The role of surgical margins in atypical Lipomatous Tumours of the extremities

Histology-Tailored Approach to Soft Tissue Sarcoma

Soft tissue sarcomas are a diverse and heterogeneous group of cancers of mesenchymal origin. Each histological type of soft tissue sarcoma has unique clinical particularities, which makes them challenging to diagnose and treat. Multidisciplinary management of these rare diseases is thus key for improved survival. The role of surgery has been well established, and it represents the cornerstone curative treatment for soft tissue sarcomas. To date, local recurrence is the leading cause of death in low-grade sarcomas located at critical sites, and distant metastasis in high-grade sarcomas, regardless of the site of origin. Management must be tailored to each individual histologic type. We describe the most common types of extremity, trunk, abdominal, and retroperitoneal soft tissue sarcoma along with characteristics to consider for optimized management.

[Translated article] Comparative study of deep lipomas and atypical lipomatous tumours: Malignancy risk factors

BACKGROUND AND OBJECTIVES

The diagnostic suspicion of an atypical lipomatous tumour (ALT) is difficult. The aim of this study is to delve into the most controversial diagnostic aspects of the subject.

MATERIAL AND METHOD

Observational, longitudinal and retrospective study of a series of 96 deep adipose tumours (75 lipomas and 21 TLA) from 2006 to 2016: demographic, clinical, imaging and pathological variables were analysed and compared, as well as other variables related to treatment and oncological outcomes of the patients. A descriptive analysis of the collected variables was performed for the statistical study. To evaluate the potential predictor variables of malignancy, a multivariate logistic regression analysis was performed, including those that were statistically significant in the univariate analysis.

RESULTS

Older age at diagnosis, lower limb location and larger size were significantly more frequent in ALTs. MRI findings showed no statistically significant differences between the two groups. In multivariate analysis, the same clinical variables were confirmed as predictors of malignancy. In the ROC curve, an optimal cut-off point of 134.0mm was used as a predictor of malignancy.

CONCLUSIONS

Advanced age, location in the lower limbs and larger size are risk factors for malignancy in the differential diagnosis of deep lipomas and atypical lipomatous tumours. No radiological variable on MRI reached significance as a predictor of malignancy in our series.

Comparative study of deep lipomas and atypical lipomatous tumours: Malignancy risk factors

BACKGROUND AND OBJECTIVES

The diagnostic suspicion of an atypical lipomatous tumour (ALT) is difficult. The aim of this study is to delve into the most controversial diagnostic aspects of the subject.

MATERIAL AND METHOD

Observational, longitudinal, and retrospective study of a series of 96 deep adipose tumours (75 lipomas and 21 TLA) from 2006 to 2016: demographic, clinical, imaging and pathological variables were analysed and compared, as well as other variables related to treatment and oncological outcomes of the patients. A descriptive analysis of the collected variables was performed for the statistical study. To evaluate the potential predictor variables of malignancy, a multivariate logistic regression analysis was performed, including those that were statistically significant in the univariate analysis.

RESULTS

Older age at diagnosis, lower limb location and larger size were significantly more frequent in ALTs. MRI findings showed no statistically significant differences between the two groups. In multivariate analysis, the same clinical variables were confirmed as predictors of malignancy. In the ROC curve, an optimal cut-off point of 134.0 mm was used as a predictor of malignancy.

CONCLUSIONS

Advanced age, location in the lower limbs and larger size are risk factors for malignancy in the differential diagnosis of deep lipomas and atypical lipomatous tumours. No radiological variable on MRI reached significance as a predictor of malignancy in our series.

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.

Development and validation of a nomogram to predict surgical site infection after soft-tissue sarcoma resection

Aims

Surgical site infection (SSI) after soft-tissue sarcoma (STS) resection is a serious complication. The purpose of this retrospective study was to investigate the risk factors for SSI after STS resection, and to develop a nomogram that allows patient-specific risk assessment.

Methods

A total of 547 patients with STS who underwent tumour resection between 2005 and 2021 were divided into a development cohort and a validation cohort. In the development cohort of 402 patients, the least absolute shrinkage and selection operator (LASSO) regression model was used to screen possible risk factors of SSI. To select risk factors and construct the prediction nomogram, multivariate logistic regression was used. The predictive power of the nomogram was evaluated by receiver operating curve (ROC) analysis in the validation cohort of 145 patients.

