Most malignant fibrous histiocytomas developed in the retroperitoneum are dedifferentiated liposarcomas: a review of 25 cases initially diagnosed as malignant fibrous histiocytoma

The association between CD34 expression status and the clinicopathological behavior of dedifferentiated liposarcoma

Lipogenic and fibrous tumors are thought to originate from CD34-positive stromal fibroblastic/fibrocystic cells. Well-differentiated lipogenic tumors typically express CD34, whereas dedifferentiated liposarcoma (DDLPS) often loses it. We conducted survival analyses involving 59 patients with DDLPS. Males comprised 53% of the cohort, and the median age at the time of wide resection of primary DDLPS was 60 years. Loss of CD34 expression was defined as when ≥50% of the dedifferentiated area was immunohistochemically negative for CD34. As a result, 39 of the 59 patients showed loss of CD34 expression during the initial operation for DDLPS. In the univariate analyses, the tumor site in the retroperitoneum/abdominal cavity and loss of CD34 expression were significantly associated with poor overall survival. In the multivariate analyses, loss of CD34 expression (HR = 2.26; 95% CI = 1.02-5.02; p = 0.04) and the tumor site in the retroperitoneum/abdominal cavity (HR = 3.11; 95% CI = 1.09-8.86; p = 0.03) were retained as independent prognostic factors. Six CD34-positive cases lost CD34 expression when they developed metastasis and/or local recurrence, suggesting that the loss was associated with the later stage of the tumor. Therefore, an association existed between the loss of CD34 expression and clinicopathological behaviors such as poorer prognoses and recurrence.

Analysis of clinical factors impacting recurrence in myxofibrosarcoma

Myxofibrosarcoma (MFS) is a malignant fibroblastic/myofibroblastic neoplasm with a prominent myxoid area. It has the clinical features of frequent local recurrence (LR) and occasional distant metastasis. Robust epidemiological data on MFS in China are lacking. The aim of this retrospective analysis was to determine the natural history of MFS, identify prognostic factors for recurrence and describe the real-life outcomes of MFS. We reviewed 52 patients with primary MFS from the First Affiliated Hospital of Nanjing Medical University diagnosed between 2016 and 2020. All tumors were subjected to retrospective univariate analysis for prognostic factors of the disease, including tumor size, grade, location and sex; patient age; planned operation; surgical margin; and laboratory results. The significant factors identified by univariate analysis were subsequently analyzed via multivariate analysis. Overall survival (OS), post-treatment LR and metastatic-free survival were assessed as outcomes. The median age was 61 years (range, 13-93). Fourteen (26.92%) patients exhibited low grade disease, and 38 (73.08%) exhibited high grade disease. Among the 29 males, and 23 females, 15 (28.85%) had tumors in the trunk, 37 (71.15%) had tumors in the extremities, 26 had undergone planned surgery, and 26 had unexpected unplanned operation. The margin was negative in 39 (75%) patients and positive in 13 patients (25%). The serum creatine kinase (CK) concentration was high level in 33 (63.46%) patients and low level in 19 (36.54%) patients. The serum lactate dehydrogenase (LDH) levels were low in 23 (44.23%) patients and high in 29 (55.77%) patients. LR was observed in 25 patients (48.08%), and 4 patients developed metastasis. A worse LR rate was found for patients with a low CK level (84.21%) than for those with a high CK level (27.27%) at 5 years (p < 0.05). The LR rate of patients who underwent planned surgery was lower than that of patients who underwent unplanned surgery (p < 0.05). There were significantly more patients with positive margins than patients with negative margins (92.30%, and 33.33%, respectively; p < 0.05). Moreover, superficial tumors were also associated with greater recurrence rate (2/20 [10%]) than deep tumors, (23/32 [71.86%]) [p < 0.05]. The probability of LR in patients with MFS was significantly greater in association with unplanned operations, positive margins, low serum CK levels or superficial tumor depth. These data could help identify high-risk patients; thus, more careful follow-up should be performed for higher-risk patients. Diagnosis and treatment at qualified regular medical centers can reduce the local recurrence rate of MFS.

Three-dimensional CT cinematic rendering of adrenal masses: Role in tumor analysis and management

The adrenal gland is home to an array of complex physiological and neoplastic disease processes. While dedicated adrenal computed tomography (CT) is the gold standard imaging modality for adrenal lesions, there exists significant overlap among imaging features of adrenal pathology. This can often make radiological diagnosis and subsequent determination of the optimal surgical approach challenging. Cinematic rendering (CR) is a novel CT post-processing technique that utilizes advanced light modeling to generate highly photorealistic anatomic visualization. This generates unique prospects in the evaluation of adrenal masses. As one of the first large tertiary care centers to incorporate CR into routine diagnostic workup, our preliminary experience with using CR has been positive, and we have found CR to be a valuable adjunct during surgical planning. Herein, we highlight the unique utility of CR techniques in the workup of adrenal lesions and provide commentary on the opportunities and obstacles associated with the application of this novel display method in this setting.

Epithelioid dedifferentiated liposarcoma: A clinicopathological and molecular study of 6 cases

In this study, we present six cases of epithelioid dedifferentiated liposarcoma to further characterize its clinical and pathological features. The patients are all adult men with age at presentation ranging from 46 to 64 years (median 58.5 years). The patients presented with nonspecific symptoms of retroperitoneal mass, intermittent dull pain or discomfort. None of the patients had any prior history of a primary tumor. Radiological examinations revealed the presence of ill-demarcated heterogenous mass located in the deep soft tissue, including retroperitoneum (4 cases), pelvis and trunk (1 case each). Grossly, they appeared as solid tumors with focal areas of necrosis being presented in 2 cases. Histologically, all tumors were characterized by sheets of epithelioid cells that displayed marked cellular atypia and brisk mitotic activity. Variable portion of atypical lipomatous tumor/well-differentiated liposarcoma was present in 3 cases. By immunohistochemistry, the high-grade epithelioid component in all 6 cases showed strong and diffuse nuclear staining of MDM2, CDK4 and P16, with partial expression of AE1/AE3 in 3 cases. Fluorescence in situ hybridization analysis revealed high-level amplification of MDM2 in all 6 cases, with co-amplification of CDK4 in 3 cases. Follow up information showed that two patients died of the disease within one year despite multidisciplinary treatment. Due to the striking epithelioid appearance, this rare variant of dedifferentiated liposarcoma may be confused with undifferentiated epithelioid sarcoma, poorly differentiated carcinoma, mesothelioma or other malignancies with epithelioid phenotype. The study presented herein further highlights the aggressive clinical behavior of this unique tumor type. For patients with advanced disease, CDK4 inhibitor may provide an optional targeted treatment.

