What's new in adipocytic neoplasia?

"Enhancing Liposarcoma Prognosis - A New Predictive Scoring System Integrating Histopathological Insights"

Introduction

Liposarcomas are malignant soft tissue tumours with heterogeneous features and variable prognosis. Each entity comprised in this group displays distinct morphology and harbours specific genetic alterations, which correlate with clinical behaviour and therapy response. The aim of this study is to analyse the clinical and histopathological features that can influence the prognosis of liposarcoma. We also present a newly designed scoring system that could be useful for predicting the risk of disease progression and death in patients with different liposarcoma subtypes.

Materials and Methods

We carried out a retrospective multicentric study on 77 liposarcomas diagnosed between 2009 and 2023 that were followed up to assess the presence of metastases and survival of the patients. We evaluated the age, gender, tumour location and dimensions, histological subtype, mitotic index, presence and percentage of necrosis, and their association with disease progression and survival.

Results

In this respect, progression-free survival was positively associated with lower mitotic index, somatic soft-tissue localization, well-differentiated and myxoid subtypes and absence of necrosis. Overall survival was negatively influenced by older age, higher mitotic index, dedifferentiated and pleomorphic subtypes and the presence of necrosis. Therefore, several clinical and histopathological features of liposarcomas, such as tumour location, mitotic index, and tumour necrosis can strongly predict the disease evolution.

Discussion

This study focuses on developing a new scoring system that considers histologic subtype, mitotic index, and tumour necrosis as indicators that could predict the risk of disease progression and overall survival in patients with liposarcoma. The system classifies liposarcomas of any histological subtype into low-risk and high-risk tumours. Diagnosing liposarcomas using this two-tiered system could be useful for providing personalized therapy, in order to avoid relapses, metastases and improve the disease's prognosis.

The Lipid Enigma: A Case Report Highlighting Diagnostic Challenges in Adipocytic Tumors

Infiltrating lipomas are a rare form of lipomas exhibiting unusual clinical behavior. We report a case of an adipocytic tumor of a 31-year-old male diagnosed with an infiltrating lipoma in the right submandibular region. It exhibits unusual clinical features such as invasion into surrounding structures, posing significant diagnostic challenges. The histopathological findings and differential diagnosis for this case are discussed, underscoring the importance of investigation techniques for accurate diagnosis and treatment planning. Infiltrating lipomas, while benign, can mimic malignant adipocytic tumors such as atypical lipomatous tumors (ALTs) and well-differentiated liposarcomas (WDLS), complicating diagnosis. This case underscores the importance of combining histopathology, immunohistochemistry (IHC), and molecular testing, particularly murine double minute clone 2 (MDM2) amplification, to distinguish between benign and malignant tumors.

HER3 (ERBB3) amplification in liposarcoma - a putative new therapeutic target?

BACKGROUND

Liposarcomas are among the most common mesenchymal malignancies. However, the therapeutic options are still very limited and so far, targeted therapies had not yet been established. Immunotherapy, which has been a breakthrough in other oncological entities, seems to have no efficacy in liposarcoma. Complicating matters further, classification remains difficult due to the diversity of morphologies and nonspecific or absent markers in immunohistochemistry, leaving molecular pathology using FISH or sequencing as best options. Many liposarcomas harbor MDM2 gene amplifications. In close relation to the gene locus of MDM2, HER3 (ERBB3) gene is present and co-amplification could occur. Since the group of HER/EGFR receptor tyrosine kinases and its inhibitors/antibodies play a role in a broad spectrum of oncological diseases and treatments, and some HER3 inhibitors/antibodies are already under clinical investigation, we hypothesized that in case of HER3 co-amplifications a tumor might bear a further potential therapeutic target.

METHODS

We performed FISH analysis (MDM2, DDIT3, HER3) in 56 archived cases and subsequently performed reclassification to confirm the diagnosis of liposarcoma.

RESULTS

Next to 16 out of 56 cases needed to be re-classified, in 20 out of 54 cases, a cluster-amplification of HER3 could be detected, significantly correlating with MDM2 amplification. Our study shows that the entity of liposarcomas show specific molecular characteristics leading to reclassify archived cases by modern, established methodologies. Additionally, in 57.1% of these cases, HER3 was cluster-amplified profusely, presenting a putative therapeutic target for targeted therapy.

CONCLUSION

Our study serves as the initial basis for further investigation of the HER3 gene as a putative therapeutic target in liposarcoma.

Primary dedifferentiated liposarcoma of the pancreas: A case report and literature review

BACKGROUND

Dedifferentiated liposarcoma (DDLPS) is a high-grade invasive tumor that more commonly occurs in the retroperitoneum, followed by the thighs and groin. DDLPS in the pancreas is very rare.

