Giant mucinous liposarcoma of the abdominal cavity: A case report.

RATIONALE: Mucinous liposarcoma myxoid liposarcoma is a malignant mucoid soft tissue tumor derived from undifferentiated stromal cells in perivascular, subbody cavity and intermuscular space, and composed of cells at different stages of differentiation from preadipocytes to mature cells. In rare cases, it may change from lipoma malignancy. The main manifestations is painless mass, relatively slow growth, the course can last decades, the prevalence of liposarcoma in the population is 14% to 18%, mainly in adults, male prevalence is higher than women, but not significant. The main good hair part is the thigh, have mucinous sex, high differentiation type, dedifferentiation type, polymorphic type. Clinical diagnosis is difficult, and there are no obvious symptoms in the early stage, so the diagnosis should be combined with B ultrasound, MRI, CT, and other auxiliary examinations. The gold standard is pathological examination. In December 2023, our department admitted a patient with a mucinous abdominal mass. The report is as follows. PATIENT CONCERNS: Does liposarcoma metastasize? Is any chemotherapy required after surgery? Will it ever relapse in the future? What is the survival period after surgery? DIAGNOSIS: Mucinous liposarcoma. INTERVENTIONS: Surgical resection of the sarcoma. RESULTS: The nodule sample was 33 * 28 * 13 cm, with complete capsule, gray and yellow sections, fine texture, soft, gray, red, grayish, and yellow mucoid nodules in some areas, and the maximum diameter of the nodules was 21cm. Immunohistochemistry was: CD34 (+), CDK 4 (+), CK (-), Desmin (weak +), Ki67 (index 5%), MDM 2 (-), p16 (weak +), S-100P (+), Vimentin (+), BCL-2 (+). He was also sent to the Department of Pathology of Peking Union Medical College Hospital for consultation with Professor Lu Zhaohui, whose consultation opinion was in line with myxoliposarcoma. CONCLUSION: Retroperitoneal liposarcoma is a common retroperitoneal tumor, but it is relatively rare in clinical practice; the overall morbidity is low, mainly manifested as abdominal pain and abdominal distension, abdominal distension, and a long course of disease; it is not sensitive to radiotherapy and chemotherapy, and should be closely follow up by CT examination to understand the recurrence and metastasis.

Clinical impact of whole-body MRI in staging and surveillance of patients with myxoid liposarcoma: a 14-year single-centre retrospective study.

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. CONCLUSION: Regular WBMRI surveillance of myxoid liposarcoma patients considerably impacts clinical management by frequently influencing treatment decisions. CLINICAL RELEVANCE STATEMENT: 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.

Diffuse intra-abdominal sarcomatosis in myxoid pleomorphic liposarcoma.

We present a case of an extremely rare type of soft-tissue sarcoma with an atypical clinical presentation. The patient, a female in her 20s with Li Fraumeni syndrome, had prior surgery for a large intra-abdominal tumour that was given the diagnosis of malignant myxoid spindle cell neoplasm. Her recurrence manifested as diffuse intra-abdominal sarcomatosis for which she ultimately underwent subtotal debulking with palliative intent. Final pathology rendered the diagnosis of myxoid pleomorphic liposarcoma, a newly described entity, distinct from the more common liposarcoma subtypes. The optimal treatment for this typically aggressive disease is currently unknown; until that is better defined, management should be carried out by sarcoma specialists.

Myxoid liposarcoma: MRI features with histological correlation.