Dedifferentiated Chondrosarcoma from Molecular Pathology to Current Treatment and Clinical Trials

Dedifferentiated chondrosarcoma (DDCS) is a rare subtype of chondrosarcoma, a primary cartilaginous malignant neoplasm. It accounts for up to 1-2% of all chondrosarcomas and is generally associated with one of the poorest prognoses among all chondrosarcomas with the highest risk of metastasis. The 5-year survival rates range from 7% to 24%. DDCS may develop at any age, but the average presentation age is over 50. The most common locations are the femur, pelvis humerus, scapula, rib, and tibia. The standard treatment for localised disease is surgical resection. Most patients are diagnosed in unresectable and advanced stages, and chemotherapy for localised and metastatic dedifferentiated DDCS follows protocols used for osteosarcoma.

Silver In Situ Hybridization for the Rapid Assessment of MDM2 Amplification in Soft Tissue and Bone Tumors. Validation Based on an Audit of 192 Consecutive Cases Evaluated by Silver In Situ Hybridization and Fluorescence In Situ Hybridization

The discovery of almost invariable mouse double minute 2 (MDM2) amplification among atypical lipomatous tumors (ALT)/well-differentiated liposarcoma and dedifferentiated liposarcoma is incorporated into the contemporary diagnostic workup of fatty lesions. MDM2 amplifications are also found frequently in intimal sarcomas and in low-grade osteogenic sarcoma. At present, fluorescence in situ hybridization (FISH) is the reference test for MDM2 assessment. We are interested in evaluating silver in situ hybridization (SISH) for this purpose. Between October 2016 and May 2020, in 192 consecutive cases requiring MDM2 FISH, SISH was also performed concurrently, including 77 (40.1%) core biopsies and 115 (58.9%) surgical specimens. The mean patient age was 61.0 years. SISH results were available overnight or within 48 hours if repeat testing was required. FISH results were available within 2 to 5 weeks. The cost of SISH was one third of FISH. FISH demonstrated MDM2 amplification in 44 cases (23.6%), was negative in 144 cases (74.4%) and nondiagnostic in 4 decalcified cases (2.0%). SISH showed MDM2 amplification in 33 cases (17.2%), no amplification in 119 cases (62.0%), and indeterminate results because of poor signal in 40 (20.8%) cases. All 33 (100%) SISH-amplified tumors and 113 of 119 (95.0%) nonamplified results were confirmed by FISH. There were no clear differences in the performance of SISH on NCB versus surgical specimens. The overall performance indices of SISH are sensitivity 75%, specificity 78.5%, positive predictive value 100%, and negative predictive value 95.8%. FISH is not required when SISH is clearly amplified. This is clinically useful and improves efficiency. Nonamplified SISH results provide early indications of the likely FISH findings, but there is a 4.2% chance of FISH being positive. At present, the main drawback of SISH is the high rate of nondiagnostic tests. Optimization of SISH signal detection to reduce the proportion of indeterminate results is our current focus.

Paratesticular Dedifferentiated Liposarcoma with Epithelioid Features: A Diagnostic Pitfall

Well-differentiated/dedifferentiated liposarcoma (WDLPS/DDLPS) represent a significant number of sarcomas arising within the paratesticular region. DDLPS is notorious for a broad histologic spectrum, but epithelioid morphology is rare. Herein, we describe a unique case of paratesticular DDLPS with prominent epithelioid features and molecular confirmation. The patient is 71-year-old-male who presented with multiple paratesticular masses. Morphologic review of the resection specimen revealed a biphasic adipocytic neoplasm consistent with DDLPS. Additionally, epithelioid foci with acinar and nested architecture and focal keratin expression were noted. These areas raised the possibility of a secondary neoplasm including sex cord stromal tumor, germ cell tumor, and paraganglioma. However, MDM2 immunohistochemistry and FISH showed these areas to express MDM2 and exhibit MDM2 amplification, respectively, confirming that they represented a component of DDLPS. This case further highlights the morphologic diversity of DDLPS as well as the utility of MDM2 studies.

Retroperitoneal Sarcoma Care in 2021

Soft-tissue sarcomas are biologically heterogenous tumors arising from connective tissues with over 100 subtypes. Although sarcomas account for <1% of all adult malignancies, retroperitoneal sarcomas are a distinct subgroup accounting for <10% of all sarcomatous tumors. There have been considerable advancements in the understanding and treatment of retroperitoneal sarcoma in the last decade, with standard treatment consisting of upfront primary surgical resection. The evidence surrounding the addition of radiation therapy remains controversial. There remains no standard with regards to systemic therapy, including immunotherapy. Adjunctive therapy remains largely dictated by expert consensus and preferences at individual centers or participation in clinical trials. In this 2021 review, we detail the anatomical boundaries of the retroperitoneum, clinical characteristics, contemporary standard of care and well as recent advancements in retroperitoneal sarcoma care. Ongoing international collaborations are encouraged to advance our understanding of this complex disease.

Undifferentiated pleomorphic sarcoma of the pancreas: a rare case report and literature review

Background

Primary undifferentiated pleomorphic sarcoma (UPS) of the pancreas is an exceedingly rare malignant tumor, with only 15 cases have been reported in the medical literature. At present, clinicians have poor recognition of the tumor, the epidemiology, diagnosis, and treatment of this disease have yet not been established.

Case presentation

In this report, we depict the clinical and imaging characteristics of a 37-year-old man presenting with a primarily cystic UPS. The patient complained of epigastric pain and distention over 20 days. Abdominal CT and pancreatic magnetic resonance imaging revealed cystic and cystic solid masses in the pancreatic body and tail. An abdominal ultrasound echogram revealed the mass in the body of the pancreas to be cystic with separation echo inside, and the wall was thick, not smooth. Besides, a hypoechoic mass was seen in the tail area of the pancreas with an inhomogeneous echoic pattern, containing small patches of no echo zone in the central. Microscopically, spindle fibroblast-like cells are arranged in a characteristic storiform pattern with pleomorphic and multinucleated cells. Immunohistochemically, tumor cells were positive for CD68 and vimentin. Seven months postoperatively, he was diagnosed with pulmonary lymph node metastasis and died 5 months later. Combined with this case report, we also reviewed the literature regarding UPS of the pancreas.

