From the archives of the AFIP: imaging of musculoskeletal liposarcoma with radiologic-pathologic correlation

Intramuscular lipomas posing diagnostic and pre-operative counselling challenges in a low-resource setting: A case series

INTRODUCTION

Intramuscular lipomas (IMLs) are uncommon primary adipose tissue tumours deep within the muscle. A high likelihood of misdiagnosing them as other benign and malignant masses necessitates imaging studies to confirm the diagnosis and plan treatment. Ultrasonography is useful but CT and MRI provide a more accurate diagnosis. While diagnostic tests are suitable, they may not always be accessible or affordable in low-resource settings. We present three cases of IMLs that emphasise the difficulties posed by limited resources and the significance of a comprehensive medical history and physical examination in low-resource settings.

PRESENTATION OF CASES

The patients included a 57-year-old male with a distal right thigh mass, a 65-year-old female with a proximal right thigh mass, and a 60-year-old female with a mass at the left scapular area. The three patients underwent surgical excision and had an uneventful postoperative course, with no reported recurrence during their ongoing follow-up.

DISCUSSION

The management of IMLs is not complicated if the requisite resources are available. Conversely, in low-resource settings with limited diagnostic facilities and human expertise, management may take a challenging path. Patient 1, despite undergoing diagnostic tests confirming IML, initially declined treatment due to challenges with pre-operative counselling. Patients 2 and 3 lacked health insurance and could not afford diagnostic imaging tests.

CONCLUSION

Healthcare professionals in low-resource settings should familiarise themselves with the clinical characteristics and pathology of IMLs to minimise misdiagnosis and ensure appropriate counselling is provided to patients. IMLs are slow-growing mostly asymptomatic benign swelling. On physical examination, they are usually non-tender, soft, masses, not fixed to the bed or overlying tissue. The overlying skin is normal and lymphadenopathy is absent.

Sclerosing well-differentiated liposarcoma: two diagnostically challenging mimicker cases and a literature review

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.

MRI Differential Diagnosis and Guidance for Puncture Biopsy of Musculoskeletal Dedifferentiated Liposarcoma and Well Differentiated Liposarcoma

Objective

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.

Case report: a case report of excision of giant lipoma in the posterior neck

Lipomas, benign tumors originating from the anomalous proliferation of adipocytes, predominantly emerge in regions rich in adipose tissue. However, their presence in the head and neck areas remains rare, constituting approximately 13% of all diagnosed lipoma cases. This study presents a case involving a substantial subcutaneous lipoma located at the posterior neck, measuring about 20 cm × 19 cm × 10 cm. The patient presented with swelling and pain in the back of the neck. And the considerable dimensions of this lipoma significantly impacted the patient's quality of life and aesthetic appearance. Concurrently, the patient exhibited symptoms indicative of degenerative cervical spine disease and cervical disc herniation. After admission, a comprehensive examination, including ultrasound, CT scan, and MRI, was conducted. Given the clinical complexity, the decision for surgical intervention was deemed essential. The surgical strategy entailed a meticulous total excision of the tumor through an incision made in the posterior cross-neck, coupled with the strategic removal of excess skin. To facilitate wound healing, postoperative management included the use of negative pressure drainage. Pathological examination conclusively identified the mass as a lipoma. Postoperative follow-ups indicated successful recovery, as evidenced by the restoration of the neck's aesthetic contour and the complete resolution of the previously observed restrictions in sagittal neck movement.

Imaging Diagnosis of Thoracic Elastofibroma Dorsi

OBJECTIVE

Elastofibroma dorsi (ED) is an uncommon benign tumor that is commonly incidentally discovered on thoracic imaging and at times misinterpreted as a more aggressive lesion. The objective of the study is to characterize the typical cross-sectional imaging findings of elastofibroma dorsi and quantify the risk of masquerading malignancy.

METHODS

Retrospective search of radiology and pathology reports over a 12-year period identified 409 cases of suspected ED. Pertinent imaging was reviewed with a focus on computed tomography (CT) and magnetic resonance imaging (MRI), specifically assessing lesion location, presence of interspersed fat, and appearances on follow-up.

RESULTS

Typical imaging appearances of 310 ED, including 10% with pathologic confirmation, were that of a mass deep to the serratus anterior (98%) and near the scapular tip (98%). Intralesional interspersed fat was present in 87% of cases imaged with CT and in 90% of cases imaged with MRI. In the 43 cases imaged with both modalities, 8 (19%) did not have interspersed fat on CT, but 7 (88%) of these did have interspersed fat on MRI. Twelve tumors (benign and malignant) were included, of which only 17% were deep to serratus anterior and 25% were at the scapular tip, P = 0.0001 and P < 0.0001 versus ED. Only a single tumor contained interspersed fat, P < 0.001 versus ED, which had benign pathology on biopsy.

CONCLUSIONS

Elastofibroma dorsi can be diagnosed with a high degree of certainty in the presence of classic location and imaging characteristics, obviating the need for further imaging or biopsy.

[Parosteal Chondrolipoma of the Scapula: A Case Report]

Parosteal lipoma is a rare tumor that occurs very close to the bone, and accounts for approximately 0.3% of all lipomas. Chondrolipoma, a lipoma with cartilaginous metaplasia, is also a rare tumor consisting of mature adipose and cartilage tissues. Therefore, a tumor with characteristics of both parosteal lipoma and chondrolipoma simultaneously is extremely rare. Herein, we report the imaging findings of a parosteal chondrolipoma arising in the right periscapular area, confirmed based on surgical resection and histopathologic examination.

