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Dedifferentiated liposarcoma with extensive lymphoid component.

An unusual variant of dedifferentiated liposarcoma with extensive lymphocytic component is described. A 71-year-old patient suffered from a relapse of an atypical lipomatous tumor/well-differentiated liposarcoma with early micronodular (low-grade) dedifferentiation, which had been resected 4 years before. The relapse revealed features of a dedifferentiated liposarcoma with spindle-cell, partly pleomorphic dedifferentiation and osseous metaplasia. Clearly separated from the spindle-cell areas, an extensive homogeneously dense lymphoid (lymphocytic) tumor-component was evident, with relative abrupt transition to the well-differentiated liposarcoma component. Using immunohistochemistry and PCR, the lymphoid ("lymphoma-like") infiltrate proved to be a polyclonal lymphocytic proliferation. Fluorescence in situ hybridization (FISII) analysis revealed no signs of MDM2- and CDK4-gene amplification in the lymphoid areas, although within this mononuclear lymphoid population, large polymorphic nuclei displayed an amplified number of MDM2/CDK4 gene copies, indicating the presence of truly dedifferentiated tumor cells within the lymphoid component. The results favor a reactive lymphocytic infiltration versus a neoplastic one, which might be caused for example by chemoattractive agents. An extensive lymphoid "overgrowth" must be considered within the spectrum of unusual variants and in the differential diagnosis of dedifferentiated liposarcoma.

Aged↗

[Giant retroperitoneal liposarcoma. One case report].

INTRODUCTION: Retroperitoneal Liposarcoma is a rare and primary malignancy developed from mesenchymal tissue. It's generally unique and shows an only one histologic component. We report a case of multicentric and synchronous liposarcoma (intraperitoneal and retroperitoneal) and with different histologic types. EXEGESES: A 53-year old man presented with abdominal pain, increased abdominal girth and weight loss. Physical examination revealed two abdominal masses. Computed tomography scan showed a very large retroperitoneal mass displacing the left kidney, digestive loops and vessels. The patient underwent surgery. One enormous mass of the left renal lodge measuring 50 cm, a retroduodenal mass measuring 15 cm and a nodule of the coecum were removed. Histological examination of the mass of the left renal lodge revealed mixed type liposarcoma (dedifferentiated and myxoid). Histological examination of the retroduodenal mass and of the nodule of the coecum revealed well-differentiated liposarcoma. CONCLUSION: Pathological, therapeutic and prognostic aspects of abdominal liposarcoma will be reviewed in this article.

Humans↗

Computerized tomography characteristics that differentiate angiomyolipomas from liposarcomas in the perinephric space.

PURPOSE: We performed a retrospective study to determine computerized tomography (CT) findings associated with perinephric angiomyolipomas or perinephric liposarcomas. MATERIALS AND METHODS: During the last 7 years 6 patients with perinephric angiomyolipoma and 12 with perinephric liposarcoma were seen at our hospital. Two radiologists who were blinded to the pathological diagnosis retrospectively evaluated the CT characteristics of perinephric angiomyolipoma and perinephric liposarcoma. The relationship of each CT characteristic with tumor type was compared using Fisher's exact test. RESULTS: The CT characteristics of perinephric angiomyolipoma were intratumoral linear vascularity (p = 0.001), aneurysmal dilatation (p = 0.025), bridging vessel sign (p = 0.005), hematoma (p = 0.025), beak sign (p = 0.001) and discrete intrarenal fatty tumors (p = 0.025). The CT characteristic of perinephric liposarcoma was a nonfatty soft tissue mass (p = 0.005). There was no significant difference in the presence of calcifications in both groups. CONCLUSIONS: This retrospective study suggests that analysis of CT characteristics (linear vascularity, aneurysmal dilatation, bridging vessel sign, hematoma, beak sign and discrete intrarenal fatty tumors) may help to differentiate perinephric angiomyolipoma from perinephric liposarcoma.

Adult↗

A subgroup of malignant fibrous histiocytomas is associated with genetic changes similar to those of well-differentiated liposarcomas.

