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Dedifferentiated liposarcoma. Clinicopathologic analysis of 32 cases suggesting a better prognostic subgroup among pleomorphic sarcomas.

Dedifferentiated liposarcoma is uncommon, and only a small number of cases have been documented. We describe the clinicopathologic features in a series of 32 cases. All patients were adults (age range, 37-83 years; median, 67 years); 20 were men and 12 were women. Commonest site was the retroperitoneum (fifteen cases); six cases arose in the limbs, four in the paratesticular region, three in the peritoneal cavity, two on the trunk, and one each in the buttock and larynx. One primary tumor was subcutaneous. Thirty tumors arose de novo (i.e., combined with well-differentiated tumor in the primary lesion), while two developed in recurrences of a previously well-differentiated liposarcoma. The well-differentiated component was most often lipoma-like and typically there was a histologically abrupt transition to spindle celled nonlipogenic tumor. The dedifferentiated component most often resembled either storiform "malignant fibrous histiocytoma" ("MFH") with limited pleomorphism or myxofibrosarcoma (myxoid "MFH"); the latter pattern is rarely otherwise seen in the retroperitoneum. A small number of cases showed appearances reminiscent of myxoid embryonal rhabdomyosarcoma. An unusual feature in three cases was the occurrence of a discontinuous micronodular pattern of dedifferentiation. Average follow-up of 5.6 years (range, 3 months to 33 years) in 27 cases have revealed local recurrence in 14 patients and systemic metastases in only four patients. The primary sites of the metastasising cases were upper back, thigh, retroperitoneum, and paratesticular region. There have been only seven tumor-related deaths. Good prognosis in de novo dedifferentiated liposarcomas seems unrelated to the extent or morphologic pattern of dedifferentiation. However, high mitotic activity in the dedifferentiated component was associated with a more aggressive clinical course. Our study underlines that dedifferentiation in peripherally located or even subcutaneous liposarcomas does occur, albeit rarely, and that dedifferentiated liposarcomas of the limbs may metastasize. The results suggest that dedifferentiated liposarcomas, as a subgroup among the "MFH-like" sarcomas, have a better prognosis than pleomorphic sarcomas as a whole.

Adult↗

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

Forty-four samples from 25 cases of retroperitoneal sarcoma initially diagnosed as malignant fibrous histiocytoma were histologically reviewed. Immunohistochemistry for mdm2 and cdk4 was performed on 20 cases. Comparative genomic hybridization was performed on 18 samples from 13 patients. Seventeen cases were reclassified as dedifferentiated liposarcoma. Twenty-one of 32 samples from these patients showed areas of well-differentiated liposarcoma, allowing the diagnosis of dedifferentiated liposarcoma. Immunohistochemistry performed in 15 of these cases showed positivity for mdm2 and cdk4. Comparative genomic hybridization analysis performed on 15 samples from 11 of these patients showed an amplification of the 12q13-15 region. Eight cases were reclassified as poorly differentiated sarcoma. Twelve samples from these patients showed no area of well-differentiated liposarcoma. Immunohistochemistry showed positivity for mdm2 and cdk4 in one of six of these patients and showed positivity for CD34 in another one. Comparative genomic hybridization analysis performed on three samples from two of these patients showed no amplification of the 12q13-15 region but showed complex profiles. This study shows that most so-called malignant fibrous histiocytomas developed in the retroperitoneum are dedifferentiated liposarcoma and that a poorly differentiated sarcoma in this area should prompt extensive sampling to demonstrate a well-differentiated liposarcoma component, immunohistochemistry for mdm2 and cdk4, and if possible, a cytogenetic or a molecular biology analysis.

Adult↗

Unique cell membrane expression of topoisomerase-II alpha as a useful diagnostic marker of liposarcoma.

