Atypical lipomatous tumors/well-differentiated liposarcomas: clinical outcome of 67 patients

[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.

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.

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.

Characterization of lipomatous tumors with high-resolution 1H MRS at 17.6T: Do benign lipomas, atypical lipomatous tumors and liposarcomas have a distinct metabolic signature?

Background

Distinguishing between some benign lipomas (BLs), atypical lipomatous tumors (ALTs), and dedifferentiated liposarcomas (DDLs) can be challenging due to overlapping magnetic resonance imaging characteristics, and poorly understood molecular mechanisms underlying the malignant transformation of liposarcomas.

Purpose

To identify metabolic biomarkers of the lipomatous tumor spectrum by examining human tissue specimens using high-resolution ¹H magnetic resonance spectroscopy (MRS).

Materials and methods

In this prospective study, human tissue specimens were obtained from participants who underwent surgical resection for radiologically-indeterminate lipomatous tumors between November 2016 and May 2019. Tissue specimens were obtained from normal subcutaneous fat (n=9), BLs (n=10), ALTs (n=7) and DDLs (n=8). Extracts from specimens were examined with high-resolution MRS at 17.6T. Computational modeling of pattern recognition-based cluster analysis was utilized to identify significant differences in metabolic signatures between the lipomatous tumor types.

Results

Significant differences between BLs and ALTs were observed for multiple metabolites, including leucine, valine, branched chain amino acids, alanine, acetate, glutamine, and formate. DDLs were distinguished from ALTs by increased glucose and lactate, and increased phosphatidylcholine. Multivariate principal component analysis showed clear clustering identifying distinct metabolic signatures of the tissue types.

Conclusion

Metabolic signatures identified in ¹H MR spectra of lipomatous tumors provide new insights into malignant progression and metabolic targeting. The metabolic patterns identified provide the foundation of developing noninvasive MRS or PET imaging biomarkers to distinguish between BLs, ALTs, and DDLs.

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.

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.

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.

Resection Status Does Not Impact Recurrence in Well-Differentiated Liposarcoma of the Extremity

BACKGROUND

Well-differentiated liposarcoma (WDLPS) is a low-grade soft tissue sarcoma with a propensity for local recurrence. The necessity of obtaining microscopically free surgical margins (R0) to minimize local recurrence is not clear. This study evaluates recurrence-free survival (RFS) of extremity WDLPS in relation to resection margin status.

METHODS

A retrospective review of adult patients with primary extremity WDLPS at seven US institutions from 2000 to 2016 was performed. Patients with recurrent tumors or incomplete resection (R2) were excluded. Clinicopathologic factors were analyzed to assess impact on local RFS.

RESULTS

97 patients with primary extremity WDLPS were identified. The majority of patients had deep, lower extremity tumors. Mean tumor size was 18.2±8.9cm. Patients were treated with either radical (76.3%) or excisional (23.7%) resections; 64% had R0 and 36% had microscopically positive (R1) resection margins. Ten patients received radiation therapy with no difference in receipt of radiation between R0 vs R1 groups. Thirteen patients (13%) developed a local recurrence with no difference in RFS between R0 vs R1 resection. Five-year RFS was 59.5% for R0 vs 85.2% for R1. Only one patient died of disease after developing dedifferentiation and distant metastasis despite originally having an R0 resection.

DISCUSSION

In this large multi-institutional study of surgical resection of extremity WDLPS, microscopically positive margins were not associated with an increased risk of recurrence. Positive microscopic margin resection for extremity WDLPS may yield similar rates of local control while avoiding a radical approach to obtain microscopically negative margins.

Primary extradural tumors of the spinal column: A comprehensive treatment guide for the spine surgeon based on the 5th Edition of the World Health Organization bone and soft-tissue tumor classification

BACKGROUND

In 2020, the World Health Organization (WHO) published the 5th version of the soft tissue and bone tumor classification. Based on this novel classification system, we reviewed the current knowledge on all tumor entities with spinal manifestations, their biologic behavior, and most importantly the appropriate treatment options as well as surgical approaches.

METHODS

All tumor entities were extracted from the WHO Soft-Tissue and Bone Tumor Classification (5th Edition). PubMed and Google Scholar were searched for the published cases of spinal tumor manifestations for each entity, and the following characteristics were extracted: Growth pattern, ability to metastasize, peak age, incidence, treatment, type of surgical resection indicated, recurrence rate, risk factors, 5-year survival rate, key molecular or genetic alterations, and possible associated tumor syndromes. Surgical treatment strategies as well as nonsurgical treatment recommendations are presented based on the biologic behavior of each lesion.

RESULTS

Out of 163 primary tumor entities of bone and soft tissue, 92 lesions have been reported along the spinal axis. Of these 92 entities, 54 have the potential to metastasize. The peak age ranges from conatal lesions to 72 years. For each tumor entity, we present recommended surgical treatment strategies based on the ability to locally destruct tissue, to grow, recur after resection, undergo malignant transformation as well as survival rates. In addition, potential systemic treatment recommendations for each tumor entity are outlined.

CONCLUSION

Based on the 5th Edition of the WHO bone and soft tumor classification, we identified 92 out of 163 tumor entities, which potentially can have spinal manifestations. Exact preoperative tissue diagnosis and interdisciplinary case discussions are crucial. Surgical resection is indicated in a significant subset of patients and has to be tailored to the specific biologic behavior of the targeted tumor entity based on the considerations outlined in detail in this article.