Increasing clinical and pathological evidence suggests that malignant fibrous histiocytomas (MFH) comprise a heterogeneous tumor group. In a series of 108 MFH tested by comparative genomic hybridization, we found in 22 tumors high-level coamplification of the 12q14 approximately q15 chromosome region with other loci, a genetics strongly reminiscent of what has been observed for well-differentiated liposarcomas. Nevertheless, these MFH differ from liposarcomas by a high recurrence of coamplified partners because coamplified loci were seen at 1p32 in nine cases, 6q23 in seven cases, and 12q24 in six cases. The same recurrence was observed in a series of dedifferentiated liposarcomas, but not in a series of well-differentiated liposarcomas. These observations demonstrate that a subgroup of MFH share a genetic partner very similar to that observed in liposarcomas, and suggest that the undifferentiated status of these tumors is closely related to the amplifications of specific chromosome loci.

Allelic Imbalance↗

[Multicentric liposarcoma. Apropos of a case].

INTRODUCTION: Though rare, observations of multiple liposarcomas show that the development of secondary tumors occur in sites usually considered as primary locations. This would be more frequent for myxoid liposarcomas than for other subtypes of the disease. Their origin, either multicentric (i.e., coexistence of several primary tumors) or due to metastatic spreading, is still debated. EXEGESIS: We report a case of myxoid-type multicentric (i.e., right popliteal fossa, retroperitoneum and soft tissue of the left arm) liposarcomas of different sizes, without pulmonary, hepatic or osseous involvement. These liposarcomas were simultaneously diagnosed in a patient who presented with pain in the right knee. CONCLUSION: This support the hypothesis that multiple liposarcomas have a multicentric origin. Initial and follow-up staging of such tumors must investigate not only usual metastatic sites but also classical primary locations.

Adult↗

Primary liposarcoma of the jejunum.

The rare case of a primary liposarcoma of the jejunum in a 52-year-old man is described. The main tumor mass was located within the submucosa and caused chronic subileus by subtotal obstruction of the jejunum. The histology showed a mixed type liposarcoma. In the main mass features of well differentiated lipoma-like and sclerosing liposarcoma predominated. In the tumor periphery they were combined with areas of pleomorphic liposarcoma, consisting of tightly packed giant lipoblasts. After an incomplete resection well differentiated sclerosing and pleomorphic liposarcoma recurred within the intestinal wall and in the mesentery near the primary anastomosis. The unusual primary site and pattern of spread of the tumor are discussed and the literature is reviewed.

Humans↗

Myxoid liposarcoma of the ankle.

Liposarcomas are among the most common soft tissue sarcomas, but are rarely found in the foot or ankle. Certain types of liposarcomas, which range from well-localized low-grade entities to highly aggressive neoplastic lesions, may resemble common benign soft tissue lesions. Myxoid liposarcoma is the most common type of liposarcoma and is important to recognize and differentiate from a benign soft tissue lesion because it may be a limb-threatening and/or life-threatening tumor. A thorough literature review and perplexing case study of myxoid liposarcoma of the ankle is presented.

Adult↗

A phase II trial with rosiglitazone in liposarcoma patients.

Agents of the thiazolidinedione drug family can terminally differentiate human liposarcoma cells in vitro by activating genes responsible for lipocyte differentiation. One study has shown clinical activity of troglitazone treatment in liposarcoma patients. We sought to find further evidence for this result. In all, 12 patients with a liposarcoma received rosiglitazone 4 mg b.d. They were followed clinically and with repeated biopsies for histological and biological studies. At the molecular level the mRNA translation of three genes that are induced by this treatment (peroxisome proliferator-activated receptor gamma (PPARgamma), adipsin and fatty acid binding protein) was determined. Nine patients were eligible for evaluation. One patient had to stop treatment due to hepatotoxicity. The mean time to progression was 6 months (2 - 16 months), with one patient still on treatment. We did not see any significant change in histologic appearance of the liposarcomas by the treatment. The level of gene expression changed significantly in two patients, but this did not result in a clinical response. Based on this study, rosiglitazone is not effective as an antitumoral drug in the treatment of liposarcomas. Increased PPARgamma activity does not correlate with the clinical evolution.