CASE SUMMARY

A patient underwent CT examination due to hidden pain in the upper abdomen, which revealed a pancreatic space occupying lesion of unknown nature. Based on the patient's preoperative medical history, physical examination, and auxiliary examination, it was considered that there was a huge space occupying lesion in the head and neck of the pancreas, with clear boundaries and surgical indications. The patient underwent pancreaticoduodenectomy at our hospital, and the postoperative pathology revealed a DDLPS of the pancreas. Three months after the surgery, tumor recurrence occurred. Dacarbazine combined with epirubicin chemotherapy had a poor effect, and the patient passed away 18 mo later.

CONCLUSION

Due to the fact that DDLPS of the pancreas is usually not significantly responsive to radiotherapy and chemotherapy, the currently most effective treatment method for DDLPS of the pancreas is resection with negative margin under a microscope. However, due to the deep location of liposarcoma in the pancreas and its proximity to many surrounding organs, it is difficult to completely remove the tumor, and many patients may develop regional recurrence.

Spindle Cell Lipoma With Florid Primary Follicular Lymphocytic Hyperplasia: A Novel Association With Potential Diagnostic Pitfalls

ABSTRACT

Spindle cell lipoma (SCL) is a benign subcutaneous lipomatous neoplasm with a heterogeneous histologic appearance that varies greatly depending on the amount of fat, collagen, and myxoid stroma, which define the multiple subtypes of SCL, such as fat poor SCL, pseudoangiomatous SCL, and dendritic fibromyxolipoma. Cutaneous lymphoid hyperplasia is a spectrum of benign conditions characterized by reactive B-cell and T-cell cutaneous lymphocytic infiltrates. Cutaneous B-cell lymphoid hyperplasia is a heterogeneous group of non-neoplastic conditions that can be observed as reactive phenomena to infections, medications, allergens, or neoplasms and must be distinguished from cutaneous B-cell lymphomas. Here, we report a novel case of spindle cell lipoma, associated with B-cell primary lymphoid follicular hyperplasia, mixed within the tumor in a peculiar pattern, while discussing potential diagnostic pitfalls with low-grade B-cell lymphomas. This is the first report of such association in the literature.

Primary renal myxoid liposarcoma with pancreatic invasion on 18F-FDG PET/CT: first case report and literature review

Background

Myxoid liposarcoma (MLS) is a rare malignant soft tissue sarcoma that predominantly manifests in the deep soft tissues of the extremities, particularly within the musculature of the thigh. Unlike other types of liposarcoma, MLS demonstrates a propensity for metastasis to atypical sites, including the lung parenchyma, soft tissues, retroperitoneum, mediastinum, breast, liver, thymus, lymph nodes, and bones. The definitive diagnosis primarily relies on histology with HE staining. Imaging modalities such as ultrasound, CT, MRI, and 18F-FDG PET/CT scans serve as valuable tools for tumor identification.

Case report

A 57-year-old man presented with symptoms of abdominal distention and vomiting 1 month ago. Contrast-enhancement CT revealed a heterogeneous hypodense mass in the upper-middle part of the left kidney, displaying irregular morphology and protrusion towards the exterior of the kidney, with abundant blood supply and had a maximum dimension of approximately 10.7 cm × 9.0 cm. Additionally, a rounded soft tissue density was identified in the pancreatic body. Multiplanar reconstruction demonstrated a connection between the pancreatic lesion and the kidney mass. 18F-FDG PET/CT was conducted for staging, revealing significant growth of the lesion in the upper-middle part of the left kidney, extending beyond the kidney and infiltrating the pancreatic body. The lesion demonstrated remarkably high 18F-FDG uptake (SUVmax = 10.2, MTV = 136.13 cm3, TLG = 484.62). The postoperative pathological examination confirmed the diagnosis of MLS. On the 10th day post-surgery, the patient presented with tumor recurrence and underwent another surgical resection. Unfortunately, during the operation, the patient experienced a sudden cardiac arrest and died.

Conclusion

Renal MLS with invasion into the pancreas is very rare in clinical practice. Due to the limited research on the utilization of 18F-FDG PET/CT in this particular context, given the rarity and low incidence of MLS, its role remains largely unexplored. As PET/CT imaging becomes increasingly prevalent, thorough imaging of disease sites becomes indispensable for the development of treatment protocols and the monitoring of treatment response.

Atypical spindle cell/pleomorphic lipomatous tumour (ASPLT): A report of three FNA cases and comparison with spindle cell/pleomorphic lipoma cytopathology

INTRODUCTION

Atypical spindle cell/pleomorphic lipomatous tumour (ASPLT) is an infrequently appreciated benign lipomatous neoplasm newly accepted into the most recent WHO classification of soft tissue tumours.