A rare case of chest wall lipoma growing into the pleural cavity: a case report

Background

Several cases of lipoma in unusual locations in the thorax have been reported. Appropriate surgical treatment depending on the location and shape is often required.

Case presentation

We herein report an extremely rare case of a chest wall lipoma growing into the pleural cavity. The tumor was successfully removed without damaging the capsule by a combination of direct and thoracoscopic approaches.

Conclusions

Chest wall lipomas growing into pleural cavity can be successfully treated by a combination of direct and thoracoscopic approaches.

Impact of Pathological Stratification on the Clinical Outcomes of Advanced Well-Differentiated/Dedifferentiated Liposarcoma Treated with Trabectedin

BACKGROUND

We previously showed that grading can prognosticate the outcome of retroperitoneal liposarcoma (LPS). In the present study, we aimed to explore the impact of pathological stratification using grading on the clinical outcomes of patients with advanced well-differentiated LPS (WDLPS) and dedifferentiated LPS (DDLPS) treated with trabectedin.

PATIENTS

We included patients with advanced WDLPS and DDLPS treated with trabectedin at the Fondazione IRCCS Istituto Nazionale dei Tumori between April 2003 and November 2019. Tumors were categorized in WDLPS, low-grade DDLPS, and high-grade DDLPS according to the 2020 WHO classification. Patients were divided in two cohorts: Low-grade (WDLPS/low-grade DDLPS) and high-grade (high-grade DDLPS).

RESULTS

A total of 49 patients were included: 17 (35%) in the low-grade cohort and 32 (65%) in the high-grade cohort. Response rate was 47% in the low-grade cohort versus 9.4% in the high-grade cohort (logistic regression p = 0.006). Median progression-free survival (PFS) was 13.7 months in the low-grade cohort and 3.2 months in the high-grade cohort. Grading was confirmed as an independent predictor of PFS in the Cox proportional-hazards regression multivariable model (adjusted hazard ratio low-grade vs. high-grade: 0.45, 95% confidence interval: 0.22-0.94; adjusted p = 0.035).

CONCLUSIONS

In this retrospective case series, sensitivity to trabectedin was higher in WDLPS/low-grade DDLPS than in high-grade DDLPS. If confirmed in larger series, grading could represent an effective tool to personalize the treatment with trabectedin in patients with advanced LPS.

Epidemiology and survival of liposarcoma and its subtypes: A dual database analysis

PURPOSE

Liposarcoma (LPS) is a one of the most commonly diagnosed soft tissue sarcomas. Little is known about the epidemiology and prognosis of each subtype. We present an analysis of epidemiology and survival of the subtypes of LPS using a national database.

METHODS

We queried the Survival Epidemiology, and End Results (SEER) and the Canadian Institute for Clinical Evaluative Sciences (ICES) databases for data on 7 types of LPS. Pearson's chi square was used to determine associations between variables and subtypes. Kaplan-Meier and Cox Regression analyses were performed for two tests: one using SEER data and the other using variables common to both SEER and ICES.

RESULTS

The well-differentiated subtype was the most common subtype identified. Metastatic disease was associated with decreased survival across all subtypes and age >35 was associated with decreased survival in well-differentiated and myxoid subtypes. Tumor grade was associated with decreased survival in the well-differentiated, myxoid, mixed, and round cell subtypes. In the secondary analysis, age >35 was associated with decreased survival in the myxoid subtype.

CONCLUSIONS

The prognosis of liposarcoma differs greatly by subtype. Clinicians should account for patient factors at the time of diagnosis to best navigate treatment of their patients.

Qualitative evaluation of MRI features of lipoma and atypical lipomatous tumor: results from a multicenter study

OBJECTIVES

The objectives of the study are (1) to distinguish lipoma (L) from atypical lipomatous tumor (ALT) using MRI qualitative features, (2) to assess the value of contrast enhancement, and (3) to evaluate the reproducibility and confidence level of radiological readings.

MATERIALS AND METHODS

Patients with pathologically proven L or ALT, who underwent MRI within 3 months from surgical excision were included in this retrospective multicenter international study. Two radiologists independently reviewed MRI centrally. Impressions were recorded as L or ALT. A third radiologist was consulted for discordant readings. The two radiologists re-read all non-contrast sequences; impression was recorded; then post-contrast images were reviewed and any changes were recorded.

RESULTS

A total of 246 patients (135 females; median age, 59 years) were included. ALT was histopathologically confirmed in 70/246 patients. In multivariable analysis, in addition to the lesion size, deep location, proximal lower limb lesions, demonstrating incomplete fat suppression, or increased architectural complexity were the independent predictive features of ALT; but not the contrast enhancement. Post-contrast MRI changed the impression in a total of 5 studies (3 for R1 and 4 for R2; 2 studies are common); all of them were incorrectly changed from Ls to ALTs. Overall, inter-reader kappa agreement was 0.42 (95% CI 0.39-0.56). Discordance between the two readers was statistically significant for both pathologically proven L (p < 0.001) and ALT (p = 0.003).

CONCLUSION

Most qualitative MR imaging features can help distinguish ALTs from BLs. However, contrast enhancement may be limited and occasionally misleading. Substantial discordance on MRI readings exists between radiologists with a relatively high false positive and negative rates.