Adult↗

The chimeric FUS/TLS-CHOP fusion protein specifically induces liposarcomas in transgenic mice.

The characteristic t(12;16)(q13;p11) chromosomal translocation, which leads to gene fusion that encodes the FUS-CHOP chimeric protein, is associated with human liposarcomas. The altered expression of FUS-CHOP has been implicated in a characteristic subgroup of human liposarcomas. We have introduced the FUS-CHOP transgene into the mouse genome in which the expression of the transgene is successfully driven by the elongation factor 1alpha (EF1alpha) promoter to all tissues. The consequent overexpression of FUS-CHOP results in most of the symptoms of human liposarcomas, including the presence of lipoblasts with round nuclei, accumulation of intracellular lipid, induction of adipocyte-specific genes and a concordant block in the differentiation program. We have demonstrated that liposarcomas in the FUS-CHOP transgenic mice express high levels of the adipocyte regulatory protein PPARgamma, whereas it is not expressed in embryonic fibroblasts from these animals following induction to differentiation toward the adipocyte lineage, indicating that the in vitro system does not really reflect the in vivo situation and the developmental defect is downstream of PPARgamma expression. No tumors of other tissues were found in these transgenic mice despite widespread activity of the EF1alpha promoter. This establishes FUS-CHOP overexpression as a key determinant of human liposarcomas and provide the first in vivo evidence for a link between a fusion gene created by a chromosomal translocation and a solid tumor.

Animals↗

Histologically low-grade dedifferentiated liposarcoma of the retroperitoneum.

A low-grade dedifferentiated liposarcoma in the retroperitoneum of a 52-year-old woman is described. The excised specimens contained six nodules of lipoma-like well-differentiated liposarcoma and a nodule of dedifferentiated liposarcoma. The latter was composed predominantly of loosely arranged, benign-appearing spindle cells and fat cells. A small number of cells with irregularly shaped nuclei were scattered. There were no mitotic figures. The fat cells showed slight variation of size and shape, and a few multivacuolated lipoblasts were found. The spindle cell areas occupied approximately 60% of the tumor. The stroma was somewhat fibrous and myxoid and no dense collagenous matrix was found. The stroma vascularity was not prominent. Immunohistochemically, the spindle cells were positive for vimentin but negative for S-100 protein, desmin, muscle actin, and alpha-smooth muscle actin. Follow up for 5 months showed no evidence of recurrence or metastasis. The tumor, in which the benign-appearing spindle cell component was predominant, was considered to be a low-grade dedifferentiated liposarcoma. Close and long-term follow up is required. In retroperitoneal lipoma-like well-differentiated liposarcomas, spindle cell components like the present tumor, which represent dedifferentiation, should not be overlooked.

Female↗

[Midterm results after treatment of liposarcoma in the extremities].

PURPOSE: In this retrospective analysis, survival time, local recurrence and rate of metastasis were appraised in patients with primary liposarcoma of the extremities depending upon the applied primary and adjuvant therapy procedures. Furthermore, we compared the representativity of histological results of the biopsy with the final histology of the resected tumour. MATERIAL AND METHOD: Between 1990 and 1998, 27 patients were surgically treated who suffered from a primary liposarcoma of the extremities. At the mean follow-up time of 62.4 months (39-141 months) postoperative survival rate, rate of metastasis and local recurrence were determined. The results were analysed with regard to intraoperative resection distance, tumour size and localisation as well as histological classification of previous biopsy and finally resected tumour. The influence of radiotherapy on the results was also determined. RESULTS: In 5 patients (18.5%) the amputation and in 22 cases (81.5%) the limb sparing resection of the liposarcoma was performed. 6 patients underwent a marginal resection and one patient an intralesional resection. At follow-up we observed a local recurrence rate of 22.2% (n = 6) and a survival rate of 74.1%. 18.5% of the patients had metastases. After adjuvant radiotherapy three patients (50%) showed local recurrence after marginal resection. In only 8 cases (29.6%) the results of primary biopsy and final tumour classification (entity, subtype and grading) were identical. CONCLUSION: The development of metastases (often pulmonary) and local recurrences even after long tumour-free interval makes adequate follow-up investigations mandatory in liposarcoma patients. With regard to the problems in assessing liposarcoma biopsies, MRI-orientated biopsies from several tumour areas via one biopsy approach are recommended.