MATERIALS AND METHODS

Our cytopathology files were searched for examples of ASPLT and spindle cell/pleomorphic lipoma (SCPL) having histopathological verification. Conventional fine needle aspiration (FNA) biopsy smears were performed using standard techniques.

RESULTS

Eleven patients including three cases of ASPLT and eight of SCPL (M:F = 4.5:1; age range: 39-97 years, mean age = 60 years) met the inclusion criteria. FNA biopsy sites included extremity (5, 45%), trunk (3, 27%), and head/neck (3, 27%). All aspirates were from primary neoplasms. FNA diagnoses of ASPLT cases were spindle cell lipomatous neoplasm, fibrotic low-grade SC neoplasm, and myxoid lipomatous neoplasm. Eight SCPL cases were diagnosed as spindle cell neoplasm (3), spindle cell lipoma (SCL) (1), pleomorphic lipoma (1), suspicious for SCL (1), benign adipose tissue (1), and benign spindle cells and connective tissue (1). Ancillary testing in two ASPLT cases showed positive CD34 and negative MDM2 immunostain in one, and negative FISH results for MDM2 and DDIT3 in another.

CONCLUSION

ASPLT is a novel lipomatous neoplasm simulating primarily SCPL and atypical lipoma/well-differentiated liposarcoma. Diligent cytomorphological observation, clinical information, and ancillary testing may allow for its specific recognition using FNA biopsy.

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.

Bioinformatics Screen Reveals Gli-Mediated Hedgehog Signaling as an Associated Pathway to Poor Immune Infiltration of Dedifferentiated Liposarcoma

Liposarcomas are the most diagnosed soft tissue sarcoma, with most cases consisting of well-differentiated (WDLPS) or dedifferentiated (DDLPS) histological subtypes. While both tumor subtypes can have clinical recurrence due to incomplete resections, DDLPS often has worse prognosis due to a higher likelihood of metastasis compared to its well-differentiated counterpart. Unfortunately, targeted therapeutic interventions have lagged in sarcoma oncology, making the need for molecular targeted therapies a promising future area of research for this family of malignancies. In this work, previously published data were analyzed to identify differential pathways that may contribute to the dedifferentiation process in liposarcoma. Interestingly, Gli-mediated Hedgehog signaling appeared to be enriched in dedifferentiated adipose progenitor cells and DDLPS tumors, and coincidentally Gli1 is often co-amplified with MDM2 and CDK4, given its genomic proximity along chromosome 12q13-12q15. However, we find that Gli2, but not Gli1, is differentially expressed between WDLPS and DDLPS, with a noticeable co-expression signature between Gli2 and genes involved in ECM remodeling. Additionally, Gli2 co-expression had a noticeable transcriptional signature that could suggest Gli-mediated Hedgehog signaling as an associated pathway contributing to poor immune infiltration in these tumors.

Malignant adipocytic tumours: A 20‑year single‑centre retrospective study

Adipocytic tumours are the most common soft tissue neoplasms. Among them, liposarcoma is the most frequent malignant neoplasm. However, to the best of our knowledge, no previously published study has assessed the evolution and oncological prognosis of the different subtypes of liposarcoma at the retroperitoneal level compared with at other locations. The present study is a retrospective observational study in which all patients were operated on between October 2000 and January 2020 with a histological diagnosis of liposarcoma. Variables, such as age, sex, location, histological type, recurrence, type of treatment and mortality, among others, were analysed. The patients were divided into two groups: Group A (retroperitoneal location) and group B (non-retroperitoneal location). A total of 52 patients with a diagnosis of liposarcoma (17 women and 35 men) and a mean age of 57.2±15.9 years were assessed. A total of 16 patients were classified into group A and 36 into group B. The OR of recurrence was 1.5 (P=0.02) for R1 vs. R0 resection in group A. The OR of recurrence in group B for R1 vs. R0 resection was 1.8 (P=0.77), whereas for R2 vs. R0 resection, the OR was 69 (P=0.011). In conclusion, 52 cases of malignant adipocytic tumours collected during 2000-2020 were analysed with the new World Health Organization classification (updated 2020). Although its recurrence potential and capacity for distant metastasis depended on each histological type, surgical treatment with unaffected margins was the main prognostic factor for survival. The present study identified differences in relation to the survival of each histological subtype and its location, finding greater survival in dedifferentiated liposarcoma, myxoid liposarcoma and pleomorphic liposarcoma located at the extraperitoneal level than in the retroperitoneal location. Resectability was not influenced by liposarcoma location.