Accurate 3-gene-signature for early diagnosis of liposarcoma progression

Background

Well- and dedifferentiated liposarcoma (WD/DDLPS) are rare mesenchymal malignant tumors that account for 20% of all sarcomas in adults. The WD form is a low-grade malignancy with a favourable prognosis which may progress to DDLPS, a high-grade aggressive counterpart. WDLPS is referred to as atypical lipomatous tumour (ALT) when localised in extremities, due to its better prognosis. Currently the final differential diagnosis to distinguish between more aggressive and less aggressive form is based on post-surgical histological examination and no molecular biomarkers for early detection are available.

Methods

Quantitative polymerase chain reaction (qPCR) analysis of 11 metabolic genes involved in general and adipose tissue-specific metabolism, was performed on ALT (= 8), WDLPS (= 9) and DDLPS (= 20) samples. Subsequent statistical analysis was carried out to determine genes that most accurately can predict DDLPS differential diagnosis. Selected genes were further validated in a separate cohort by qPCR and the data statistically analysed. Deep sequencing was performed on DDLPS specimen from the metastatic patient and on five random WDLPS specimens.

Results

We established a three-gene signature based on PNPLA2, LIPE and PLIN1, which identified DDLPS with 100% sensitivity and 90% specificity, even in specimens from the WD component of DDLPS tumors. Interestingly, the PNPLA2 gene is deleted in 45% of DDLPS samples analyzed under TCGA project, and the deletion is associated with significantly lower PNPLA2 expression level. However, other mechanisms causing loss or downregulation of the expression of these three genes may be involved. Moreover, the significantly lower level of PNPLA2 is associated with R1 surgical margins, compare to R0 margins, which suggests the more invasive tumor phenotype in the absence of PNPLA2.

Conclusions

The identified metabolic signature allows highly accurate differential diagnosis between WD- and DDLPS even in samples containing lipid droplets, a marker of differentiation, which makes it very suitable for the use on biopsies. In respect to the pathogenesis of the disease, our results give a new insight into possible molecular mechanisms involved and support the recent observation that deletion of PNPLA2 is a novel factor in liposarcoma progression.

Atypical Lipomatous Tumors: Does Our Inconsistent Terminology Have Patient Repercussions? Results of a Meta-Analysis

OBJECTIVES

Misnaming low-grade lipomatous tumors poses a clinical and medicolegal challenge, potentially subjecting patients to expensive and unnecessary surgeries. The terms atypical lipomatous tumor (ALT) and "well-differentiated" liposarcoma (WDL) have been used interchangeably in pathology reports, scholarly works and consensus recommendations, creating vagaries between low-virulence extremity tumors and retroperitoneal disease with metastatic potential.

METHODS

A systematic review was performed on all studies that reported on the local recurrence rate and metastasis of ALTs and WDLs in living human subjects. Local recurrence and metastases were compared using Fisher's Exact Test.

RESULTS

In total, 20 studies evaluated ALTs (n=936), whereas 13 studied WDLs (n=626). Mean follow-up was 6.6±2.0 years (median, 7.0 y). No metastatic disease was observed among ALTs, whereas 15 patients with WDLs (2.7%, P<0.0001) had metastases. The local recurrence rate of ALTs was significantly lower than WDLs after both marginal (15.1%, 141/936 vs. 46.0%, 288/626, P<0.0001) and wide excisions (3.3%, 2/59 in ALT vs. 17.4%, 19/109, P=0.007).

CONCLUSIONS

ALT should be reserved for extremity lesions meeting appropriate histopathologic criteria that represent nonmetastatic disease, reducing over-diagnosis, over-treatment, and patient risk.

Diagnostic performance of MRI and histology in assessment of deep lipomatous tumours

BACKGROUND

Deep lipomatous tumours can be benign lipomas or intermediate/locally recurring atypical lipomatous tumours (ALTs). Differentiating between these two entities clinically and radiologically is difficult. The aims of this study were to report a series of deep lipomatous tumours, comparing the clinical, radiological and pathological features of ALTs and lipomas; and to predict the likelihood of a lipomatous tumour being ALT based on anatomical site and MRI characteristics.

METHODS

This was a retrospective review of patients with deep lipomatous tumours presenting over 6 years to a tertiary sarcoma centre, with preoperative MRI, and preoperative or postoperative histology including MDM2 gene analysis. Sensitivity, specificity, predictive values and accuracy in diagnosing ALT were calculated for MRI and histopathological features.

RESULTS

Some 248 patients were included; 81 (32·7 per cent) had a final diagnosis of ALT. ALTs were larger than lipomas (median 19 versus 10 cm; P < 0·001); there was no ALT smaller than 5 cm. A tumour presenting in the lower limb was more likely to be an ALT than a lesion at any other site (48·4 versus 13·5 per cent; P < 0·001). In patients with lipomatous tumours at sites other than the lower limbs, MRI had a negative predictive value of 95 per cent for excluding ALT.

CONCLUSION

Despite concern, most deep lipomatous tumours (nearly 70 per cent) are benign lipomas. Certain features imply that tumours are almost never ALT: smaller than 5 cm or located outside the lower limb with no suspicious characteristics on MRI. Tumours with these features might safely and confidently be managed outside tertiary sarcoma centres.

