Atypical lipomatous tumor/well differentiated liposarcoma and related mimics with updates. When is molecular testing most cost-effective, necessary, and indicated?

The classification and work-up of adipocytic neoplasms remains challenging and sometimes controversial. Since its initial description by Dr. Enterline, the variety of subtypes and morphological appearances considered to represent the spectrum of atypical lipomatous tumor/well differentiated liposarcoma (ALT/WDL) has expanded, resulting in significant morphologic overlap with other entities, including the recently described atypical spindle cell/pleomorphic lipomatous tumor (ASPLT), conventional spindle cell/pleomorphic lipoma (SPL), and so-called "low-grade" forms of dedifferentiated liposarcoma (DL). Nevertheless, the distinction of most examples of ALT/WDL from lipomas/lipoma-like lesions is easily performed on routine histologic examination but can be problematic if the characteristic atypical cells are poorly represented, particularly in small biopsy specimens, obscured by other cellular elements (inflammation), or simply not recognized. The discovery that lipomatous tumors harbor specific and unique karyotypes and molecular events has resulted in ancillary tests that can help provide more accurate diagnoses, especially in less-than-optimal scenarios. Confirmation of MDM2 immunohistochemical over-expression and detection of the MDM2 gene rearrangement via fluorescent in situ hybridization (FISH) have proven particularly reliable and useful. While FISH analysis for MDM2 gene amplification may be helpful for confirming (or excluding) ALT/WDL, it also can lead to overutilization and overdependence. Furthermore, a small subset of otherwise typical ALT/WDL lack MDM2 gene amplification, employing alternative molecular pathways. The recent recognition of ASPLT has introduced a tumor easily mistaken morphologically for ALT/WDL, often exhibiting bizarre and pleomorphic lipoblasts, but lacking the underlying molecular abnormalities and subsequent risk of dedifferentiation. ASPLT also have overlapping features with the better-established SPL but with a greater tendency to locally recur and more frequent involvement of the distal extremities. The precise criteria separating cellular forms of ALT from what some consider "low grade" forms of DL remains controversial and inconsistently applied, even among individual pathologists within institutions. Given their underlying shared cytogenetic abnormality, molecular testing has no utility in this distinction. Herein is a comprehensive historical overview of ALT/WDL, with updates on its distinction from other similar lipomatous tumors and DL, including practical evidence-based criteria for the appropriate cost-effective use of MDM2 testing.

FISH Diagnostic Assessment of MDM2 Amplification in Liposarcoma: Potential Pitfalls and Troubleshooting Recommendations.

MDM2 amplification represents the leading oncogenic pathway and diagnostic hallmark of liposarcoma, whose assessment is based on Fluorescence In Situ Hybridization (FISH) analysis. Despite its diagnostic relevance, no univocal interpretation criteria regarding FISH assessments of MDM2 amplification have been established so far, leading to several different approaches and potential diagnostic misinterpretations. This study aims to address the most common issues and proposes troubleshooting guidelines for MDM2 amplification assessments by FISH. We retrospectively retrieved 51 liposarcomas, 25 Lipomas, 5 Spindle Cell Lipoma/Pleomorphic Lipomas, and 2 Atypical Spindle Cell Lipomatous Tumors and the corresponding MDM2 FISH analysis. We observed MDM2 amplification in liposarcomas cases only (43 out of 51 cases) and identified three MDM2-amplified patterns (scattered (50% of cases), clustered (14% of cases), and mixed (36% of cases)) and two nonamplified patterns (low number of signals (82% of cases) and polysomic (18% of cases)). Based on these data and published evidence in the literature, we propose a set of criteria to guide MDM2 amplification analysis in liposarcoma. Kindled by the compelling importance of MDM2 assessments to improve diagnostic and therapeutic liposarcoma management, these suggestions could represent the first step to develop a univocal interpretation model and consensus guidelines.

Oncological outcome, functional results and costs after unplanned excision of musculoskeletal soft tissue sarcoma.