Results

LASSO regression analysis selected possible risk factors for SSI, including age, diabetes, operating time, skin graft or flap, resected tumour size, smoking, and radiation therapy. Multivariate analysis revealed that age, diabetes, smoking during the previous year, operating time, and radiation therapy were independent risk factors for SSI. A nomogram was developed based on the results of multivariate logistic regression analysis. In the development cohort, the incidence of SSI was 4.5% in the low-risk group (risk score < 6.89) and 26.6% in the high-risk group (risk score ≥ 6.89; p < 0.001). In the validation cohort, the incidence of SSI was 2.0% in the low-risk group and 15.9% in the high-risk group (p = 0.004).

Conclusion

Our nomogram will enable surgeons to assess the risk of SSI in patients with STS. In patients with high risk of SSI, frequent monitoring and aggressive interventions should be considered to prevent this.

The Effect of chemo- and radiotherapy on tumor necrosis in soft tissue sarcoma- does it influence prognosis?

BACKGROUND

Soft tissue sarcomas (STSs) are a heterogeneous group of tumors. Wide surgical resection is standard, often combined with neoadjuvant chemotherapy, radiotherapy, or both. Studies have shown the predictive value of tumor necrosis in bone sarcoma (BS); however, the role of necrosis in STS after neoadjuvant therapies is still unclear. This study aimed to investigate the role of chemo- and radiotherapy in the formation of tumor necrosis and to evaluate the influence of tumor necrosis on overall survival and local recurrence-free survival. Data from BS patients and patients who did not receive neoadjuvant therapy were compared.

METHODS

A total of 779 patients with STS or BS were treated surgically. In all patients, tumor-specific factors such as type, size, or grading and the type of adjuvant therapy were documented. Local recurrence (LR), the diagnosis of metastatic disease, and survival during follow-up were evaluated.

RESULTS

A total of 565 patients with STS and 214 with BS were investigated. In STS, 24.1% G1 lesions, 34.1% G2 lesions, and 41.8% G3 lesions were observed. Two hundred twenty-four of the patients with STS and neoadjuvant therapy had either radiotherapy (RTx) (n = 80), chemotherapy (CTx) (n = 93), or both (n = 51). Three hundred forty-one had no neoadjuvant therapy at all. In STS, tumor necrosis after neoadjuvant treatment was significantly higher (53.5%) than in patients without neoadjuvant therapy (15.7%) (p < 0.001). Patients with combined neoadjuvant chemo-/radiotherapy had substantially higher tumor necrosis than those with radiotherapy alone (p = 0.032). There was no difference in tumor necrosis in patients with combined chemo-/radiotherapy and chemotherapy alone (p = 0.4). The mean overall survival for patients with STS was 34.7 months. Tumor necrosis did not influence survival in a subgroup of G2/3 patients. In STS with no neoadjuvant therapy and grading of G2/3, the correlation between necrosis and overall survival was significant (p = 0.0248). There was no significant correlation between local recurrence (LR) and necrosis.

CONCLUSION

STS shows a broad spectrum of necrosis even without neoadjuvant chemo- or radiotherapy. After CTx or/and RTx necrosis is enhanced and is significantly pronounced with a combination of both. There is a trend toward higher necrosis with CTx than with RTx. Grading substantially influences the necrosis rate, but necrosis in soft-tissue sarcoma following neoadjuvant therapy does not correlate with better survival or a lower local recurrence rate, as in bone sarcomas.

Low local recurrence rates following marginal surgical resection of non-coelomic Atypical Lipomatous Tumours/Well-differentiated Liposarcomas

INTRODUCTION

High rates of local recurrence (LR) have been reported following resection of extremity Atypical lipomatous tumours/Well-differentiated liposarcomas (ALTs). This retrospective study of patients who underwent resection of primary deep extremity and trunk ALTs at a specialist sarcoma centre aims to assess morbidity and factors associated with low local recurrence rates (LRR).

METHODS

To review a homogeneous cohort of patients with low-grade disease, tumours with known high-risk histological features were excluded. Prognostic variables potentially influencing local recurrence (LR) (age, size, site, margin status, and histological findings) were analysed. Endpoints were LR, distant recurrence (DR) and local disease-free survival (LDFS).