Natural history of well-differentiated liposarcoma of the extremity compared to patients treated with surgery

BACKGROUND

Patients with well-differentiated liposarcoma (WDLPS) of the extremity are mostly treated surgically, thereby possibly inducing severe morbidities. Despite the excellent prognosis, the natural history is barely studied. The aim of this study was to evaluate the natural history of extremity WDLPS by evaluating the outcome of patients treated with active surveillance (AS), who thereby exhibited the natural history of extremity WDLPS, and of patients treated surgically.

METHODS

A large retrospective database of patients with extremity WDLPS was assessed to evaluate treatment, dedifferentiation and disease-specific survival. Lastly, our experience with patients treated with AS was explored.

RESULTS

Distant metastases (5/191 patients, 2.6%) were mainly seen after a dedifferentiated local recurrence. Death of disease occurred in 4/191 patients (2.1%); two patients died from metastatic disease (although not pathologically proven), two patients died of treatment-related complications. In our center, 24 patients are treated with AS. Time of AS varied from 0.1 to 8.9 years (median 1.8). Four patients eventually underwent surgery after a period of AS (range 14-52 months) because of symptoms and/or tumor growth. No areas of dedifferentiation were found in these resection specimens. The other patients are still under active surveillance.

CONCLUSION

Since surgical treatment might induce morbidity and even mortality, there might be overtreatment of these patients. Evaluation of the natural history of extremity WDLPS showed that AS could be a reasonable option for selected patients. Prospective studies in patients with extremity WDLPS are needed to assess the safety of AS as a treatment option.

Mesenchymal Neoplasms of the Genitourinary System: A Selected Review with Recent Advances in Clinical, Diagnostic, and Molecular Findings

Mesenchymal neoplasms of the genitourinary (GU) tract often pose considerable diagnostic challenges due to their wide morphologic spectrum, relative rarity, and unexpected incidence at GU sites. Soft tissue tumors arise throughout the GU tract, whether from adventitia surrounding or connective tissues within the kidneys, urinary bladder, and male and female genital organs. This selected article focuses on a subset of these lesions, ranging from benign to malignant and encompassing a range of patterns of mesenchymal differentiation, where recent scholarship has lent greater insight into their clinical, molecular, or diagnostic features.

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

Background

Atypical lipomatous tumours (ALT) are common adipocytic tumours. Due to their large size and deep-seated location, wide resection might result in severe functional deficits. The question which margins should be aimed is hence discussed controversially.

Methods

Forty consecutive patients underwent limb-sparing resections. Margins were defined as R0 (wide resection), R1 (marginal resection) or R2 if tumour was left. All patients were followed for evidence of local recurrence or remote metastases. Overall and recurrence-free survival was calculated.

Results

The mean age at the time of surgery was 61.9 years. The mean tumour diameter was 17 cm with no patient having metastatic disease. In 8 cases a wide (R0) resection, in 31 cases a marginal (R1) and in one patient a R2-resection was performed. The median follow-up time was 40 months. Four patients died due to causes that were not tumour-related. 3 (7.5%) patients (all R1) developed local recurrences. Two of our 3 recurrences in this series occurred in 6 already recurring cases. We observed no dedifferentiation of tumours and no metastatic disease.

Conclusions

ALT represents a comparatively common diagnosis in large deep-seated lesions of the extremities, especially in patients over 60 years. Marginal resection shows an acceptable rate of local recurrence. The risk of dedifferentiation as proven also in a metaanalysis of the English literature of the last 30 years is close to 1%, metastatic disease is exceedingly rare.

The Value of MRI in Distinguishing Subtypes of Lipomatous Extremity Tumors Needs Reassessment in the Era of MDM2 and CDK4 Testing

Introduction

Extremity lipomas and well-differentiated liposarcomas (WDLs) are difficult to distinguish on MR imaging. We sought to evaluate the accuracy of MRI interpretation using MDM2 amplification, via fluorescence in-situ hybridization (FISH), as the gold standard for pathologic diagnosis. Furthermore, we aimed to investigate the utility of a diagnostic formula proposed in the literature.

Methods

We retrospectively collected 49 patients with lipomas or WDLs utilizing MDM2 for pathologic diagnosis. Four expert readers interpreted each patient's MRI independently and provided a diagnosis. Additionally, a formula based on imaging characteristics (i.e. tumor depth, diameter, presence of septa, and internal cystic change) was used to predict the pathologic diagnosis. The accuracy and reliability of imaging-based diagnoses were then analyzed in comparison to the MDM2 pathologic diagnoses.

Results

The accuracy of MRI readers was 73.5% (95% CI 61-86%) with substantial interobserver agreement (κ=0.7022). The formula had an accuracy of 71%, which was not significantly different from the readers (p=0.71). The formula and expert observers had similar sensitivity (83% versus 83%) and specificity (64.5% versus 67.7%; p=0.659) for detecting WDLs.

Conclusion

The accuracy of both our readers and the formula suggests that MRI remains unreliable for distinguishing between lipoma and WDLs.

Primary Atypical Lipomatous Tumor of the Orbit: A Case Report

Purpose

To describe a case of primary atypical orbital lipomatous tumor (ALT).