The Conundrum of Dedifferentiation in a Liposarcoma at a Peculiar Location: A Case Report and Literature Review

Dedifferentiated liposarcoma of the deep soft tissue of the lower extremities is an infrequent finding. Myxoid liposarcoma is considered the most common soft tissue neoplasia arising in this anatomic region. Divergent differentiation usually occurs within well-differentiated liposarcoma and is exceedingly rare in a myxoid liposarcoma. We report a 32-year-old man who developed a dedifferentiated liposarcoma of the thigh on the background of a pre-existing myxoid liposarcoma. The gross examination of the surgical specimen showed a 11/7/2 cm tumour mass with solid tan-grey areas and focal myxoid degeneration. The microscopic examination revealed a malignant lipogenic proliferation, containing round cells with hyperchromatic nuclei and atypical lipoblasts, confined to the basophilic stroma with a myxoid aspect. Abrupt transition towards a hypercellular, non-lipogenic area consisting of highly pleomorphic spindle cells with atypical mitotic figures was also noted. Immunohistochemical staining was performed. Tumour cells in the lipogenic area were intensely positive for S100 and p16, and CD34 staining highlighted an arborizing capillary network. The dedifferentiated tumour areas showed positive MDM2 and CDK4 staining within neoplastic cells, with the Ki 67 proliferation marker expressed in approximately 10% of the cells. Wild-type TP53 protein expression pattern was documented. Thus, the diagnosis of a dedifferentiated liposarcoma was established. This paper aims to provide further knowledge about liposarcomas with divergent differentiation at peculiar locations, emphasizing the importance of histopathologic examination and immunohistochemical analysis for establishing the diagnosis and assessing the therapeutic response and prognosis of this condition.

Atypical Spindle Cell and Pleomorphic Lipomatous Tumor of the Ocular Adnexa: Two Cases of a Rare Entity

Atypical spindle cell and pleomorphic lipomatous tumor (ASCPLT) is a rare lipomatous neoplasm that was recently introduced into the World Health Organization Classification of Soft Tissue and Bone tumors as a distinct entity. ASCPLT has potential for local recurrence but does not metastasize. This biologic behavior separates ASCPLT from its morphologic mimics. Ocular adnexal ASCPLT has not been previously reported. Described herein are two patients with ASCPLT. The subcutaneous orbital rim lesion featured markedly pleomorphic spindle and multinucleated cells. The eyelid lesion was dominated by atypical spindle cells in a background of mature adipocytes. Both neoplasms demonstrated infiltrative margins, rare mitotic figures, immunoreactivity for CD34 and loss of Rb1, and the absence of MDM2 amplification by fluorescence in situ hybridization. Recognition of ASCPLT in the differential of ocular adnexal neoplasms may lead to a re-evaluation of morphologically similar tumors, which may have varied biologic behavior and warrant a different management approach.

An extremely rare neoplasm 'atypical spindle cell pleomorphic lipomatous tumor': a case report

Spindle cell lipoma is a rare histological variant of lipoma accounting for 1.5% of adipocytes tumors. It is composed of an admixture of mature adipocytes and fibroblast-like spindle cells in a myxoid stroma. Retroperitoneal atypical spindle cell lipomatous tumor are extremely rare only a single report in the literature reported. Herein we describe a case of a giant lipomatous tumor that was causing partial bowel obstruction. Successful excision with en block resection of the tumor, distal ureter and posterior wall of the bladder was achieved by teamwork between gastrointestinal surgeons and Urologist. The bladder defect was repaired, and left ureteric reimplantation was done. The patient made a good recovery with excellent progress. He has resumed his normal activities as a farmer.

Atypical spindle cell lipomatous tumor of the tongue: A rare entity arising in an unusual location

Atypical spindle cell/pleomorphic lipomatous tumor (ASCPT) constitutes an emerging entity of lipomatous tumors. It is a benign tumor. It occurs typically in limbs and limb girdles. The occurrence in oral cavity is unusual. The diagnosis of this neoplasm is challenging. Herein, we report a case of ASCPT arising in the tongue.