BACKGROUND AND AIMS: Myxoid liposarcoma is classified in the group of sarcomas with adipose differentiation, which is the second most common group of sarcomas. However, myxoid liposarcoma is not a homogeneous entity, because the behavior and clinical course of these tumours can vary widely. This study aimed to describe the magnetic resonance imaging (MRI) features of myxoid liposarcomas and to determine whether the MRI features are associated with the histologic grade and can differentiate between low-grade and high-grade tumours and thus help in clinical decision making. MATERIAL AND METHODS: We studied 36 patients with myxoid liposarcomas treated at our centre between 2010 and 2018. We analysed clinical variables (age, sex, and tumour site) and MRI features (size, depth, borders, fatty component, myxoid component, non-fatty/non-myxoid component, apparent diffusion coefficient (ADC), and type of enhancement after the administration of intravenous contrast material). We correlated the MRI features with the histologic grade and the percentage of round cells. RESULTS: In our series, patients with myxoid liposarcomas were mainly young adults (median age, 43 years). There were no differences between sexes; 97.2% were located in the lower limbs, 86.1% were deep, and 77.8% had well-defined borders. Of the 23 myxoid liposarcomas that contained no fat, 16 (69.6%) were high grade (p = 0.01). All the tumors with a myxoid component of less than 25% were high grade (p = 0.01); 83.3% of those with a non-fatty/non-myxoid component greater than 50% were high grade (p = 0.03) and 61.5% had more than 5% round cells (p = 0.01). Diffusion sequences were obtained in 14 of the 36 patients; ADC values were high (median, 2 × 10-3 mm2/s), although there were no significant associations between low-grade and high-grade tumours. Contrast-enhanced images were available for 30 (83.3%) patients; 83.3% of the tumours with heterogeneous enhancement were high grade (p = 0.01). CONCLUSIONS: MRI can be useful for differentiating between high- and low-grade myxoid liposarcomas and can help in clinical decision making.

[Contribution of whole-body MRI to the initial assessment of myxoid liposarcoma]. / Apport de l'IRM corps entier au bilan initial du liposarcome myxoïde.

INTRODUCTION: Myxoid liposarcoma is a soft tissue sarcoma associated with multifocal metastases at diagnosis. These metastases are asymptomatic and occult on CT and FDG-PET and can alter the therapeutic management and prognosis. In this context, we evaluated the contribution of whole-body MRI to the initial workup of patients with myxoid liposarcoma. METHOD: This retrospective study was conducted between January 2015 and December 2020 at the Oscar Lambret Center. We enrolled 22 patients who were diagnosed with myxoid liposarcoma and underwent whole-body MRI at diagnosis. The number of metastases at diagnosis, their location, and the visibility of these lesions on CT were evaluated. Associations between clinical features, presence of metastasis, and their impact on management were assessed. RESULTS: Sixteen patients (72.7%) had non-metastatic disease at the initial diagnosis, and 15 of these patients were managed using local treatment. Six patients (27.3%) had metastases at multiple locations and received chemotherapy. The main locations were the bones (n=5) and lungs (n=3). In five patients with metastases, whole-body MRI demonstrated additional lesions that were not visible on CT (bone and soft tissue lesions). Only the presence of a round cell contingent (P=0.009) was found as a criterion associated with the presence of metastases. CONCLUSION: The patients' young age, absence of reliable prognostic factors at diagnosis, asymptomatic nature of the lesions, and the benefits of early and targeted therapeutic management encourage the use of whole-body MRI as part of the initial work-up as it seems to provide a better initial staging compared with conventional imaging.

Myxoid liposarcoma metastatic to the mandible: First case report and review of the literature.

Unlike other soft tissue sarcomas, myxoid liposarcoma tends to metastasize to bone even before developing lung metastases. In this report, we present a unique case of myxoid liposarcoma metastatic to the mandible. A 40-year-old male who had a history of myxoid liposarcoma in the buttock presented with paresthesia in the left lower face and mandible. Radiographic examination revealed an ill-defined radiolucent lesion with cortical destruction in the left mandibular body and ramus. Histopathological examination showed a mixture of small lipoblasts and round primitive mesenchymal cells in a myxoid stroma. Hypercellular areas comprising high-grade round cells were frequently found. The final diagnosis of metastatic myxoid liposarcoma was made. Despite postoperative chemoradiotherapy, further metastases occurred in the lungs and liver, and the patient died of the tumor 23 months after the treatment of the mandibular lesion. This is the first report of myxoid liposarcoma metastatic to the jaw, which may help in the differential diagnosis of intraosseous myxoid tumors of the jaws and highlights unfavorable clinical outcome of metastatic high-grade myxoid liposarcoma.

Artificial intelligence significantly improves the diagnostic accuracy of deep myxoid soft tissue lesions in histology.

