showed that neither size, depth or age were significantly associated with MDM2 positivity. Among the MDM2-positive cohort, 91% had tumor sizes <10 cm, 14% were superficial, 23% were non-recurrent and 15% were less than the median cohort patient age of 58 years. If the aforementioned “traditional criteria” were used as the sole basis for MDM2 testing, 50 (46.29%) of the 108 cases that were ultimately classified as MDM2 positive would not have been tested. Conclusion Our findings suggest that a strict adherence to “traditional criteria” may result in a significant subset of MDM2 positive tumors not being tested in lipomatous tumors. A more expansive approach that incorporates additional indications for testing, should be evaluated.

Anti-LAN Antibodies: Clinical Implications and Case Presentation

Abstract Introduction/Objective The LAN system, originating from the 901 Series of High Incidence antigens, transitioned to a recognized System in 2012. The LAN antigen, situated on ABCB6, a multipass membrane protein associated with porphyrin transport, plays a crucial role in heme synthesis. Functionally, LAN acts as an ATP-binding cassette transporter on the red blood cell membrane. Comprising a single antigen, LAN exhibits elevated expression in various tissues including the heart, skeletal muscles, fetal liver, mitochondrial membrane, eye, and Golgi apparatus. Notably, LAN shows no specific association with any particular geographic or ethnic group. Resistant to Ficin/Papain, Trypsin, α-Chymotrypsin, and 0.2M DTT, LAN antibodies primarily consist of IgG and necessitate IAT for detection. While Anti-LAN has been implicated in Hemolytic Transfusion Reactions (HTRs), its involvement in Hemolytic Disease of the Fetus and Newborn (HDFN) remains infrequent. LAN-negative blood is exceedingly rare, often requiring Monocyte Monolayer Assay Testing (MMA) for clinical assessment. Methods/Case Report Case Presentation: An 81-year-old female with a medical history including seizure disorder, hypertension (HTN), hyperlipidemia (HLD), gastroesophageal reflux disease (GERD), small bowel obstruction, and high-grade de-differentiated metastatic retroperitoneal liposarcoma presented for preoperative evaluation. A type and screen ordered as part of outpatient preoperative assessments revealed a positive antibody screen. Further investigation traced the origin of the anti-LAN antibody to an external facility since 2017. Antibody identification indicated the reactivity of the patient’s plasma with all cells (1+ AHG in PEG), excluding the auto control. Utilizing rare frozen antisera anti-LAN, the patient was phenotyped for LAN, yielding a LAN-negative status. Subsequent testing with three rare frozen LAN-negative group O cells aimed to exclude clinically significant antibodies. Differential adsorption, employing a comprehensive baseline RBC phenotype record obtained from the external facility, ruled out anti-E, anti-K, and anti-Fyb, thereby confirming Anti-LAN specificity. Results (if a Case Study enter NA) NA Conclusion The exceptional rarity of LAN-negative blood underscores the high prevalence of reactivity to Anti-LAN antibodies, exceeding 99% in most populations. In select cases, autologous transfusion may emerge as a viable management strategy. Consequently, the patient’s surgical procedure has been deferred, with no immediate requirement for blood products.

Characterizing the Transformation and Diagnosis of Atypical Lipomatous Tumor to Dedifferentiated Liposarcoma: Single Institutional Outcomes.

