Myxoid liposarcoma (MLPS) is a rare sarcoma, typically arising in deep soft tissues during the fourth to fifth decades of life. Histologically, MLPS is composed of uniform oval cells within a background of myxoid stroma and chicken-wire capillaries. Genetically, MLPS is characterized by the FUS/EWSR1::DDIT3 fusion gene, which generally results from balanced interchromosomal translocation and is detectable via DDIT3 break-apart fluorescence in situ hybridization (FISH). Here, we report an unusual intra-articular MLPS case, negative for DDIT3 break-apart FISH but positive for EWSR1::DDIT3. An 18-year-old female was referred to our hospital complaining of an intra-articular mass in the right knee joint. Histologically, the tumor was mainly composed of mature adipocytes, brown fat-like cells, and lipoblasts. Nanopore sequencing detected DNA rearrangements between EWSR1 and DDIT3 and clustered complex rearrangements involving multiple chromosomes, suggesting chromoplexy. Methylation classification using random forest, t-distributed stochastic neighbor embedding, and unsupervised hierarchical clustering correctly classified the tumor as MLPS. The copy number was almost flat. The TERT promoter C-124T was also detected. This report highlights, for the first time, the potential value of a fast and low-cost nanopore sequencer for diagnosing sarcomas.

Myxoid/round cell liposarcomas (MRCLPS) are a rare soft tissue sarcoma. We report the largest sarcoma in our institutional history. We discuss the patient\'s surgical management and treatment of the tumor and challenges given its dimensions. Several complications arose following primary resection that were managed by a multidisciplinary team. Although MRCLPS can vary in size, large MRCLPS must be treated cautiously given the potential for complications. Additionally, multidisciplinary treatment of MRCLPS is essential in diagnosing and treating these complex cases.

Liposarcomas are an uncommon occurrence in the paratesticular region that makes about 20 % of all sarcomas. The clinical appearance is an inguinal lump, which can resemble a hydrocele or hernia. There would be no conventional treatment accessible because it is such a rare disease. We report the case of a 68-year-old man with paratesticular myxoid liposarcoma. Ultrasound and CT-scan came back in favor of a paratesticular tumor. A high inguinal orchidectomy has been done and the diagnostic of myxoid liposarcoma was first evoked by histology and confirmed by molecular biology. At 12 months follow up the patient remains tumor free.

BACKGROUND: Myxoid liposarcoma (MLS) displays a distinctive tumor microenvironment and is characterized by the FUS::DDIT3 fusion oncogene, however, the precise functional contributions of these two elements remain enigmatic in tumor development.
METHODS: To study the cell-free microenvironment in MLS, we developed an experimental model system based on decellularized patient-derived xenograft tumors. We characterized the cell-free scaffold using mass spectrometry. Subsequently, scaffolds were repopulated using sarcoma cells with or without FUS::DDIT3 expression that were analyzed with histology and RNA sequencing.
RESULTS: Characterization of cell-free MLS scaffolds revealed intact structure and a large variation of protein types remaining after decellularization. We demonstrated an optimal culture time of 3 weeks and showed that FUS::DDIT3 expression decreased cell proliferation and scaffold invasiveness. The cell-free MLS microenvironment and FUS::DDIT3 expression both induced biological processes related to cell-to-cell and cell-to-extracellular matrix interactions, as well as chromatin remodeling, immune response, and metabolism. Data indicated that FUS::DDIT3 expression more than the microenvironment determined the pre-adipocytic phenotype that is typical for MLS.
CONCLUSIONS: Our experimental approach opens new means to study the tumor microenvironment in detail and our findings suggest that FUS::DDIT3-expressing tumor cells can create their own extracellular niche.

OBJECTIVE: Because myxoid liposarcomas are more radiosensitive than other soft tissue sarcomas, there have been several reports of 50 Gy preoperative radiation therapy combined with surgery, but the wound complication rate is reportedly high. We have performed preoperative irradiation at a reduced dose of 40 Gy and definitive radiation therapy for unresectable cases. This study aimed to report the tumor reduction rate and oncological results with a reduced dose of preoperative irradiation and the outcome of definitive irradiation for unresectable cases.
METHODS: Forty-one patients with myxoid liposarcoma treated in our institution between 2002 and 2021 were included. We examined the tumor volume shrinkage rate with preoperative radiation, compared complications and oncological outcomes between preoperative radiation and surgery-only cases, and investigated the prognosis and tumor shrinkage of definitive radiation cases.
RESULTS: The total dose irradiated was 40 Gy except in two cases. The mean tumor volume reduction rate was 52.0%. A decreased dose of preoperative radiation did not worsen clinical outcomes with fewer complications. The total dose of definitive radiation was approximately 60 Gy. The mean tumor volume reduction rate was 55.0%. The tumor shrinkage maintenance rate was 100% in a median follow-up period of 50.5 months.
CONCLUSIONS: Preoperative radiation therapy for myxoid liposarcoma near vital organs is a good approach because even with a reduced dose of 40 Gy, significant tumor reduction and excellent results were achieved. Definitive radiation therapy is the recommended treatment for older patients with serious comorbidities or inoperable patients.