Atypical spindle cell/pleomorphic lipomatous tumor with a sarcomatous component showing high mitotic activity and Ki-67 labeling index: report of a unique case mimicking dedifferentiated liposarcoma

Atypical spindle cell/pleomorphic lipomatous tumor (ASPLT) is a new entity of benign adipocytic tumor that spans a wide spectrum of histology from adipocytic to spindle cell/pleomorphic tumors. The latter non-adipocytic component rarely shows sarcomatous features although ASPLTs are not thought to dedifferentiate. A 78-year-old woman with ASPLT in the left thigh had a sarcomatous component with high mitotic activity and Ki-67 labeling index (LI) mimicking dedifferentiated liposarcoma. The adipocytic component consisted of various-sized adipocytic cells with few lipoblasts. The sarcomatous component consisted of a fascicular proliferation of atypical spindle cells with scattered large bizarre and multinucleated giant cells. Mitotic figures including atypical mitoses were frequently observed. Immunohistochemically, the tumor cells were positive for cluster of differentiation 34 but not mouse double minute 2 homolog (MDM2), cyclin-dependent kinase 4 (CDK4), or retinoblastoma (Rb) protein. Ki-67 LI in the sarcomatous component reached 40%. MDM2 and CDK4 genes were not amplified and 13q14 including the RB1 locus was deleted according to fluorescence in situ hybridization. The patient is alive with no evidence of local recurrence or distant metastasis 3.5 years after surgery. As ASPLT may exhibit morphological variation, it is important to rule out dedifferentiated liposarcoma with careful pathological examination.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

Atypical Spindle Cell/Pleomorphic Lipomatous Tumor with Pleomorphic Hyalinizing Angiectatic Tumor-Like Growth Pattern: A Search for Diagnostic Clues

Atypical spindle cell/pleomorphic lipomatous tumor (ASPLT) is a newly described adipocytic tumor type, recently included as a separate tumor entity in the fifth edition of the World Health Organization (WHO) classification of soft tissue and bone tumors. Here, we describe a case of an ASPLT with a striking pleomorphic hyalinizing angiectatic tumor (PHAT)-like growth pattern and discuss the diagnostical clues, which led to the diagnosis of ASPLT. To our knowledge, a PHAT-like growth pattern has not yet been reported in the setting of ASPLT.

Update of Pediatric Lipomatous Lesions: A Clinicopathological, Immunohistochemical and Molecular Overview

Lipomatous neoplasms are a rare entity in the pediatric population, comprising less than 10% of soft tissue tumors in the first two decades of life. Some characteristics of pediatric adipocytic tumors are analogous to their adult counterparts, some pediatric lipomatous lesions however harbor unique features. In recent years, there have been significant advances in the understanding of the pathogenesis and hence in the classification and treatment of pediatric adipocytic tumors. This literature-based article will provide a review of the presently known clinicopathological, immunohistochemical and molecular features of pediatric lipomatous lesions.

Myxoid pleomorphic liposarcoma-a clinicopathologic, immunohistochemical, molecular genetic and epigenetic study of 12 cases, suggesting a possible relationship with conventional pleomorphic liposarcoma

Myxoid pleomorphic liposarcoma is a recently defined subtype of liposarcoma, which preferentially involves the mediastinum of young patients and shows mixed histological features of conventional myxoid liposarcoma and pleomorphic liposarcoma. While myxoid pleomorphic liposarcoma is known to lack the EWSR1/FUS-DDIT3 fusions characteristic of the former, additional genetic data are limited. To further understand this tumor type, we extensively examined a series of myxoid pleomorphic liposarcomas by fluorescence in situ hybridization (FISH), shallow whole genome sequencing (sWGS) and genome-wide DNA methylation profiling. The 12 tumors occurred in 6 females and 6 males, ranging from 17 to 58 years of age (mean 33 years, median 35 years), and were located in the mediastinum (n = 5), back, neck, cheek and leg, including thigh. Histologically, all cases consisted of relatively, bland, abundantly myxoid areas with a prominent capillary vasculature, admixed with much more cellular and less myxoid foci containing markedly pleomorphic spindled cells, numerous pleomorphic lipoblasts and elevated mitotic activity. Using sWGS, myxoid pleomorphic liposarcomas were found to have complex chromosomal alterations, including recurrent large chromosomal gains involving chromosomes 1, 6-8, 18-21 and losses involving chromosomes 13, 16 and 17. Losses in chromosome 13, in particular loss in 13q14 (including RB1, RCTB2, DLEU1, and ITM2B genes), were observed in 4 out of 8 cases analyzed. Additional FISH analyses confirmed the presence of a monoallelic RB1 deletion in 8/12 cases. Moreover, nuclear Rb expression was deficient in all studied cases. None showed DDIT3 gene rearrangement or MDM2 gene amplification. Using genome-wide DNA methylation profiling, myxoid pleomorphic liposarcomas and conventional pleomorphic liposarcomas formed a common methylation cluster, which segregated from conventional myxoid liposarcomas. While the morphologic, genetic and epigenetic characteristics of myxoid pleomorphic liposarcoma suggest a link with conventional pleomorphic liposarcoma, its distinctive clinical features support continued separate classification for the time being.

