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Liposarcoma is a malignant soft tissue tumor with several subtypes, the most common of which is well-differentiated liposarcoma (WDL) or atypical lipomatous tumor (ALT). WDL/ALTs are further divided into three histological subtypes, including lipoma-like, sclerosing, and inflammatory. While the majority of these tumors are predominantly fatty, the sclerosing variant demonstrates diverse histologic and radiographic characteristics, including variable amounts of fibrosis and fat. Because of this histological variability and relative rarity, the sclerosing WDL/ALT can present diagnostic dilemmas. We present two cases of sclerosing WDL/ALT, both of which demonstrated high degrees of fibrosis and a paucity of fat, mimicking desmoid fibromatosis and other fibrotic soft tissue tumors. Thus, it is important for radiologists to be aware of the subtypes of liposarcoma and their unique characteristics, and to consider sclerosing WDL/ALT in cases of fibrotic soft tissue tumors. [ABSTRACT FROM AUTHOR]

Liposarcoma is the most prevalent sarcoma in adults representing 20% of all sarcomas with well-differentiated/dedifferentiated among the most common subtypes represented. Despite multimodality treatment approaches, there has not been any appreciable change in survival benefit in the past 10 years. The future of targeted therapy for WD/DDLPS is promising with the intention to spare multi-visceral removal due to radical surgical resection. Therefore, there is a need to expand upon the molecular landscape of WDLPS and DDLPS which can help identify potential therapeutic targets for the treatment of this disease. Targeted transcriptome analysis using the NanoString tumor signaling 360 panel revealed a dysregulation in glucose metabolism and HIF1 signaling pathways in both WDLPS and DDLPS when compared to normal fat controls. WDLPS, however, demonstrated upregulation of HIF-1A and TGF-β when compared to DDLPS by targeted transcriptome analysis and orthogonal validation by RT-qPCR suggesting activation of EMT pathway in WDLPS when compared to DDLPS. Our findings implicate a putative role for dysregulation in glucose metabolism, TGF-β and HIF1 signaling in the pathogenesis of both WD/DDLPS suggesting a possible proinflammatory tumor environment within WDLPS and subsequent activation of the TGF-β signaling pathway. [ABSTRACT FROM AUTHOR]

Liposarcoma of the uterine corpus represents an exceptionally rare tumor, with few cases documented in the literature, underscoring its unique histopathologic characteristics and management challenges. This case describes the clinical management of a 57-year-old patient with well-differentiated liposarcoma of the uterine corpus who presented with a three-month history of abdominal pain and distension. She underwent an abdominal hysterectomy followed by chemotherapy but experienced local recurrence in the mesentery and retroperitoneum after 21 months. Tumor resection was performed again, followed by chemotherapy, but the patient experienced a second recurrence 15 months later, involving the small intestine, vaginal stump, and ureter, with evidence of dedifferentiated liposarcoma. A third surgical resection was carried out without administering chemotherapy and the patient remained asymptomatic at follow-up appointments every 3 months for a year. This case highlights the importance of acknowledging the aggressive nature of recurrent liposarcoma, especially its transition into dedifferentiated liposarcoma, and the need for tailored management strategies.

Liposarcoma is the most prevalent sarcoma in adults representing 20% of all sarcomas with well-differentiated/dedifferentiated among the most common subtypes represented. Despite multimodality treatment approaches, there has not been any appreciable change in survival benefit in the past 10 years. The future of targeted therapy for WD/DDLPS is promising with the intention to spare multi-visceral removal due to radical surgical resection. Therefore, there is a need to expand upon the molecular landscape of WDLPS and DDLPS which can help identify potential therapeutic targets for the treatment of this disease. Targeted transcriptome analysis using the NanoString tumor signaling 360 panel revealed a dysregulation in glucose metabolism and HIF1 signaling pathways in both WDLPS and DDLPS when compared to normal fat controls. WDLPS, however, demonstrated upregulation of HIF-1A and TGF-β when compared to DDLPS by targeted transcriptome analysis and orthogonal validation by RT-qPCR suggesting activation of EMT pathway in WDLPS when compared to DDLPS. Our findings implicate a putative role for dysregulation in glucose metabolism, TGF-β and HIF1 signaling in the pathogenesis of both WD/DDLPS suggesting a possible proinflammatory tumor environment within WDLPS and subsequent activation of the TGF-β signaling pathway.

BackgroundAlthough IGF2BP3 has been implicated in tumorigenesis and poor outcomes in multiple cancers, its role in soft-tissue sarcoma (STS) remains unknown. Preliminary data have suggested an association with IGF2BP3 expression among patients with well-differentiated/dedifferentiated liposarcoma (WD/DD LPS), a disease where molecular risk stratification is lacking.MethodsWe examined the survival associations of IGF2BP3 via univariate and multivariate Cox regression in three unique datasets: (1) the Cancer Genome Atlas (TCGA), (2) an in-house gene microarray, and (3) an in-house tissue microarray (TMA). A fourth dataset, representing an independent in-house TMA, was used for validation.ResultsWithin the TCGA dataset, IGF2BP3 expression was a poor prognostic factor uniquely in DD LPS (OS 1.6 vs. 5.0 years, p = 0.009). Within the microarray dataset, IGF2BP3 expression in WD/DD LPS was associated with worse survival (OS 7.7 vs. 21.5 years, p = 0.02). IGF2BP3 protein expression also portended worse survival in WD/DD LPS (OS 3.7 vs. 13.8 years, p < 0.001), which was confirmed in our validation cohort (OS 2.7 vs. 14.9 years, p < 0.001). In the multivariate model, IGF2BP3 was an independent risk factor for OS, (HR 2.55, p = 0.034).ConclusionIGF2BP3 is highly expressed in a subset of WD/DD LPS. Across independent datasets, IGF2BP3 is also a biomarker of disease progression and worse survival.

Tianwen Zhang, Bin Liu Department of Orthopaedic Soft Tissue Surgery, Guangxi Medical University Cancer Hospital, Nanning, 530021, People’s Republic of ChinaCorrespondence: Bin Liu, Email lbstar@gxmu.edu.cnObjective: The study aimed to investigate the significantly different imaging characteristics of musculoskeletal dedifferentiated liposarcoma (DDLP) and well differentiated liposarcoma (WDLP) on MRI, which in turn could guide puncture biopsy.Materials and Methods: This study included 14 patients with DDLP and 16 patients with WDLP, all of whom were confirmed by histopathological examination. The MRI manifestations of these two pathologies were retrospectively reviewed and compared. Furthermore, a step-by-step procedure regarding preoperative puncture biopsy of fatty masses that are suspicious for WD/DD was designed.Results: Fatty signals can be found in almost all WDs, with a greater proportion of non-fatty areas in DD compared to WD, and it is reasonable to consider WD more likely when the non-fatty areas of the tumor are < 25% (p < 0.05), while it is reasonable to consider DD more likely when the non-fatty areas of the tumor are > 50% (p < 0.05), and the MRI signals in DD are more complex, inhomogeneous (p < 0.01), usually showed significant enhancement (p < 0.01), and the margins of the tumor were usually indistinct (p < 0.01); and imaging features such as tumor size, vascularity, necrosis, and peritumoral edema did not serve as distinguishing features between the two (p > 0.05).Conclusion: DD has a greater proportion of non-fatty components, with more complex and inhomogeneous MRI signals, and typically shows significant enhancement, with usually indistinct margins of the tumor, in which the inhomogeneous manifestations are associated with the histological components. The possibility of DD should be considered in fatty tumors with non-fatty areas > 25%, for which puncture biopsy is necessary, while simultaneous puncture of low, moderate, high-signal areas within the non-fatty area could improve the accuracy of preoperative puncture pathology.Keywords: liposarcoma, dedifferentiated liposarcoma, well-differentiated liposarcoma, magnetic resonance imaging, puncture biopsy