RESULTS

127 patients were identified, with median follow-up of 54 months (0-235). Median tumour size was 17.5 cm (5-36). 85 % occurred in the lower limb. 93.7 % underwent marginal resection. No patients received radiotherapy. Median hospital stay was 3 days (0-16). 7.9 % returned to theatre for evacuation of haematoma or infected seroma and 18.1 % had outpatient seroma aspiration. Surgical margins were R0/R1 in 93.7 % of patients and R2 in 6.3 % with a LR rate of 8.4 % and 75 % respectively at median time of 54 months. One- and 5-year LDFS was 100 % and 88.4 %, respectively. DR rate was 0.8 % (1/127) this patient had pleomorphic liposarcomatous transformation on recurrence and subsequently developed distant metastases. No patients died of disease.

CONCLUSION

Function-preserving marginal resection of non-coelomic ALTs has low morbidity, low LR and extremely low rates of distant relapse. Patients with lower limb ALT were found to have significantly lower LR, which may impact follow-up protocols.

Giant atypical lipomatous tumors of the thigh: a case series

BACKGROUND AND AIM

Atypical Lipomatous Tumors (ALTs) are low-grade locally aggressive soft tissue tumors. Deep large sized ALTs of the thigh can cause significant functional impairment due to their mass effect. Surgical resection, which is the treatment of choice for these lesions, can be a though procedure, especially if the neoplasm comes in proximity with noble structures such as large sized arteries or nerves. The aim of our study is to assess risks and effectiveness of surgical resection, evaluating complications, local recurrences and post-operative functionality.

METHODS

We evaluated all the giant ALT (larger diameter of 10 cm or more) of the thigh that received surgery in our institution between 2017 and 2022. Each patient's personal data and tumor size were evaluated. The quality of surgical margins was analyzed. MRI scans were performed both pre-operatively and during patients' follow-up. Lower limb's functional status was assessed using the MSTS score before and after surgery. Intra-operative and post-operative complications were recorded, as well as local recurrences.

RESULTS

Twentythree cases were included in our study. Tumors' mean major diameter was 19.1cm. The mean pre-operative MSTS score was 25.9. Only one case suffered from significant post-operative complications. Only 2 of our cases (8.7%) developed a local recurrence after surgery. The mean post-operative MSTS score was 29.1 Conclusions: A careful surgical resection can be effective in treating giant ALTs of the thigh in reason of good functional outcomes, low complications risks and reasonable local recurrence rates.

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.

Upper extremity mass with lipomatous axillary involvement and multiple level encasement of the brachial plexus

A 40-year-old female presented for surgical consultation of an upper extremity soft tissue mass. Initial ultrasound report recorded a 5.5 cm mass, consistent with a subcutaneous lipoma. Intra-operative visualization revealed an intramuscular lipoma emerging from brachialis muscle. Post-excision MRI was ordered for continued axillary fullness which revealed lipomatous extension into axilla and posterior arm with multiple level encasement of the brachial plexus. Lipomas with brachial plexus involvement are rare and can present with a range of symptoms and distortion of local anatomy. Surgical debulking is challenging requiring microsurgical expertise for adequate removal and to minimize long-term neurological deficits.

Adjuvant Radiation after Primary Resection of Atypical Lipomatous Tumors of the Extremity Reduces Local Recurrence but Increases Complications: A Multicenter Evaluation

Background

Radiation after resection of an atypical lipomatous tumor (ALT) is controversial. This study evaluates local control and complications after the first resection of ALTs of the extremity with or without adjuvant radiation.

Methods

A dual institution, retrospective review of patients treated from 1995 to 2020 with first-time resection of an ALT in the extremity was performed. In total, 102 patients underwent adjuvant radiation (XRT group) and 68 patients were treated with surgery alone (no-XRT group). The median follow-up time was 4.6 years (interquartile range (IQR) 2.0–7.3 years). The median radiation dose was 60 Gy (IQR 55–66 Gy). Univariable and multivariable analyses evaluated the association of patient, tumor, and treatment variables with recurrence and complications. Kaplan–Meier analysis evaluated local recurrence-free survival (LRFS) and time to complication.