Conclusions

As we know, this is the first report on ultrasonography findings of pancreatic UPS. Despite there are no distinctive manifestation of UPS, a solid cystic lesion on ultrasonography or a hypodense area in the lesion on T2-weighted imaging, should be considered for differential diagnosis with pancreatic UPS. We believe this article may add some ideas into the diagnosis and therapy of patients with this tumor.

Dedifferentiated Liposarcoma: A Rare Case Report of Retroperitoneal Myxoid Soft Tissue Tumour with Diagnostic Dilemma

Background:

The retroperitoneum can host a wide spectrum of soft tissue lesions. These tumours pose a challenge to the pathologist as the morphology is not of much help and immunohistochemistry becomes a necessity.

Case report:

Sixty years old male presented with 2 months history of abdominal lump, pain and dyspepsia. The MRI revealed a heterogeneous mass in the retroperitoneum involving right para spinal muscle, right iliac fossa and right perinephric region with destruction of right transverse process and erosion of adjacent L3 vertebra. Trucut biopsy of the mass was reported as fibroliposarcoma at an outside lab. Patient underwent a wide local excision. Grossly the tumour gave an impression of a liposarcoma but the microscopy showed areas of spindle cells, epitheloid cells, focal areas of ganglion like cells and large areas of myxoid change. IHC panel of S-100, SMA, caldesmon, myogenin, myoglobin and Alk-1 was negative. MDM2, CDK4 and p16 IHC came positive proving it to be a dedifferentiated liposarcoma.

Conclusion:

We report a curious case of retroperitoneal soft tissue tumour with complex morphology and IHC features diagnosed as dedifferentiated liposarcoma based on MDM2, CDK and p16 positivity.

Spindle Cell Tumors of the Pleura and the Peritoneum: Pathologic Diagnosis and Updates

A diverse group of both benign and malignant spindle cell tumors can involve the pleura or the peritoneum. Due to their rarity and overlapping morphologic features, these tumors can pose considerable diagnostic difficulty in surgical pathology. As these tumors differ in their prognosis and clinical management, their correct pathologic diagnosis is critical. In addition to histologic assessment, select immunohistochemical and molecular tools can aid the distinction among these tumors. In this review, we consider some of the major histologic differential diagnosis of spindle cell tumors involving these serosal membranes. This list of tumors includes: solitary fibrous tumor, inflammatory myofibroblastic tumor, desmoid fibromatosis, synovial sarcoma, sarcomatoid carcinoma, spindle cell melanoma, dedifferentiated liposarcoma, epithelioid hemangioendothelioma, and sarcomatoid mesothelioma. We describe their salient clinicopathologic and genetic findings, with a review on some of the recent discoveries on their molecular pathogenesis.

Retroperitoneal Dedifferentiated Liposarcoma

OBJECTIVES

We aimed to test the hypothesis that in retroperitoneal dedifferentiated liposarcoma (DDLS) the presence of the dedifferentiated (DD) component at the resection margin is associated with adverse outcome.

METHODS

We retrospectively searched the archive for primary resections of retroperitoneal DDLS performed at our institution between 1990 and 2017. Slides were rereviewed for diagnosis, Fédération Nationale des Centres de Lutte Contre le Cancer grade, myogenic differentiation, and the presence of the well-differentiated (WD) or DD component at the resection margin. The medical records were reviewed for patient age, sex, tumor size, tumor focality, adjuvant/neoadjuvant therapy, local recurrence, distant metastases, local recurrence-free survival (LRFS), overall survival (OS), and follow-up duration.

RESULTS

The presence of the DD component at the resection margin was associated with worse LRFS compared with cases without the DD component at the margin (P = .002). However, OS was not significantly affected (P = .11).

CONCLUSIONS

LRFS is significantly shorter in cases with the DD component at the margin compared with cases without DD tumor at the margin, while there is no association with OS. We recommend reporting the presence or absence of DD tumor at the margin in retroperitoneal DDLS, as it adds meaningful prognostic information.

Undifferentiated and dedifferentiated soft tissue neoplasms: Immunohistochemical surrogates for differential diagnosis

Undifferentiated soft tissue sarcomas (USTS) are described in the current World Health Organization Classification of Soft Tissue and Bone Tumours as those showing no identifiable line of differentiation when analyzed by presently available technologies. This is a markedly heterogeneous group, and the diagnosis of USTS remains one of exclusion. USTS can be divided into four morphologic subgroups: pleomorphic, spindle cell, round cell and epithelioid undifferentiated sarcomas, with this combined group accounting for up to 20% of all soft tissue sarcomas. As molecular advances enable the stratification of emerging genetic subsets within USTS, particularly within undifferentiated round cell sarcomas, other groups, particularly the category of undifferentiated pleomorphic sarcomas (UPS), still remain difficult to substratify and represent heterogeneous collections of neoplasms often representing the common morphologic endpoints of a variety of malignant tumors of various (mesenchymal and non-mesenchymal) lineages. However, recent molecular developments have also enabled the identification and correct classification of many tumors from various lines of differentiation that would previously have been bracketed under 'UPS'. This includes pleomorphic neoplasms and dedifferentiated neoplasms (the latter typically manifesting with an undifferentiated pleomorphic morphology) of mesenchymal (e.g. solitary fibrous tumor and gastrointestinal stromal tumor) and non-mesenchymal (e.g. melanoma and carcinoma) origin. The precise categorization of 'pleomorphic' or 'undifferentiated' neoplasms is critical for prognostication, as, for example, dedifferentiated liposarcoma typically behaves less aggressively than other pleomorphic sarcomas, and for management, including the potential for targeted therapies based on underlying recurrent molecular features. In this review we focus on undifferentiated and dedifferentiated pleomorphic and spindle cell neoplasms, summarizing their key genetic, morphologic and immunophenotypic features in the routine diagnostic setting, and the use of immunohistochemistry in their principal differential diagnosis, and highlight new developments and entities in the group of undifferentiated and dedifferentiated soft tissue sarcomas.