Adult↗

Terminal differentiation of human liposarcoma cells induced by ligands for peroxisome proliferator-activated receptor gamma and the retinoid X receptor.

Induction of terminal differentiation represents a promising therapeutic approach to certain human malignancies. The peroxisome proliferator-activated receptor gamma (PPAR gamma) and the retinoid X receptor alpha (RXR alpha) form a heterodimeric complex that functions as a central regulator of adipocyte differentiation. Natural and synthetic ligands for both receptors have been identified. We demonstrate here that PPAR gamma is expressed at high levels in each of the major histologic types of human liposarcoma. Moreover, primary human liposarcoma cells can be induced to undergo terminal differentiation by treatment with the PPAR gamma ligand pioglitazone, suggesting that the differentiation block in these cells can be overcome by maximal activation of the PPAR pathway. We further demonstrate that RXR-specific ligands are also potent adipogenic agents in cells expressing the PPAR gamma/RXR alpha heterodimer, and that simultaneous treatment of liposarcoma cells with both PPAR gamma- and RXR-specific ligands results in an additive stimulation of differentiation. Liposarcoma cell differentiation is characterized by accumulation of intracellular lipid, induction of adipocyte-specific genes, and withdrawal from the cell cycle. These results suggest that PPAR gamma ligands such as thiazolidinediones and RXR-specific retinoids may be useful therapeutic agents for the treatment of liposarcoma.

Adipocytes↗

Distinction between lipoma and liposarcoma by MDM2 alterations: a case report of simultaneously occurring tumors and review of the literature.

We investigated a lipoma and a well-differentiated/dedifferentiated liposarcoma (WD/DDL), occurring simultaneously in one patient for the possible role of p53 and mdm2 in the molecular oncogenesis of liposarcoma and tumor progression. The hypothesis tested was if there is a continuum in the development from lipoma to liposarcoma. Lipoma was characterized by a lack of p53 mutation, p53 LOH and p53 protein expression, as well as by mdm2 amplification and mdm2 protein expression. p53 mutation and p53 LOH were found neither in the well-differentiated nor in the dedifferentiated parts of the liposarcoma. In contrast, mdm2 amplification and an increase in mdm2 protein expression were found to be associated with malignancy and dedifferentiation, whereas p53 protein expression was only slightly increased. These findings indicate that mdm2 constitutes one of the most common targets for molecular aberration in WD/DDL. We suggest that mdm2 is a marker distinguishing between ordinary lipoma and well-differentiated liposarcoma, and that the genesis of these tumors is different.

Cell Division↗

Differential gene expression in liposarcoma, lipoma, and adipose tissue.

Malignant transformation is thought to be associated with changes in the expression of a number of genes, and this alteration in gene expression is felt to be critical to the development of the malignant phenotype. Sarcomas represent a diverse group of tumors derived from cells of mesenchymal origin. Marked heterogeneity exists in the biological behavior of sarcomas, even within histologic subtypes of sarcomas. In an effort to better understand the biology of liposarcomas, gene expression in normal adipose tissue, lipomas, and liposarcomas was examined using the Affymetrix microarray technology. Differences in gene expression were quantified as the fold change in gene expression among the sample sets. Differences in gene expression among normal adipose tissue, lipomas, and liposarcomas were observed. In addition, genes expressed uniquely in liposarcoma among these and 18 other tissue sample sets were identified. Gene sets were devised that allowed the separation of liposarcomas from other samples, and most normal adipose tissue from most lipomas using the Eisen clustering software "Cluster." We conclude that differences in gene expression can be identified among different tumors derived from the adipocyte series. Such differences in gene expression may help differentiate among subtypes of sarcomas, and may also yield clues to the pathophysiology of this heterogeneous group of tumors.

Adipose Tissue↗

Well-differentiated inflammatory liposarcoma: an uncommon and easily overlooked variant of a common sarcoma.