Results

The overall incidence of local recurrence was 1% (1/102) in the XRT group and 24% (16/68) in the no-XRT group (p < 0.001). The median time-to-recurrence was 8.2 years (IQR 6.5–10.5 years). In the XRT and the no-XRT groups, 5-yr LRFS was 98% and 92% (p=0.21) and 10-yr LRFS was 98% and 41% (p < 0.001), respectively. The absence of radiation (HR = 23.63, 95% CI (3.09–180.48); p < 0.001) and R2 surgical resection margins (HR = 11.04, 95% CI (2.07–59.03); p < 0.001) incurred a 23-fold and 11-fold increased risk of local recurrence, respectively, while tumor size, depth, location, and neurovascular involvement were not found to be independent predictors of recurrence. The complication rate was 37% (38/102) in the XRT group and 10% (7/68) in the no-XRT group (p < 0.001). Eight patients (8/102, 8%) required surgical management for complication in the XRT group compared with two patients (2/68, 3%) in the no-XRT group (p=0.10). Higher radiation dose had a modest correlation with increased severity of complication (ρ=0.24; p=0.02).

Conclusions

Adjuvant radiation after first-time resection of an ALT of the extremity was associated with a significantly reduced risk of local recurrence but a three-fold increase in complication rate. These data support a 10-year follow-up for these patients and inform a notable clinical trade-off if considering adjuvant radiation for this tumor with recurrent potential.

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.

Japanese Orthopaedic Association (JOA) clinical practice guidelines on the management of soft tissue tumors 2020 - Secondary publication

BACKGROUND

These clinical practice guidelines are intended to provide recommendations based on the best evidence obtained to date on key issues in clinical practice to improve the prognosis, diagnostic and therapeutic processes for patients with soft tissue tumors.

METHODS

The Guidelines Development Committee and Systematic Review Committee were composed of a multidisciplinary team of specialists who play an important role in soft tissue tumor care. Clinical questions (CQs) were determined by choosing key decision-making points based on Algorithms for the diagnosis and treatment of soft tissue tumors. The guidelines were developed according to the "Medical Information Network Distribution Service (Minds) Handbook for Clinical Practice Guideline Development 2014" and "Minds Manual for Clinical Practice Guideline Development 2017." Recommendation strength was rated on two levels and the strength of evidence was rated on four levels. The recommendations were decided based on agreement by 70% or more voters.

RESULTS

Twenty-two CQs were chosen by the Guidelines Development Committee. The Systematic Review Committee reviewed the evidence concerning each CQ, a clinical value judgment was added by experts, and the text of each recommendation was determined.

CONCLUSION

We established 22 CQs and recommendations for key decision-making points in the diagnosis and treatment of soft tissue tumors according to the Minds Clinical Practice Guideline development methods. We hope that these guidelines will assist the decision-making of all medical staff engaged in the treatment and diagnosis of soft tissue tumors, and eventually lead to improved soft tissue tumor care in the country.

Management of adipose tumors in the limbs

Adipose tumors of the limbs are the most common soft tissue lesions and are essentially benign (lipomas). However, in some cases, they can be considered as tumors with intermediate malignancy (atypical lipomatous tumor [ALT]) or sarcoma lineage (liposarcoma [LS]). The essential work-up for a potential adipose tumor consists of a clinical examination and initial ultrasound imaging to determine the size (more or less than 5 cm), the location (over or under the fascia) and any potential atypical vascularization. As needed, MRI will complete the assessment and validate the ultrasound results and confirm the fatty nature of the lesion. Percutaneous biopsy will be done when a deep fatty lesion is larger than 5 cm (long axis), with detection by amplification of the MDM2 gene that guides the diagnosis towards ALT or dedifferentiated LS. Superficial lesions without atypia are not challenging from a surgical point of view. However, large ALT can be more difficult to manage. Their local malignancy does not justify sacrificing any critical structures. As for true LS, their treatment is well defined, with tumor excision addressed at a center belonging to the Network of Sarcomas Reference Centers in France (NETSARC+) and for potential (neo)adjuvant treatment if needed. Inappropriate treatment of a malignant tumor can have serious consequences (loss of chance to survive or to be cured) for the patient. Furthermore, treatment at a specialized cancer center has been proven to be effective as it improves overall survival and reduces local recurrences.