Primary Undifferentiated Pleomorphic Sarcoma of the Biceps Femoris Muscle Complicated by Hemorrhage: An Underrecognized Entity

Malignant fibrous histiocytoma currently known as undifferentiated pleomorphic sarcoma is the commonest soft tissue sarcoma of mesenchymal origin. Undifferentiated pleomorphic sarcoma is commonly located in the extremities, trunk, head and neck in decreasing order of frequency. We report a case of primary undifferentiated pleomorphic sarcoma of the biceps femoris muscle in a 50-year-old male complicated by hemorrhage. Diagnostic workup included ultrasonography, magnetic resonance imaging (MRI), histopathology and positive results on immunohistochemistry especially CD-68. High-grade liposarcoma and rhabdomyosarcoma were regarded as differential diagnoses of undifferentiated pleomorphic sarcoma. Demonstration of spontaneous hemorrhage within the lesion on follow-up ultrasonography done at one month from the time of diagnosis deserves a special mention in this report. Radical excision with tumor-free margins of the biceps femoris and tendon reconstruction was undertaken. MRI at six months follow-up did not reveal tumor recurrence at the site of surgery and CT chest did not reveal metastases.

Novel Nomograms-Based Prediction Models for Patients with Primary Undifferentiated Pleomorphic Sarcomas Resections

Simple Summary

Undifferentiated pleomorphic sarcomas (UPS) are one of the most common soft tissue sarcomas which have relatively high potentials of recurrence and metastasis. Surgery remains the mainstream treatment for UPS patients. However, in modern medicine, doctors nowadays lack proper models to tell patients the exact prognosis of individuals after they have undergone primary surgery. In this work, we for the first time develop two nomograms that are able to predict 3- and 5-year overall survival (OS) and time to recurrence (TTR) for UPS patients. These nomograms show relatively good accuracy and practicability which may contribute a lot to the modern medical decision-making process.

Abstract

Background: Undifferentiated pleomorphic sarcomas (UPS) were one of the most common soft tissue sarcomas. As UPS had relatively high potentials of recurrence and metastasis, we designed two nomograms to better predict the overall survival (OS) and time to recurrence (TTR) for patients who underwent primary surgery. Methods: The data of UPS patients who underwent primary surgery were extracted from Shanghai Cancer Center, Fudan University. Multivariate analyses were performed using Cox proportional hazards regression to identify independent prognostic factors. Kaplan–Meier analysis was used to compare differences for patients who underwent primary surgery in OS and TTR. Nomograms were designed with the help of R software and validated using calibration curves and receiver operating characteristic curves (ROC). Results: Kaplan–Meier curves showed that patients with older ages (p = 0.0024), deeper locations (p = 0.0422), necrosis (p < 0.0001), G3 French Federation Nationale des Centres de Lutte Contre le Cancer (FNCLCC) classification (p < 0.0001), higher Ki-67 (p < 0.0001), higher mitotic index (p < 0.0001), R1/R2 resections (p = 0.0002) and higher invasive depth (p = 0.0099) had shorter OS than the other patients while patients with older ages (p = 0.0108), necrosis (p = 0.0001), G3 FNCLCC classification (p < 0.0001), higher Ki-67 (p = 0.0006), higher mitotic index (p < 0.0001) and R1/R2 resections (p < 0.0001) had shorter TTR compared with those without. Multivariate analyses demonstrated that mitotic rates and surgical margin were independent factors for TTR while age and invasive depth were independent factors for OS. Three parameters were adopted to build the nomograms for 3- and 5-year OS and TTR. The Area Under Curve (AUC) of this nomogram at 3- and 5-year TTR reached 0.802, 0.814, respectively, while OS reached 0.718, 0.802, respectively. Calibration curves for the prediction of 3- and 5-year OS and TTR showed excellent agreement between the predicted and the actual survival outcomes. Conclusions: Some important parameters could be used to predict the outcome of individual UPS patients such as mitotic age, rates, surgical margin, and invasive depth. We developed two accurate and practicable nomograms that could predict 3- and 5-year OS and TTR for UPS patients, which could be involved in the modern medical decision-making process.

G-CSF Production by Undifferentiated Pleomorphic Sarcoma with Leukemoid Reaction Occurred in the Lower Leg: A Case Report

CASE

A 46-year-old woman presented with a mass in the lower leg and severe leukocytosis. Diffuse uptake in the bones was detected with F-fluorodeoxyglucose positron emission tomography with computed tomography (F-FDG PET/CT) imaging. The serum granulocyte-colony stimulating factor (G-CSF) was elevated, and immunostaining for G-CSF was positive. When diagnosed as G-CSF-producing undifferentiated pleomorphic sarcoma (UPS), a wide resection was performed. The leukocytosis and serum G-CSF were remarkably improved after tumor resection. No local recurrence or metastasis was detected.

CONCLUSION

We report the first case of inflammatory UPS in the extremity which demonstrated the neoplastic production of G-CSF. In our case, F-FDG PET/CT, the serum G-CSF, and immunostaining for G-CSF were useful for diagnosis.

Intimal sarcomas and undifferentiated cardiac sarcomas carry mutually exclusive MDM2, MDM4, and CDK6 amplifications and share a common DNA methylation signature

Undifferentiated mesenchymal tumors arising from the inner lining (intima) of large arteries are classified as intimal sarcomas (ISA) with MDM2 amplification as their molecular hallmark. Interestingly, undifferentiated pleomorphic sarcomas (UPS) of the heart have recently been suggested to represent the cardiac analog of ISA due to morphological overlap and high prevalence of MDM2 amplifications in both neoplasms. However, little is known about ISAs and cardiac UPS without MDM2 amplifications and molecular data supporting their common classification is sparse. Here, we report a series of 35 cases comprising 25 ISAs of the pulmonary artery, one ISA of the renal artery and 9 UPS of the left atrium. Tumors were analyzed utilizing the Illumina Infinium MethylationEPIC BeadChip array, enabling copy number profile generation and unsupervised DNA methylation analysis. DNA methylation patterns were investigated using t-distributed stochastic neighbor embedding (t-SNE) analysis. Histologically, all ISAs and UPS of the left atrium resembled extra-cardiac UPS. All cases exhibited highly complex karyotypes with overlapping patterns between ISA and UPS. 29/35 cases showed mutually exclusive amplifications in the cell-cycle associated oncogenes MDM2 (25/35), MDM4 (2/35), and CDK6 (2/35). We further observed recurrent co-amplifications in PDGFRA (21/35), CDK4 (15/35), TERT (11/35), HDAC9 (9/35), and CCND1 (4/35). Sporadic co-amplifications occurred in MYC, MYCN, and MET (each 1/35). The tumor suppressor CDKN2A/B was frequently deleted (10/35). Interestingly, DNA methylation profiling (t-SNE) revealed an overlap of ISA and cardiac UPS. This "ISA" methylation signature was distinct from potential histologic and molecular mimics. In conclusion, our data reveal MDM4 and CDK6 amplifications in ISAs and UPS of the left atrium, lacking MDM2 amplification. We further report novel co-amplifications of various oncogenes, which may have therapeutic implications. Finally, the genetic and epigenetic concordance of ISAs and UPS of the left atrium further supports a shared pathogenesis and common classification.