Magnetic resonance imaging of trunk and extremity myxoid liposarcoma: diagnosis, staging, and response to treatment

Myxoid liposarcoma (MLS) accounts for approximately 30% of all liposarcomas. The majority are intermediate-grade tumours, but the presence of >5% round cell component renders it a high-grade sarcoma with subsequent poorer outcome. MLS most commonly arises in the lower extremities, has a predilection for extra-pulmonary sites of metastatic disease, and is recognized to be radiosensitive. The purpose of the current article is to review the role of MRI in the management of MLS, including the characteristic features of the primary tumour, features which help to identify a round cell component and thus determine prognosis, the role of whole-body MRI for evaluation of extra-pulmonary metastatic disease, and the utility of MRI for assessing treatment response. The MRI differential diagnosis of MLS is also considered.

Pleomorphic liposarcoma with liver metastasis diagnosed by combined fine-needle aspiration cytology and core-needle biopsy

Pleomorphic liposarcoma (PLPS) is the rarest liposarcoma subtype, with high‐local recurrence and metastasis rates. Fine‐needle aspiration cytology (FNAC) is successfully used in the diagnosis of primary or metastatic soft tissue tumors, but liver metastases of PLPS diagnosed by FNAC have never been reported. The cytological diagnosis depends on the identification of lipoblasts with sharply defined cytoplasmic vacuoles indenting and distorting the nucleus in the context of a pleomorphic tumor and in a proper clinical and imaging context. Despite its aggressive behavior, hematogenous liver metastases are rare, with just one case reported in literature. A case of PLPS liver metastasis and concomitant primary tumor diagnosed by FNAC and core needle biopsy is herein described.

Lessons learnt from MDM2 fluorescence in-situ hybridisation analysis of 439 mature lipomatous lesions with an emphasis on atypical lipomatous tumour/well-differentiated liposarcoma lacking cytological atypia

AIMS

Amplification of the murine double minute-2 (MDM2) gene, which is usually detected with fluorescence in-situ hybridisation (FISH), is the key driving event for atypical lipomatous tumours (ALTs)/well-differentiated liposarcomas (WDLs). We sought to determine the concordance between the histopathological findings and MDM2 FISH in the diagnosis of ALT/WDL, and to identify the histological features of MDM2-amplified tumours lacking classic atypia.

METHODS AND RESULTS

We performed a retrospective analysis of all mature lipomatous lesions subjected to MDM2 FISH analysis at our institution. MDM2 FISH analysis was performed on 439 mature lipomatous lesions: 364 (82.9%) were negative and 75 (17%) were positive. In 17 of 75 (22.6%) ALTs/WDLs, cytological atypia was not identified on initial histological assessment, thus favouring lipoma. On review, these cases shared common histological features, consisting of a very low number of relatively small stromal cells within the tumour lobules, with mildly coarse chromatin and oval nuclei, admixed with unremarkable adipocytes in a tumour background devoid of fibroconnective septa, areas of fibrosis, or blood vessels. These cells matched the cells in which FISH showed MDM2 amplification. In contrast, 13 cases (3.5%) regarded as suspicious for ALT/WDL on the basis of histology lacked MDM2 amplification and were reclassified following the FISH findings.

CONCLUSIONS

We conclude that a subset of lipoma-like ALTs/WDLs are not associated with any of the features typically described in ALT/WDL. Our study also showed that tumours >100 mm are more likely to be ALT/WDL; however, a history of recurrence or concerning clinical/radiological features was not significantly associated with classification as ALT/WDL.

Diagnostic value and potential clinical significance of duodenal lipoma based on computed tomography imaging data

BACKGROUND

To explore the diagnostic value of computed tomography (CT) imaging for duodenal lipoma and the potential clinical significance of the findings.

METHODS

Clinicopathological and CT data from 57 patients, who were diagnosed with duodenal lipoma at the first affiliated Hospital of Zhengzhou University (Zhengzhou, China) between June 2014 and March 2019, were retrospectively reviewed. Data collected included location and size of the tumor, morphological manifestations (shape, density, boundary), concomitant diseases, pathology and gastroscopy results, and follow-up. Follow-up was performed via telephone, and surgical patients were followed-up for recurrence, metastasis and tumor size, and morphological changes. The follow-up period was up to January 2019.