The presence of abundant inflammation is uncommon in well-differentiated liposarcomas (WDLPS). We describe ten cases of WDLPS in which an extensive lymphoplasmacytic infiltrate was present to such a degree that the differential diagnoses included inflammatory pseudotumor and Castleman's disease, and in which the lipogenic component could easily be overlooked. The median age (62 years) and tumor location (six retroperitoneal, three head/neck, one paratesticular) was comparable to usual WDLPS, as was the fact that six of ten cases recurred locally, but none metastasized during the period of follow-up (range 13 to 228 months, median 72 months). Key histologic features included (1) nodular lymphoplasmacytic aggregates; (2) intervening paucicellular stroma containing fibroblastic elements, frequently with plasma cell-rich zones and scattered atypical, often multinucleate cells; (3) merging of atypical adipocytic and inflammatory elements; and (4) adjacent clearly defined zones of lipoma-like or, more rarely, sclerosing-type liposarcoma. In recurrences, two cases "reverted" to purely lipoma-like liposarcoma, and two cases dedifferentiated. Immunoperoxidase studies demonstrated that B cells predominated in the lymphoid aggregates, and that the abundant plasma cells were polytypic in nature. We support the use of the term well-differentiated inflammatory liposarcoma for tumors of this type, which should be distinguished from high-grade liposarcoma containing inflammatory cells, and in order to identify a subgroup of WDLPS at high risk for misdiagnosis.

Adipocytes↗

MR imaging of liposarcomas: correlation of MR features and histology.

The magnetic resonance (MR) imaging features of liposarcoma were correlated with histology in 15 patients. The MR findings for liposarcoma were not specific. The six myxoid liposarcomas and two atypical lipomatous tumors, however, had distinctive MR features, i.e., nodular masses of slightly heterogeneous intermediate to high signal intensity (SI), intermingled with high SI septa on T1-weighted images. The T2-weighted images demonstrated the relative reversal of these regional SI characteristics. Additionally, MR correctly identified the presence of fat in all eight cases in which it was pathologically present. The fat in two atypical lipomatous tumors was inseparable on MR from the subcutaneous fat. Magnetic resonance appears useful for preoperative staging and follow-up studies of liposarcomas. It may be helpful in identifying patients with myxoid liposarcoma and atypical lipomatous tumors who have longer survival times.

Adult↗

Grading liposarcomas with PET using [18F]FDG.

Five patients with liposarcomas of the thigh were studied using positron emission tomography (PET) with [18F]2-deoxy-2-fluoroglucose (FDG). There were three low-grade tumors (all National Cancer Institute Grade 1 myxoid liposarcomas) and two high-grade tumors (both pleomorphic liposarcomas, Grades 2 and 3). The low-grade liposarcomas were easily identified with an average dose uptake ratio (DUR) of 1.38 +/- 0.045 (mean +/- SD). The high-grade lesions were more avid for FDG with a mean DUR of 2.45 +/- 0.24. There was a significant difference (p = 0.004) in the DUR for the two groups and the histological grade of malignancy was highly correlated with the DUR for FDG (Rho = 0.89). These findings suggest that FDG-PET may be useful for distinguishing between low-grade and high-grade liposarcomas.

Deoxyglucose↗

Liposarcoma in the epidural space.

STUDY DESIGN: A patient with myxoid liposarcoma in the lumbar epidural space is reported. OBJECTIVE: The subject was treated with marginal resection and posterior instrumentation. SUMMARY OF THE BACKGROUND DATA: Liposarcoma is a malignant tumor of the soft tissues. It is commonly seen in the thigh. Lumbar extradural space is an unusual localization. Two cases have been reported with this localization in the literature. METHODS: The authors have treated a female patient with myxoid liposarcoma in lumbar extradural space with marginal resection and posterior instrumentation. RESULTS: The histopathologic examination showed myxoid liposarcoma. Two cases have been reported in the literature. CONCLUSION: Myxoid liposarcoma is a malignant tumor of the soft tissues. The extradural tumor was probably originated from the epidural fat tissue. Although wide resection is advised in the thigh localization, extradural localization of the tumor can be treated with marginal resection if there is no invasion to the surrounding tissue.

Aged↗