Case report of a successful conservative surgical treatment of a giant liposarcoma of the forearm invading the median nerve

Liposarcomas (LPS) are the most common malignant tumors among soft tissue sarcomas. We report a rare case of well-differentiated liposarcoma (lipoma-like) located along the anterior compartment of the right forearm, which was successfully treated with complete excision, resulting in good functional recovery without recurrence during a 2-year follow-up. Surgery is the primary treatment for localized forms, involving complete and radical excision with clear resection margins. LPS represents a heterogeneous group of soft tissue sarcomas, with diagnosis primarily relying on histological examination. Their care requires a multidisciplinary approach.

Inguinoscrotal Hernia: An Unusual Presentation of Retroperitoneal Liposarcoma

Liposarcoma presenting within an inguinal hernia is rare. It may manifest as either primary spermatic cord liposarcoma or as an extension of retroperitoneal liposarcoma into the inguinoscrotal region. Tumors originating in the retroperitoneum can extend toward the inguinal region through the gonadal vein pathway. Utilizing imaging modalities is crucial for differentiating between a retroperitoneal component and a fat-containing inguinal mass. Identification of non-lipomatous components within a fat-containing tumor provides diagnostic clues on radiological imaging.

Giant liposarcoma of the thigh: A case report

Liposarcoma is a tumor derived from primitive cells that undergo adipose differentiation. They comprise 10%-35% of all soft tissue sarcomas. We present a 46-year-old female patient with a 4-year history of a giant swelling on the lateral aspect of the left thigh. Wide local excision of the mass was performed and histopathological analysis revealed a well-differentiated liposarcoma. Liposarcomas commonly appear in the extremities and have distinct features on imaging studies. Surgical treatment and histology are the most important prognostic factors for patients with lipomatous tumors, as complete surgical excision reduces local recurrence rate.

Characteristic findings of primary perirenal angiosarcoma on chemical shift subtraction magnetic resonance imaging (CSS-MRI): A case report

A 70-year-old man with supraglottic carcinoma underwent computed tomography (CT) for staging purposes. A tumor measuring approximately 7 × 10 cm was found incidentally in the left perirenal space. The tumor showed homogeneous high signal intensity on chemical shift subtraction magnetic resonance imaging (CSS-MRI) suggesting the presence of minimal amounts of fat. Five months later, the tumor had grown to approximately 10 × 12 cm with indistinct margins. CSS-MRI showed high signal intensity in the tumor periphery only. The tumor was resected and the pathological diagnosis was angiosarcoma. Angiosarcomas are malignant endothelial vascular neoplasms that are highly invasive to their surroundings. Here we report a case of primary perirenal angiosarcoma that was difficult to differentiate from a dedifferentiated liposarcoma. On CSS-MRI, high signal intensity within a tumor may be a characteristic feature of primary perirenal angiosarcoma.

Primary Pathology of the Parapharyngeal Space

The radiologically defined parapharyngeal space is a distinct location on cross-sectional imaging and is often described based on its displacement or invasion by tumors or other pathologies in adjacent spaces; however, there are multiple primary pathologic entities of the parapharyngeal space, which are often forgotten. Recognizing that a lesion is arising from the parapharyngeal space is important in generating an accurate differential diagnosis that will guide management.

Giant dedifferentiated liposarcoma of the gastrocolic ligament: A case report

BACKGROUND

Dedifferentiated liposarcoma (DDLS) has a worse prognosis and occurs most commonly in the retroperitoneal region and rarely in the intraperitoneal region. Histological diagnosis was revolutionized by the combined contributions of histo-immuno-chemistry and molecular biology. Aside from surgery, there is no consensus on the optimal treatment for this chemoresistant cancer.

CASE SUMMARY

A thirty-year-old black female presented with a large painful abdominal mass occupying nearly the entire abdomen and progressive weight loss was admitted for surgery. Abdominal computed tomography showed a large heterogeneous mass of the mesentery that was sized 18 cm × 16 cm in size and had heterogeneous contrast enhancement. During laparotomy, en bloc excision of the large and multilobulated gastrocolic ligament mass was performed. The initial postoperative histopathological diagnosis was undifferentiated sarcoma. Finally, the results of immunohistochemistry and molecular biology allowed us to confirm the diagnosis of DDLS. The tumour followed an aggressive evolution with diffuse metastasis, causing the death of the patient less than 5 mo after the operation.

CONCLUSION

Dedifferentiated liposarcomas are rare tumours that typically originate in the retroperitoneum but may arise in unexpected locations.

Prognostic value of clinical and MRI features in the screening of lipomatous lesions

BACKGROUND AND OBJECTIVES

Differentiation of lipomatous tumors mostly requires diagnostic biopsy but is essential to decide for the most adequate therapy. This study aims to investigate the prognostic value of available clinical and radiological features with regard to malignancy of the lesion, recurrence and survival.

METHODS

In this retrospective cohort study, 104 patients with a biopsy-proven lipomatous tumor between 2010 and 2015 and a minimum clinical follow-up of two years were enrolled. Next to clinical features (age, gender, location of the lesion, histopathologic diagnosis, stage of disease, time to recurrence and death), MRI parameters were recorded retrospectively and blinded to the histological diagnosis.

RESULTS

Malignant lipomatous tumors were associated with location in the lower extremities and MRI features like thick septation (>2 mm), presence of a non-adipose mass, foci of high T2/STIR signal and contrast agent enhancement. A non-adipose mass was a predictor for recurrence and inferior overall survival, while lesions with high T2/STIR signal showed higher risk of recurrence only. In combination, clinical and radiological features (lower extremities, septation > 2 mm, existence of non-adipose mass, contrast enhancement, and foci of high T2/STIR signal) predicted a malignant lipomatous tumor with an accuracy of 0.941 (95% CI of 0.899-0.983; 87% sensitivity, 86% specificity).