Atypical lipomatous tumor (ALT) in the extremities is a locally aggressive adipocytic tumor with the potential risk of transformation into dedifferentiated liposarcoma (DDLS). Studies seldom differentiate whether DDLS was diagnosed on initial biopsy, final resected specimen, or subsequent recurrence. Our study seeks to characterize how and when patients received their ALT or DDLS diagnoses to better understand the relationship between the two neoplasms. We performed a retrospective review of patients diagnosed with ALT or DDLS of the extremities. Clinical characteristics, including the method of diagnosis of an ALT or DDLS, time between diagnoses, and tumor recurrence was recorded. Univariate/multivariate analysis was performed to identify risk factors. Forty-five patients were diagnosed with ALT after core needle biopsy (CNB) and 41 of them received marginal en bloc excision. Three (7.3%) of these patients had a heterogeneous tumor on final resection, pathology revealed both ALT and DDLS. Four patients (8.2%) were diagnosed with DDLS from CNB and received negative margin en bloc excision. One of these tumors was identified as heterogeneous ALT/DDLS after resection. Fifty-three patients received marginal en bloc resection without CNB after a benign lipomatous mass was suspected on CT/MRI. Among these, one (1.9%) had a tumor with a heterogeneous composition of both ALT and DDLS on pathology. There were 11 (11.7%) ALT recurrences and 1 (1.0%) DDLS recurrence after ALT resection. Obtaining a proper diagnosis whether ALT or DDLS is critical. Our cohort found that amongst those concerning lipomatous lesions biopsied, 7.84% will show biopsy proven DDLS. Additionally, 6.67% of the biopsies will be false negatives and show DDLS on final pathology. Furthermore, our local recurrence for ALT was 11.7% recurring as ALT and 1.0% recurring as DDLS.

Efficacy of surgery in the management of multiple recurrences of retroperitoneal dedifferentiated liposarcoma.

Retroperitoneal dedifferentiated liposarcoma is associated with a high risk of recurrence; however, treatment strategies that are more effective than surgery remain to be established. This study aimed to determine the optimal number of surgeries that would be effective for patients with recurrent disease. Furthermore, the improvement in prognosis was evaluated according to the malignancy level. The effect of each type of surgery on the prognosis of 118 patients with retroperitoneal dedifferentiated liposarcoma treated at the Osaka International Cancer Institute between 1997 and 2022 was investigated. Among the 118 patients, 103 underwent initial surgery, while 54 and 30 patients underwent second and third surgeries, respectively. The overall and disease-free survival rates of each group were compared using the Kaplan-Meier method, and the log-rank test was used to determine statistical significance in univariate analysis. 18F-Fluorodeoxyglucose Positron Emission Tomography (FDG-PET) was used to assess malignancy. Maximum standardized uptake values (SUVmax) of ≥ 4 and < 4 were classified as high and low malignancy, respectively. The first and second surgeries resulted in a significant improvement in the overall survival rate, regardless of the malignancy level (p < 0.001); however, no significant improvement in prognosis was observed after the third surgery (p = 0.077). Low-grade malignancies are associated with a better postoperative prognosis, even in cases of recurrence. In contrast, high-grade malignancies exhibit a reduction in surgical efficacy. This study highlights the importance of considering the tumor malignancy level and the patient's overall condition when deciding whether to perform repeated surgical interventions. Surgical treatment can prolong overall survival, even in patients with recurrence; however, it is advisable to assess malignancy levels when determining the suitability of surgery beyond the second recurrence.

S2615 Unveiling the Unusual: Dedifferentiated Liposarcoma Mimicking Pancreatic Pathology in a Gastroenterology Setting

S2615 Unveiling the Unusual: Dedifferentiated Liposarcoma Mimicking Pancreatic Pathology in a Gastroenterology Setting

Mesenteric Dedifferentiated liposarcoma presenting as a massive abdominal lump: A Rare Case

This case study examines a sixty five-year-old male presenting with a distended abdomen, lower back discomfort, and dyspnea on lying down, progressing over three months. Physical examination revealed multiple hard palpable lumps in the abdomen. Initial radiological evaluation indicated a connective tissue tumor, leading to a trucut biopsy revealing a spindle cell neoplasm of uncertain malignant potential. The tumor was found to be resistant to immunotherapy and neoadjuvant chemotherapy. Surgical resection unveiled multiple mesenteric tumors along the small bowel and also involving the descending colon, diagnosed as a dedifferentiated liposarcoma. Liposarcoma encompasses five histological subtypes, with dedifferentiated being the least common and comprised of poorly differentiated cells. Although liposarcomas typically originate from the retroperitoneum, the occurrence of dedifferentiated liposarcoma in the small bowel mesentery is exceedingly rare. This case report aims to underscore this uncommon occurrence, discuss diagnostic and treatment strategies, and advocate for further research into targeted therapies addressing specific immunohistochemistry markers to enhance outcomes for such patients, who generally face a grim prognosis Keywords – dedifferentiated liposarcoma , mesenteric tumors, spindle cell malignancy, mesenchymal tumors of GIT.