Case Report

A 35-year-old man presented with a two-month history of left eye proptosis and vertical diplopia. His visual acuity was 20/30 OD and 20/60 OS. External examination showed proptosis and downward displacement of the left eye with mild lid erythema. Extraocular movements were reduced in the left eye, with 10% and 70% motility in upgaze and abduction/adduction, respectively. Imaging showed a mass (22 × 16 × 46 mm) in the superior left orbit that infiltrated the orbital fat and the superior rectus muscle. A biopsy of the mass showed mature adipose tissue intermingled with fibrous zones of hyperchromatic stromal cells with nuclear atypia. Fluorescence in situ hybridization analysis demonstrated positive amplification for MDM2/CEP12. The MDM2 to CEP12 ratio was 5:7. A diagnosis of ALT was confirmed. An orbital exenteration was recommended, which the patient declined.

Conclusion

Although rare, the differential for unilateral proptosis with or without diplopia should include orbital liposarcomas including the ALT subtype. Imaging, biopsy, staining, and/or FISH analysis for proto-oncogenes can assist with diagnosis and staging, while the standard treatment is exenteration.

A clinical review of 11 cases of large-sized well-differentiated liposarcomas

Well-differentiated liposarcomas of the extremities are one of the most frequent types of malignant soft tissue tumors in adults. These tumors are typically locally aggressive and show a tendency to recurrence after surgical excision even though they do not metastasize and very rarely dedifferentiate. Its clinical presentation is generally a progressively growing mass causing aesthetic, functional, or compressive symptoms depending on the tumor's size and localization. Several authors recommend a wide excision with free margins in order to minimize the risk of recurrence, while others report good results and a low rate of recurrence with more conservative or even marginal excision thereby avoiding complications due to surgical site morbidity. We present a retrospective study of 11 patients with a large-sized well-differentiated liposarcoma of the lower limb with a mean follow-up of 3.2 years. The mean size was 22 × 19 × 17 cm, and a marginal resection was made, respecting the affected neurovascular structures, in all cases. Only one recurrence was found and the functional results were 81.6% according to the MSTS functional scale 1 year after surgery. We believe that the marginal excision is a good alternative when the tumor is located near vascular or nerve structures, and as to our experience, it is not associated with elevated recurrences.

Huge mediastinal liposarcoma resected by clamshell thoracotomy: a case report

BACKGROUND

Liposarcoma is the single most common soft tissue sarcoma. Because mediastinal liposarcomas often grow rapidly and frequently recur locally despite adjuvant chemotherapy and radiotherapy, they require complete excision. Therefore, the feasibility of achieving complete surgical excision must be carefully considered. We here report a case of a huge mediastinal liposarcoma resected via clamshell thoracotomy.

CASE PRESENTATION

A 64-year-old man presented with dyspnea on effort. Cardiomegaly had been diagnosed 6 years previously, but had been left untreated. A computed tomography scan showed a huge (36 cm diameter) anterior mediastinal tumor expanding into the pleural cavities bilaterally. The tumor comprised mostly fatty tissue but contained two solid areas. Echo-guided needle biopsies were performed and a diagnosis of an atypical lipomatous tumor was established by pathological examination of the biopsy samples. Surgical resection was performed via a clamshell incision, enabling en bloc resection of this huge tumor. Although there was no invasion of surrounding organs, the left brachiocephalic vein was resected because it was circumferentially surrounded by tumor and could not be preserved. The tumor weighed 3500 g. Pathologic examination of the resected tumor resulted in a diagnosis of a biphasic tumor comprising dedifferentiated liposarcoma and non-adipocytic sarcoma with necrotic areas. The patient remains free of recurrent tumor 20 months postoperatively.

CONCLUSIONS

Clamshell incision provides an excellent surgical field and can be performed safely in patients with huge mediastinal liposarcomas.

A diagnostic approach to popliteal fossa masses

There is a myriad of potential mass lesions that occur in the popliteal fossa, which present as palpable masses or are found incidentally on imaging. With a thorough knowledge and understanding of the appearances and locations of these different entities, one can narrow the differential diagnoses in the majority of cases. This will eliminate unnecessary additional investigations and enable a more rapid management. We present a review of frequently encountered and less common entities using an anatomical sieve, with the aim of providing a diagnostic approach to popliteal fossa masses.

Intramuscular atypical lipomatous tumor/well-differentiated liposarcoma of the pectoralis major masquerading as a breast tumor: management and review of the literature

Atypical lipomatous tumor (ALT)/well-differentiated liposarcoma (WDL) of the pectoralis major muscle is an exceedingly rare clinical entity. We describe here a case of intramuscular ALT/WDL of the pectoralis major muscle in a female patient who presented with clinical manifestations of a rapidly growing breast tumor. Diagnostic evaluation and management of the patient are discussed along with a review of the relevant literature. We conclude that although the clinical examination may be inconclusive, the mammogram and especially the magnetic resonance imaging scan can precisely delineate the anatomic location and extent of the ALT/WDL of the pectoralis major muscle, thus allowing a correct preoperative diagnosis and adequate preoperative surgical planning. Complete resection is the treatment of choice for ALT/WDL. Long-term follow-up, however, remains mandatory because of the risk of local recurrence or delayed dedifferentiation.

Atypical Lipomatous Tumors of the Extremities and Trunk Wall-The First Case Series of Chinese Population With 45 Cases

BACKGROUND

Atypical lipomatous tumor (ALT) is a low-grade, slow-growing, locally aggressive malignant mesenchymal neoplasm. ALT of the extremities and trunk wall is associated with a relatively favorable outcome. However, these tumors can still recur locally and secondary dedifferentiation after recurrence has been reported. There is currently no consensus about the optimal surgical treatment of ALT. Therefore, we aimed to clarify the clinical behavior, appropriate treatment, and outcomes of ALT of the extremities and trunk wall.