CONCLUSION

Localization and characteristic MR features predict malignancy in most lipomatous lesions. Non-adipose masses are a poor prognostic factor, being associated with tumor recurrence and disease-related death.

[Contribution of whole-body MRI to the initial assessment of myxoid liposarcoma]

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.

Survival of a patient with five recurrences of retroperitoneal liposarcoma over a period of 13 years: A case report and review

Retroperitoneal liposarcoma (RPLS) is a rare tumor that occurs in the retroperitoneal region and accounts for ~0.2% of all malignant tumor incidence. The present study describes the treatment of a surviving patient with RPLS that recurred five times in 13 years. This case has a long survival time and numerous relapses, which is a rare occurrence. The 40-year-old female patient was admitted to Shaoxing Second Hospital (Shaoxing, China) with an abdominal mass. Abdominal computed tomography (CT) scan revealed multiple liposarcoma recurrences in the abdominal, pelvic and retroperitoneal areas. As the diagnosis of RPLS was the fifth recurrence, cytoreductive surgery was performed and post-operative pathology suggested mixed liposarcoma. The patient underwent six cycles of doxorubicin and ifosfamide regimen chemotherapy and targeted therapy with anlotinib following surgery; no evidence of disease progression was found on abdominal CT scan during follow-up. The present study also reviewed the literature in terms of the clinical diagnosis, treatment, pathological characteristics and similar cases of liposarcoma with the aim of improving diagnosis and treatment.

Giant retroperitoneal well differentiated liposarcoma: A case report and literature review

INTRODUCTION AND IMPORTANCE

The most prevalent type of primary retroperitoneal tumors is soft tissue sarcoma (STS). Liposarcoma accounts for 40 % of retroperitoneal tumors (Mack, 1995). Retroperitoneal liposarcoma accounts for 12 % to 40 % of all liposarcomas (Vijay and Ram, 2015). They typically present with advanced disease and often carry a poor prognosis. Because of their rarity and anatomic location, these malignant tumors can cause a diagnostic dilemma and present several therapeutic challenges (Vijay and Ram, 2015).

CASE PRESENTATION

A 48-year-old male patient presented to our gastrointestinal oncology clinic with a 2-year history of abdominal discomfort, weight loss and steadily growing abdominal swelling. A soft, rubbery lobulated mass with a positive "slippage sign" was palpable over all the quadrants of the abdomen. CT scan conclusion was retroperitoneal lipoma with internal enhancing nodular components. During laparotomy, a fatty mass measuring 55*60*22 cm and weighing 14 kg was excised. Histopathologic report showed a well differentiated liposarcoma (WDLS).

CLINICAL DISCUSSION

Giant retroperitoneal liposarcoma (RPL) is exceedingly rare. Liposarcomas have diverse MRI and CT appearances due to the various subtypes. WDLS are difficult to identify from lipomas before surgery. Histopathology is the only way to provide a reliable diagnosis; therefore en block resection is the recommended approach when malignancy cannot be ruled out.

CONCLUSION

Although imaging with ultrasound, CT, and MRI can aid in the diagnosis, differentiating WDLS from lipoma pre-operatively can be difficult, and en block resection is the recommended approach when malignancy cannot be ruled out.

Recommendations for the Management of Incidental Musculoskeletal Findings on MRI and CT

The Canadian Association of Radiologists (CAR) Incidental Findings Working Group consists of both academic subspeciality and general radiologists tasked with either adapting American College of Radiology (ACR) guidelines to meet the needs of Canadian radiologists or authoring new guidelines where appropriate. In this case, entirely new guidelines to deal with incidental musculoskeletal findings that may be encountered on thoracoabdominal computed tomography or magnetic resonance imaging were drafted, focussing on which findings should prompt recommendations for further workup. These recommendations discuss how to deal with incidental marrow changes, focal bone lesions, abnormalities of the pubic symphysis and sacroiliac joints, fatty soft tissue masses, manifestations of renal osteodystrophy and finally discuss opportunistic osteoporosis evaluation.

Myxoid Liposarcoma of the Breast Mimicking Phyllodes Tumor: A Case Report

Myxoid liposarcoma is an extremely rare malignant breast tumor. We report the case of a 44-year-old woman who had myxoid liposarcoma of the breast with a history of phyllodes tumor and describe the imaging findings on US, mammography, and MRI. Before surgery, the mass was considered to be a recurrent phyllodes tumor. However, using US, we retrospectively identified some differences between myxoid liposarcomas and phyllodes tumors.

Increasing differential diagnosis between lipoma and liposarcoma through radiomics: a narrative review

Soft tissue sarcomas (STSs) are rare, heterogeneous, and very often asymptomatic diseases. Their diagnosis is fundamental, as is the identification of the degree of malignancy, which may be high, medium, or low. The Italian Medical Oncology Association and European Society of Medical Oncology (ESMO) guidelines recommend magnetic resonance imaging (MRI) because the clinical examination is typically ineffective. The diagnosis of these rare diseases with artificial intelligence (AI) techniques presents reduced datasets and therefore less robust methods. However, the combination of AI techniques with radiomics may be a new angle in diagnosing rare diseases such as STSs. Results obtained are promising within the literature, not only for the performance but also for the explicability of the data. In fact, one can make tumor classification, site localization, and prediction of the risk of developing metastasis. Thanks to the synergy between computer scientists and radiologists, linking numerical features to radiological evidence with excellent performance could be a new step forward for the diagnosis of rare diseases.