High throughput profiling of undifferentiated pleomorphic sarcomas identifies two main subgroups with distinct immune profile, clinical outcome and sensitivity to targeted therapies

Background

Undifferentiated pleomorphic sarcoma (UPS) is the most frequent, aggressive and less-characterized sarcoma subtype. This study aims to assess UPS molecular characteristics and identify specific therapeutic targets.

Methods

High-throughput technologies encompassing immunohistochemistry, RNA-sequencing, whole exome-sequencing, mass spectrometry, as well as radiomics were used to characterize three independent cohorts of 110, 25 and 41 UPS selected after histological review performed by an expert pathologist. Correlations were made with clinical outcome. Cell lines and xenografts were derived from human samples for functional experiments.

Findings

CD8 positive cell density was independently associated with metastatic behavior and prognosis. RNA-sequencing identified two main groups: the group A, enriched in genes involved in development and stemness, including FGFR2, and the group B, strongly enriched in genes involved in immunity. Immune infiltrate patterns on tumor samples were highly predictive of gene expression classification, leading to call the group B ‘immune-high’ and the group A ‘immune-low’. This molecular classification and its prognostic impact were confirmed on an independent cohort of UPS from TCGA. Copy numbers alterations were significantly more frequent in immune-low UPS. Proteomic analysis identified two main proteomic groups that highly correlated with the two main transcriptomic groups. A set of nine radiomic features from conventional MRI sequences provided the basis for a radiomics signature that could select immune-high UPS on their pre-therapeutic imaging. Finally, in vitro and in vivo anti-tumor activity of FGFR inhibitor JNJ-42756493 was selectively shown in cell lines and patient-derived xenograft models derived from immune-low UPS.

Interpretation

Two main disease entities of UPS, with distinct immune phenotypes, prognosis, molecular features and MRI textures, as well as differential sensitivity to specific anticancer agents were identified. Immune-high UPS may be the best candidates for immune checkpoint inhibitors, whereas this study provides rational for assessing FGFR inhibition in immune-low UPS.

Funding

This work was partly founded by a grant from La Ligue.

Establishment and characterization of NCC-DDLPS1-C1: a novel patient-derived cell line of dedifferentiated liposarcoma

Dedifferentiated liposarcoma (DDLPS) is one of the four subtypes of liposarcomas; it is characterized by the amplification of the 12q13-15 region, which includes MDM2 and CDK4 genes. DDLPS has an extremely high local recurrence rate and is refractory to chemotherapy and radiation, which leads to poor prognosis. Therefore, a novel therapeutic strategy should be urgently established for improving the prognosis of DDLPS. Although patient-derived cell lines are important tools for basic research, there are no DDLPS cell lines available from public cell banks. Here, we report the establishment of a novel DDLPS cell line. Using the surgically resected tumor tissue from a patient with DDLPS, we established a cell line and named it NCC-DDLPS1-C1. The NCC-DDLPS1-C1 cells contained 12q13-15, 1p32, and 1q23 amplicons and highly expressed MDM2 and CDK4 proteins. NCC-DDLPS-C1 cells exhibited constant growth, spheroid formation, aggressive invasion, and tumorigenesis in mice. By screening a drug library, we identified that the proteasome inhibitor, bortezomib, had inhibitory effects on the proliferation of NCC-DDLPS1-C1 cells. We concluded that the NCC-DDLPS1-C1 cell line may serve as a useful tool for basic and pre-clinical studies of DDLPS.

Retroperitoneal Sarcomas: An Update on the Diagnostic Pathology Approach

Retroperitoneal sarcomas are a heterogenous group of rare tumors arising in the retroperitoneum. Retroperitoneal sarcomas comprise approximately 10% of all soft tissue sarcomas. Though any soft tissue sarcoma histologic types may arise in the retroperitoneal space, liposarcoma (especially well-differentiated and dedifferentiated types) and leiomyosarcoma do so most commonly. Retroperitoneal sarcomas are diagnostically challenging, owing to their diversity and morphological overlap with other tumors arising in the retroperitoneum. An accurate diagnosis is necessary for correct management and prognostication. Herein, we provide an update on the diagnostic approach to retroperitoneal sarcomas and review their key histologic findings and differential diagnoses.

Diagnostic Utility and Limitations of Immunohistochemistry of p16, CDK4, and MDM2 and Automated Dual-color In Situ Hybridization of MDM2 for the Diagnosis of Challenging Cases of Dedifferentiated Liposarcoma

The diagnosis of dedifferentiated liposarcoma (DDLPS) is challenging when an atypical lipomatous tumor component is absent or obscure. To analyze the utility and limitations of ancillary techniques, we studied 11 cases of DDLPS in challenging conditions and 17 cases of nonlipogenic high-grade sarcomas with immunohistochemistry (IHC) for p16, CDK4, and MDM2 and automated dual-color in situ hybridization (DISH) for MDM2 amplification. All DDLPS specimens lacked clear lipogenic components and were immunoreactive for p16, CDK4, and MDM2. DISH analyses also revealed high-level amplification of MDM2 in all DDLPS. In contrast, among nonlipogenic sarcomas, p16, CDK4, and MDM2 were expressed in 8, 9, and 3 cases, respectively. MDM2 amplification was detected in 3 of 8 studied. The MDM2-amplified tumors were the same as the MDM2-immunoreactive tumors. After careful reevaluation of these 3 sarcomas, 2 were reclassified as DDLPS because small areas of lipogenic components were detected in the original specimens. The respective sensitivities and specificities of these markers were as follows: p16 IHC (100% and 60%), CDK4 IHC (100% and 53.3%), MDM2 IHC (100% and 93.3%), and MDM2 DISH (100% and 83.3%). The results of MDM2 IHC completely coincided with those of MDM2 DISH. The present study confirmed the substantial utility of MDM2 IHC and MDM2 DISH in the diagnosis of DDLPS, especially when lipogenic components were indistinct compared with IHC for p16 and CDK4. Furthermore, automated DISH was more practical than fluorescent in situ hybridization.