RESULTS

Of the 57 patients with duodenal lipoma, contrast-enhanced scanning was performed in 7 cases. The tumor was located in the descending duodenum in 33 cases, the ascending in 4 cases, the horizontal in 16 cases, and the bulb in 4 cases. Mean tumor size was 13.0 ± 5.8 mm. CT morphological features of the tumor were as follows: tumor shape, round, quasi-round, or oval (n = 42); long strip (n = 3); nodular (n = 2); triangular (n = 1); and irregular lobulated (n = 9). Among the 57 patients, tumor density was homogeneous in 52 cases, inhomogeneous in 4 cases, and nodular with calcification in 1 case. The tumor boundary was classified as clear and with no capsule. Diseases concomitant with the tumor were as follows: gastritis (n = 23), gastric adenocarcinoma (n = 1), and gastric lymphoma (n = 1). Esophageal disease was found in 16 cases, including reflux esophagitis (n = 12) and esophageal cancer (n = 4). There were 13 cases of gallbladder and biliary disease, including cholecystolithiasis and cholecystitis (n = 9), common bile duct disease (n = 2), colorectal cancer (n = 4), lung cancer (n = 2), duodenal carcinoma with obstruction (n = 1), and ureteral space narrowing (n = 1).

CONCLUSION

CT was an effective, non-invasive method for diagnosis of duodenal lipoma. CT imaging could clearly discern location, size, shape, and nature of duodenal lipomas. Duodenal lipoma can be associated with digestive tract inflammatory diseases and tumors in different locations, and its diagnosis is potentially valuable for their prevention and treatment.

The utility of fluorescence in situ hybridization (FISH) in determining DNA damage-inducible transcript 3 (DDIT3) amplification in dedifferentiated liposarcomas - an important diagnostic pitfall

BACKGROUND AND OBJECTIVE

Dedifferentiated liposarcoma (DDLPS) is characterized by non-lipogenic sarcoma fields coexisting with adipocyte-rich well-differentiated areas. Amplification of the 12q13-15 region includes the MDM2 and DDIT3 genes. MDM2 amplification is considered a genetic hallmark of DDLPS, while DDIT3 is typically rearranged in myxoid liposarcoma. Recent studies showed that DDIT3 amplification is associated with myxoid liposarcoma-like (LPS-like) morphology in DDLPS. Our study aimed to evaluate the status of MDM2 and DDIT3 by FISH in DDLPS and correlate it with MLPS-like features.

MATERIAL AND METHODS

Six patients with MLPS-like morphology DDLPS were investigated pathologically, immunohistochemically, and genetically. The control groups of patients with classical DDLPS morphology and well-differentiated liposarcoma (WDLPS) were established and molecularly assessed as well. Fluorescence in situ hybridization (FISH) used in routine diagnostics was performed to determine the status of MDM2 and DDIT3 genes.

RESULTS

The patient's mean age was 64 (range from 43 to 85 years) with a 5:4 male to female ratio. Tumors were localized retroperitoneally (15) and extra-retroperitoneally (3). All cases demonstrated amplification of the 12q15 region containing MDM2 gene and co-amplification of the 5' DDIT3 FISH Probe representing DDIT3 telomeric tag. However, we did not find the relation of myxoid LPS-like morphology with DDIT3 amplification as previously reported.

CONCLUSIONS

The biopsy material from DDLPS with myxoid areas can be misclassified as myxoid liposarcoma. Indeed, according to the histological image, DDIT3 status may be evaluated first. In these cases, we show that the DDIT3 telomeric tag amplification assessed by FISH, is a common, nonspecific feature, which is also found in classical DDLPS and WDLPS. Therefore, we believe that co-amplification of DDIT3 and MDM2 may be considered a spectrum of the 12q13-15 region amplification due to the specification of FISH methodology.

MDM2 Amplified Sarcomas: A Literature Review

Murine Double Minute Clone 2, located at 12q15, is an oncogene that codes for an oncoprotein of which the association with p53 was discovered 30 years ago. The most important function of MDM2 is to control p53 activity; it is in fact the best documented negative regulator of p53. Mutations of the tumor suppressor gene p53 represent the most frequent genetic change in human cancers. By overexpressing MDM2, cancer cells have another means to block p53. The sarcomas in which MDM2 amplification is a hallmark are well-differentiated liposarcoma/atypical lipomatous tumor, dedifferentiated liposarcoma, intimal sarcoma, and low-grade osteosarcoma. The purpose of this review is to summarize the typical clinical, histopathological, immunohistochemical, and genetic features of these tumors.

The recurrence of well-differentiated liposarcoma from benign giant intramuscular lipoma: A case (CARE-compliant) report

RATIONALE

Recurrent liposarcoma, previously confirmed as lipoma, has rarely been reported. However, the risk factors for recurrence and the correlation between benign lipoma and malignant liposarcoma remain unclear. In this case study, we suggest a precise diagnostic strategy to minimize recurrence and malignant transformation.

PATIENT CONCERNS

A 60-year-old male patient with a history of left chest wall swelling without any symptoms underwent excisional surgery, and the mass was confirmed as a benign lipoma in 2015. In 2019, the patient returned to the hospital with symptoms of a palpable mass on the left chest wall.