[Ultrasound of the neck]

Ultrasound examination of the neck organs enables an assessment that in many cases is superior to that of magnetic resonance imaging and computed tomography. Ultrasound is therefore not only a first line or point of care imaging modality but can provide imaging for the concluding diagnosis in cases. Because of the good sonographic accessibility of the majority of the structures of the neck, many technical advances, in particular high-resolution ultrasound and signal post-processing have a major influence on the possibilities of ultrasound. Lymph nodes and salivary glands are the main focus in clinical applications, although other diseases and swellings of the neck can also be clarified with ultrasound. Special applications are ultrasound-guided interventions, e.g., biopsies or the sonographic assessment of peripheral nerves. As in any imaging modality, a comprehensive clinical knowledge is necessary for the diagnostic assessment. Because of constant assessment and thus continuous modification of the examination, ultrasound examinations may only be performed adequately with the appropriate clinical knowledge.

Sarcoma Imaging Surveillance

Soft tissue sarcomas (STS) are a heterogeneous group of solid tumors. There are many histologic subtypes. The prognosis after treatment may be estimated by the analysis of the type of tumor, grade, depth, size at diagnosis, and age of the patient. These type of sarcomas most commonly metastasize to the lungs and may have a relatively high rate of local recurrence, depending on the histologic type and surgical margins. Patients with recurrence have a poorer prognosis. The surveillance of patients with STS is therefore extremely important. This review analyzes the role of MR imaging and US in detecting local recurrence.

Review of primary superficial soft tissue mesenchymal tumors of malignant or intermediate biological potential

The majority of the sarcomas are deep in location, larger than 5 cm in size, and heterogenous in imaging appearance. However, when sarcomas occur superficially, these typical features may be absent, failing to alert the radiologist to a malignancy and mimicking one of the more numerous benign superficial tumors that make up the bulk of soft tissue mass evaluations. This manuscript will discuss the current role of imaging in recognizing features concerning for superficial soft tissue sarcomas. Provided is an overview of the demographic, clinical, and imaging features of the most commonly encountered superficial soft tissue sarcomas, including undifferentiated pleomorphic, leiomyosarcoma, synovial sarcoma, liposarcoma, myxofibrosarcoma, dermatofibrosarcoma protuberans, epithelioid sarcoma, and angiosarcoma. A less common but primary superficial tumor, angiomatoid fibrous histiocytoma, is also reviewed as the diagnosis may be confounding both clinically and on imaging studies.

The Characteristics of magnetic resonance imaging and immunohistochemical findings in de-differentiated liposarcoma

PURPOSE

Radiological imaging in Dedifferentiated liposarcoma (DDLPS) often shows the coexistence of fatty and non-fatty solid components; however, it has been shown that when fatty components were not identified on magnetic resonance imaging (MRI), the diagnosis of DDLPS would not have been diagnosed if immunohistochemical (IHC) staining had not been performed. The aim of this study was to investigate the pattern of MRI and relationship between MRI and IHC findings in DDLPS.

METHODS

We retrospectively reviewed the cases of 25 patients with DDLPS. To identify the MRI spectrum of DDLPS, tumors were classified into the following four categories based on MRI findings: I = a well-defined fatty mass and juxtaposed well-defined non-fatty mass, II = a non-fatty component within a predominantly fatty mass, III = a focal fatty component within a large non-fatty mass, and IV = a non-fatty mass with atypical MRI findings. IHC staining for CDK4, MDM2, and p16 were evaluated.

RESULTS

Category IV tumor was the most common tumor in this population. Of the 22 patients who underwent IHC staining, MDM2, CDK4, and p16 were positive in 21, 20, and 19 patients, respectively. MDM2 was positive in all 11 patients with category IV tumors; CDK4 and p 16 were positive in 10 and eight patients, respectively. There was no difference of survival between the patients with category I, II and III and category IV.

CONCLUSIONS

DDLPS without fatty components on MRI scans was mostly found. We recommend IHC staining to screen for DDLPS even if the tumors in STS cases have a non-fatty component.

Intra-articular osteolipoma of the elbow: A case report and a review of the literature

Introduction

Lipomas are the most common benign mesenchymal tumors. The intra-articular localization is exceptional.We report the first case of an intra-articular osteolipoma at the elbow.

Case report

A 36-year-old patient with no pathological history, presented to the emergency room with a two weeks history of a painless, progressively left elbow swelling in a context of apyrexia.Physical examination revealed a hot, edematous left elbow. The gentle mobilization of the joint was painless. Biologie was normal. Initial radiograph showed a well-defined lobular image. Ultrasound revealed an anechoic intra-articular collection associated to a synovium hyperaemia and the MRI shows an aspect of synovitis. An arthrotomy was done via an internal approach of the elbow. Joint fluid was red. A free ossified intraarticular mass was discovered. Bacteriological samples were sterile. Histological examination concluded to an osteolipoma with no histological signs of malignancy. At the last 3-year follow-up, the patient didn't report any pain or functional discomfort. Elbow mobility was complete, with the absence of recurrences.

Discussion

Osteolipoma is defined as a histological variant of lipoma having undergone bone metaplasia. Allen found 06 cases in a series of 635 lipomas over five years. Pain has not been reported in the literature. In our case the pain was explained by the interposition of the tumoral mass between the articular surfaces. Histological examination confirms the diagnosis and recurrences are rare.

Conclusion

Osteolipoma is an extremely rare entity of mesenchymal tumors whose intra-articular location, although exceptional, does not worsen the prognosis.