Marginal resection for patients with atypical lipomatous tumours of the extremities and trunk wall: a systematic review and meta-analysis

BACKGROUND

This systematic review assessed and compared the efficacy of marginal resection to wide resection in patients with atypical lipomatous tumours (ALT) by evaluating the local recurrence rates, overall survival and adverse event rates.

METHODS

We evaluated studies published between 1 January 1990 and 31 January 2019. The risks of bias in the selected studies were analyzed using the Cochrane Collaboration Risk of Bias Tool. The quality of the evidence was evaluated using the Grading of Recommendations, Assessment, Development and Evaluation approach.

RESULTS

Three case-control studies and three case series studies were identified. A meta-analysis was performed of six studies to evaluate the local recurrence rate after resection. Comparison of marginal and wide resections showed that the local recurrence rate was not significantly higher in the marginal resection group (14.2 and 1.4%, odds ratio: 2.88, 95% confidence interval 0.99-8.33, P = 0.05). We observed no difference in overall survival. In one study, the rates of adverse events were 14.7% in the marginal resection group and 45.4% in the wide treatment group (odds ratio, 0.32; 95% confidence interval 0.11-80.91, P < 0.05).

CONCLUSIONS

In our analyses, five of six studies reported no recurrence for wide resection, compared to three to seven recurrences in the marginal resection group. One study reported only one case of recurrence for wide resection. Because ALT has a relatively good prognosis, the use of marginal resection is acceptable to preserve musculoskeletal function.

The Utility of Chest Imaging for Surveillance of Atypical Lipomatous Tumors

Background

Unlike other soft tissue sarcomas, atypical lipomatous tumors (ALTs) are thought to have a low propensity for metastasis. Despite this, a standard of care for pulmonary metastasis (PM) surveillance has not been established. This study aimed to evaluate the utility of chest imaging for PM surveillance following ALT excision.

Methods

This was a multi-institution, retrospective review of all patients with primary ALTs of the extremities or superficial torso who underwent excision between 2006 and 2018. Minimum follow-up was two years. Long-term survival was evaluated using the Kaplan-Meier method.

Results

190 patients with ALT were included. Average age was 61.7 years and average follow-up was 58.6 months (24 to 180 months). MDM2 testing was positive in 88 patients (46.3%), and 102 (53.7%) did not receive MDM2 testing. 188 patients (98.9%) had marginal excision, and 127 (66.8%) had marginal or positive margins. Patients received an average of 0.9 CT scans and 1.3 chest radiographs over the surveillance period. 10-year metastasis-free survival was 100%, with no documented deaths from disease.

Conclusions

This study suggests that chest imaging does not have a significant role in PM surveillance following ALT excision, but advanced local imaging and chest surveillance may be considered in cases of local recurrence or concern for dedifferentiation.

Resection of a giant mediastinal atypical lipomatous tumor involving the esophagus

Liposarcoma is one of the common soft tissue tumors but barely arises from the mediastinum. Complete surgical resection with a negative surgical margin is required for the treatment; however, mediastinal liposarcomas tend to be large due to its slow-growing nature. A 57-year-old man was referred to us for having an abnormal mediastinal shadow in a chest X-ray. Computed tomography scanning revealed a giant posterior mediastinal tumor, completely involving the esophagus. Because of the unusual size and location of the tumor, we took a bilateral video-assisted thoracoscopic approach. First, the soft lipomatous compartment of the tumor was dissected from the esophagus and the descending aorta via the left thoracic cavity complete thoracoscopic procedure. Then, the patient was placed in the left lateral position, and the solid part of the tumor was completely resected using 13 cm of right-side thoracotomy. There was no complication or local recurrence in the first 26 months of follow-up.

Recent advances in the understanding and management of liposarcoma

Liposarcomas are a common subfamily of soft tissue sarcoma with several subtypes recognized by the World Health Organization: atypical lipomatous tumors (ALT)/well-differentiated liposarcoma (WDLPS), dedifferentiated liposarcoma (DDLPS), myxoid liposarcoma (MLPS), pleomorphic liposarcoma (PLPS), and myxoid pleomorphic liposarcoma (MPLPS). Despite shared adipocytic features among liposarcomas, the clinical approach to each subtype differs based on histology, location, clinical behavior, and specific oncogenic drivers. In this review, we highlight subtype-specific molecular features with the potential to generate novel therapies. We discuss recent clinical trials investigating the use of preoperative radiation therapy for retroperitoneal liposarcoma, chemotherapy, small molecule inhibitors, and innovative immunotherapy approaches and describe how we incorporate these advancements into the management of liposarcoma.