Topoisomerase-II alpha (Topo-II alpha) is known as a cell cycle-related intranuclear marker. To the best of our knowledge, the expression of Topo-II alpha on extranuclear sites has not been reported. The aim of the present study was to determine the usefulness of Topo-II alpha immunostaining for detecting the lipoblasts that are essential to diagnosing liposarcoma. Surgical specimens, including benign lipomatous tumors (four cases), well-differentiated liposarcomas (three cases), myxoid liposarcomas (six cases), pleomorphic liposarcomas (two cases), dedifferentiated liposarcomas (two cases), myxoid malignant fibrous histiocytomas (six cases), and one case of mesenteric panniculitis, were studied. Samples were immunostained using antibodies for Topo-II alpha, S-100 protein and Ki-67. In addition, we used the western blot method to investigate immunohistochemical-affinity in adipocytes. Mature adipocytes and lipoblasts in all of the benign and malignant lipomatous tumors intensively expressed cell contours positivity for Topo-II alpha. Cytoplasm of the lipoblasts occasionally reacted to the antibody and highlighted intracytoplasmic small unilocular, multivacuolated, or bubble-like patterns. Western blot analysis confirmed a 70 kDa product reactive to Topo-II alpha in the cell membrane fragment of mature adipocytes. S-100 protein expressed adipocytes and lipoblasts, but the detection of lipoblasts was not as easy as in Topo-II alpha immunostaining. Immunoreactivity of Ki-67 was limited to the nuclei, and the nuclear labeling index of Ki-67 correlated with that of Topo-II alpha. The immunoreactivity of Topo-II alpha for lipoblasts was more sensitive and obvious than those of S-100 protein. Immunostaining using the antibody for Topo-II alpha seems to be useful in recognizing lipoblasts that have been overlooked in hematoxylin-eosin-stained preparations, and is a useful marker for diagnosing liposarcoma.

Adipocytes↗

Liposarcoma metastatic to the orbit.

PURPOSE: To describe a patient with liposarcoma metastatic to the left orbit. METHODS: A 72-year-old man was admitted with diplopia and proptosis of the left eye. Previously, a retroperitoneal liposarcoma had been surgically removed followed by postoperative radiation. Visual acuity was normal. There was proptosis of the left eye, increased retrobulbar resistance and reduced mobility. Trans-septal orbital biopsies showed liposarcoma. The patient was initially treated with prednisolone and later received radio- and chemotherapy. Despite treatment he lost vision of the left eye and died a few months later. RESULTS: Histological examination of the orbital tumor revealed a spindle-cell liposarcoma similar to the primary tumor of the retroperitoneum. CONCLUSIONS: Liposarcoma metastatic to the orbit is rare, but should be suspected in a patient with proptosis caused by a space-occupying lesion and a history of liposarcoma.

Aged↗

Liposarcoma of the tongue: case report and review of the literature.

BACKGROUND: Liposarcoma most commonly arises in the retroperitoneum and lower extremities. Liposarcoma of the head and neck is rare, with only 12 previously reported cases of liposarcoma in the tongue. CASE PRESENTATION: We present a case of well-differentiated liposarcoma of the tongue occurring in a 39 year old man, treated with surgical excision. At 14 years of follow-up, the patient remains free of disease. CONCLUSION: Liposarcoma of the head and neck is rare, and may easily be misdiagnosed clinically. The diagnosis is made histologically. Clinical behavior is related to histopathologic subtype. Wide surgical excision is the treatment of choice, with limited data to support the use of radiation or chemotherapy. Our case represents the longest follow-up period for a tongue liposarcoma, with 14 years disease-free following surgical extirpation.

Adult↗

Expression of growth hormone receptor in human liposarcomas and lipomas.

Our immunohistochemical results clearly demonstrated the occurrence of growth hormone receptors (GH-R) in the tumour cells of lipomas and liposarcomas. In liposarcomas staining intensity in the cytoplasm of tumour cells varied between weak and distinct but could not be correlated to the histological grade of the malignant tumours. These findings were corroborated to some extent by the RT-PCR results. RT-PCR analysis of human lipomas and liposarcomas revealed the amplified cDNA fragment of GH-R in 8 out of 12 lipomas but only in 3 out of 10 liposarcomas. The reduced number of GH-R positive tumours found with PCR may be explained by the extraction method of RNA from paraffin sections. An interesting finding was the distinct immunoreactivity of the endothelium of blood vessels in liposarcomas, which was especially pronounced in the newly forming capillaries. This points to an important role of GH-R in tumour angiogenesis which could significantly contribute to tumour growth in liposarcomas and may open the possibility for therapeutic intervention using antiangiogenic substances.

Endothelium, Vascular↗

[Perinephric liposarcoma mimicking cystic renal tumor].