Differentiation Between Lipomas and Atypical Lipomatous Tumors of the Extremities Using Radiomics

BACKGROUND

The differentiation of soft tissue lipomas from atypical lipoma tumors (ALTs) of the extremities is important because of the distinction of the cytogenetic profiles and the treatment decisions.

PURPOSE

To investigate a radiomics method to differentiate between lipomas and ALTs of the extremities.

STUDY TYPE

Retrospective.

POPULATION

Imaging data of 122 patients including 90 cases of lipomas and 32 cases of ALTs.

FIELD STRENGTH/SEQUENCE

Axial T1-weighted imaging and fat suppressed T2-weighted imaging at 3.0T MRI.

ASSESSMENT

Analysis of variance and the least absolute shrinkage and selection operator methods were used for feature selection and the random forest method was used to build three radiomics models based on T1WI, FS T2WI, and their combination (T1&T2WI). Three independent radiologists classified the tumors based on the subjective assessments.

STATISTICAL TESTS

The area under the curve (AUC) of the receiver operating characteristic curve, accuracy, F1-score, specificity, and sensitivity were employed. The differences of the classifiers and discriminating ability of the radiologists and the radiomics model were compared by Delong test. A P value <0.05 was considered significant. Kappa test was used to determine the inter-reader agreements between the radiologists.

RESULT

The AUCs were 0.952 (95% confidence interval [CI]: 0.785-0.998), 0.944 (95% CI: 0.774-0.997), and 0.968 (95% CI: 0.809-1) for T1WI, FS T2WI, and T1&T2WI models in testing sets respectively. Delong test showed there were no significant difference between the different radiomics models (P > 0.05). The AUCs of the radiologists were 0.893 (95% CI: 0.824-0.942), 0.831 (95% CI: 0.752-0.893), and 0.893 (95% CI: 0.824-0.94), respectively. There were significant difference between radiomics model and radiologists' model in the training and entire cohorts (P < 0.05) while there were no significant difference in the testing sets (P > 0.05).

DATA CONCLUSION

Radiomics has the potential to distinguish between lipomas and ALTs of the extremities and their discrimination ability is no weaker than the senor radiologists.

LEVEL OF EVIDENCE

3 TECHNICAL EFFICACY STAGE: 2.

The Immune Contexture of Liposarcoma and Its Clinical Implications

Liposarcomas (LPS) are the most frequent malignancies in the soft tissue sarcoma family and consist of five distinctive histological subtypes, termed well-differentiated LPS, dedifferentiated LPS (DDLPS), myxoid LPS (MLPS), pleomorphic LPS, and myxoid pleomorphic LPS. They display variations in genetic alterations, clinical behavior, and prognostic course. While accumulating evidence implicates a crucial role of the tumor immune contexture in shaping the response to anticancer treatments, the immunological landscape of LPS is highly variable across different subtypes. Thus, DDLPS is characterized by a higher abundance of infiltrating T cells, yet the opposite was reported for MLPS. Interestingly, a recent study indicated that the frequency of pre-existing T cells in soft tissue sarcomas has a predictive value for immune checkpoint inhibitor (CPI) therapy. Additionally, B cells and tertiary lymphoid structures were identified as potential biomarkers for the clinical outcome of LPS patients and response to CPI therapy. Furthermore, it was demonstrated that macrophages, predominantly of M2 polarization, are frequently associated with poor prognosis. An improved understanding of the complex LPS immune contexture enables the design and refinement of novel immunotherapeutic approaches. Here, we summarize recent studies focusing on the clinicopathological, genetic, and immunological determinants of LPS.

Myxomatous Liposarcoma of the Mediastinum: A Review of the Literature

Myxomatous liposarcoma is an extremely rare type of mediastinal tumour that manifests in a manner comparable to other lung pathologies. Chest pain, shortness of breath, and dysphagia are the common presenting complaints. Radiological examinations or postoperative histological examinations provide the majority of the diagnostic evidence. The cornerstone of therapy consists of surgery and sometimes chemotherapy. Those who are afflicted have a better chance of experiencing favourable outcomes if they receive a diagnosis and treatment quickly.

Lipoma and Its Doppelganger: The Atypical Lipomatous Tumor/Well-Differentiated Liposarcoma

Lipomatous tumors are among the most common soft tissue lesions encountered by the general surgeon. Shared history and clinical presentation make differentiation between benign lipomas and low-grade liposarcomas a diagnostic dilemma. This article reviews the epidemiology, clinical history, diagnostic workup, management, natural history, and surveillance of benign lipomas and atypical lipomatous tumors/well-differentiated liposarcomas. Although it is important that aggressive, potentially malignant atypical lipomatous tumors and liposarcomas be managed in a multidisciplinary, preferably high-volume setting, it is equally as important for the nonspecialist general surgeon to be familiar with lipoma and its doppelganger-the well-differentiated liposarcoma.

Primary gastric dedifferentiated liposarcoma resected endoscopically: A case report

BACKGROUND

Liposarcoma is one of the most common adult mesenchymal tumors but is uncommon in the gastrointestinal tract and extremely rare in the stomach. Furthermore, the histological subtypes of liposarcoma usually reported in the stomach are well-differentiated or myxoid, and few reports have been issued on small-sized gastric liposarcomas resected endoscopically and followed up. Herein, we report a case of primary gastric dedifferentiated liposarcoma (DL) that was resected endoscopically.