Definitive particle therapy using protons or carbon ions for dedifferentiated liposarcoma

BackgroundParticle therapy is effective for the treatment of soft tissue sarcomas. However, the clinical outcomes of definitive particle therapy, particularly for dedifferentiated liposarcoma (DDLS), remain unknown. PurposeTo analyze the treatment outcomes of proton and carbon ion particle therapies for DDLS. MethodsWe retrospectively included patients with DDLS who were treated with particle therapy between 2008 and 2022. The local control (LC), progression-free survival (PFS), and overall survival (OS) rates were evaluated. ResultsFifty-seven patients were included in this analysis. The median patient age was 68 years (range, 36–91 years). The most common tumor site was the retroperitoneum (n = 37), with a median gross tumor volume (GTV) of 181 cm3. Twenty-nine patients received proton therapy, and 28 patients received carbon ion therapy. The most common fractionation dose was 70.4 Gy (relative biological effectiveness) in 32 fractions (72.7 Gy equivalent dose in 2 Gy fractions [EQD2]). The median follow-up time was 33 months (range, 1–128 months). The 3-year LC, PFS, and OS rates were 73.1 %, 44.6 %, and 70.6 %, respectively. Patients who received a higher prescribed dose (≥72.7 Gy EQD2) showed significantly better LC (p = 0.04) than did those who received a lower prescribed dose. Moreover, those with a larger GTV (≥181 cm3) had significantly worse OS (p = 0.04) than did those with a smaller GTV. Late adverse events occurred in five (9 %) patients. ConclusionsParticle therapy using protons or carbon ions for the treatment of DDLS is safe and provides good OS and LC. However, further studies with longer follow-up periods and larger cohorts are warranted.

Predictive Value of Quantitative Parameters of 18F-FDG PET/CT in Patients with Liposarcoma.

The purpose of this study was to evaluate the predictive features of baseline F-18-fluorodeoxy-D-glucose positron emission tomography (18F-FDG PET)/computed tomography (CT) parameters in patients with dedifferentiated liposarcomas (DDLPSs) and well-differentiated liposarcomas (WDLPSs) receiving systemic treatment. A total of 24 patients with liposarcoma who underwent longitudinal 18F-FDG PET/CT in systemic therapy were included. All volumetric segmentation of each tumor section and semiquantitative imaging parameters were extracted from the axial field of view from both PET and CT images. Maximum, mean, and minimum standardized uptake values (SUVmax, SUVmean, and SUVmin), Hounsfield units (HUs), and their respective changes from baseline and posttreatment were calculated. The voxel values from unenhanced CT images were correlated with PET-derived parameters. The 18F-FDG uptake decreased by more than 56% on average in responders for both SUVmax and SUVmean in DDLPS. There was a decrease in HUmax in DDLPS among responders. Using AUC > 0.8 as a reasonable predictor, we found that the ratios of SUVmaxD/HUmean, SUVmaxD/HUmedian, and SUVmeanD/HUmedian at baseline were significant indicators of the response to treatment in patients with liposarcoma. The changes in SUVmean and not just SUVmax parameters could be considered as accurate tumor response indicators. For the first time, we introduced baseline SUV/HU ratios as a valuable diagnostic tool in predicting liposarcoma treatment outcomes. This ability was not revealed by classic semiquantitative PET or CT parameters at baseline.

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.