Objective: Liposarcoma (LPS) is classified into 4 subtypes. As some subtypes have a high recurrence rate, knowing the risk of recurrence before surgery is important. Here, we aimed to investigate the relationship between Hounsfield units (HU) derived from preoperative computed tomography (CT) and the prognosis of patients undergoing surgery. Materials and Methods: We included 32 patients who underwent surgery for LPS between 2014 and 2022. Preoperative plain CT images were collected, and the HU value of each LPS was measured. The association between 2 HU categories (HU < cut-off vs. = cut-off) and clinical variables was assessed. The optimal cut-off value was determined using statistical methods. We used the Kaplan-Meier method to determine the differences between the 2 HU categories at 2 endpoints: recurrence-free survival (RFS) and overall survival (OS). Results: The dedifferentiated subtype showed significantly higher HU values than the other subtypes (P < .001). The optimal cut-off value for HU was 20. HU < 20 was associated with young age, low-performance status, low Charlson Comorbidity Index, and well-differentiated pathology. The Kaplan-Meier curves demonstrated that RFS and OS were significantly shorter in patients with HU = 20 than in those with HU < 20 (P = .007 and .04, respectively). However, when stratified based on subtype, no significant differences were observed between dedifferentiated and other subtypes. Conclusion: HU = 20 on preoperative CT was associated with poor prognosis in LPS patients. Our findings suggest that preoperative CT-derived HU values may serve as useful predictors of prognosis. [ABSTRACT FROM AUTHOR]

Pleomorphic lipoma is an uncommon benign adipocytic tumor that arises from the subcutis. It has no risk of recurrence, metastasis or malignant transformation. The cytological findings of pleomorphic lipoma are often overdiagnosed as suspicious of malignancy owing to the pleomorphic morphology of the floret giant cells. We present a rare case of pleomorphic lipoma of the parotid gland which was misdiagnosed as a malignant tumor on fine needle aspiration cytology. Histopathological examination and positive expression for CD34 helped to arrive at the final diagnosis. Awareness about this rare entity will prevent overdiagnosis as a malignant tumor and unnecessary radical resections for this benign tumor. [ABSTRACT FROM AUTHOR]

Atypical lipomatous tumor/well-differentiated liposarcoma (ALT/WDLPS) is usually a solitary adipocytic tumor. ALT/WDLPS shows no potential for metastasis unless it undergoes dedifferentiation. No case of multiple ALT/WDLPS has been reported in recent years. We present a rare case of multiple recurrent liposarcomas. A 71-year-old man with a history of scrotal ALT/WDLPS at 61 years presented with multiple large tumors spread throughout the body. The patient was bedridden and severely limited in his activities of daily living (ADL) due to multiple large tumors in the trunk and lower extremities. Radiological examination revealed multiple adipocytic tumors, mainly in the soft tissues of the trunk and extremities, with several visceral lesions. Tumors were resected in stages, starting with large tumors directly related to disability. Repeated palliative resections improved the patient’s ADL; he regained ambulation and was discharged 18 months after admission. Twelve surgeries were performed to remove 44 adipocytic tumors from the testis, left chest wall, perigastric area, ileum, left inguinal region, both buttocks, thighs, and lower legs. Histological examination revealed dedifferentiated components in five tumors, while 39 tumors were diagnosed as ALT/WDLPS. At the age of 76 years, the patient developed an unresectable dedifferentiated liposarcoma between the heart and aorta, leading to fatality at 79 years. The patient’s clinical course suggested multiple metastases of ALT/WDLPS of scrotal origin or ALT/WDLPS of multicentric origin. Although multicentric ALT/WDLPS or ALT/WDLPS metastases are rare, they should be considered when multiple large adipocytic tumors are found throughout the body. Despite the presence of numerous large malignant tumors, surgical treatments of the lesions can improve ADL and prolong life if the tumors are of low-grade malignancy.

Purpose: To present a rare case of dedifferentiated liposarcoma of the orbit. Observations: A 61-year-old male complained of left-sided proptosis, diplopia, and limited ocular motility for two years. Biopsy results at that time were suggestive of an atypical lipomatous neoplasm. Ten years later, he presented with increase in size of the mass and worsening of his symptoms. Imaging showed a multi-lobulated mass in the left orbit involving the intraconal, medial, and anterior orbit. Decompression and orbitotomy with biopsy were performed to debulk the mass. Pathology showed a low-grade well-differentiated liposarcoma and the patient was monitored thereafter annually. Eight years later, he complained of persistent proptosis and mass effect from the tumor resulting in ptosis and diplopia and underwent orbital exenteration. Histopathological analysis of the exenterated orbit revealed a focal area of dedifferentiated liposarcoma. Conclusions and importance: Dedifferentiation of an orbital mass can occur as a late complication years after the diagnosis of well-differentiated liposarcoma. Compared to the previously published cases of orbital liposarcoma, this presentation shows a prolonged timeline prior to dedifferentiation (18 years after initial diagnosis). Symptoms of growth or invasive features could indicate dedifferentiation and should warrant a biopsy.

Herein, we report a case of a giant well-differentiated liposarcoma located subgluteally and extending into the pelvis through the obturator foramen, nearby the urinary bladder and rectum without causing functional disturbances. The tumor was removed simultaneously with transgluteal posterior and anterior transabdominal approach. Six months postoperatively, no clinical and radiological evidence of recurrence was observed.

Simple Summary: Liposarcoma is the most widespread soft-tissue sarcoma in adults. This review summarizes the molecular genetics and epigenetics of the main liposarcoma subtypes and corresponding aberration in signaling forming the basis for targeted therapy selection. In recent years, specific inhibitors of CDK4/6 and MDM2 and VEGFR/FGFR/PDGFR multi-kinase inhibitors have been proposed for the treatment of liposarcoma. Liposarcoma (LPS) is one of the most common adult soft-tissue sarcomas (STS), characterized by a high diversity of histopathological features as well as to a lesser extent by a spectrum of molecular abnormalities. Current targeted therapies for STS do not include a wide range of drugs and surgical resection is the mainstay of treatment for localized disease in all subtypes, while many LPS patients initially present with or ultimately progress to advanced disease that is either unresectable, metastatic or both. The understanding of the molecular characteristics of liposarcoma subtypes is becoming an important option for the detection of new potential targets and development novel, biology-driven therapies for this disease. Innovative therapies have been introduced and they are currently part of preclinical and clinical studies. In this review, we provide an analysis of the molecular genetics of liposarcoma followed by a discussion of the specific epigenetic changes in these malignancies. Then, we summarize the peculiarities of the key signaling cascades involved in the pathogenesis of the disease and possible novel therapeutic approaches based on a better understanding of subtype-specific disease biology. Although heterogeneity in liposarcoma genetics and phenotype as well as the associated development of resistance to therapy make difficult the introduction of novel therapeutic targets into the clinic, recently a number of targeted therapy drugs were proposed for LPS treatment. The most promising results were shown for CDK4/6 and MDM2 inhibitors as well as for the multi-kinase inhibitors anlotinib and sunitinib. [ABSTRACT FROM AUTHOR]

Liposarcomas are among the most usual cancerous growths of mesenchymal tissues and represent about 1% of head and neck sarcomas. They are extremely rare in childhood and are mostly seen between 30 and 60 years of age. The biologic behavior and histologic features of liposarcomas vary. Although these tumors grow very slowly and have a benign behavior, sometimes they grow rapidly and metastasize early, with fatal results. This case report presents a 63-year-old man with a tumor of the left side of the cervical region which has grown to a large size over four years. For an accurate diagnosis, fine needle aspiration biopsy (FNA) biopsy was performed. The cytological examination showed an adipose tumor. Surgical removal was done under local anesthesia and the pathologic examination showed a well-differentiated liposarcoma. These are usually early stage tumors, with fewer metastases than other sarcomas. Surgical abscission is the gold standard for the treatment of liposarcomas. The efficacy of postoperative radiotherapy or/and chemotherapy is controversial. [ABSTRACT FROM AUTHOR]