CASE SUMMARY

A 67-year-old female Korean patient was referred to our institution for further evaluation of a gastric submucosal tumor (SMT) located in the lesser curvature of the gastric body by esophagogastroduodenoscopy. Endoscopic ultrasound revealed a well-circumscribed, slightly heterogeneous, isoechoic, 17 mm × 10 mm sized mass originating from the third sonographic layer. Computed tomography showed no evidence of significant lymph node enlargement or distant metastasis. Endoscopic resection was undertaken using the snare resection technique after mucosal precutting to provide a definitive histopathologic diagnosis, which proved to be consistent with DL, based on its morphology and the immunoexpressions of MDM2 and CDK4. The patient was planned for surgery because the deep resection margin was positive for malignancy. After declining any invasive procedure or adjuvant treatment, the patient was placed under close follow-up, and at one year after endoscopic resection, remained disease free.

CONCLUSION

This is the first reported case of a small primary gastric DL resected endoscopically and followed up. This report demonstrates that when diagnosis of a SMT is uncertain, the use of invasive techniques, including endoscopic resection, should be considered.

Can homogeneous, lipomatous tumors be primarily resected without biopsy? A retrospective analysis of 240 tumors

BACKGROUND

According to guidelines, every soft tissue tumor (STT) larger than 3 cm should be biopsied before definitive resection. Advances in magnetic resonance imaging (MRI) improve the possibility to give a provisional diagnosis of the tumor's entity. Can lipomas and atypical lipomatous tumors (ALTs) of the extremities therefore be primarily marginally resected based on interpretation of MR images without a previous biopsy?.

METHODS

In this retrospective, single-center study, 240 patients with the suspicion of a lipomatous tumor in MRI and surgical treatment in our institution between 2011 and 2020 were included. MR imaging was performed before surgery. All resected specimens underwent histopathological analysis.

RESULTS

The collective comprised 142 tumors that were suspected as lipoma or ALT by the radiologist and underwent primary marginal resection (PMR). One case had myxoid liposarcoma that was underestimated on MRI and needed radical follow-up resection. One-hundred forty-one patients were cured after PMR. Ninety-eight patients were biopsied initially and in 93 cases resected afterwards according to the necessary oncological margins.

CONCLUSION

In our institution, PMR is performed if a lipoma or ALT is suspected on MR imaging. Our treatment method and the diagnostic algorithm are presented. Primary resection spares patients from one surgical procedure, but a slight risk for underestimation of the tumor remains.

Novel computer aided diagnostic models on multimodality medical images to differentiate well differentiated liposarcomas from lipomas approached by deep learning methods

BACKGROUND

Deep learning methods have great potential to predict tumor characterization, such as histological diagnosis and genetic aberration. The objective of this study was to evaluate and validate the predictive performance of multimodality imaging-derived models using computer-aided diagnostic (CAD) methods for prediction of MDM2 gene amplification to identify well-differentiated liposarcoma (WDLPS) and lipoma.

MATERIALS AND METHODS

All 127 patients from two institutions were included with 89 patients in one institution for model training and 38 patients in the other institution for external validation between January 2012 and December 2018. For each modality, handcrafted radiomics analysis with manual segmentation was applied to extract 851 features for each modality, and six pretrained convolutional neural networks (CNNs) extracted 512-2048 deep learning features automatically. Extracted imaging-based features were selected via univariate filter selection methods and the recursive feature elimination algorithm, which were then classified by support vector machine for model construction. Integrated with two significant clinical variables, age and LDH level, a clinical-radiological model was constructed for identification WDLPS and lipoma. All differentiation models were evaluated using the area under the receiver operating characteristics curve (AUC) and their 95% confidence interval (CI).

RESULTS

The multimodality model on deep learning features extracted from ResNet50 algorithm (RN-DL model) performed great differentiation performance with an AUC of 0.995 (95% CI 0.987-1.000) for the training cohort, and an AUC of 0.950 (95% CI 0.886-1.000), accuracy of 92.11%, sensitivity of 95.00% (95% CI 73.06-99.74%), specificity of 88.89% (95% CI 63.93-98.05%) in external validation. The integrated clinical-radiological model represented an AUC of 0.996 (95% CI 0.989-1.000) for the training cohort, and an AUC of 0.942 (95% CI 0.867-1.000), accuracy of 86.84%, sensitivity of 95.00% (95% CI 73.06-99.74%), and specificity of 77.78% (95% CI 51.92-92.63%) in external validation.

CONCLUSIONS

Imaging-based multimodality models represent effective discrimination abilities between WDLPS and lipoma via CAD methods, and might be a practicable approach in assistance of treatment decision.

Diagnostic and Imaging Approaches to Chest Wall Lesions

Chest wall lesions are relatively uncommon and may be challenging once they are encountered on images. Radiologists may detect these lesions incidentally at examinations performed for other indications, or they may be asked specifically to evaluate a suspicious lesion. While many chest wall lesions have characteristic imaging findings that can result in an accurate diagnosis with use of imaging alone, other entities are difficult to distinguish at imaging because there is significant overlap among them. The interpreting radiologist should be familiar with the imaging features of both "do not touch" benign entities (which can be confidently diagnosed with imaging only, with no need for biopsy or resection unless the patient is symptomatic) and lesions that cannot be confidently characterized and thus require further workup. CT and MRI are the main imaging modalities used to assess the chest wall, with each having different benefits and drawbacks. Chest wall lesions can be classified according to their predominant composition: fat, calcification and ossification, soft tissue, or fluid. The identification or predominance of signal intensities or attenuation for these findings, along with the patient age, clinical history, and lesion location, can help establish the appropriate differential diagnosis. In addition, imaging findings in other organs, such as the lungs or upper abdomen, can at times provide clues to the underlying diagnosis. The authors review different chest wall lesions classified on the basis of their composition and highlight the imaging findings that can assist the radiologist in narrowing the differential diagnosis and guiding management. ^©RSNA, 2022.