A single institutional experience treating adipocytic tumors: incidence, disease-related outcomes, and the clinical significance of MDM2 analysis

Adipocytic tumors exist either as a benign or malignant form. The benign variant, lipoma, is composed of normal fat tissue. Lipomas typically develop from superficial fat cells beneath the skin or mucous membranes. Liposarcoma, the malignant counterpart, often develops in deeper tissues and is the most commonly diagnosed Soft Tissue Sarcoma (STS), comprising at least 20% of adult STS. However, malignant tumors of fatty origin exist as a spectrum of diagnoses, each carrying a unique risk of recurrence, metastasis, and longterm survival. The World Health Organization classifies liposarcomas into five categories: i) Atypical Lipomatous Tumors/Well Differentiated (ALT/WD); Ii) Dedifferentiated (ALT/DD); Iii) Myxoid; Iv) Round cell; and v) Pleomorphic. Lipomatous tumors often exhibit different immunohistochemical patterns. Benign lipomas are distinguished by the absence of Murine Double-Minute 2 (MDM2) amplification. Similarly, ALT/WD, classically defined as a low-grade and locally aggressive tumor, demonstrates consistent patterns of MDM2 amplification. Some studies suggest 10% of ALT/WD progress to the highgrade DD form, with others report a dedifferentiation rate of as high as 20% for primary ALT/WD based on location. The ALT/DD subtype is aggressive and has a high capacity to metastasize. While the mechanism of pathogenesis of ALT/DD metastasis is unknown, previous studies suggest that increased MDM2 amplification may play a role. This study sought to evaluate a single institutional experience treating the entire spectrum of lipomatous tumors and describe utilization patterns of MDM2 testing. The group hypothesized: i) Atypical Lipomatous Tumors (ALT), which include ALT/DD and ALT/WD, would exhibit a higher rate of local recurrence than lipomas with no significantly increased incidence of metastases; and ii) at least 50% of our MDM2 testing of ALT would prove positive for the MDM2 overamplification. This study retrospectively reviewed 105 cases (66 lipomas, 27 ALTs, 12 liposarcomas) of patients who underwent lipomatous tumor excision at our institution from 2013 to 2017. Twenty-five tumors (6 lipomas, 18 ALT, 1 liposarcoma) were tested for MDM2 amplification. Three of the tested tumors recurred (2 ALT, 1 liposarcoma), and each exhibited MDM2 overamplification. Five tumors (5 liposarcoma) developed late metastases. These data suggest that although ALT is associated with a higher rate of local recurrence, metastases are quite rare. Additionally, the data demonstrate a high rate of positive MDM2 testing (76%) based on clinical and imaging characteristics of the tumors.

Atypical Spindle Cell Lipomatous Lesion Resected From Patient With History of CLL

Atypical spindle cell lipomatous neoplasm, also known as well-differentiated spindle cell liposarcoma, represents a newly discovered entity of adipocytic tumors. Recent research has shown this tumor variant to be more related to spindle cell lipoma, rather than the originally hypothesized atypical lipomatous tumor spectrum. Here we present a case of a 58-year-old man with a history of chronic lymphocytic leukemia with an enlarging mass on the posterior left shoulder, initially hypothesized to be a benign lipoma. However, magnetic resonance imaging showed a large, multiseptated, heterogeneous mass concerning for soft tissue sarcoma. After resection, pathologic analysis showed cells closely resembling spindle cell lipoma, with additional cellular and fascicular zones containing lipoblasts and mitotic figures. Molecular analysis showed no MDM2 amplification. This lack of amplification indicates this tumor is distinctly different from an atypical lipomatous tumor, which characteristically displays MDM2 amplification. However, tumor expression of RB1 was normal. The majority of atypical spindle cell lipomatous neoplasms are associated with RB1 deletions. We conclude that we have a unique example of an atypical spindle cell lipomatous tumor.