METHODS

We retrospectively reviewed the files of 45 patients treated between 2000 and 2014 with the diagnosis of atypical lipomatous tumors of the extremities and trunk wall at our institution. The median follow-up period was 84.5 months (range, 24-183 months). The patient demographics, clinical presentation, surgical methods, margin status, and administration of radiation therapy were recorded. Patients were evaluated for their local recurrence, dedifferentiation, and postoperative complications.

RESULTS

Wide resection was performed on 11 patients, and marginal resection was performed on 34 patients. Seven patients underwent adjuvant radiotherapy. The overall recurrence rate was 17.8% (8/45), and dedifferentiation rates was 0% (0/8). The mean time to local recurrence was 5.25 years (range, 2.6-10.6 years). No ALT-related deaths occurred during the follow-up period. There were no differences in recurrence-free survival for the different surgical methods (P = 0.337) and radiotherapy (P = 0.228), whereas the R0 resection had better recurrence-free survival (P = 0.031). The postoperative complication rates were higher in wide resection group than in marginal resection group. (45.5% vs 14.7%, P = 0.048).

CONCLUSIONS

Atypical lipomatous tumors of the extremities and trunk wall are associated with a favorable overall survival and do not metastasis. Although they have a tendency to recur, the risk of secondary dedifferentiation is small. Wide resection had similar recurrence rates to marginal resection, but it might lead to more complications. Therefore, marginal resection is considered appropriate for the treatment of ALTs.

The histological variants of liposarcoma: predictive MRI findings with prognostic implications, management, follow-up, and differential diagnosis

Liposarcoma is the single most common soft tissue sarcoma accounting for up to 35 % of sarcomas. It represents a histologically diverse group of soft tissue tumors that demonstrate a wide range of imaging appearances with varied behavior patterns. Correspondingly, more aggressive histological subtypes often require management that includes a combination of surgery, chemotherapy, and radiation therapy. Distinguishing among liposarcoma subtypes has important therapeutic and prognostic implications. In this manuscript, we review the liposarcoma subtypes and their histologic and MRI findings, prognostic implications, and differential diagnostic considerations.

Recurrence After Marginal Excision for Atypical Lipomatous Tumors Versus Lipomas of the Extremities

This study reviewed the medical records of 90 patients with lipomas (47 patients) and atypical lipomatous tumors (ALT)/well-differentiated liposarcomas (WDL) (43 patients) of the extremities treated from 2006 to 2012. All patients had preoperative biopsy and postoperative histologic analysis of the tumors; surgical margins were marginal in all cases. Histologic sections of the tissue blocks from the excised specimens were re-reviewed for all patients; a consensus with postoperative histologic analysis was confirmed. Molecular chromosome analysis was performed on fluorescence in situ hybridization in tissue sections from the tissue blocks in all cases for the purpose of this study; a ratio greater than 2 was considered to represent murine double-minute 2 (MDM2) amplification consistent with a diagnosis of ALT/WDL. Mean follow-up was 52 months (range, 14-96 months). Local recurrence and metastasis rates and the relationship of patient age and sex with tumor size and location were evaluated. None of the patients with lipomas experienced local recurrence compared with 6 patients (13.9%) with ALT/WDL who experienced local recurrence within a mean of 48 months (range, 33-96 months); this difference was statistically significant. None of the patients in either group experienced metastasis prior to the study period. Local recurrence did not correlate statistically with patient age or sex, or with tumor size or location. [Orthopedics. 2016; 39(4):e610-e614.].

Rare case of a liposarcoma in the brachial plexus

Introduction A liposarcoma is a rare cancer of connective tissues that resemble fat cells under light microscopy. Case History A 73-year old female patient presented to our tertiary cancer centre with an eight-year history of a large, slow-growing painless mass in the right axilla. Magnetic resonance imaging showed a lipomatous, well-circumscribed mass of dimension 30 × 16 × 10cm extending towards the right clavicle and causing deformation to the right chest wall and right breast. Surgery revealed a large tumour that had stretched all three cords of the brachial plexus. Histopathology was consistent with a diagnosis of a low-grade liposarcoma. After a period of neuropraxia, the patient returned to normal activities 4 months after surgery. Conclusions Although extremely rare, low-grade liposarcomas of the brachial plexus should be considered in the differential diagnosis of a slow-growing axillary mass. Referral to a tertiary sarcoma centre is essential for an appropriate diagnosis, adequate treatment, and long-term follow-up.

ACR Appropriateness Criteria Follow-Up of Malignant or Aggressive Musculoskeletal Tumors

Appropriate imaging modalities for the follow-up of malignant or aggressive musculoskeletal tumors include radiography, MRI, CT, (18)F-2-fluoro-2-deoxy-D-glucose PET/CT, (99m)Tc bone scan, and ultrasound. Clinical scenarios reviewed include evaluation for metastatic disease to the lung in low- and high-risk patients, for osseous metastatic disease in asymptomatic and symptomatic patients, for local recurrence of osseous tumors with and without significant hardware present, and for local recurrence of soft tissue tumors. The timing for follow-up of pulmonary metastasis surveillance is also reviewed. The ACR Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed every three years by a multidisciplinary expert panel. The guideline development and review include an extensive analysis of current medical literature from peer-reviewed journals and the application of a well-established consensus methodology (modified Delphi) to rate the appropriateness of imaging and treatment procedures by the panel. In those instances in which evidence is lacking or not definitive, expert opinion may be used to recommend imaging or treatment.