What morphological MRI features enable differentiation of low-grade from high-grade soft tissue sarcoma?

Objective:

To assess the diagnostic performance of morphological MRI features separately and in combination for distinguishing low- from high-grade soft tissue sarcoma (STS).

Methods and materials:

We retrospectively analysed pre-treatment MRI examinations with T1, T2 with and without fat suppression (FS) and contrast-enhanced T1 obtained in 64 patients with STS categorized histologically as low (n = 21) versus high grade (n = 43). Two musculoskeletal radiologists blinded to histology evaluated MRI features. Diagnostic performance was calculated for each reader and for MRI features showing significant association with histology (p < 0.05). Logistic regression analysis was performed to develop a diagnostic model to identify high-grade STS.

Results:

Among all evaluated MRI features, only six features had adequate interobserver reproducibility (kappa>0.5). Multivariate logistic regression analysis revealed a significant association with tumour grade for lesion heterogeneity on FS images, intratumoural enhancement≥51% of tumour volume and peritumoural enhancement for both readers (p < 0.05). For both readers, the presence of each of the three features yielded odds ratios for high grade versus low grade from 4.4 to 9.1 (p < 0.05). The sum of the positive features for each reader independent of reader expertise yielded areas under the curve (AUCs) > 0.8. The presence of ≥2 positive features indicated a high risk for high-grade sarcoma, whereas ≤1 positive feature indicated a low-to-moderate risk

Conclusion:

A diagnostic MRI score based on tumour heterogeneity, intratumoural and peritumoural enhancement enables identification of lesions that are likely to be high-grade as opposed to low-grade STS.

Advances in knowledge:

Tumour heterogeneity in Fat Suppression sequence, intratumoural and peritumoural enhancement is identified as signs of high-grade sarcoma.

Desmoid fibromatosis in the pharyngeal wall: A case report and literature review

Desmoid fibromatosis (DF) is one of the rarest locally aggressive growing benign tumor entities. We present an overview of the literature and a rare clinical case of a 22-year-old female patient, who was diagnosed with aggressive DF in the left pharyngeal wall at the age of 4 years old.

Fat Chance for Hidden Lesions: Pictorial Review of Hoffa's Fat Pad Lesions

Hoffa's fat pad (HFP) is the most commonly afflicted among all the knee fat pads. Anterior knee pain is common in various pathologies of HFP, as it is richly innervated. A potpourri of the intrinsic and extrinsic pathologies and the tumors and tumor-like conditions affect HFP, and MRI remains the fundamental modality to assess them and provide a specific diagnosis.

Diagnosis strategy of adipocytic soft-tissue tumors in adults: a consensus from European experts

Fat-containing tumors are very commonly found in daily practice with benign lipoma accounting for the majority of superficial tumors. Overlap in imaging findings between benign and intermediate or malignant fat-containing tumor is common. Guidelines recommend a core needle biopsy (CNB) for all deep tumors, and superficial tumors over 3 cm. However, specific strategy for diagnosis and referral to a sarcoma center should be applied on adipocytic tumors. The aim of this consensus statement is to provide a specific algorithm for adipocytic tumors, to discriminate patients who do require a CNB for preoperative diagnosis from those who can simply undergo active surveillance or a simple excision.

Overview of malignant soft-tissue sarcomas of the limbs

Although soft-tissue masses are common, sarcomas are rare malignant neoplasms showing variable mesenchymal differentiation and can occur at any anatomical site. Limb soft-tissue sarcomas (STS) are rare, but often lethal tumours. Although there are scores of historical pathological subtypes, this article will deal with the commonest: liposarcoma, leiomyosarcoma (LMS), undifferentiated pleomorphic sarcoma (UPS), synovial sarcoma, myxofibrosarcoma, malignant peripheral nerve sheath tumour (MPNST), epithelioid sarcoma, alveolar rhabdosarcoma, angiosarcoma and radiation-induced sarcoma (RIS). Following a review of >4,000 adult patients with limb sarcoma from our specialist soft-tissue tumour database, we summarise the literature and their imaging findings, with emphasis on radiological hallmarks that can aide in diagnosis and management. Increased awareness of sarcoma when challenged with a new mass in the extremity can ensure timely and appropriate treatment.

A rare case of myxoid pleomorphic liposarcoma in an infant: A report

INTRODUCTION AND IMPORTANCE

MPL (myxoid pleomorphic liposarcoma) is an uncommon type of liposarcoma that affects mostly children and infants. Its aggressive behavior and tendency to recur warrant complete excision despite the challenges of troublesome locations.

CASE PRESENTATION

A 12-month-old infant presented with an insidious onset of noisy breathing and respiratory distress not relieved by supplemental oxygen via face mask. Examination revealed dullness and decreased air entry on the left chest. Computed Tomographic (CT) scan showed a large solid mass occupying the left hemithorax and displacing the mediastinum to the right. Intraoperatively, a large solid mass arising from the left chest wall and attached to the fifth rib was seen. Histopathology of the resected mass showed myxoid pleomorphic liposarcoma which is non-reactive for MDM2 immunostain.

CLINICAL DISCUSSION

Unlike other liposarcomas, myxoid pleomorphic liposarcoma occurs in children, commonly in the chest. CT scan is the preferred imaging modality. Treatment is by complete excision where possible. Molecular studies like Fluorescent in-situ Hybridization (FISH) and Immunohistochemistry (IHC) is used for confirmation. It has a high propensity to metastasize and recurrence is expected. Chemotherapy and irradiation following complete resection decrease the disease recurrence.