[Resection of soft tissue tumours : Pitfalls, typical complications and prevention strategies]

Benign soft tissue lesions are 300 times as common as soft tissue sarcomas; hence, the likelihood of confusion is high. Lesions that are larger than 5 cm, deep, show infiltrative growth, or recur despite benign histology are suspicious for soft tissue sarcoma. The biopsy incision must be carefully chosen; in large lipomas, atypical lipomatous tumor should be considered in the differential diagnosis. Lymphomas can be misdiagnosed and treated as undifferentiated soft tissue sarcoma. Vascular tumors and epithelioid lesions require more attention in histopathologic diagnostics and staging. Inflammatory lesions and aggressive fibromatosis (desmoid tumor) should also be borne in mind. In general, staging should be adapted to the underlying tumor biology. Neoadjuvant and adjuvant multimodal therapy must be discussed with the patient and used in a targeted manner. Superficial infiltrating sarcomas are prone to intralesional resection and may require intraoperative frozen section histology. If plastic reconstruction is necessary, a two-step procedure after proven tumor-free margins can be beneficial. Cavities and seromas, tight sutures, and closing the wound with clips are particularly critical. Wound drains at the thigh, pelvis, and groin should be left longer. Early revision in cases of hematoma or critical wound healing have proven beneficial. Adjuvant therapies are best planned before discharge from hospital. Overall, tumor-specific follow-up can significantly reduce the disadvantages of a recurrence resection.

Low Recurrence Rate and Risk of Distant Metastases following Marginal Surgery of Intramuscular Lipoma and Atypical Lipomatous Tumors of the Extremities and Trunk Wall

OBJECTIVE

The purpose of the present study was to determine the local recurrence rate, risk of dedifferentiation, and distant metastasis after surgical excision of intramuscular lipomas (IML) and atypical lipomatous tumors (ALT).

SUBJECTS AND METHODS

We retrospectively assessed all IML and ALT surgically removed from the extremities or trunk wall in our clinic between 1997 and 2006. Data from 141 patients with IML and 35 patients with ALT were extracted from the National Pathology Registry and patient files.

RESULTS

IML and ALT recurred in 10 and 6 tumors, respectively. No metastases were observed in either group. The 5- and 10-year local recurrence-free survival rates were 97.1% (94.3-99.9) and 94.8% (CI: 91.1-98.6) for IML and 84.6% (CI: 72.1-97.1) and 81.1% (CI: 67.6-94.8) for ALT, respectively. ALT were found to dedifferentiate in 2/35 cases.

CONCLUSION

Both IML and ALT showed a low recurrence rate when removed surgically from the extremities or trunk wall with intended marginal resection. No distant metastases were observed in any of the groups. It, therefore, seems safe to treat these tumors with marginal resection.

Distribution of intramuscular giant lipomas in the functional compartments of the forearm: a report of 12 cases

PURPOSE

The aim of this study was to investigate the distribution of intramuscular giant lipomas in the functional compartments of the forearm and to compare their clinical, radiological and histopathological features with those reported in the current literature.

METHODS

The study included 12 patients who were surgically treated for intramuscular lipomas > 5 cm in size located in the forearm that had been confirmed histopathologically between April 2006 and March 2017. Data about the patients with respect to age, sex, affected side, localisation of the lipomas in the forearm functional compartments, size, histopathological features and recurrence were collected. According to the clinical complaints, direct radiography and magnetic resonance imaging were applied.

RESULTS

The average diameter was 6.5 cm (range: 5.5-9 cm). All lipomas had a well-defined border. All the patients presented with soft-tissue masses that were painless in seven patients. Five patients had nerve compression symptoms. When the lipomas were classified according to the functional compartments of the forearm, six of them were located in the superficial volar compartment, two in the deep volar compartment, two in the deep dorsal compartment and two in the lateral compartment. All lipomas were surgically removed by marginal excision. None had complications or recurrence at a mean of 6.5 years follow-up (range: 1-12 years) after surgery.

CONCLUSIONS

Intramuscular lipoma is a relatively uncommon tumour, especially in the forearm. Because of the proximity to the neurovascular structures in the forearm, excision of lipomas should be performed with care and include wide incisions. Additionally, knowing the anatomical features of the compartment where the lipoma is localised in the forearm is important in planning surgery to enable easier dissection of the lipoma and lessen the risk of damage to adjacent neurovascular structures.

LEVEL OF EVIDENCE

Level 4.