OBJECTIVE: To assess the clinical impact of regular whole-body magnetic resonance imaging (WBMRI) surveillance in myxoid liposarcoma patients.
METHODS: This was a retrospective cohort study of myxoid liposarcoma patients who underwent at least one WBMRI at our institution between October 2006 and December 2020. The effect of WBMRI on clinical management, namely treatment modification or additional diagnostic investigations was studied. A standardised WBMRI surveillance protocol was instituted in 2015. We compared patient outcomes for the metastatic patients who had and had not received regular WBMRI surveillance and performed survival analysis for both subgroups.
RESULTS: Of the 56 patients (60.7% male, median age: 48.1 years) who underwent 345 WBMRI, 17 (30.3%) had metastases, and 168 WBMRI were performed in this group. The median imaging follow-up for the entire cohort was 35 months; the metastatic group had a median follow-up of 42 months. WBMRI changed the clinical management in 13 (76.5%) metastatic patients, with 33 instances of treatment modification. Thirty-five lesions were labelled \'indeterminate,\' 16 (45.7%) had additional investigations/interventions, and 4 (11.4%) were confirmed to be metastatic. Twenty-one metastatic lesions were missed initially on WBMRI and confirmed on subsequent WBMRI, of which 5 (23.8%) were clinically significant. The 5-year survival since the detection of metastasis was better in the regular surveillance subgroup (85.7% vs. 45%), but this was not statistically significant (p = 0.068). Five patients (8.9%) developed their first metastasis more than 5 years after diagnosing the primary lesion.
CONCLUSIONS: Regular WBMRI surveillance of myxoid liposarcoma patients considerably impacts clinical management by frequently influencing treatment decisions.
CONCLUSIONS: WBMRI has been recently recommended as an imaging option for the staging and surveillance of myxoid liposarcoma patients. Our study highlights the impact of regular WBMRI surveillance on the clinical management of these patients and how it affects their survival.

Liposarcomas are described as soft tissue sarcomas derived from adipose tissue. The finding of this tumor in the mandibular region is exceedingly rare. As of now, it has been described mainly in case reports and small series. A multidisciplinary approach is required to offer optimal treatment and may involve surgery, radiation and systemic therapies. Surgical repair of these defects represents a major challenge in oral and maxillofacial reconstructive surgery. We present the case of a 54-year-old man referred to our center with a progressively increasing mass in the anterior portion of the mandible. Biopsy revealed a well-differentiated myxoid liposarcoma. Resection of the tumor was performed with an additional primary reconstruction.

Currently, it is difficult to predict the prognosis of myxoid liposarcoma (MLS) in biopsy specimens. In this study, we determined whether nuclear morphology may be used to predict the prognosis of MLS in primary biopsy specimens. Two pathologists evaluated nuclear morphology using the modified WHO/ISUP and Fuhrman grades. Survival analyses were performed by grouping nuclear high- and low-grades. We examined 53 MLS cases, which included 29 (54.7%) male and 24 (45.3%) female patients with a median age of 46 years (interquartile range, 37 - 60). In total, 7 (13.2%) and 16 (30.2%) cases were assigned to the high nuclear grade group based on the modified WHO/ISUP and Fuhrman gradings, respectively. Survival analyses revealed a significantly worse disease-free survival in the high-grade group (hazard ratio (HR), 7.51; 95% confidence interval (CI), 2.67-21.1, p < 0.001 by the modified WHO/ISUP grading; HR, 4.45; 95% CI, 1.63-12.1, p = 0.001 by the modified Fuhrman grading). Moreover, the modified WHO/ISUP grade showed a significantly worse overall survival in the high-grade group (HR, 4.39; 95% CI, 1.04-18.6, p = 0.028), and the modified Fuhrman grade exhibited a similar, but not significant, trend. Our results indicate that nuclear morphology grading is a good predictor of patient prognosis at the time of biopsy in MLS. Even when cell density is sparse, treatment strategies should be carefully considered when individual tumor cells exhibit atypical nuclei.

BACKGROUND: This study aimed to compare the local recurrence, distant metastasis and disease-specific survival rates of patients with localized myxoid liposarcoma in the surgery and adjuvant chemotherapy group versus the surgery alone group.
METHODS: A total of 456 patients in the Japanese National Bone and Soft Tissue Tumour Registry database who had localized myxoid liposarcoma and underwent surgery and adjuvant chemotherapy or surgery alone between 2001 and 2019 were included in this retrospective study. The study adjusted for background differences between patients who underwent surgery and adjuvant chemotherapy (n = 228) or surgery alone (n = 228) using propensity score matching.
RESULTS: Univariate analysis showed no significant difference in local recurrence rate between the two groups (5-year local recurrence-free survival: 98.6% [95% confidence interval: 95.9-99.6] vs. 94.0% [95% confidence interval: 89.7-96.6], P = 0.052). Univariate analysis showed no difference in the incidence of distant metastases between the two groups (5-year distant metastasis-free survival: 80.5% [95% confidence interval: 73.9-85.8] vs. 75.1% [95% confidence interval: 67.7-81.2], P = 0.508). Univariate analysis showed no difference in disease-specific survival between the two groups (5-year disease-specific survival: 92.6% [95% confidence interval: 86.1-96.2] vs. 93.2% [95% confidence interval: 87.6-96.4], P = 0.804). In the high-risk group (n = 203) with high-grade tumours and tumour size ≥10 cm, there were no significant differences in the local recurrence, distant metastasis and disease-specific survival rates between the surgery and adjuvant chemotherapy group and the surgery alone group.
CONCLUSIONS: The effect of adjuvant chemotherapy on localized myxoid liposarcoma appears to be limited.

Metastasis to the breast from non-mammary malignancies are rare and suggestive of advanced disease. Accurate and prompt diagnosis of breast metastasis can provide important prognostic information and guide treatment planning. Interestingly, in contrast to primary breast malignancies, non-mammary metastatic breast lesions often have benign-appearing imaging characteristics. Knowing a patient\'s clinical history and having prior breast imaging studies for comparison is important for making accurate assessments and appropriate recommendations. Imaging-guided biopsy is often indicated for definitive tissue diagnosis. We report a rare case of solitary metastasis to the breast from thigh myxoid liposarcoma.