CONCLUSION

Soft tissue malignancy must be considered in the differential diagnosis of a large intrathoracic tumor in an infant. FISH and IHC are essential for confirmation.

Primary pleomorphic liver liposarcoma: A case series and literature review

Primary hepatic liposarcoma is an extremely rare mesenchymal tumor that accounts for only 0.1% to 2% of primary malignant liver tumors. Due to its rarity, there is a lack of knowledge about its clinical course, management, and prognosis. Only 15 cases of primary liposarcoma of the liver have been reported since 1973. Among these 15 cases, only two involved primary liver liposarcoma with a pleomorphic subtype. Here we report the third and fourth cases of primary pleomorphic liver liposarcoma. A 57-year-old female presented with abdominal discomfort and progressive abdominal distension for two weeks. Computed tomography (CT) of her abdomen revealed a large well-defined solid nodule mass with an area of necrosis and hemorrhage occupying segment IV-B of the liver. Wide local excision was performed. She had an uneventful recovery and remained well at six months post-treatment. A 65-year-old male presented with an abdominal mass for two-month. CT demonstrated a mass in the left lobe of the liver with mixed soft tissues and fat attenuation. He underwent wide local excision. He was discharged on day three postoperatively. Histological analysis for both cases revealed liposarcoma of the liver with a pleomorphic subtype.

Biology and Management of Dedifferentiated Liposarcoma: State of the Art and Perspectives

Dedifferentiated liposarcoma (DDL) is defined as the transition from well-differentiated liposarcoma (WDL)/atypical lipomatous tumor (ALT) to non-lipogenic sarcoma, which arises mostly in the retroperitoneum and deep soft tissue of proximal extremities. It is characterized by a supernumerary ring and giant marker chromosomes, both of which contain amplified sequences of 12q13-15 including murinedouble minute 2 (MDM2) and cyclin-dependent kinase 4 (CDK4) cell cycle oncogenes. Detection of MDM2 (and/or CDK4) amplification serves to distinguish DDL from other undifferentiated sarcomas. Recently, CTDSP1/2-DNM3OS fusion genes have been identified in a subset of DDL. However, the genetic events associated with dedifferentiation of WDL/ALT remain to be clarified. The standard treatment for localized DDL is surgery, with or without radiotherapy. In advanced disease, the standard first-line therapy is an anthracycline-based regimen, with either single-agent anthracycline or anthracycline in combination with the alkylating agent ifosfamide. Unfortunately, this regimen has not necessarily led to a satisfactory clinical outcome. Recent advances in the understanding of the pathogenesis of DDL may allow for the development of more-effective innovative therapeutic strategies. This review provides an overview of the current knowledge on the clinical presentation, pathogenesis, histopathology and treatment of DDL.

Radiologic-Pathologic Correlation of Primary Retroperitoneal Neoplasms

An earlier incorrect version of this article appeared in print. The online version is correct.

Liposarcoma of the pelvic fossa masquerading as hematoma: a rare case report and its surgical management

Liposarcomas constitute rare malignant tumors of the soft tissue, with wide anatomical distribution. The prompt diagnosis of a liposarcoma is extremely challenging since these tumors tend to remain asymptomatic, until they grow enough to displace adjacent anatomical structures. In the presented case, a 55-year-old Caucasian male proceeded to our institution complaining about irreducible swelling of the right iliac fossa and constant discomfort, over the course of a year. His medical history revealed injury of the right groin and pelvis a year ago. The diagnosis was ilioinguinal liposarcoma masquerading as hematoma, due to the previous injury. The patient underwent primary complete tumor resection, and the operation was uneventful. The essential diagnostic and surgical steps for the management of a liposarcoma, mimicking a hematoma are meticulously described.

Myelolipoma mimicking osteosarcoma in the distal femur

Introduction and importance

Periosteal reactions indicate malignant bone tumors, including osteosarcoma; establishing an accurate diagnosis is key to determining the most appropriate treatment strategy. We describe a rare case of myelolipoma in the distal femur metaphysis with massive extraskeletal lesions and periosteal reactions.

Case presentation

A 25-year-old woman was referred to our hospital to treat a gradually expanding mass around her knee that grew to the size of a baby's head. She had a history of hydrocephalus caused by congenital cytomegalovirus infection and was bedridden for life. Radiography showed a prominent osteoblastic rim and osteolytic lesion with a moth-eaten appearance. Osteosarcoma was suspected due to excessive extraskeletal invasion and periosteal reactions. T1- and T2-weighted magnetic resonance images showed a high-signal-intensity homologous lesion. Biopsy specimens contained adipose and hematopoietic tissues. A myelolipoma was diagnosed. Due to her fragility, surgical intervention was suspended. Two years after diagnosis, the tumor size did not change.

Clinical discussion

Myelolipomas are benign tumors that typically arise from the adrenal gland and rarely develop in the extremities. This type of tumor typically does not cause any tumor-related symptoms or endocrine disturbances and has been reported as a type of incidentaloma. To effectively manage myelolipoma patients, differential diagnosis of tumors mimicking malignant bone tumors is important.

Conclusion

We successfully managed a destructive ectopic myelolipoma in the distal femoral metaphysis, with massive extraskeletal lesions and periosteal reactions. Clinicians should appropriately differentiate myelolipoma from tumors mimicking malignant bone tumors.

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Report discusses a rare case of ectopic extra-adrenal myelolipoma in the femur.

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The extraskeletal invasion and periosteal reactions resemble malignant bone tumors.

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Clinicians should properly differentiate it from mimics of malignant bone tumors.