Well-Differentiated/Dedifferentiated Liposarcoma Arising in the Upper Aerodigestive Tract: 8 Cases Mimicking Non-adipocytic Lesions

Well-differentiated (WDL) and dedifferentiated liposarcomas (DL) of the pharynx, larynx and oral cavity are rare, often mimicking benign lipomatous neoplasms or non-lipogenic mesenchymal tumors. Cases of WDL/DL arising in the upper aerodigestive tract, exclusive of the cervical esophagus, were reviewed. Morphologic features, ancillary studies, including fluorescence in situ hybridization (FISH) studies for CPM/MDM2, and clinical data was catalogued. Eight WDL/DL (4 WDL, 4 DL); were identified in patients ranging from 32 to 77 years (median 52.5 years; 6 males, 2 females) with sites of origin including hypopharynx (5 cases), larynx (2 cases) and oral cavity (1 case). Six of the 8 cases were received for expert consultation, and the remaining 2 cases were initially misdiagnosed as benign lymphangiomatous or fibroepithelial polyps. Morphologically, 4 tumors had areas mimicking various non-lipomatous soft tissue tumors including nodular fasciitis, mammary-type myofibroblastoma, low-grade myofibroblastic sarcoma and undifferentiated pleomorphic sarcoma, 2 cases simulated benign hypopharyngeal polyps, and 1 lesion was notable for a dense lymphoplasmacytic infiltrate suggestive of hematolymphoid neoplasm or IgG4-related sclerosing disease. FISH showed amplification of CPM/MDM2 (8/8 cases). All cases (4/4) with longer than 1-year of follow-up recurred (45-118 months) with 1 tumor showing progression to DL. WDL/DL presenting in the upper aerodigestive tract are rare and diagnostically challenging. Awareness of the morphologic spectrum of WDL/DL coupled with appropriate use of MDM2 FISH is essential for accurate classification and management, as these tumors appear to have a high risk for local recurrence and eventual dedifferentiation in these anatomical locations.

Comparative Study of Myxofibrosarcoma With Undifferentiated Pleomorphic Sarcoma: Histopathologic and Clinicopathologic Review

Myxofibrosarcoma (MFS) is a malignant fibroblastic/myofibroblastic neoplasm with the prominent myxoid area. It has the clinical features of frequent local recurrence and occasional distant metastasis. Morphologically, MFS is occasionally difficult to distinguish from undifferentiated pleomorphic sarcoma (UPS), especially in the case of high-grade MFS. Here, we reviewed clinical and histologic data of 162 MFS cases and 43 UPS cases. MFS was distinguished from UPS with the criterion of 10% myxoid area as a cutoff value. Overall, 52 MFS (34.4%) and 9 UPS (20.9%) cases showed local recurrence, 18 MFS (12.2%) and 19 UPS (44.2%) cases developed distant metastasis, and 13 MFS (9.5%) and 14 UPS (32.6%) cases resulted in tumor-related death. Statistically, MFS had a better prognosis than UPS. Moreover, MFS with less myxoid area had a tendency to present a poorer prognosis. FNCLCC grade was a statistically significant prognostic factor (distant metastasis: P=0.0021, tumor-related death: P=0.0021). Cellularity and nuclear atypia had only a statistical tendency for associations with a poorer prognosis. The overall survival rate of MFS after transformation into a UPS-like condition (<10% myxoid area) was close to that of UPS. It was suggested that MFS is a biologically distinct tumor from UPS, and MFS with less myxoid area had a tendency to present a poorer prognosis. We considered that evaluation of the amount of myxoid area, cellularity, and nuclear atypia may be important as prognostic predictors. MFS may become similar to histologic malignancy of UPS in terms of morphology and biology via local recurrence.

The clinical outcomes of undifferentiated pleomorphic sarcoma (UPS): A single-centre experience of two decades with the assessment of PD-L1 expressions

INTRODUCTION

Little is known about undifferentiated pleomorphic sarcoma (UPS) because of the low incidence and heterogeneous diagnosis of sarcoma. We investigated the oncologic outcomes of patients with UPS in a real-practice setting in association with adjuvant treatments and assessment of PD-L1 expression.

MATERIALS AND METHODS

We retrospectively reviewed consecutive patients who were diagnosed with UPS in Asan Medical Center between January 1995 and December 2016. PD-L1 staining was performed using formalin-fixed paraffin-embedded tumour tissue by immunohistochemistry, and positive PD-L1 expression was defined as staining in ≥1% of tumour cells. The PD-L1 H-score, which was calculated for statistical analysis as intensity (0-3) multiplied by proportion (0-100), ranged from 0 to 300.

RESULTS

Of 205 patients included in our analysis, 176 underwent a curative-intent operation for localised disease. The five-year disease-free survival (DFS) rate of resected UPS patients was 54.3%. Administration of adjuvant therapy did not overcome the poor prognostic factors such as primary tumour size (>5 cm) and locations, especially the abdomen and pelvis. The PD-L1 analysis was available for 114 patients, and 83 (72.8%) showed immunoreactivity for PD-L1 with weak (44/83), intermediate (29/83), and strong (10/83) staining intensities. The positive PD-L1 expression seemed to be associated with prolonged DFS, though no statistical significance was observed.

CONCLUSION

Complete surgical resection was the most important UPS treatment strategy, and adjuvant radio- or chemotherapy was insufficient to improve survival. Our results raise the possibility that immunotherapy could be a breakthrough in the treatment of UPS patients.

Immunohistochemistry as a Genetic Surrogate in Dermatopathology: Pearls and Pitfalls

Immunohistochemistry (IHC) is routinely performed in most laboratories, and other than purchase of commercially available antibodies, requires no additional equipment or reagents. As such, IHC is an accessible and relatively inexpensive test and one that can be performed quite quickly. This is in sharp contrast to genomic or mutational testing methodologies that are routinely "send out" tests as they require specialized equipment and reagents as well as individuals with expertise in the performance of the tests and analysis of the results, resulting in a prolonged turn-round-time and enhanced associated costs. However, many open questions remain in a rapidly changing therapeutic and scientific landscape with most obvious one being what exactly is the utility of "good old fashioned" IHC in the age of targeted therapy? For molecular applications, is a negative immunohistochemical result enough as a stand-alone diagnostic or predictive product? Is a positive immunohistochemical result perhaps more suitable for a role in screening for molecular alterations rather than a definitive testing modality? This review is an attempt to answer those very questions. We elucidate the broad range of entities in which IHC is currently used as a molecular surrogate and underscore pearls and pitfalls associated with each. Special attention is given to entities for which targeted therapies are currently available and to entities in which molecular data is of clinical utility as a prognosticator.