BACKGROUND: Treatment of soft tissue sarcomas (STS) should only be initiated once the diagnosis is fully established. Resection of tumors of unknown nature should be avoided. Nevertheless, specialized centers continue to face numbers of unplanned excisions (UPE) in STS. AIM: To compare oncologic and functional outcomes, number of surgeries, length of hospital stay and treatment costs of UPE versus planned excision (PE) in STS. METHOD: A retrospective single tertiary center study was performed on 201 patients. Survival, local and distant recurrence rates were compared between PE (n = 137) and UPE (n = 64). In a subgroup analysis of 60 patients, functional outcome (MSTS and TESS scores), and socio-economic impact (number of surgeries, length of hospital stay and treatment costs) in "functional planned excision" (fPE) group (n = 30) and "functional unplanned excision" (fUPE) group (n = 29) were compared. RESULTS: There was no significant difference in oncological outcome between PE and UPE. In the subgroup analysis, we found a non-significant difference in functional outcome. Patients in the fUPE had significantly more surgeries (3.5 vs. 1.4; p < 0.00001) and costs of their management was 64% higher than fPE (p = 0.048). Hospital stay was longer after fUPE but not statistically significant (18.3 days vs. 11.8 days; p = 0.13). CONCLUSION: Even though oncological and functional outcomes are comparable after PE and UPE of STS, the number of surgeries, length of hospital stay and treatment costs were higher in patients with UPE. Our data underscore the importance of specialized STS treatment centers including multidisciplinary management.

Histologic Appearance After Preoperative Radiation Therapy for Soft Tissue Sarcoma: Assessment of the European Organization for Research and Treatment of Cancer-Soft Tissue and Bone Sarcoma Group Response Score.

PURPOSE: To critically assess the prognostic value of the European Organization for Research and Treatment of Cancer-Soft Tissue and Bone Sarcoma Group (EORTC-STBSG) response score and define histologic appearance after preoperative radiation therapy (RT) for soft tissue sarcoma (STS). METHODS AND MATERIALS: For a cohort of 100 patients with STS of the extremity/trunk treated at our institution with preoperative RT followed by resection, 2 expert sarcoma pathologists evaluated the resected specimens for percent residual viable cells, necrosis, hyalinization/fibrosis, and infarction. The EORTC response score and other predictors of recurrence-free survival (RFS) and overall survival (OS) were assessed by Kaplan-Meier and proportional hazard models. RESULTS: Median tumor size was 7.5 cm; 92% were intermediate or high grade. Most common histologies were unclassified sarcoma (34%) and myxofibrosarcoma (25%). Median follow-up was 60 months. The 5-year local recurrence rate was 5%, 5-year RFS was 68%, and 5-year OS was 75%. Distribution of cases according to EORTC response score tiers was as follows: no residual viable tumor for 9 cases (9% pathologic complete response); <1% viable tumor for 0, ≥1% to <10% for 9, ≥10% to <50% for 44, and ≥50% for 38. There was no association between EORTC-STBSG response score and RFS or OS. Conversely, hyalinization/fibrosis was a significant independent favorable predictor for RFS (hazard ratio 0.49, P=.007) and OS (hazard ratio 0.36, P=.02). CONCLUSION: Histologic evaluation after preoperative RT for STS showed a 9% pathologic complete response rate. The EORTC-STBSG response score and percent viable cells were not prognostic. Hyalinization/fibrosis was associated with favorable outcome, and if validated, may become a valid endpoint for neoadjuvant trials.

Magnetic Resonance Imaging Assessment of Lipomatous Soft-tissue Tumors.