Deep myxoid soft tissue lesions have posed a diagnostic challenge for pathologists due to significant histological overlap and regional heterogeneity, especially when dealing with small biopsies which have profoundly low accuracy. However, accurate diagnosis is important owing to difference in biological behaviors and response to adjuvant therapy, that will guide the extent of surgery and the need for neo-adjuvant therapy. Herein, we trained two convolutional neural network models based on a total of 149,130 images representing diagnoses of extra skeletal myxoid chondrosarcoma, intramuscular myxoma, low-grade fibromyxoid sarcoma, myxofibrosarcoma and myxoid liposarcoma. Both AI models outperformed all the pathologists, with a significant improvement of accuracy up to 97% compared to average pathologists of 69.7% (p < 0.00001), corresponding to 90% reduction in error rate. The area under curve of the best AI model was on average 0.9976. It could assist pathologists in clinical practice for accurate diagnosis of deep soft tissue myxoid lesions, and guide clinicians for precise and optimal treatment for patients.

Myxoid liposarcoma originating in the retroperitoneum with metastasis to the calcaneus: a rare case report and review of literature.

Myxoid liposarcoma (MLPS) is known to have a variety of metastatic manifestations. We report a MLPS originating in the pelvis with metastasis to the calcaneus. The patient was a 72-year-old man who developed lumbar pain and right lower extremity pain 2 years ago. He visited a nearby clinic and underwent a radiographic examination. Computed tomography (CT) revealed a tumor in the right retroperitoneum. A CT-guided needle biopsy was performed, and pathological examination revealed myxoid liposarcoma. Wide surgical resection was not performed due to the patients' wishes, technical difficulties, and magnitude of the invasion, and the patient received heavy particle radiation therapy (HPRT) of 70.4 Gy. After HPRT, the tumor mass was slightly reduced. However, 11 months after HPRT, a recurrent lesion in the liver was observed. Although HPRT was performed again for the metastatic liver lesion (70.4 Gy), the tumor increased in size. Furthermore, 1 month later, the patient complained of pain in the left foot, and CT and magnetic resonance imaging revealed an osteolytic lesion in the calcaneus. A biopsy was performed, and pathological examination showed a metastatic lesion of myxoid-type liposarcoma. The patient wore a short lower limb orthosis and was able to walk but died 1 month later. Oncologists should note that MLPS can metastasize to the calcaneus.

A case report of primary myxoid liposarcoma mimicking as a parotid cystic lesion.

RATIONALE: Myxoid liposarcoma (MLS) is an extremely rare tumor of the salivary gland and it arises from undifferentiated pluripotent mesenchymal cells. We report a rare case of a primary MLS in the parotid gland. PATIENT CONCERNS: The patient was a 49-year-old female who presented with a hard fixed mass in the left parotid region. DIAGNOSIS: On computed tomography and MR images, this tumor has a low attenuation center with a thick enhancing wall and ill-defined margins. The absence of high-signal-intensity foci on T1-weighted images makes a MLS indistinguishable from most other soft-tissue masses. Pathologically, the tumor was diagnosed as MLS. INTERVENTIONS: The patient received total parotidectomy with facial nerve preservation and selective neck dissection. OUTCOMES: Immediate facial nerve function was House Brackmann Grade III and recovered within 3 months after the surgery. Follow-up period is 57 months and there was no recurrence until now. LESSONS: In this report, we report a rare case of primary MLS mimicking a cystic lesion of the parotid gland.

CIC rearranged sarcomas: A single institution experience of the potential pitfalls in interpreting CIC FISH results.

AIM: The aim of this study was to establish how reliable FISH CIC analysis using an IVD (in vitro diagnostic) commercial probe is. METHODS AND RESULTS: A series of 19 CIC-DUX4 sarcomas were evaluated. The samples presenting CIC-DUX4 fusion transcript detected by Reverse Transcription-Polymerase Chain Reaction (RT-PCR) and Sanger sequencing and/or Next Generation Sequencing were selected for Fluorescent in Situ Hybridization (FISH) CIC analysis with CIC break-apart IVD probe and compared to molecular analysis. CIC FISH analysis showed 26% of false negatives. CONCLUSION: Our results indicate that, in the setting of CIC-DUX4 fusion positive small round cell sarcomas, CIC FISH using IVD commercial probe may lead to false-negative results. This novel study evaluates the diagnostic use of a commercial IVD CIC probe for FISH.