DIAGNOSIS

The mass was considered a recurrent lipomatous tumor with the possibility of malignant transformation. Magnetic resonance imaging (MRI) revealed a deep-seated, septate, intramuscular, irregular margin, and large lipomatous tumor invading the ribs, pleura, and adjacent muscle, suggestive of malignancy. The MRI findings were similar to those 4 years ago, except for margin irregularity and invasion to adjacent tissue.

INTERVENTIONS

Wide en bloc excisions encompassing the 5th to 7th ribs, pleura, and adjacent muscle were followed by reconstruction with a pedicled latissimus dorsi muscle flap.

OUTCOMES

The recurrent large lipomatous tumor was confirmed as well-differentiated liposarcomas through histological and MDM2-FISH immunohistochemical staining. Postoperatively, follow-up visits continued for 1.5 years without recurrence.

LESSONS

We suggest that deep-seated, septate, and giant lipomatous tumors should be considered as risk factors for recurrence with the possibility of malignancy and misdiagnosis. It is important to inform patients of all these possibilities and plan close and long-term follow-up.

Recent advances in the understanding and management of liposarcoma

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

The 2020 WHO Classification of Tumors of Soft Tissue: Selected Changes and New Entities

Soft tissue tumors are a relatively rare and diagnostically challenging group of neoplasms that can have varying lines of differentiation. Accurate diagnosis is important for appropriate treatment and prognostication. In the 8 years since the publication of the 4th Edition of World Health Organization (WHO) classification of soft tissue tumors, significant advances have been made in our understanding of soft tissue tumor molecular biology and diagnostic criteria. The 5th Edition of the 2020 WHO classification of tumors of soft tissue and bone incorporated these changes. Classification of tumors, in general, but particularly in soft tissue tumors, is increasingly based on the molecular characteristics of tumor types. Understanding tumor molecular genetics improves diagnostic accuracy for tumors that have been difficult to classify on the basis of morphology alone, or that have overlapping morphologic features. In many large hospitals in the United States and Europe, molecular tests on soft tissue tumors are a routine part of diagnosis. Therefore, surgical pathologists should be familiar with newly emerging molecular genetic techniques in clinical settings. In the near future, molecular tests, particularly in soft tissue tumor diagnosis, will become as routine during diagnosis as immunohistochemistry is currently. This new edition provides an updated classification scheme and essential diagnostic criteria for soft tissue tumors. Newly recognized entities and subtypes of existing tumor types, several reclassified tumors, and newly defined molecular and genetic data have been incorporated. Herein, we summarize the updates in the WHO 5th Edition, focusing on major changes in each category of soft tissue tumor, and the newly described tumor entities and subtypes.

Anisometric Cell and Dysplastic Lipomas in a Retinoblastoma Patient

Anisometric cell lipoma (ACL) and dysplastic lipoma (DL) are underrecognized subtypes of benign lipomatous tumors, with wide variation in cell size, microscopic fat necrosis, and no or mild nuclear changes (DL). ACL/DL appear more commonly in retinoblastoma patients, in whom an increased incidence of lipomas has been established. The occurrence of ACL/DL in retinoblastoma patients suggests that RB1 aberrations play a role in its pathogenesis, similar to spindle cell/pleomorphic lipoma. In this article, we present a patient with a history of retinoblastoma with multiple lipomas histologically consistent with ACL/DL. Analysis of the lipomas supports involvement of RB1 in the development of ACL/DL. Dysplastic changes were only seen in a single lipoma, which harbored an additional TP53 mutation. While providing further support for the occurrence of ACL/DL in retinoblastoma patients, we also suggest that DL is an ACL with TP53 mutation.

Atypical spindle cell/pleomorphic lipomatous tumor

Atypical spindle cell/pleomorphic lipomatous tumor (ASPLT) is a recently described morphologically low-grade and clinically indolent adipocytic tumor, which will be incorporated as a new tumor entity in the upcoming 5th edition of the WHO Classification of Soft tissue and Bone tumors. Histologically, ASPLTs are characterized by ill-defined tumor margins and the presence of variable proportions of mild-to-moderately atypical spindle cells, adipocytes, lipoblasts, pleomorphic multinucleated cells and a myxoid or collagenous extracellular matrix. ASPLTs can show a wide variety of microscopic appearances and there is histologic overlap with diverse mimics. The diagnosis of ASPLT can therefore be challenging. Molecular studies have shown a consistent absence of MDM2 or CDK4 amplification. On the other hand, deletions or losses of 13q14, including RB1, have been identified in a significant subset of cases. This review provides an overview of the currently known clinical and pathological features of ASPLTs, detailing its most relevant differential diagnoses.