Liposarcoma is one of the most common primary retroperitoneal neoplasms, and the perinephric region is a frequent location for them. Liposarcomas show a variety of radiographic features in terms of histological types and tumor sizes, so the specific diagnosis of liposarcoma is often difficult. We present a unique case of perinephric dedifferentiated liposarcoma mimicking cystic renal tumor. A 71-year-old man presented himself at our hospital with a palpable mass in his upper right abdomen. Abdominal computerized tomography (CT) revealed a well-defined cystic mass at the lower pole of the right kidney that contained heterogeneous solid components and small foci of fat. There were no signs of lymphadenopathy or tumor thrombus in the renal vein. Metastatic evaluation by chest x-ray and bone scan was negative. The probable diagnosis was cystic renal cell carcinoma or atypical angiomyolipoma. Because we could not exclude the possibility of cystic malignancy, a right radical nephrectomy was performed. Grossly, the tumor was predominantly encapsulated by a unilocular fibrous capsule and was filled with bloody fluid and debris. The anterior portion of the tumor was composed of various-sized soft and rubbery masses covered with necrotic tissue. The histological diagnosis was dedifferentiated liposarcoma arising in the perinephric retroperitoneum with extensive necrosis, and the cyst wall was composed of a necrotic tumor with a well differentiated liposarcoma and a fibrous capsule. Although the tumor widely covered the right kidney, there was no microscopic invasion of the kidney. No signs of tumor recurrence were noted six months after the operation.

Aged↗

Monoclonality of multifocal myxoid liposarcoma: confirmation by analysis of TLS-CHOP or EWS-CHOP rearrangements.

Multifocal presentation, defined as the presence of tumor at two or more anatomically separate sites, before the manifestation of disease in sites where sarcomas usually metastasize (e.g., lungs) occurs in about 1% of extremity soft tissue sarcomas (STSs). Debate still persists whether multifocal STSs represent an unusual pattern of metastasis or multiple separate primary tumors. Among STSs with multifocal presentation, myxoid liposarcoma is the predominant histological type. This subtype of liposarcoma contains the specific t(12;16) chromosomal translocation, which results in rearrangement of the TLS and CHOP genes that is clone specific at the DNA level. We, therefore, sought to address the question of clonality by molecular analysis in six patients who presented with either synchronous or metachronous multifocal myxoid liposarcoma. In all six cases, adequate frozen tumor was available for DNA extraction from at least two distinct anatomical sites. Southern blot analysis using CHOP, TLS, and EWS cDNA probes was performed on genomic DNA. Five cases contained a TLS-CHOP rearrangement, and one case had the variant EWS-CHOP fusion (seen in <5% of cases). The size of the rearranged CHOP fragment differed among the six patients, as expected, but was identical in all anatomically separate tumor samples from each patient. Likewise, the sizes of the rearranged bands observed with either the TLS or EWS probes supported the monoclonality of all cases. Our results confirm the monoclonal origin of multifocal myxoid liposarcoma, establishing the metastatic nature of distant soft tissue lesions in these cases. It remains unclear whether this unusual pattern of metastasis represents an intrinsic property of this subset of myxoid liposarcoma or merely a rare chance occurrence. The clinical outcomes observed in this small series suggest that the prognosis of multifocal myxoid liposarcoma is poor, regardless of its often bland or "low-grade" histological appearance.

Adult↗

Neurological deficit from metastatic low grade liposarcoma.

Myxoid liposarcoma is a malignant soft tissue tumor with a relatively indolent natural history. It commonly occurs in the extremities with extrapulmonary metastatic potential. Round cell liposarcoma, recently, is widely agreed to be the aggressive counterpart of the myxoid liposarcoma, mostly arising in adverse, local recurrence, and metastatic lesions. Metastatic liposarcoma with pure myxoid element is unusual. The authors report an extremely rare case of a 47-year-old Thai male patient having a metastatic pure myxoid liposarcoma to the thoracic vertebrae, one year after primary tumor documented on the left thigh. Histology of the primary and metastatic sites shows only myxoid pattern. Round cell feature was not documented. To the best of the authors' knowledge, this is the second case report of metastatic myxoid liposarcoma without round cell morphology.

Humans↗

[Retroperitoneal mixed type liposarcoma: a case report].

Primary retroperitoneal tumors are reported to account for 0.2% of all malignancies. Furthermore, 10-20% of all primary retroperitoneal tumors are liposarcomas. Up to 1989, 213 cases of retroperitoneal liposarcoma have been reported in the Japanese literature to our knowledge. Mixed type liposarcomas were rare, and composed 13.8% of all retroperitoneal liposarcomas in this series. We described here a case of retroperitoneal mixed type liposarcoma. A 50-year-old man was admitted to our department with a mass in the left abdomen. Computed tomography and aortography revealed a huge and hypovascular tumor in the retroperitoneal cavity, not containing fat tissue. It was diagnosed as a retroperitoneal tumor and treated surgically. The tumor and the left kidney were encapsulated and could be removed en bloc. The size and weight of the tumor were 28 x 18 x 12 cm and 3,100 g, respectively. Histological examination of the mass proved it to be a mixed type liposarcoma. He was administered OK-432 as adjuvant therapy. After 11 months, bone metastasis to the vertebra appeared. Moreover, lung metastasis also occurred and he died of the disease 15 months after the operation.