Introduction Liposarcoma is the most common retroperitoneal soft tissue tumor. Liposarcomas are often asymptomatic and are discovered after they become huge. Surgical resection is the first‐line treatment for retroperitoneal liposarcoma, but the surrounding organs are often resected with the liposarcoma. Case presentation A man saw a hospital with a complaint of left lower abdominal distention, and a left retroperitoneal mass was noted on imaging examination. The patient was referred to our hospital. The mass extended from the retroperitoneum through the inguinal canal to the thigh and involved the femoral nerve and psoas major muscle. A well‐differentiated liposarcoma was suspected, and an open surgical resection was performed. Complete resection of a retroperitoneal liposarcoma extending to the thigh was achieved without postoperative complications. Conclusion Treatment strategies for huge retroperitoneal liposarcomas are important to balance antitumor efficacy and postoperative quality of life.

Abstract Background Liposarcomas are malignant tumours of adipocytic differentiation and their occurrence within the head and neck region is very uncommon. Lipomas are the most common types of benign mesenchymal tumours. The clinical, histological and imaging features of well-differentiated liposarcoma may resemble that of lipoma, causing challenges in the diagnosis. The management and prognosis of benign lipomas and well-differentiated liposarcoma are different. Case presentation A 73-year-old man presented with a painless soft mass in the left temporal region for 15 years with recent rapid growth. The scalp mass was clinically diagnosed as lipoma, while MRI suspected an atypical lipomatous lesion. Complete surgical resection was performed, and histopathological examination confirmed a well-differentiated liposarcoma. The patient recovered completely and will be followed up with long-term surveillance. Conclusion This report is to highlight that clinicians must have a high index of suspicion for this rare entity when dealing with scalp masses and suspicious radiological findings, which can affect the overall management and prognosis.

BackgroundCommon kinds of soft tissue sarcomas (STS) include well-differentiated liposarcoma (WDLPS) and dedifferentiated liposarcoma (DDLPS). In this case, we present a comprehensive clinical profile of a patient who underwent multiple recurrences during the progression from WDLPS to DDLPS.Case presentationA 62-year-old Asian female underwent retroperitoneal resection of a large tumor 11 years ago, the initial pathology revealed a fibrolipoma-like lesion. Over the next six years, the patient underwent three resections for recurrence of abdominal tumors. Postoperative histology shows mature adipose tissue with scattered “adipoblast”-like cells with moderate-to-severe heterogeneous spindle cells, pleomorphic cells, or tumor giant cells. Immunohistochemistry (IHC) demonstrated positive staining for MDM2 and CDK4, confirming that the abdominal tumor was WDLPS and gradually progressing to DDLPS. Post-operative targeted sequencing and IHC confirmed the POC1B::ROS1 fusion gene in DDLPS. Whole-exome sequencing (WES) revealed that WDLPS and DDLPS shared similar somatic mutations and copy number variations (CNVs), whereas DDLPS had more mutated genes and a higher and more concentrated amplification of the chromosome 12q region. Furthermore, somatic mutations in DDLPS were significantly reduced after treatment with CDK4 inhibitors, while CNVs remained elevated.ConclusionDue to the high likelihood of recurrence of liposarcoma, various effective treatments should be taken into consideration even if surgery is the primary treatment for recurrent liposarcoma. To effectively control the course of the disease following surgery, combination targeted therapy may be a viable alternative to chemotherapy and radiotherapy in the treatment of liposarcoma.

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Atypical lipomatous tumor/well-differentiated liposarcoma (ALT/WDLPS) is usually a solitary adipocytic tumor. ALT/WDLPS shows no potential for metastasis unless it undergoes dedifferentiation. No case of multiple ALT/WDLPS has been reported in recent years. We present a rare case of multiple recurrent liposarcomas. A 71-year-old man with a history of scrotal ALT/WDLPS at 61 years presented with multiple large tumors spread throughout the body. The patient was bedridden and severely limited in his activities of daily living (ADL) due to multiple large tumors in the trunk and lower extremities. Radiological examination revealed multiple adipocytic tumors, mainly in the soft tissues of the trunk and extremities, with several visceral lesions. Tumors were resected in stages, starting with large tumors directly related to disability. Repeated palliative resections improved the patient's ADL; he regained ambulation and was discharged 18 months after admission. Twelve surgeries were performed to remove 44 adipocytic tumors from the testis, left chest wall, perigastric area, ileum, left inguinal region, both buttocks, thighs, and lower legs. Histological examination revealed dedifferentiated components in five tumors, while 39 tumors were diagnosed as ALT/WDLPS. At the age of 76 years, the patient developed an unresectable dedifferentiated liposarcoma between the heart and aorta, leading to fatality at 79 years. The patient's clinical course suggested multiple metastases of ALT/WDLPS of scrotal origin or ALT/WDLPS of multicentric origin. Although multicentric ALT/WDLPS or ALT/WDLPS metastases are rare, they should be considered when multiple large adipocytic tumors are found throughout the body. Despite the presence of numerous large malignant tumors, surgical treatments of the lesions can improve ADL and prolong life if the tumors are of low-grade malignancy. [ABSTRACT FROM AUTHOR]

Background: Liposarcoma (LPS) is one of the most common soft-tissue sarcomas. However, intrathoracic LPS is rare, as only 1% of all LPS cases are found in the thorax. Methods: A systematic literature review through PubMed and Embase databases was performed. Only eligible case reports and case series reporting intrathoracic LPS in adult patients were included. Kaplan–Meier curves were calculated to evaluate the survival rate of included patients based on the histological subtype of LPS. Results: 123 studies reporting 197 patients were included. We added a case of a 69-year-old female patient with recurrent giant intrathoracic LPS. The primary tumor measured 15.1cm × 22.9 cm × 21.9 cm and weighed 3100 g. Six months later, the patient was admitted to the hospital with another intrathoracic tumor measuring 9.5 cm × 9 cm× 1.4 cm. The immunohistochemical studies showed expression of murine double minute 2 (MDM2) antigen in both primary and recurrent tumor cells. Conclusions: Dyspnea, chest pain, and cough were the most common symptoms reported in included studies. Overall, the 5-year survival rate was 62%. The highest survival was observed in well-differentiated LPS patients (80%) and the lowest in myxoid LPS (31%). [ABSTRACT FROM AUTHOR]

Background: Liposarcoma and lymphoma are very rare tumors, and their combination is extremely rare. Moreover, there have been no reports of liposarcoma and lymphoma occurring in the same region., Case: A 58-year-old man presented to Kanagawa Cancer Center with a mass in his left thigh and underwent a needle biopsy. Histological analysis showed an increase in the number of small lymphocytes and plasma cells; immunohistochemical analysis showed an increase in CD20-positive cells with Lambda light-chain restriction; therefore, the diagnosis of B-cell malignancy with plasma cell differentiation was made. A bone marrow biopsy specimen showed infiltration of atypical cells of the same phenotype and increased serum IgM-M levels; therefore, a diagnosis of Waldenström macroglobulinemia/lymphoplasmacytic lymphoma (LPL) was made. The needle biopsy specimen showed scattered CDK4-positive cells in the background of the lymphoma cells and sporadic MDM2 signal amplification on fluorescence in situ hybridization, suggesting mixed well-differentiated liposarcoma (WDL). Tumor resection was performed. The tumor contained a mixture of WDL and LPL areas. RNA sequencing revealed upregulated expression of chemokine genes, including CCL5, CCL18, and CCL19, in WDL and that of the corresponding chemokine receptor genes CCR4, CCR6, and CCR7 in the lymphoma cells., Conclusion: Chemokine-chemokine receptor axes may be involved in the pathogenesis of LPL cell-infiltrating WDL. This is an extremely rare case, and we have reported some considerations regarding the tumorigenesis of LPL cell-infiltrating WDL., (© 2025 The Author(s). Cancer Reports published by Wiley Periodicals LLC.)