Radiological progression of extremity soft tissue sarcoma following pre-operative radiotherapy predicts for poor survival.

OBJECTIVES: To determine if radiological response to pre-operative radiotherapy is related to oncologic outcome in patients with extremity soft tissue sarcomas (STSs). METHODS: 309 patients with extremity STS who underwent pre-operative radiation and wide resection were identified from a prospective database. Pre- and post-radiation MRI scans were retrospectively reviewed. Radiological response was defined by the modified Response Evaluation Criteria in Solid Tumours. Local recurrence-free, metastasis-free (MFS) and overall survival (OS) were compared across response groups. RESULTS: Tumour volume decreased in 106 patients (34.3%; PR - partial responders), remained stable in 97 (31.4%; SD - stable disease), increased in 106 (34.3%; PD - progressive disease). The PD group were older (p = 0.007), had more upper extremity (p = 0.03) and high-grade tumours (p < 0.001). 81% of myxoid liposarcomas showed substantial decrease in size. There was no difference in initial tumour diameter (p = 0.5), type of surgery (p = 0.5), margin status (p = 0.4), or complications (p = 0.8) between the three groups. There were 10 (3.2%) local recurrences with no differences between the three response groups (p = 0.06). 5-year MFS was 52.1% for the PD group vs 73.8 and 78.5% for the PR and SD groups, respectively (p < 0.001). OS was similar (p < 0.001). Following multivariable analysis, worse MFS and OS were associated with higher grade, larger tumour size at diagnosis and tumour growth following pre-operative radiation. Older age was also associated with worse OS. CONCLUSION: STS that enlarge according to Response Evaluation Criteria in Solid Tumour criteria following pre-operative radiotherapy identify a high risk group of patients with worse systemic outcomes but equivalent local control. ADVANCES IN KNOWLEDGE: Post-radiation therapy, STS enlargement may identify patients with potential for worse systemic outcomes but equivalent local control. Therefore, adjunct therapeutic approaches could be considered in these patients.

[Neoadjuvant Use of Isolated Limb Perfusion in Large Myxoid Liposarcoma of the Thigh: a Case Report]. / Neoadjuvantní uzití izolované perfuze koncetiny u objemného myxoidního liposarkomu stehna: kazuistika.

Large unresectable STS presents a therapeutic challenge. Several options are being explored to avoid amputation without compromising the oncological outcome. Neoadjuvant chemotherapy delivers inconsistent and rather unsatisfactory results, preoperative radiotherapy compromises healing, hence it can impede adjuvant systemic treatment. We present a case report of neoadjuvant use of isolated limb perfusion with TNF-alfa and Alkeran (Melphalan) in a patient with initially unresectable large myxoid liposarcoma of the thigh. We achieved 55% reduction in size of the tumor that allowed for wide resection with a safe margin. Pathology confirmed 99% tumor necrosis. The patient has a full function of his extremity and is disease-free at one year follow-up. ILP should be considered as a treatment option which, in selected cases, can contribute to limb sparing surgery. Key words: sarcoma, soft tissue, regional perfusion, chemotherapy, surgery, orthopedic, limb salvage.

Descriptive analysis of MRI functional changes occurring during reduced dose radiotherapy for myxoid liposarcomas.