AIM: To establish the accuracy of magnetic resonance imaging (MRI) in distinguishing between benign and malignant lipomatous tumors; to evaluate the reproducibility of the MRI interpretation assessing the agreement between judgments of two radiologists with the same experience in soft-tissue sarcomas; to identify an association among MRI findings (size, depth, septa, nodules, signal homogeneity) and nature of the lesion. MATERIALS AND METHODS: A total of 54 patients (28 men and 26 women), with a mean age of 56 (range=27-84) were included years. All subjects followed-up by the Multidisciplinary Sarcoma Group. The following MRI findings were judged in a blind study by two radiologists: size, localization, septa, nodules and signal homogeneity. A diagnostic indication was then given from among lipoma, atypical lipomatous tumour (ALT) and liposarcoma. Accuracy in distinguishing between benign and malignant lesions, and between lipoma and ALT (Fisher's exact test), inter-operator agreement (Cohen's kappa), association of MRI findings and malignancy of the lesion (Fisher's exact test and odds ratio) were evaluated. RESULTS: The inter-operator agreement was complete (100%). The agreement between diagnostic hypothesis and histological diagnosis was statistically significant (p<0.05). Among the radiological findings taken into account, only septa and signal homogeneity were significantly associated with the malignancy of the lesion (p<0.05). CONCLUSION: MRI could be helpful in distinguishing lipomatous tumors, allowing biopsy to be avoided in some cases (negative predictive value=100%).

Racial Disparities in Extremity Soft-Tissue Sarcoma Outcomes: A Nationwide Analysis.

BACKGROUND: Racial disparities in access and survival have been reported in a variety of cancers. These issues, however, have yet to be explored in detail in patients with soft-tissue sarcomas (STS). The purpose of this paper was to investigate the independent role of race with respect to survival outcomes in STS. METHODS: A total of 7601 patients were evaluated in this study. A SEER registry query for patients over 20 years old with extremity STS diagnosed between 2004 and 2009 (n=7225) was performed. Survival outcomes were analyzed after patients were stratified by race. Multivariable survival models were used to identify independent predictors of sarcoma-specific death. The Wilcoxon rank-sum test was used to compare continuous variables. Statistical significance was maintained at P<0.05. RESULTS: This study showed that African American patients were more likely to die of their STS. They were younger at presentation (P=0.001), had larger tumors (P<0.001), had less surgery (P=0.002), received radiotherapy less frequently (P=0.024), had higher family income (P<0.001), and were less likely to be married (P<0.001). African American race by itself was not an independent predictor of death. CONCLUSIONS: African Americans encounter death due to STS at a much larger proportion and faster rate than their respective white counterparts. African Americans frequently present with a larger size tumor, do not undergo surgical resection, or receive radiation therapy as frequently as compared with their white peers. Barriers to timely and appropriate care should be further investigated in this group of at-risk patients.

Correlation between radiological assessment and histopathological diagnosis in retroperitoneal tumors: analysis of 291 consecutive patients at a tertiary reference sarcoma center.

OBJECTIVES: Aim of study was to assess the correlation between computed tomography scan (CT) findings and histopathology. MATERIAL AND METHODS: Data were collected on consecutive patients with suspected retroperitoneal sarcoma (RPS) referred to a tertiary sarcoma center. Patients underwent contrast enhanced multi-detector CT scans. Radiological features of lesions were classified according to the presence of a fatty (Group A) mass, or non-fatty (Group B) mass, both subdivided according to homogeneity and intralesional high-contrasted appearance. Radiological classification was compared with histopathological diagnosis. Sensitivity, specificity, positive/negative predictive value (PPV, NPV) were analyzed. RESULTS: Of 291 patients, 103/291 (35.4%) masses were classified in Group A and 188/291 (64.6%) in Group B. Diagnosis of mesenchymal tumor was obtained in 231/291 cases (79%) and non-mesenchymal tumor in 60/291 (21%). Sensitivity and specificity of Group A for liposarcoma were 76.7% and 92.0%; PPV and NPV were 86.4% and 85.6%. Sensitivity of Group B for a mesenchymal tumor was 55.4% and specificity was 0%; PPV and NPV were 68.1% and 0%. CONCLUSIONS: None of radiological criteria were sufficient to anticipate a specific diagnosis, with the only exception of well differentiated liposarcoma and angiomyolipoma. In a series of suspected RPS, 21% of the lesions were finally non-mesenchymal tumors.

Head and neck sarcomas: epidemiology, pathology, and management.