Background/AimMost paratesticular liposarcomas (PLPSs) are well-differentiated liposarcomas (WDLPSs) with favourable prognoses. As such, the rare occurrence of PLPS often leads to its misdiagnosis as a hernia or hydrocele on physical examination. Curative resection of the tumour may not be possible in cases where PLPSs have transformed into dedifferentiated liposarcomas (DDLPSs) owing to a delay in diagnosis. Herein, we describe a case of unresectable paratesticular dedifferentiated liposarcoma (PDDLPS) with poor prognosis due to delayed diagnosis.Case ReportA 57-year-old man visited our hospital with a chief complaint of a right scrotal mass, which was diagnosed as scrotal hydrocele but without treatment or follow-up. Eight years later, the patient complained of abdominal distension, and a computed tomography scan revealed the presence of retroperitoneal and right scrotal masses. The right scrotal mass was removed, and histopathology revealed DDLPS. The patient was diagnosed with unresectable PDDLPS metastasising to the retroperitoneum, and the left pleura was treated with doxorubicin. After an initial response, pleural effusion and ascites increased during the sixth cycle of chemotherapy. The patient subsequently received eribulin but died 5 months after the initial DDLPS diagnosis.ConclusionIt is difficult to distinguish PLPS from benign inguinal hernia and hydrocele testis on physical examination. PLPS generally has a considerably good prognosis. However, failure to diagnose WDLPS can be dangerous as it might lead to malignant transformation to DDLPS, which has a poor prognosis. Physicians should consider this malignancy when examining patients with hernias or hydroceles of the inguinal region and should perform ultrasonography or magnetic resonance imaging.

Liposarcoma is one of the most common forms of soft tissue sarcoma in adults, and usually occurs in the lower extremities and retroperitoneum. It has several histological subtypes, including myxoid, welldifferentiated, dedifferentiated and pleomorphic. Liposarcomas originating from the mediastinum are extremely rare, and usually grow slowly and remain asymptomatic, but may become symptomatic when they become large enough to press on the adjacent structures. Computed tomography and magnetic resonance imaging provide useful data for diagnosis, while tissue biopsy based on typical pathological features is required for a definitive diagnosis. Complete surgical resection is the first-line treatment option as it is resistant to chemoradiotherapy. Due to the high risk of recurrence, long-term follow-up should be continued. We present here the rare case of a 56-year-old female patient with primary mediastinal liposarcoma who presented with a complaint of cough. [ABSTRACT FROM AUTHOR]

Castleman disease is a rare benign lymphoproliferative disorder that includes a spectrum of distinct histopathological entities. The differential diagnosis of Castleman disease is broad and includes lymphomas, HIV-related lymphadenopathy, autoimmune disorders, and inflammatory liposarcoma. When Castleman disease occurs in the retroperitoneum, the distinction from the inflammatory variant of well-differentiated liposarcoma can be very challenging in small biopsies. Herein we report a case of Castleman disease that presented as a retroperitoneal mass and expressed MDM2 and CDK4 by immunohistochemistry. To our knowledge, this is the first report of Castleman disease staining positively for MDM2/CDK4, and it underscores how immunohistochemistry can potentially serve as a pitfall when differentiating this rare entity from retroperitoneal sarcomas. [ABSTRACT FROM AUTHOR]

Background: While soft-tissue sarcomas (STSs) are rare tumors, liposarcomas are among the most common type of STS and are divided into four main subtypes: atypical lipomatous tumor/well-differentiated liposarcoma; dedifferentiated liposarcoma; myxoid/round-cell liposarcoma (MLPS); and pleomorphic liposarcoma (PLPS). The four different subtypes of liposarcomas have varying underlying molecular pathology, clinical behavior, and treatment sensitivity. Summary: Surgical resection is the mainstay of treatment for patients with localized liposarcoma. Radiotherapy is often used in conjunction with surgery for improving local control of liposarcoma, with MLPS being the most radiosensitive of the four subtypes. For unresectable, advanced, or metastatic disease, the effectiveness of chemotherapy can vary by subtype, with MLPS and PLPS being considered to be chemo-sensitive; however, median survival is low at around 2 years. Current first-line treatment options for patients with liposarcoma include local treatment with or without doxorubicin, ifosfamide, or a doxorubicin-ifosfamide combination, while second-line (and beyond) treatment options include ifosfamide, gemcitabine-based combinations, trabectedin, eribulin, and possibly pazopanib as established therapies. A number of other experimental treatment options are being evaluated, including mouse double minute 2 homolog antagonists, cyclin-dependent kinase 4/6 inhibitors, immune checkpoint modulators, nuclear export inhibitors, multi-kinase inhibitors, peroxisome proliferator-activated receptor gamma agonists, or various combination regimens. This review discusses established systemic therapies and emerging experimental treatment options for the treatment of patients with liposarcoma. Key Message: New treatments are needed to effectively treat liposarcomas. Results from trials exploring experimental therapeutic options will further define the role that these new treatments will play in the management of the different subtypes of liposarcoma. [ABSTRACT FROM AUTHOR]

Paratesticular liposarcomas are extremely rare malignant tumors originating from fat tissues, with an often-challenging diagnosis. We present here the case of a 76-year-old man with a giant paratesticular liposarcoma, initially misdiagnosed as a scrotal hernia. After two years, the progressively enlarging mass underwent surgical resection, and a diagnosis of well-differentiated liposarcoma (lipoma-like subtype) was made. Post-operative treatments were not indicated, and the patient remains relapse free. Next generation sequencing performed on the neoplastic tissue showed co-amplification of MDM2 and CDK4. These alterations are molecular hallmarks of well-differentiated liposarcomas and corroborate the histological diagnosis. Clinical and molecular features of the presented case are in line with the majority of previously published experiences. In conclusion, the presence of a liposarcoma should be taken into account during the diagnostic workup of scrotal masses, in order to minimize the rate of misdiagnosis and improper management. Molecular analysis may support histological characterization of these rare entities and potentially disclose novel therapeutic targets. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the diagnostic capability of radiomics in distinguishing lipoma and Atypic Lipomatous Tumors/Well-Differentiated Liposarcomas (ALT/WDL) with Magnetic Resonance Imaging (MRI). Materials and methods: Patients with a histopathologic diagnosis of lipoma (n = 45) and ALT/WDL (n = 20), who had undergone pre-surgery or pre-biopsy MRI, were enrolled. The MDM2 amplification was accepted as gold-standard test. The T1-weighted turbo spin echo images were used for radiomics analysis. Utility of a predefined standardized imaging protocol and a single type of 1.5 T scanner were sought as inclusion criteria. Radiomics parameters that show a certain level of reproducibility were included in the study and supplied to Support Vector Machine (SVM) as a machine learning method. Results: No significant difference was found in terms of gender, location and age between the lipoma and ALT/WDL groups. Sixty-five parameters were accepted as reproducible. Fifty-seven parameters were able to distinguish the two groups significantly (AUC range 0.564–0.902). Diagnostic performance of the SVM was one of the highest among literature findings: sensitivity = 96.8% (95% CI 94.03–98.39%), specificity = 93.72% (95% CI 86.36–97.73%) and AUC = 0.987 (95% CI 0.972–0.999). Conclusion: Although radiomics has been proven to be useful in previous literature regarding discrimination of lipomas and ALT/WDLs, we found that its accuracy could further be improved with utility of standardized hardware, imaging protocols and incorporation of machine learning methods. [ABSTRACT FROM AUTHOR]