OBJECTIVES: Myxoid liposarcomas (MLS) show enhanced response to radiotherapy due to their distinctive vascular pattern and therefore could be effectively treated with lower radiation doses. This is a descriptive study to explore the use of functional MRI to identify response in a uniform cohort of MLS patients treated with reduced dose radiotherapy. METHODS: 10 patients with MLS were imaged pre-, during, and post-radiotherapy receiving reduced dose radiotherapy and the response to treatment was histopathologically assessed post-radiotherapy. Apparent diffusion coefficient (ADC), T2* relaxation time, volume transfer constant (Ktrans), initial area under the gadolinium curve over 60 s (IAUGC60) and (Gd) were estimated for a central tumour volume. RESULTS: All parameters showed large inter- and intrasubject variabilities. Pre-treatment (Gd), IAUGC60 and Ktrans were significantly different between responders and non-responders. Post-radiotherapy reductions from baseline were demonstrated for T2*, (Gd), IAUGC60 and Ktrans for responders. No statistically significant ADC differences were demonstrated between the two response groups. Significantly greater early tumour volume reductions were observed for responders. CONCLUSIONS: MLS are heterogenous lesions, characterised by a slow gradual contrast-agent uptake. Pre-treatment vascular parameters, early changes to tumour volume, vascular parameters and T2* have potential in identifying response to treatment. The delayed (Gd) is a suitable descriptive parameter, relying simply on T1 measurements. Volume changes precede changes in MLS functionality and could be used to identify early response. ADVANCES IN KNOWLEDGE: MLS are are characterised by slow gradual contrast-agent uptake. Measurement of the delayed contrast-agent uptake (Gd) is simple to implement and able to discriminate response.

A moderate dose of preoperative radiotherapy may improve resectability in myxoid liposarcoma.

BACKGROUND: Histotype specific neoadjuvant therapy response data is scarce in soft tissue sarcomas. This study aimed to assess the impact of a moderate radiotherapy (RT) dose on resectability and to correlate MRI parameters to pathological treatment response in Myxoid Liposarcoma (MLS). METHODS: This prospective, multicenter, single-arm, phase 2 trial assessed the radiological effects of 36 Gy of preoperative radiotherapy in primary non-metastatic MLS (n=34). Distance of the tumor to the neurovascular bundle, tumor dimensions, fat fraction, enhancing fraction were determined on MRI scans at baseline, after 8 and 16 fractions, and preoperatively. Pathological response was established by central pathology review. RESULTS: Preoperative radiotherapy resulted in a median increase of 2 mm (IQR 0 to 6) of the distance of the tumor to the neurovascular bundle. As compared to baseline, the median change of the tumor volume, craniocaudal diameter and axial diameter at preoperative MRI were -60% (IQR -74 to -41), -19% (IQR -23 to -7) and -20% (IQR -29 to -12), respectively. The median fat fraction of 0.1 (IQR 0.0-0.1) and enhancing fraction of 0.8 (IQR 0.6 to 0.9) at baseline, changed to 0.2 (IQR 0.1 to 0.5) and to 0.5(IQR 0.4 to 0.9) preoperatively, respectively. Radiological signs of response in terms of volume, enhancing fraction and fat fraction were correlated with specific pathological signs of response like hyalinization, necrosis and fatty maturation. CONCLUSIONS: A moderate dose of preoperative radiotherapy may improve resectability in MLS and could facilitate achievement of clear margins and function preservation. MRI features which were predictive for expressions of pathological response, can play a role in further personalization of neoadjuvant treatment strategies in order to improve outcome in MLS.

Staging and Surveillance of Myxoid Liposarcoma: Follow-up Assessment and the Metastatic Pattern of 169 Patients Suggests Inadequacy of Current Practice Standards.

BACKGROUND: Unlike other sarcoma subtypes, myxoid liposarcoma (MLS) has a propensity for extra-pulmonary metastases. Computed tomography (CT) scan of the chest, abdomen, and pelvis has become an accepted practice for surveillance. However, recent literature suggests that this may be inadequate. This study aimed to assess the ability of current imaging methods to detect metastases adequately in this population. METHODS: The study identified 169 patients with MLS diagnosed between 2000 and 2016. The timing and location of metastases, the reasons leading to the MLS diagnosis, and the imaging methods were recorded. The locations of metastases were classified into the following categories: pulmonary, soft tissue, bone, retroperitoneal, intraperitoneal, solid organ, and lymph node. RESULTS: An initial diagnosis of metastasis was made at presentation with staging CT scan for 3 (10 %) of 31 patients, with a follow-up surveillance CT scan for 15 (48 %) of the patients or with subsequent imaging obtained in response to patient-reported symptoms for 13 (42 %) of the patients. The proportions of patients who had metastases in each location were as follows: soft tissue (84 %), pulmonary (68 %), intraabdominal (48 %), solid organ (48 %), bone (45 %), lymph node (32 %), and retroperitoneal (29 %). Although 14 patients had bone metastases, only 1 patient had a sclerotic/blastic presentation visualized on CT scan, and the diagnosis for the remaining 13 patients was determined by magnetic resonance imaging (MRI). CONCLUSION: Due to metastatic disease identified outside surveillance imaging for 58 % of the patients, the diversity of locations, and the significant failure of CT and bone scan to identify bone metastases, this study questioned the adequacy of CT scan for surveillance of MLS. Consideration should be given to the use of whole-body MRI for detection of metastasis in MLS.