Combined Modality Therapy↗

Myxoid liposarcoma with t(12;16) (q13;p11) contains site-specific differences in methylation patterns surrounding a zinc-finger gene mapped to the breakpoint region on chromosome 12.

The q13 to q15 region of human chromosome 12 is frequently and consistently rearranged in malignant and benign adipose tissue tumors as well as benign tumors of smooth muscle and salivary glands. A reciprocal translocation, (12;16) (q13;p11), is characteristic of the myxoid subtype of liposarcoma, whereas translocations within 12q13-14 are frequently observed in benign lipomas. We are using pulsed-field gel electrophoresis to study the 12q13-q14 region in order to detect and clone the respective translocation breakpoints in these tumors. The locus GLI, which encodes a zinc-finger protein, has been mapped to the same region as the myxoid liposarcoma breakpoint. Pulsed-field analysis of myxoid liposarcoma and lipoma DNA has allowed us to construct a 600-kilobase physical map surrounding the GLI locus, which shows that breakpoints in both types of tumor are outside this region. However, myxoid liposarcoma DNA samples contained altered restriction fragments detectable with GLI probes that were highly specific and reproducible from case to case. These altered fragments are due to highly specific and reproducible methylation differences that are unique to myxoid liposarcoma DNA. These methylation changes may prove to be useful clinically as a diagnostic tool to differentiate subtypes of liposarcoma.

Cell Line↗

[Myxoid liposarcoma. MRI imaging].

PURPOSE: Myxoid liposarcoma is the most common type of liposarcoma (approximately 40 to 50% of all liposarcomas). The main tissue component is a myxoid matrix present primarily in extracellular compartments; proliferating lipoblasts account for less 10% of the tumor: MRI appearances are not typical for lipomatous tumor. Nevertheless histological features may permit understanding MRI findings and identifying patients with myxoid liposarcoma. MATERIALS AND METHODS: Clinical history and radiologic images of 7 patients with histologically verified myxoid liposarcoma were retrospectively studied. In all patients the tumor presented in a lower extremity as a painless, slowly growing mass. MR images were available for review in all cases (T1- and T2-weighted images); in addition fat-suppression before and after gadolinium enhancement were assessed with T1-weighted sequences. RESULTS: MRI examination revealed an "encapsulated" tumor, non infiltrating and septated. On T1-weighted sequences all the lesions show lacy, amorphous and linear foci of high signal within a low signal of the tumor due to the predominance of a myxoid matrix. The high sensitivity of MRI demonstrates the presence of small areas of high signal and fat-suppression technique is valuable for characterizing soft-tissue tumors: suppression of high signal intensity on fat-saturated T1-weighted images indicates the presence of fatty tissue components. CONCLUSION: Clinical correlation with MRI appearances on T1-weighted sequences (in addition to fat-suppression technique) may suggest the possibility of myxoid liposarcoma.

Adult↗

Analysis of FUS-CHOP fusion transcripts in different types of soft tissue liposarcoma and their diagnostic implications.

In myxoid and round cell liposarcomas, a specific chromosomal translocation [(12;16)(q13;p11)] results in the expression of chimeric fusion transcripts encompassing parts of the FUS gene (16p11) at their 5' ends and the CHOP gene (12q13) at their 3' ends. Using a reverse transcription-PCR protocol, we determined the prevalence of FUS-CHOP fusion transcripts in a series of liposarcoma samples. Fusion transcripts were detected in 13 of 30 biopsy samples from soft tissue liposarcomas. Expression of fusion transcripts was not restricted to myxoid and round cell liposarcomas, as suggested previously; it was also detected in 1 of 3 well-differentiated and 4 of 14 pleomorphic liposarcomas. Sequence analysis revealed four different FUS-CHOP fusion transcript variants, two of which have not been described before. Furthermore, using FUS-CHOP fusion transcripts as targets in reverse transcription-PCR assays, we detected disseminated tumor cells in peripheral blood or bone marrow in 3 of 5 patients undergoing surgery for soft tissue liposarcoma.