Sarcomas of the head, neck, and skull base represent a heterogeneous group of tumors with distinct prognostic features. There have been significant improvements in characterizing these sarcomas using traditional morphologic assessments and more recent immunohistochemical analysis. Surgery is the mainstay of treatment followed by radiation therapy. Treatment modalities have changed in select pediatric sarcomas, for which new chemotherapeutic combinations have improved survival statistics. The high rate of distant failure emphasizes the need for novel systemic and directed molecular therapies. Tumor grade, size, and margin status are key factors in survival.

Clinicopathological assessment of T1 soft tissue sarcomas.

INTRODUCTION: Many studies have identified factors prognostic for soft tissue sarcomas of local recurrence, and distant metastasis. Several studies demonstrated that some subsets of patients could be safely treated by surgery alone, with acceptable rates of local recurrence. The aim of this study was to better clarify the necessity for adjuvant therapy and the width of the resected margin, by investigating the clinicopathological results of T1 (≤5 cm) soft tissue sarcomas. PATIENTS AND METHODS: A retrospective review was conducted in 96 adult patients treated for nonmetastatic AJCC T1 primary non-small round cell soft tissue sarcomas in our institution from 1995 to 2008. There were 49 men and 47 women ranging in age from 18 to 85 years (mean 51), and the observation period was 6-159 months (mean 52). The site of origin was the upper extremity in 21 cases, the lower extremity in 45, and the trunk in 30. Forty-four cases had high-grade malignant tumors, and 52 had low-grade malignant ones. Tumor size ranged from 0.7 to 5.0 cm (median size, 3.5 cm). Thirty-nine cases (41%) had previously undergone unplanned excision elsewhere. RESULTS: Eighty-nine (93%) of the patients were continuously free of disease, four were alive and currently free of disease, one was alive with metastasis, and two had died. The event-free survival rate at 5 years was 93.3%. The overall survival rate at 5 years was 94.1%. In 23 of the 45 cases with unplanned excisions (51%) residual tumor was found on histological examination. After definitive surgery, 92 patients (96%) had R0 margins. Four patients (4%) had R1 margins and were treated with postoperative radiotherapy. Forty-five of 51 cases after planned biopsies (88%) showed infiltrative growth microscopically. CONCLUSION: Tumor size was found to have a major impact on the prognosis of soft tissue sarcomas, emphasizing the importance of early detection and early treatment of these tumors. Most patients suffering from T1 soft tissue sarcomas might be able to avoid adjuvant therapies including radiotherapy and chemotherapy. To achieve good local control with surgery alone, an adequate surgical margin must be achieved even for small lesions.

The combination of a decision tree technique with the computer-assisted microscope analysis of Feulgen-stained nuclei to assess aggressiveness in lipomatous and smooth muscle tumors.

The present study describes a computer-assisted methodology whose purpose is to reduce the degree of subjectivity in the diagnosis of soft tissue tumors. This methodology associates three complementary techniques, namely digital cell image analysis, the discretisation of numerical data and a Decision Tree technique (DT). The first technique relies on the use of the digital cell image analysis of Feulgen-stained nuclei, a technique which makes possible a quantitative and thus objective description of nuclei with the help of 24 numerical parameters (15 morphonuclear and 9 DNA content- (ploidy level and proliferation activity) related). The second technique transforms each numerical parameter into an ordinal one with a small number of values (2 to 4) so that only the relevant physical significance of the parameters is retained. The Decision Tree technique generates classification rules on the basis of the discretised parameters quoted above. This methodology was applied to 53 human soft tissue tumors which included 26 lipomatous tumors (13 malignant liposarcomas and 13 benign lipomas) and 27 smooth muscle tumors (11 malignant leiomyosarcomas and 16 benign leiomyomas). The results show that a distinction between benign (lipoma) and malignant (liposarcoma) lipomatous tumors can easily be made by means of simple logical rules depending on only four discretised cytological parameters (two ploidy- and two morphonuclear-related). In contrast, no stable or predictive characterisation can be obtained with respect to the difference between leiomyosarcomas and the leiomyomas. Hence, while lipomas and liposarcomas appeared to be two completely distinct biological entities, leiomyomas and leiomyosarcomas seem to involve a continuous biological process.