Clinical outcome in patients with peripherally-sited atypical lipomatous tumours and dedifferentiated liposarcoma

The reported incidence of local recurrence of peripheral atypical lipomatous tumours is highly variable and is likely to reflect the different inclusion criteria of cases, and the design of previous studies. We aimed to study the incidence of local recurrence of 90 cases of atypical lipomatous tumours and an additional 18 cases of de novo dedifferentiated liposarcoma. All tumours were diagnosed on the basis of MDM2 amplification: all patients had their first treatment in the same specialist sarcoma unit and were followed for a minimum of 60 months. The tumours were diagnosed between 1997 and 2009 and followed until the end of 2014. Seventy cases (78%) of atypical lipomatous tumours were located in the thigh (mean size 195 mm on presentation). Eight atypical lipomatous tumours (8.9%) recurred locally, of which 50% recurred after 60 months. The only two tumours with intralesional excisions recurred. Seven of the eight recurrent tumours were detected by the patient by self‐examination. One case recurred a second time as a dedifferentiated liposarcoma. Seventeen per cent of the de novo dedifferentiated liposarcomas recurred within 60 months of presentation. Extending the study period revealed that atypical lipomatous tumour could recur up to 40 years after the first surgery. Furthermore, of 26 tumours that recurred in the extended study, 27% recurred more than once, and three of the seven that recurred more than once transformed into a dedifferentiated liposarcoma. We recommend that, following post‐operative wound care, patients with atypical lipomatous tumour are referred back to their general practitioner for follow up, but that in the event of a suspected recurrence they have rapid access back to the specialist unit using a ‘supported discharge’ scheme. In the event of an intralesional excision and if a lesion recurs, patients are followed in a specialist unit at regular intervals: whether MRI scanning is a valuable means of monitoring such patients is unclear and requires an evidence base

Clinical outcome of deep-seated atypical lipomatous tumor of the extremities with median-term follow-up study

AIMS

There is no consensus on the best surgical treatment for deep-seated atypical lipomatous tumor (ALT) of the extremities; furthermore, the appropriate duration for follow-up observation remains unclear. We investigated clinical and functional median-term outcomes in the primary operations for ALT of the extremities in order to find its best treatment methods and observation periods.

METHODS

From 1996 to 2009, we diagnosed 41 patients with deep-seated ALT of the extremities. Wide resection was performed on 11 patients and marginal resection was performed on 30 patients. The minimum follow-up was 5 years (median, 8.5; range, 5-17.4). Patients were evaluated for their local recurrence, dedifferentiation, and post-operative function using the ISOLS/MSTS scoring system.

RESULTS

Recurrence and dedifferentiation rates were both 0% for the wide resection group, while the rates were 23% (7/30) and 3% (1/30) for the marginal resection group, respectively. Median duration before recurrence was 7.2 years (range, 4.0-14.2). Local recurrence-free survival rate was significantly higher in the wide resection group (P = 0.013). In the marginal resection group, 10% (3/30) of the cases showed residual tumor. The localization of these tumors was all intermuscular. The ISOLS/MSTS scores were 98% (range, 90-100) for wide resection and 99% (range, 93-100) for marginal resection, with no statistical difference (P = 0.694). No ALT-related deaths occurred during the observation period.

CONCLUSIONS

In addition to long-term (at least 8 years) of continuous observation, a wide resection is necessary in order to prevent recurrence, dedifferentiation, and residual tumor.

The effect of the setting of a positive surgical margin in soft tissue sarcoma

BACKGROUND

The objectives of this study were to evaluate the risk of local recurrence and survival after soft tissue sarcoma (STS) resection with positive margins and to evaluate the safety of sparing adjacent critical structures.

METHODS

One hundred sixty-nine patients with localized STS who had positive resection margins were identified from a prospective database. Patients who had positive margins were stratified into 3 groups, each representing a specific clinical scenario: critical structure positive margin (eg major nerve, vessel, or bone), tumor bed resection positive margin, and unexpected positive margin. The rates of local recurrence-free survival (LRFS) and cause-specific survival (CSS) were calculated and compared with relevant control patients who had negative margins after STS resection.

RESULTS

After planned close dissection to preserve critical structures, the 5-year LRFS and CSS rates both depended on the quality of the surgical margins (97% and 80.3%, respectively, for those with negative margins vs 85.4% and 59.4%, respectively, for those with positive margins; P = .015 and P = .05, respectively). Negative margins achieved through resection of critical structures because of tumor invasion or encasement only slightly improved the 5-year rates of LRFS (91.2%) and CSS (63.6%; P = .8 and P = .9, respectively). The lowest 5-year LRFS and CSS rates were 63.4% and 59.2%, respectively, after an unexpected positive margin during primary surgery.

CONCLUSIONS

After patients undergo resection of STS with positive margins, oncologic outcomes can be predicted based on the clinical context. Sparing adjacent critical structures in this setting is safe and contributes to improved functional outcomes.