Abstract Background The fibroblast growth factor receptor substrate 2 (FRS2) gene is located close to MDM2 and CDK4 within the 12q13-15 chromosomal region. FRS2 gene was recently found to be consistently amplified in atypical lipomatous tumor (ALT)/well-differentiated liposarcoma (WDL) and dedifferentiated liposarcoma (DDL), suggesting the detection of FRS2 amplification could be a diagnostic tool for ALT/WDL/DDLs. However, the expression of FRS2 protein and diagnostic value of FRS2 immunohistochemistry (IHC) has not been evaluated in a large cohort of ALT/WDL/DDLs. Methods A SNOMED search of hospital surgical pathology files from January 2007 to July 2020 identified 182 ALT/WDL/DDLs with available materials. FRS2 fluorescence in situ hybridization (FISH) and IHC were performed on 182 ALT/WDL/DDLs and 64 control samples. The expression of FRS2 was also compared with that of classic immunomarkers (MDM2 and CDK4) of this tumor entity. Results This study included 91 ALT/WDLs and 91 DDLs. The FISH results showed 172 of 182 (94.5%) cases were FRS2-amplified, and 10 cases were FRS2-nonamplified. Immunostaining results showed 171 (94.0%) ALT/WDL/DDLs were positive for FRS2 and 11 cases (6.0%) were FRS2-immunonegative. In 172 FRS2-amplified cases, 166 (96.5%) were FRS2-immunopositive, and 6 (3.5%) were negative. Among 10 FRS2-nonamplified ALT/WDL/DDL cases, 5 cases were FRS2-immunonegative, and 5 tumors displayed 1+ staining for this marker. In 64 control cases, none of them exhibited FRS2 amplification. Forty-seven (73.5%) control cases were negative for FRS2 immunostaining, while 17 cases (26.5%) were FRS2-immunopositive. Fifteen of these false positive samples (15/17, 88.2%) showed 1+ positivity and only 2 cases (2/17, 11.8%) displayed 2+ positivity. In ALT/WDL/DDLs, the sensitivity of FRS2 immunostaining was slightly lower than MDM2 (FRS2 vs. MDM2: 94.0% vs 100.0%) and CDK4 (FRS2 vs. CDK4: 94.0% vs 97.0%). However, the specificity of FRS2 (73.5%) was slightly higher than that of MDM2 (67.8%) and CDK4 (64.4%). Conclusion This study indicated that FRS2 IHC had relatively good consistency with FRS2 FISH, suggesting that FRS2 immunostaining could be utilized as an additional screening tool for the diagnosis of ALT/WDL/DDL. It must be emphasized that MDM2/CDK4/FRS2 especially MDM2 FISH remains the gold standard and the most recommended method to diagnose this entity.

Introduction. Liposarcoma is the most common retroperitoneal sarcoma. The majority of retroperitoneal liposarcomas are represented by highly differentiated and dedifferentiated liposarcomas. To date, clinical practice has not developed an effective method of the stratification of patients with RLPS into prognostic groups to determine the tactics of patient management. Objective. To develop a method for stratification of patients with retroperitoneal well-differentiated (WDLPS) and dedifferentiated (DDLPS) liposarcomas into prognostic groups. Materials and methods. A retrospective study included 111 patients with WDLPS and 74 patients with DDLPS. The staging of the disease was carried out according to the modified TNM-classification, the analysis of survival was performed depending on the histological type of retroperitoneal liposarcoma (RLPS), the effect of age on overall survival (OS) was evaluated in WDLPS and DDLPS. Further, multivariate Cox regression analyzes were performed to assess the independent factors influencing the prognosis of patients. Then, we developed a methodology for stratification of patients into prognostic groups. OS and recurrence-free survival (RFS) were analyzed in accordance with it.Results and discussion. OS and RFS were statistically significantly worse in DDLPD compared with WDLPS (p = 0.000; log-rank test). At the same time, the results of the work demonstrated the absence of a statistically significant difference in OS and RFS depending on the degree of malignancy of DDLPS. In case of WDLPS and DDLPS, significant differences in OS were achieved only between groups of patients whose age was (at the time of the initial detection of RLPS) under 60 years and older (p = 0.008; p = 0.026; logrank test). Thus, the borderline value of the age of patients, which affects the prognosis, was determined – 60 years. OS and RFS were statistically significantly different between all prognostic groups (p = 0.000; log-rank test). The highest OS was achieved in the group with a “favorable prognosis”, while the shortest OS was in the group with the extremely poor prognosis (p = 0.000; log-rank test). The median OS in the “favorable prognosis” group was 225 (95% CI, 174, 276) months; in the “intermediate prognosis” group – 130 (95% CI, 115, 145) months; in the “poor prognosis” group – 90 (95% CI, 79, 101) months; in the “extremely poor prognosis” group – 22 (95% CI, 15, 29) months. The highest RFS was achieved in the group with a “favorable prognosis”, while the shortest RFS was achieved in the group with an “extremely poor prognosis” (p = 0.000; log-rank test). The median RFS in the “favorable prognosis” group was 80 (95% CI, 65, 95) months; in the “intermediate prognosis” group – 47 (95% CI, 33, 61) months; in the “poor prognosis” group – 26 (95% CI, 24, 28) months; in the “extremely poor prognosis” group – 10 (95% CI, 6, 14) months.Conclusion. The proposed method for stratification of patients with RLPS into prognostic groups demonstrates an adequate distribution of patients and the reliability of intergroup differences in the survival rate.

We present a 55-year-old woman with a palpable mass in the right upper abdomen. Contrast-enhanced computed tomography showed a highly vascularized and primary resectable tumor of the spleen. We performed an open splenectomy with locoregional lymphadenectomy. Histopathological and immunohistochemical evaluation did not reveal classic markers of angiosarcoma, littoral cell angioma, or follicular dendritic cell sarcoma, but showed MDM2-amplification by FISH in all tumor cells as a marker for liposarcoma. The tumor showed growth limited to the spleen tissue. No MDM2-amplification was detectable in the perisplenic adipose tissue, so that infiltration of the spleen by retroperitoneal liposarcoma could be excluded. In summary, well-differentiated liposarcoma confined to the spleen was diagnosed. To the best of our knowledge, this is the first description of a primary liposarcoma of the spleen reported in the literature. Due to the local recurrence risk of liposarcomas, even after R0 resection, we recommended long-term periodic follow-up. [ABSTRACT FROM AUTHOR]

Introduction: Primary intrathoracic liposarcoma is extremely rare, and most published series lack genetic analyses. The aim of our study is to better understand the clinicopathologic and genetic features of these rare lesions. Materials and methods: Forty-three primary intrathoracic liposarcomas were identified and most cases were analyzed by systematic genetic studies, including fluorescence in situ hybridization (FISH), whole-exome sequencing (WES), and Sanger sequencing. Results: This series included 27 males and 16 females (ratios, 1.68:1) aged 24-73 years (median, 53 years). Tumors mainly occurred in the mediastinum (n=23, 53.5%), followed by pleural cavity (n=16, 37.2%) and lung (n=4, 9.3%). The study included 21 well-differentiated liposarcomas (WDLs), 19 dedifferentiated liposarcomas (DDLs), 2 myxoid pleomorphic liposarcomas (MPLs) and 1 pleomorphic liposarcoma (PL), without identification of myxoid liposarcoma. FISH analysis identified MDM2 amplification in 17 of 18 WDLs (94.4%) and all DDLs (16/16, 100.0%). The MDM2-nonamplified WDL was CDK4-nonamplified but FRS2-amplified. WES and Sanger sequencing found somatic TP53 mutation in the 2 MPLs. Follow-up information was available for 33 of 38 cases (86.8%). Thirteen patients (39.4%) showed no evidence of disease, 10 patients (30.3%) were alive with disease, and 8 patients (24.2%) died of disease. Fourteen cases developed recurrence and 1 with metastasis. Conclusions: WDL/DDL was the overwhelming subtype in this location, followed by MPL and PL. Analysis of the FRS2 gene, in combination with MDM2 and other genes of 12q13-15, may more precisely characterize WDL/DDLs. MPL is the most fatal subtype of this site. Further studies are needed to explore the role of TP53 in the pathogenesis of MPL. [ABSTRACT FROM AUTHOR]