Unusual cardiac tamponade: Giant primary cardiac myxoid liposarcoma.

Primary cardiac myxoid liposarcoma is an extremely rare disease. We reported a 61-year-old man with a 1-month history of aggressive dyspnea and anorexia due to a giant primary cardiac myxoid liposarcoma. Radical resection, whenever feasible, is considered to be an appropriate surgical strategy for this disease. Heart transplantation may be an alternative therapy for such isolated and unresectable tumor.

Magnetic resonance imaging of trunk and extremity myxoid liposarcoma: diagnosis, staging, and response to treatment.

Myxoid liposarcoma (MLS) accounts for approximately 30% of all liposarcomas. The majority are intermediate-grade tumours, but the presence of >5% round cell component renders it a high-grade sarcoma with subsequent poorer outcome. MLS most commonly arises in the lower extremities, has a predilection for extra-pulmonary sites of metastatic disease, and is recognized to be radiosensitive. The purpose of the current article is to review the role of MRI in the management of MLS, including the characteristic features of the primary tumour, features which help to identify a round cell component and thus determine prognosis, the role of whole-body MRI for evaluation of extra-pulmonary metastatic disease, and the utility of MRI for assessing treatment response. The MRI differential diagnosis of MLS is also considered.

Carbon ion radiotherapy for recurrent calf myxoid liposarcoma: a case report.

Liposarcoma (LPS) is the most common soft tissue sarcoma. Myxoid LPS (MLPS) is the second most common subtype of LPS and accounts for 25% to 50% of all LPSs. Like most other soft tissue sarcomas, the mainstay of treatment for LPS is inevitably surgery. Multidisciplinary approaches, including surgery, chemotherapy, and radiotherapy, have been successful in the treatment of LPS during the last three decades. Even so, recurrence of LPS remains challenging. Carbon ion beams produce increased energy deposition at the end of their range to form a Bragg peak while minimizing irradiation damage to surrounding tissues, which facilitates more precise dosage and localization than that achieved with photon beams. Furthermore, carbon ion beams have high relative biologic effectiveness. We herein describe a patient who developed recurrent MLPS in the right calf after two surgeries and underwent carbon ion radiotherapy (CIRT), achieving complete disappearance of the tumor. The patient developed Grade 1 radiation dermatitis 30 days after CIRT, but no other acute toxicities were observed. The tumor had completely disappeared by 120 days after CIRT, and the patient remained disease-free for 27 months after CIRT. The CARE guidelines were followed in the reporting of this case.

Report of two primary renal tumors with myxoid features. Differential diagnosis between benign and malignant entities.

Renal mesenchymal neoplasms are rare entities which can have a benign or a malignant behavior. Herein we describe two renal mesenchymal tumors with myxoid stroma, investigating the wide spectrum of differential diagnosis. With our first case we considered some benign entities such as myxoma, myxoid leiomyoma, and mixed epithelial and stromal tumor; with our second case we considered some sarcomas with myxoid features such as myxofibrosarcoma, low-grade fibromyxoid sarcoma, dedifferentiated liposarcoma, and myxoid liposarcoma. During the diagnostic process, it is important to integrate histopathological, immunohistochemical, and molecular data in order to avoid misdiagnosis. We concluded our second case report was a myxofibrosarcoma grade 1. To the best of our knowledge, we described the fourth primary renal myxofibrosarcoma reported in literature.