Disruptions in antigen processing and presentation machinery on sarcoma

BackgroundThe antigen processing machinery (APM) plays a critical role in generating tumor-specific antigens that can be recognized and targeted by the immune system. Proper functioning of APM components is essential for presenting these antigens on the surface of tumor cells, enabling immune detection and destruction. In many cancers, defects in APM can lead to immune evasion, contributing to tumor progression and poor clinical outcomes. However, the status of the APM in sarcomas is not well characterized, limiting the development of effective immunotherapeutic strategies for these patients.MethodsWe investigated 126 patients with 8 types of bone and soft tissue sarcoma operated between 2001–2021. Tissue microarrays mapped 11 specific areas in each case. The presence/absence of APM protein was determined through immunohistochemistry. Bayesian networks were used.ResultsAll investigated sarcomas had some defects in APM. The least damaged component was HLA Class I subunit β2-microglobulin and HLA Class II. The proteasome LMP10 subunit was defective in leiomyosarcoma (LMS), myxoid liposarcoma (MLPS), and dedifferentiated liposarcoma (DDLPS), while MHC I transporting unit TAP2 was altered in undifferentiated pleomorphic sarcoma (UPS), gastrointestinal stromal tumor (GIST), and chordoma (CH). Among different neoplastic areas, high-grade areas showed different patterns of expression compared to high lymphocytic infiltrate areas. Heterogeneity at the patient level was also observed. Loss of any APM component was prognostic of distant metastasis (DM) for LMS and DDLPS and of overall survival (OS) for LMS.ConclusionSarcomas exhibit a high degree of defects in APM components, with differences among histotypes and tumoral areas. The most commonly altered APM components were HLA Class I subunit β2-microglobulin, HLA Class I subunit α (HC10), and MHC I transporting unit TAP2. The loss of APM components was prognostic of DM and OS and clinically relevant for LMS and DDLPS. This study explores sarcoma molecular mechanisms, enriching personalized therapeutic approaches.

Diagnostic Accuracy of Immunohistochemical Expression of p16, MDM2, and CDK4 in Well-Differentiated and De-Differentiated Liposarcoma in MDM2 Fluorescent in situ Hybridisation Confirmed Cases.

To establish the diagnostic utility of immunohistochemistry markers p16 along with MDM2 and CDK-4 in confirming the diagnosis of well-differentiated and de-differentiated liposarcoma while taking Fluorescent in situ Hybridisation (FISH) as a gold standard. A cross-sectional study. Place and Duration of the Study: Department of Histopathology, Armed Forces Institute of Pathology, Rawalpindi, Pakistan, from 30th January 2022 to 30th June 2023. A standard panel of three immunohistochemistry markers p16, MDM2, and CDK4 were applied to 36 cases of atypical lipomatous tumours, well-differentiated liposarcoma (WDLPS), and de-differentiated liposarcoma (DDLPS), on which the gold standard FISH was already performed. The sample size was calculated with the help of a WHO calculator taking prevalence 1-2% in Pakistani population. Qualitative variables such as gender and site of tumour were presented by calculating frequency and percentages and comparison of Immunohistochemistry results with FISH was done by using a 2x2 table. The sensitivity and specificity of this triple marker panel for detecting WDLPS/DDLPS were 43.47% and 15.38%, respectively. The sensitivity and specificity of CDK4 for detecting WDLPS / DDLPS were 82.6% and 15.4%, those of MDM2 were 73.9% and 61.5 %, and those of p16 were 60.9% and 53.8%, respectively. Among all three markers, CDK4 was the most sensitive and MDM2 was the most specific marker for detecting WDLPS-DDLPS. It also showed that a combination of these three markers improves the diagnostic credibility of the immunohistochemistry in diagnosing DDLPS and WDLPS but FISH is the most reliable and confirmatory method. De-differentiated liposarcoma, Well-differentiated liposarcoma, P16, CDK4, MDM2.

1746P Real-world characterization of patients with advanced or metastatic dedifferentiated liposarcoma (DDLPS) in Japan in MASTER KEY project

1746P Real-world characterization of patients with advanced or metastatic dedifferentiated liposarcoma (DDLPS) in Japan in MASTER KEY project

1720MO A phase II study of palbociclib combined with the PD-1 inhibitor retifanlimab in patients with advanced dedifferentiated liposarcoma

1720MO A phase II study of palbociclib combined with the PD-1 inhibitor retifanlimab in patients with advanced dedifferentiated liposarcoma