Adipocytic tumors are the most common subtype of soft tissue tumors. In current clinical practice, distinguishing benign lipomas from well-differentiated liposarcomas (WDLPS), as well as dedifferentiated liposarcomas (DDLPS) from their morphologic mimics, remains a significant diagnostic challenge. This is especially so when examining small biopsy samples and without the aid of additional ancillary tests. Recognizing the important role that microRNAs (miRNAs) play in tumorigenesis and their potential utility in tumor classification, we analyzed routine clinical tissue samples of benign and malignant lipomatous tumors, as well as other sarcoma mimics, to identify distinguishing miRNA-based signatures that can aid in the differential diagnosis of these entities. We discovered a 6-miRNA signature that separated lipomas from WDLPS with high confidence (AUC of 0.963), as well as a separate 6-miRNA signature that distinguished DDLPS from their more aggressive histologic mimics (AUC of 0.740). Functional enrichment analysis unveiled possible mechanistic involvement of these predictive miRNAs in adipocytic cancer-related biological processes and pathways such as PI3K/AKT/mTOR and MAPK signaling, further supporting the relevance of these miRNAs as biomarkers for adipocytic tumors. Our results demonstrate that miRNA expression profiling may potentially be used as an adjunctive tool for the diagnosis of benign and malignant adipocytic tumors. Further validation studies are warranted. [ABSTRACT FROM AUTHOR]

Dermoid cysts are lined by keratinizing squamous epithelium and consist of skin appendages such as hair follicles, apocrine glands, and sebaceous glands. They are usually diagnosed during infancy or early childhood, commonly reported in the head and neck region. A dermoid cyst on the back is extremely rare, with only three cases in the pediatric and adult populations. We report a rare case of a dermoid cyst in the subcutaneous layer of the back in an adult. A 75-year-old man presented with a soft, painless mass on his left upper back. Computed tomography revealed a low-density mass nearly identical to the subcutaneous fat in the subcutaneous layer with nodular soft-tissue density components. It was a heterogeneously hyperechoic mass without internal vascularity on ultrasonography. On magnetic resonance imaging, the lesion showed nearly identical signal intensity (SI) to subcutaneous fat on T1 and T2-weighted images. The soft tissue component was intermediately hyperintense on T1- and T2- weighted images with enhancement. This lesion was pre-operatively suspected as a lipoma variant or a well-differentiated liposarcoma/atypical lipomatous tumor because of the fat density or SI and enhancing portion. We demonstrated and reviewed the multimodality imaging features of dermoid cysts at an unusual location and suggested imaging features that could help readers differentiate dermoid cysts from lipomatous tumors. When a mass shows fat density or SI with or without enhancing soft tissue components at the trunk or extremity, dermoid cysts as well as lipomatous tumors could be considered in the differential diagnosis.

Objective: to assess the influence of the myxoid matrix in retroperitoneal well-differentiated liposarcoma(WDLPS ) on the long-term results of surgical treatment of patients.Material and Methods. The study included 111 patients with primary retroperitoneal WDLPS who underwent radical surgical treatment in Federal State Budgetary Institution «N.N. Blokhin National Medical Research Center of Oncology» of the Ministry of Health of the Russian Federation. Histological slides of all surgical specimens were reviewed by experienced pathologist and reclassified according to criteria of WHO (2013) for histological subtypes of the WDLPS . Patients were divided into groups depending on presence or absence of the myxoid matrix in WDLPS and enrolled in intergroup analysis of overall (OS ) and recurrence-free (RFS) survival.Results. OS was significantly worse in the group of patients with the myxoid matrix in the tumor (p=0.002; log-rank test). The median OS was 142 (95 % CI , 108, 176) months in the group without the myxoid matrix, and 84 (95 % CI , 29, 139) months in the group with the myxoid matrix. The 5-year survival rates were 79 % and 44 % in the groups without myxoid matrix and with myxoid matrix, respectively. RFS was also significantly worse in the group of patients with the myxoid matrix than in the group of patients without the myxoid matrix (p=0.006; log-rank test). The median RFS was 55 (95 % CI , 38, 72) months in the WDLPS group without the myxoid matrix, and 31 (95 % CI , 15, 47) months in the WDLPS group with the myxoid matrix. The 2-year RFS rates were 75 % and 44 % in the groups without the myxoid matrix and with the myxoid matrix, respectively.Conclusion. The results of the study demonstrated that the presence of the myxoid matrix in WDLPS was associated with poor prognosis. We believe that the presence of the myxoid matrix in WDLPS can serve as an effective morphological marker of a less favorable prognosis for retroperitoneal WLPS .

Background: To elucidate the clinicopathological features of multiply recurrent retroperitoneal liposarcoma referred to a tertiary center. Methods: We retrospectively analyzed the clinical data of 40 patients with pathologically proven primary retroperitoneal liposarcoma treated between January 2015 and June 2019. Results: The initial pathology was well-differentiated liposarcoma (WDLS) in 23 patients, dedifferentiated liposarcoma (DDLS) in 15 patients, and myxoid liposarcoma in two patients. Before and after referral to our hospital, the patients underwent 142 surgeries (median number of surgeries: 3) for initial and recurrent tumors. Of these, 35 (87.5%) patients underwent surgeries for recurrent tumors. In 11 (47.8%) of the 23 patients with initial WDLS, pathological progression (PP) to DDLS was observed in recurrent tumors at the median interval of 7.8 years. In eight patients (72.7%), the PP occurred at the first recurrence. In contrast, all 15 patients with DDLS recurred as DDLS. Distant metastases developed in eight patients (34.8%) with WDLS and five patients (29.4%) with DDLS/myxoid subtype. All eight WDLS patients who developed metastasis were alive with disease at the median interval of 3.6 years, whereas four of the five patients with primary diagnosis of DDLS/myxoid subtype died at the median interval of 5.6 months from the development of metastasis. The 5-year overall survival of the patients with initial WDLS and those with DDLS/myxoid subtype were 100% and 67.4% (p = 0.0006), respectively. Conclusions: The prognosis of the initial-WDLS patients was favorable despite multiple recurrences. In WDLS patients, if distant metastases develop, it is possible to remain alive with disease for years.

Abstract Background Dedifferentiated liposarcoma, one of the most deadly types of soft tissue sarcoma, is an aggressive and high-grade form of liposarcoma. Liposarcoma occurs most commonly in the retroperitoneum, extremities and trunk, but less frequently in the female genital tract. The vagina is a very rare site of origin. Herein we report the first case of dedifferentiated Liposarcoma deriving from vagina and discuss its clinical course. Case presentation A 38-year-old female patient presented to our institution with a painless vaginal mass. Abdominal computed tomography showed a 17.6 cm× 10.4 cm solid mass originating from the right lateral wall of her vagina. Then she underwent complete surgical resection of the tumor mass, and postoperative pathological result confirmed the diagnosis of dedifferentiated liposarcoma deriving from vagina. Six courses of combination chemotherapy with pirarubicin plus ifosfamide were performed after surgery. The patient remains with no evidence of disease recurrence with 13 months of follow-up. Conclusions Liposarcoma is very rare in female genital tract, and more rare for dedifferentiated liposarcoma in gynecologic field. Little is known about the clinical characteristics, pathological diagnosis, prognosis and optimal management strategy of vaginal dedifferentiated liposarcoma. Complete surgical resection followed by systemic chemotherapy is suggested to be standard treatment for dedifferentiated liposarcoma. Combination chemotherapy with pirarubicin and ifosfamide may be effective for treating vaginal dedifferentiated liposarcoma.