RETROPERITONEAL NON-ORGAN LIPOSARCOMAS: THE MODERN CONCEPT

Objective:to conduct a systematic literature review of the published studies on retroperitoneal non-organ liposarcomas.

Material and Methods.A literature search was performed using Pubmed, Elibrary, COSMIC databases. The data of retrospective and prospective clinical trials were analyzed. Results. The article reviews contemporary data on epidemiology, classification, clinicalmorphological and molecular-genetic characteristics, as well as diagnosis and treatment of retroperitoneal non-organ liposarcomas. Conclusion. Retroperitoneal sarcomas account for about 13 % of all types of soft tissue sarcomas. Liposarcoma is the most common retroperitoneal mesenchymal tumor. Diagnosis and treatment of non-organ retroperitoneal liposarcoma remain challenging due to poor long-term treatment outcomes. As experience is gained with the diagnosis and treatment of retroperitoneal nonorganic liposarcomas, changes occur in the system of understanding the problem that determines the strategy for providing medical care in this category of patients. The article presents modern concept of retroperitoneal non-organ liposarcomas.

Huge primary dedifferentiated pancreatic liposarcoma mimicking carcinosarcoma in a young female: A case report

BACKGROUND

Pancreatic liposarcoma is a rare tumor. According to a literature review, the patient described in this study is the seventh case of pancreatic liposarcoma reported in the English literature and the third case of dedifferentiated liposarcoma. Furthermore, this case had the largest primary tumor volume, and a primary pancreatic liposarcoma was diagnosed based on sufficient evidence.

CASE SUMMARY

We here report a rare case of a 28-year-old female with a huge dedifferentiated liposarcoma in the pancreatic tail. In June 2015, the patient underwent distal pancreatectomy with splenectomy. During the operation, a huge liposarcoma of approximately 28.0 cm × 19.0 cm × 8.0 cm was found, which had a yellow and white fish-like incisal surface. Based on both pathology and MDM2 gene amplification, the tumor was diagnosed as a dedifferentiated liposarcoma. The patient was treated with surgery but declined postoperative chemotherapy. She was well at the 26-mo follow-up, and no relapse was observed.

CONCLUSION

Pancreatic liposarcoma has a low incidence. Chemotherapy should be included in the treatment regimens. Complete resection is the only effective treatment.

Update on Lipomatous Tumors with Emphasis on Emerging Entities, Unusual Anatomic Sites, and Variant Histologic Patterns

This article reviews the histologic patterns of spindle cell/pleomorphic lipoma, well-differentiated liposarcoma, and dedifferentiated liposarcoma in the context of both usual and atypical anatomic presentation. The utility of molecular and immunohistochemical diagnostic modalities to distinguish these entities is described. In addition, more recently described and controversial entities, including atypical spindle cell lipomatous tumor and anisometric cell lipoma, are discussed.

Pleomorphic Sarcomas: The State of the Art

This article focuses on pleomorphic sarcomas, which are malignant mesenchymal tumors with complex genetic background at the root of their morphologic pleomorphism. They are poorly differentiated tumors that may retain different lines of differentiation, sometimes correlating with clinicopathological or prognostic features. Accurate diagnosis in this group of tumors relies on adequate sampling due to their heterogeneity and assessment with both microscopy and large panels of immunohistochemistry. Molecular analyses have a limited role in their diagnosis as opposed to translocation-related sarcomas but may provide theranostic and important prognostic information in the future.

Well-differentiated liposarcoma and dedifferentiated liposarcoma: An updated review

Well-differentiated liposarcoma (WDL)/atypical lipomatous tumor and dedifferentiated liposarcoma (DDL) together comprise the largest subgroup of liposarcomas, and constitute a histologic and behavioral spectrum of one disease. WDL and DDL typically occur in middle-aged to older adults, particularly within the retroperitoneum or extremities. WDL closely resembles mature adipose tissue, but typically shows fibrous septation with variable nuclear atypia and enlargement. WDL does not metastasize, but can dedifferentiate to DDL, which is associated with more aggressive clinical behavior, with a greater propensity for local recurrence and the capacity for metastasis. Although distant metastasis is rarer in DDL compared with other pleomorphic sarcomas, behavior is related to location, with a significantly worse outcome in retroperitoneal tumors. DDL typically has the appearance of undifferentiated pleomorphic or spindle cell sarcoma, and is usually a non-lipogenic sarcoma that is adjacent to WDL, occurs as a recurrence of WDL or which can arise de novo. WDL and DDL share similar background genetic aberrations; both are associated with high-level amplifications in the chromosomal 12q13-15 region, which includes the CDK4 and MDM2 cell cycle oncogenes. In addition, DDL harbor further genetic changes, particularly 6q23 and 1p32 coamplifications. While surgical excision remains the treatment mainstay with limited medical options for patients with aggressive recurrent disease or metastases, novel targeted therapies towards the gene products of chromosome 12 are being evaluated. This review summarizes the pathology of WDL and DDL, discussing morphology, immunohistochemistry, genetics and the differential diagnosis.

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.

Primary endobronchial liposarcoma successfully resected via bronchoscopy: A rare case report with genetic analysis

Liposarcoma is the most common type of soft-tissue sarcoma, and predominantly originates from the extremities and retroperitoneal cavity. However, primary endobronchial liposarcoma is extremely rare. The present study reports on the case of a 54-year-old man, a smoker, diagnosed with primary endobronchial atypical lipomatous tumor/well-differentiated liposarcoma (ALT-WDLS), which was successfully resected via bronchoscopy. Chest computed tomography (CT) revealed a neoplasm in the left main bronchus measuring 12.8×7.8 mm. Bronchoscopy demonstrated multiple roundish, pedunculated, polypoid masses in the left main bronchus. Bioptic specimens were obtained from the roundish masses, and pathological examination revealed an adipose tissue-derived tumor. The masses were completely resected during the second bronchoscopy under general anesthesia. Histopathological examination of the radical resection specimen revealed that it was an ALT-WDLS. The patient showed good quality of life at the 6-month postoperative follow-up without evidence of recurrence. Immunohistochemistry was completed with the human homologue of murine double-minute type 2 (MDM2) (+), cyclin-dependent kinase 4 (CDK4) (+), p16 (+), S-100 (+), Ki-67 (+), cluster of differentiation 34 (CD34) (+) and retinoblastoma protein (+), confirming ALT-WDLS. However, the fluorescence in situ hybridization assay revealed no amplification of MDM2 and CDK4 in the ALT-WDLS. To the best of our knowledge, the present case report is the first to describe the clinicopathologic features and genetic analysis of endobronchial liposarcoma. Although rare, this case is a reminder that clinicians should consider the possibility of this rare endobronchial tumor in patients with nonspecific symptoms including chronic cough, chest pain and recurrent pneumonia. As in this case, endoscopic treatment provided an excellent clinical outcome in patients with primary endobronchial ALT-WDLS.