Equivalent cross-relaxation rate imaging positively correlates with pathological grade and cell density of adipocytic tumors

OBJECTIVE

Equivalent cross-relaxation rate imaging (ECRI) is an MRI technique used to evaluate qualitative changes in protein-water interactions. We aimed to prospectively evaluate the utility of ECRI for classification of adipocytic tumors.

MATERIALS AND METHODS

Institutional Review Board approval was obtained and all patients provided informed consent. Study participants included 40 patients with adipocytic tumors who were diagnosed with lipomas (n=22), atypical lipomatous tissue/well-differentiated liposarcoma (ALT/WDL; n=9), myxoid/round cell liposarcoma (MyL; n=6), and dedifferentiated liposarcoma (DDL; n=3), and 20 control patients for whom subcutaneous fat in the buttock or thigh was analyzed.

RESULTS

Mean ECR values of lipomas, ALT/WDL, and subcutaneous fat were low, and those of MyL and DDL were high. Mean ECR values of MyL and DDL were significantly higher than those of ALT/WDL. The cut-off value was 5.1%. There was a positive correlation between ECR value, pathological grade, and cell density in adipocytic tumors.

CONCLUSION

The ECR value positively correlates with pathological grade and cell density of adipocytic tumors. Our findings suggest that ECRI is a useful method for preoperative evaluation of adipocytic tumors.

The General Surgeon's quandary: atypical lipomatous tumor vs lipoma, who needs a surgical oncologist?

BACKGROUND

Differentiating large lipomas from atypical lipomatous tumors (ALT) is challenging, and preoperative management guidelines are not well defined. The diagnostic ambiguity leads many surgeons to refer all patients with large lipomatous masses to an oncologic specialist, perhaps unnecessarily.

STUDY DESIGN

In this retrospective cohort study of patients with nonretroperitoneal lipomatous tumors, preoperative characteristics discernible without invasive diagnostic procedures were evaluated for diagnostic predictive value.

RESULTS

We identified 319 patients (256 with lipomas, 63 with ALTs) treated between 1994 and 2012. Patients with ALTs were older (60.5 vs 53.5 years, p < 0.0001), had larger tumors (16.0 vs 8.3 cm, p < 0.0001), had tumors more often located on an extremity (88.9% vs 60.5% torso, p < 0.0001), and more frequently had a history of previous operations at the same site, exclusive of excision leading to diagnosis and referral (20.6% vs 5.9%, p = 0.001). Local recurrence was observed in 2 patients with lipomas (0.8%) vs 14 with ALTs (22.6%, p < 0.0001). No patients with ALTs developed distant metastases or disease-specific mortality, with a median follow-up of 27.4 months (range 0 to 164.6 months). On multivariate analysis, age ≥ 55 years, tumor size ≥ 10 cm, extremity location, and history of previous resections were predictors for diagnosis of ALT (p < 0.05).

CONCLUSIONS

Characteristics of lipomatous masses associated with a diagnosis of ALT include patient age ≥ 55 years, tumor size ≥ 10 cm, previous resection, and extremity location (vs torso). These easily identifiable traits may guide surgical management or referral to a specialist.

Resection of soft tissue tumors extending through the obturator ring

Pelvic soft tissue sarcomas are rare tumors often presenting larger than other soft tissue sarcomas and can extend into the thigh through various anatomic routes. Surgical resection is the main modality of curative treatment. En bloc tumor excision with wide, negative margins may reduce the risk of local recurrence. Soft tissue sarcomas extending through the obturator foramen create unique challenges to operative management. This case report describes 2 cases of lipomatous lesions that extend through the obturator foramen, presenting as dumbbell-shaped lesions with large intra- and extrapelvis portions. One possible surgical approach performed in both patients is detailed with long-term follow-up. Postoperatively, 1 incidence of infection was reported. Functional outcomes were acceptable, with full restoration of ambulation without assistive devices in both cases and no hernia observed. Oncologic outcomes included locoregional recurrence in 1 patient at 24 months outside the radiation field. The ideal primary treatment for all localized soft tissue sarcomas, including those extending through the obturator foramen, is resection. However, the unique subgroup of obturator ring soft tissue sarcomas has undefined outcomes and complications. The authors' goal was to achieve en bloc resection with wide negative margins while preserving ipsilateral limb function. The surgical approach described in this case study offers a description of feasibility and discussion of theoretical and observed complications.

The use of radiation therapy in the management of selected patients with atypical lipomas

Background and Objectives. Atypical lipomas are uncommon, slow-growing benign tumors. While surgery has been the primary treatment modality, we have managed some patients with radiation (RT) as a component of the treatment and have reported their outcomes in this study. Methods. A retrospective review of all cases of extremity and trunk atypical lipomas in The Sarcoma Database at the study institution was conducted. Results. Thirteen patients were identified. All patients underwent surgical resection at initial presentation and received pre- or postoperative radiation for subtotal resection (n = 2), local recurrence (n = 8), or progressive disease (n = 3). The median total radiation dose was 50 Gy. Median followup was 65.1 months. All patients treated with RT remained free of disease at the last followup. No grade 3 or higher late toxicity from radiation was observed. No cases of tumor dedifferentiation occurred. Conclusion. For recurrent or residual atypical lipomas, a combination of reexcision and RT can provide long-term local control with acceptable morbidity. For recurrent tumors, pre-op RT of 50 Gy appears to be an effective and well-tolerated management approach.