Well-differentiated liposarcoma (WDL) is one of the most common soft tissue sarcomas in adults. It has a predilection for middle-aged males and arises in deep-seated locations such as retroperitoneum, mediastinum, and spermatic cord. Its occurrence in young individuals at the hypopharyngeal region is an exceedingly rare event. Myxoid liposarcoma (ML)-like changes can seldom occur in some cases of WDL, which makes the diagnosis of WDL more challenging. Amplification of DDIT3 gene in a subset of cases of WDL has shown to be associated with such unique morphology. Herein, we present a case of a 36-year-old gentleman who presented with difficulty in breathing and swallowing for 3 months duration. CT scan of the neck revealed a lesion along the posterior wall of the hypopharynx measuring 3.5 cm. Histopathologic examination revealed a tumor composed of lobules of oval to spindle cells in a prominent myxoid stroma with delicate chicken-wire vasculature. In the vicinity, there were lobules composed of variably sized adipocytes separated by thick fibrous septa that contains atypical hyperchromatic spindle cells. By immunohistochemistry, the tumor cells in both components were immunoreactive for CDK4, but negative for MDM2. Fluorescence in-situ hybridization (FISH) confirmed the presence of MDM2 gene amplification. There was no evidence of FUS-DDIT3 gene rearrangement, however, DDIT3 gene was also amplified. The diagnosis of well-differentiated liposarcoma with prominent myxoid stroma was rendered. This is the first documentation of WDL with ML-like morphology harboring co-amplification of MDM2 and DDIT3 in the hypopharynx. [ABSTRACT FROM AUTHOR]

Abstract Background Liposarcoma arising from the mediastinum is rare, accounting for less than 1% of mediastinal tumors. Furthermore, a rapidly growing well-differentiated liposarcoma is extremely rare. A well-differentiated liposarcoma is usually considered a low-grade malignancy. However, we present an extremely rare case of a sclerosing variant of well-differentiated liposarcoma that grew rapidly within a year. Case presentation A 77-year-old man with a giant mass in the left thoracic cavity was referred to our hospital. This mass measured about 10 cm and occupied the left-sided mediastinum on a chest radiography; however, there was no abnormal finding on the previous year’s chest radiography. Chest-enhanced computed tomography revealed a well-circumscribed 11-cm mass in the left-sided anterior mediastinum. Positron emission tomography showed accumulation of fluorodeoxyglucose uptake in this tumor (maximum standard uptake value = 3.3). The radiological findings of computed tomography and positron emission tomography indicated that this tumor was a benign or low-grade malignancy; therefore, the chest radiographic findings were difficult to explain. To explain this discrepancy and establish the diagnosis, tumor resection was performed via left posterolateral thoracotomy. Intraoperatively, the left phrenic nerve and pericardium were adhered tightly to the tumor, so we resected them. The tumor was well-circumscribed and fibrous; therefore, the initial diagnosis was solitary fibrous tumor. However, based on its histopathological and immunohistochemical patterns, the tumor was diagnosed as a sclerosing variant of well-differentiated liposarcoma. Five years postoperatively, the patient remains alive with no evidence of disease recurrence. Conclusions A well-differentiated liposarcoma is usually considered a low-grade malignancy. Nevertheless, the giant tumor in the present case appeared within 1 year. Thus, this was an extremely rare case of a sclerosing variant of well-differentiated liposarcoma with rapid growth.

Liposarcomas are common mesenchymal malignant tumors arising from adipose tissue. Although liposarcomas are the most frequent type of soft tissue sarcomas, accounting for approximately 20% of all soft tissue sarcomas, they are rare in the head and neck, particularly in the oral cavity. Oral liposarcomas have been reported to occur mainly on the buccal mucosa, with other sites including the floor of the mouth, tongue, palate, and mandible. This report describes a 76-year-old male patient with an atypical lipomatous tumor/well-differentiated liposarcoma of the tongue that underwent surgical excision. This report also reviews published data on these rare tumors.

Background: Lipomas and atypical lipomatous tumors or well-differentiated liposarcomas (ALTs/WDLs), pose a diagnostic challenge due to their overlapping clinical and imaging features. Accurate differentiation is crucial as treatment strategies differ significantly between benign lipomas and malignant ALTs/WDLs. In recent years, medical imaging techniques have shown promise in distinguishing lipomas from ALTs/WDLs by providing enhanced visualization and assessment of various imaging parameters., Objective: This systematic review aimed to investigate the use of magnetic resonance (MR) imaging and computed tomography (CT) scan to differentiate lipomas from ALTs/WDLs., Methods: A systematic review was conducted by using MEDLINE, PubMed, PubMed Central, Cochrane Library, Google Scholar, and clinical trail.gov to identify imaging studies published between 2001 and 2022. Two independent reviewers reviewed 221 record to scrutinize the studies. The methodological quality of each included studies was assessed the using Quality Assessment of Diagnostic Accuracy Studies 2 (QUADAS-2) tool., Results: Thirteen retrospective cohort studies included 1,390 of total patients. Among them, 11 studies used MR imaging, 2 studies used CT scan and MR imaging both to differentiate lipoma from ALTs/WDLs. The significant diagnostic variables identified in the included studies were age, size, texture, mean intensity, contrast enhancement, location, septation, and nodularity. The overall, sensitivity, specificity, and accuracy of the included studies for diagnosis of lesions range from 66% to 100%, 37% to 100%, and 76% to 95%, respectively. The positive and negative predictive values range from 46.9% to 90% and 86% to 100%, respectively., Conclusion: The most frequent diagnostic features of ALTs/ WDLs include tumors ⩾110 mm in size, often in patients over 60, predominantly in the lower extremities, with an irregular shape, incomplete fat suppression, contrast enhancement, nodularity, septation >2 mm, and predictive markers such as lactate dehydrogenase >220 and a short tau inversion recovery-signal intensity ratio >1.18., Competing Interests: The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article., (© The Author(s) 2024.)

Introduction: 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., Methods: 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., Results: 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., Conclusion: 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., (© 2024 Wiley Periodicals LLC.)