Immunohistochemical Biomarkers of Mesenchymal Neoplasms in Endocrine Organs: Diagnostic Pitfalls and Recent Discoveries

Mesenchymal neoplasms rarely present in or adjacent to endocrine organs. In this context, the recognition of these rare tumor types can be challenging, with significant potential for misdiagnosis as sarcomatoid carcinomas (i.e., anaplastic thyroid carcinoma and sarcomatoid adrenal cortical carcinoma) or neuroendocrine carcinomas, depending upon the dominant histologic patterns. In this review, we address potential pitfalls in diagnosing selected mesenchymal neoplasms arising within or near endocrine organs, including dedifferentiated liposarcoma, synovial sarcoma, angiosarcoma, PEComa, proximal-type epithelioid sarcoma, Ewing sarcoma, and neuroblastoma. For each of these tumor types, we review clinical and pathologic features, histologic clues to distinguish them from endocrine neoplasms, and recently developed immunohistochemical markers that can be particularly useful for establishing the correct diagnosis.

Undifferentiated Pleomorphic Sarcoma of Pancreas: A Case Report and Review of the Literature for the Last Updates

The most prevalent type of soft tissue sarcoma is undifferentiated pleomorphic sarcoma (UPS) or previously known as malignant fibrous histiocytoma. It accounts over 20% of all soft tissue sarcomas and occurs most frequently in the extremities, trunk, and retroperitoneum. However, it has been rarely observed in the digestive system. Pancreas sarcoma represents less than 1% of all pancreatic tumors, and primary UPS of the pancreas is even rarer. It exhibits high recurrence and poor prognosis. In this case, a 72-year-old woman with a UPS tumor which was located in the pancreas head and neck without adhesion to the retroperitoneum will be discussed.

Imaging in Soft Tissue Sarcomas: Current Updates

Soft tissue sarcomas (STS) are heterogeneous malignant tumors that have nonspecific imaging features. A combination of clinical, demographic, and imaging characteristics can aid in the diagnosis. Imaging provides important information regarding the tumor extent, pretreatment planning, and surveillance of patients with STS. In this article, we illustrate the pertinent imaging characteristics of the commonly occurring STS and some uncommon sarcomas with unique imaging characteristics.

Targeted next generation sequencing of well-differentiated/dedifferentiated liposarcoma reveals novel gene amplifications and mutations

Well-differentiated/dedifferentiated liposarcoma is a common soft tissue sarcoma with approximately 1500 new cases per year. Surgery is the mainstay of treatment but recurrences are frequent and systemic options are limited. 'Tumor genotyping' is becoming more common in clinical practice as it offers the hope of personalized targeted therapy. We wanted to evaluate the results and the clinical utility of available next-generation sequencing panels in WD/DD liposarcoma. Patients who had their tumor sequenced by either FoundationOne (n = 13) or the institutional T200/T200.1 panels (n = 7) were included in this study. Significant copy number alterations were identified, but mutations were infrequent. Out of the 27 mutations detected in 7 samples, 8 (CTNNB1, MECOM, ZNF536, EGFR, EML4, CSMD3, PBRM1, PPP1R3A) were identified as deleterious (on Condel, PolyPhen and SIFT) and a truncating mutation was found in NF2. Of these, EGFR and NF2 are potential driver mutations and have not been reported previously in liposarcoma. MDM2 and CDK4 amplification was universally present in all the tested samples and multiple other recurrent genes with high amplification or high deletion were detected. Many of these targets are potentially actionable. Eight patients went on to receive an MDM2 inhibitor with a median time to progression of 23 months (95% CI: 10-83 months).

Tumours composed of fat are no longer a simple diagnosis: an overview of fatty tumours with a spindle cell component

This is a review of the morphological spectrum of fatty tumours containing a component of spindle cells, highlighting the immunohistochemical and cytogenetic workup that is now mandatory for accurate diagnosis, with the goal of providing a practical approach for practising surgical pathologists. There have been significant advances in recent years in classifying and understanding the pathogenesis of fatty tumours with spindle cells, based on the correlation of histological, immunohistochemical and cytogenetic/molecular findings. In spite of this, morphological diagnosis and accurate classification of fatty tumours with spindle cells can be challenging to diagnostic pathologists. A group of three lesions: spindle cell lipoma, mammary-type myofibroblastoma and cellular angiofibroma share morphological features and are united by retinoblastoma protein (pRb) loss. Closely allied to these lesions, especially spindle cell lipoma is the newly designated atypical spindle cell lipomatous tumour, which shares morphological, immunohistochemical and cytogenetic features with the trio of tumours lacking nuclear pRb. All of these lesions lack MDM2 and CDK4 amplification as well and separation is based on clinical features, principally location. Atypical lipomatous tumour or well-differentiated liposarcoma shows retention of pRb but overexpression and amplification of MDM2. Fatty tumours with spindle cells need to be extensively sampled, with careful attention paid to cellular atypia and location, and they need to have immunohistochemical workup with pRb, MDM2, desmin, CD34 and p16. In addition, cytogenetic analysis for MDM2 and CDK4 amplification has become crucial for the proper identification of these lesions.

Biology and Management of Undifferentiated Pleomorphic Sarcoma, Myxofibrosarcoma, and Malignant Peripheral Nerve Sheath Tumors: State of the Art and Perspectives

Undifferentiated pleomorphic sarcomas, myxofibrosarcomas, and malignant peripheral nerve sheath tumors are characterized by complex genomic characteristics and aggressive clinical behavior. Recent advances in the understanding of the pathogenesis of these tumors may allow for the development of more-effective innovative therapeutic strategies, including immunotherapies. This review describes the current knowledge of the epidemiology, clinical presentation, treatment, and pathogenesis of these tumors and highlights ongoing and future research.