Aims: Amplification of the murine double minute-2 (MDM2) gene, which is usually detected with fluorescence in-situ hybridisation (FISH), is the key driving event for atypical lipomatous tumours (ALTs)/welldifferentiated liposarcomas (WDLs). We sought to determine the concordance between the histopathological findings and MDM2 FISH in the diagnosis of ALT/WDL, and to identify the histological features of MDM2-amplified tumours lacking classic atypia. Methods and results: We performed a retrospective analysis of all mature lipomatous lesions subjected to MDM2 FISH analysis at our institution. MDM2 FISH analysis was performed on 439 mature lipomatous lesions: 364 (82.9%) were negative and 75 (17%) were positive. In 17 of 75 (22.6%) ALTs/WDLs, cytological atypia was not identified on initial histological assessment, thus favouring lipoma. On review, these cases shared common histological features, consisting of a very low number of relatively small stromal cells within the tumour lobules, with mildly coarse chromatin and oval nuclei, admixed with unremarkable adipocytes in a tumour background devoid of fibroconnective septa, areas of fibrosis, or blood vessels. These cells matched the cells in which FISH showed MDM2 amplification. In contrast, 13 cases (3.5%) regarded as suspicious for ALT/WDL on the basis of histology lacked MDM2 amplification and were reclassified following the FISH findings. Conclusions: We conclude that a subset of lipomalike ALTs/WDLs are not associated with any of the features typically described in ALT/WDL. Our study also showed that tumours >100 mm are more likely to be ALT/WDL; however, a history of recurrence or concerning clinical/radiological features was not significantly associated with classification as ALT/WDL. [ABSTRACT FROM AUTHOR]

Aims: Amplification of the murine double minute‐2 (MDM2) gene, which is usually detected with fluorescence in‐situ hybridisation (FISH), is the key driving event for atypical lipomatous tumours (ALTs)/well‐differentiated liposarcomas (WDLs). We sought to determine the concordance between the histopathological findings and MDM2 FISH in the diagnosis of ALT/WDL, and to identify the histological features of MDM2‐amplified tumours lacking classic atypia. Methods and results: We performed a retrospective analysis of all mature lipomatous lesions subjected to MDM2 FISH analysis at our institution. MDM2 FISH analysis was performed on 439 mature lipomatous lesions: 364 (82.9%) were negative and 75 (17%) were positive. In 17 of 75 (22.6%) ALTs/WDLs, cytological atypia was not identified on initial histological assessment, thus favouring lipoma. On review, these cases shared common histological features, consisting of a very low number of relatively small stromal cells within the tumour lobules, with mildly coarse chromatin and oval nuclei, admixed with unremarkable adipocytes in a tumour background devoid of fibroconnective septa, areas of fibrosis, or blood vessels. These cells matched the cells in which FISH showed MDM2 amplification. In contrast, 13 cases (3.5%) regarded as suspicious for ALT/WDL on the basis of histology lacked MDM2 amplification and were reclassified following the FISH findings. Conclusions: We conclude that a subset of lipoma‐like ALTs/WDLs are not associated with any of the features typically described in ALT/WDL. Our study also showed that tumours >100 mm are more likely to be ALT/WDL; however, a history of recurrence or concerning clinical/radiological features was not significantly associated with classification as ALT/WDL. [ABSTRACT FROM AUTHOR]

Background: The fibroblast growth factor receptor substrate 2 (FRS2) gene is located close to MDM2 and CDK4 within the 12q13-15 chromosomal region. FRS2 gene was recently found to be consistently amplified in atypical lipomatous tumor (ALT)/well-differentiated liposarcoma (WDL) and dedifferentiated liposarcoma (DDL), suggesting the detection of FRS2 amplification could be a diagnostic tool for ALT/WDL/DDLs. However, the expression of FRS2 protein and diagnostic value of FRS2 immunohistochemistry (IHC) has not been evaluated in a large cohort of ALT/WDL/DDLs. Methods: A SNOMED search of hospital surgical pathology files from January 2007 to July 2020 identified 182 ALT/WDL/DDLs with available materials. FRS2 fluorescence in situ hybridization (FISH) and IHC were performed on 182 ALT/WDL/DDLs and 64 control samples. The expression of FRS2 was also compared with that of classic immunomarkers (MDM2 and CDK4) of this tumor entity. Results: This study included 91 ALT/WDLs and 91 DDLs. The FISH results showed 172 of 182 (94.5%) cases were FRS2-amplified, and 10 cases were FRS2-nonamplified. Immunostaining results showed 171 (94.0%) ALT/WDL/DDLs were positive for FRS2 and 11 cases (6.0%) were FRS2-immunonegative. In 172 FRS2-amplified cases, 166 (96.5%) were FRS2-immunopositive, and 6 (3.5%) were negative. Among 10 FRS2-nonamplified ALT/WDL/DDL cases, 5 cases were FRS2-immunonegative, and 5 tumors displayed 1+ staining for this marker. In 64 control cases, none of them exhibited FRS2 amplification. Forty-seven (73.5%) control cases were negative for FRS2 immunostaining, while 17 cases (26.5%) were FRS2-immunopositive. Fifteen of these false positive samples (15/17, 88.2%) showed 1+ positivity and only 2 cases (2/17, 11.8%) displayed 2+ positivity. In ALT/WDL/DDLs, the sensitivity of FRS2 immunostaining was slightly lower than MDM2 (FRS2 vs. MDM2: 94.0% vs 100.0%) and CDK4 (FRS2 vs. CDK4: 94.0% vs 97.0%). However, the specificity of FRS2 (73.5%) was slightly higher than that of MDM2 (67.8%) and CDK4 (64.4%). Conclusion: This study indicated that FRS2 IHC had relatively good consistency with FRS2 FISH, suggesting that FRS2 immunostaining could be utilized as an additional screening tool for the diagnosis of ALT/WDL/DDL. It must be emphasized that MDM2/CDK4/FRS2 especially MDM2 FISH remains the gold standard and the most recommended method to diagnose this entity. [ABSTRACT FROM AUTHOR]

Background: Liposarcoma of the larynx is a rare entity. Well-differentiated spindle cell liposarcoma of the larynx has not been yet reported in the literature. Case Report: We report the first case of well-differentiated spindle cell liposarcoma of the larynx on a 59-year-old male who presented with change of voice and phlegmy cough for several months. Laryngoscopy revealed a mucosal covered pedunculated mass on the supraglottis. Computerized tomography (CT) scan showed a low-attenuation mass causing moderate narrowing of the airway. The lesion was excised. Grossly, a 4.2 cm ovoid, solid and soft mass with homogeneously white-gray and rubbery cut surface was identified. Microscopic examination revealed a well-demarcated neoplasm composed of predominantly atypical and pleomorphic spindle cells distributed in collagenous stroma, with admixed adipocytes showing variation in cell size and rare lipoblasts. Immunohistochemical stains showed that the spindle cells were positive for MDM2, CDK4, and CD34. Overall, the histology and immunoprofile are consistent with a welldifferentiated liposarcoma, spindle cell type. Due to the positive resection margin, the patient subsequently received endoscopic local re-excision with a carbon dioxide laser. He did well at 4 months after primary excision. Conclusion: This case illustrates that while well-differentiated spindle cell liposarcoma rarely occurs in the larynx, it should be considered in the differential diagnosis of patients with laryngeal lesions. A panel of immunohistochemistry markers including MDM2, CDK4 and CD34 is helpful to render accurate diagnosis. Wide excision with long-term follow-up is necessary for this rare variant of liposarcoma. [ABSTRACT FROM AUTHOR]

Background: Neoplasms of the retroperitoneum that contain a major fat component may represent either benign entities, such as lipomas or angiomyolipomas, or malignancy such as liposarcoma. Distinguishing these diagnoses has important implications for management. While liposarcomas often stain positively for MDM2 and CDK4 proteins, absence of these markers can lead to diagnostic and management challenges. Methods: We examined three cases in our institution of fat-containing masses of the retroperitoneum that lacked MDM2 and CDK4 markers to highlight the challenges in diagnosing and managing these cases. A thorough review of the literature examining radiologic and histologic features that can be used to determine that diagnosis was conducted and summarized. Results: The three cases we present represent the three main diagnostic entities that can be found in among fatty tumors of the retroperitoneum: lipoma, angiomyolipoma, and liposarcoma. While radiologic features and analysis of histology helped to inform management, these cases in conjunction with the literature also illustrate the limitations of the diagnostic work up and importance also factoring the biologic behavior of the tumor in its management. Conclusion: Fat-containing tumors of the retroperitoneum that do not stain for MDM2 or CDK4 can pose a diagnostic challenge. Assessing radiologic and pathologic features in conjunction with the biologic behavior of these tumors should inform their management. [ABSTRACT FROM AUTHOR]