CCAAT-Enhancer-Binding Proteins↗

Long-term follow up of pure myxoid liposarcomas with special reference to local recurrence and progression to round cell lesions.

Myxoid and round cell liposarcomas cytogenetically share the t(12;16)(q13;p11) translocation, and represent a continuous morphological spectrum including pure myxoid liposarcoma (PML), mixed (myxoid/round cell) liposarcoma (MXL) and pure round cell liposarcoma (RCL). It has been documented that a critical amount of RC lesion in low-grade, MXL is associated with poor prognosis. The present long-term follow-up study examined the factors that influence the progression of PML to RCL and several other prognostic factors and compared the results with those of liposarcomas initially diagnosed as MXL. Using 34 primary PML and their local recurrences after curative resection, and two initially diagnosed MXL, the appearance of RC lesion in PML was examined, and the prognostic significance of the local recurrence rate (times/month), tumor size, infiltrative proliferation (defined as entrapping of striated muscle fibers in the tumor), tumor necrosis and mitotic figures. The follow-up period ranged from 19 to 378 months (mean, 173.4 months). Based on Cox's proportional hazards regression model, a recurrence rate >/= 0.01 in 24 PML with recurrences (P = 0.037) and the presence of infiltrative proliferation in 34 PML (P = 0.043) were significant independent factors associated with poor prognosis. Round cell lesions were detected in the last recurrences of two surviving PML. These results indicate that through their recurrence, PML might potentially become malignant, independent of the proportion of RC lesions in the tumor. The appearance of RC lesions in subsequent recurrences may indicate a progression from PML to MXL.

Adult↗

The ultrastructure of liposarcomas with attention to "dedifferentiation".

Liposarcomas are among the most common soft tissue sarcomas. It is recognized that dedifferentiation can occur within a well-differentiated liposarcoma, but there is limited information concerning the ultrastructure of the dedifferentiated cells. A series of 8 cases has been studied by light and electron microscopy and compared with well-differentiated, myxoid, and pleomorphic liposarcomas. No definite evidence of lipoblastic differentiation could be found in the dedifferentiated cases. The tumor cells resembled atypical cells in the well-differentiated liposarcomas, supporting the close relationship between these two types of tumors. However, since no conclusive line of differentiation could be found in the dedifferentiated cases, this study supports the contention that these neoplasms are undifferentiated counterparts of well-differentiated liposarcomas.

Aged↗

[Pathological type of liposarcoma and its effects of clinical treatment].

To study the pathological type of liposarcoma and it effects of clinical treatment, reviewed 21 cases of liposarcoma. Since Oct. 1976 to Dec. 1995, 21 cases of liposarcoma were treated by operation. 15 cases were male and 6 cases female. The onset of the disease occurred between 6-79 years of age with an average of 49.9 years. 13 cases were well-differentiated, 4 Myxoid, 4 cases of andifferentiaed. All cases were followed up with an average of 8.9 years. The 5-, 10-year survival rate was 94%, the 5-, 10-year unrecurernce rate was 72% and 52%. Among the malignant soft tissue tumors liposarcoma, was most common. The survival rate was related to the pathological type, the site and the size. Good clinical results were well-differentiated and myxoid. The poor was retroperitoneal liposarcoma. The smaller the tumor, the better the result. For the treatment, wide margin excision is a good method of choice.

Adolescent↗

[Ultrastructural analysis of liposarcoma].

9 cases of liposarcoma, including 5 myxoid type, 3 pleomorphic type and 1 well differentiated type, were studied with light, electron microscopy and immunohistochemistry. Comparative observations revealed similarities between liposarcoma cells and cells of developing fat tissue. Liposarcoma cells resemble primary mesenchymal cells, fibroblasts, early, midstage and late lipoblasts or mature lipocytes. But certain differences also exist: First, atypia in liposarcoma cells, such as the appearance of mono- or multinuclei giant lipoblasts in some cases. Second, certain types of liposarcoma are predominated by lipoblasts of a specific stage. Under electron microscope, transitional morphology from both primary mesenchymal cell and fibroblast to lipoblast can be observed, which is an indication that lipoblasts may originate from these two types of cells. Differential diagnosis by electron microscopy is also discussed.

Adult↗

Incidental liposarcomas identified during hernia repair operations.

BACKGROUND AND OBJECTIVES: Since the inguinal region communicates with the retroperitoneum, both retroperitoneal as well as de novo spermatic cord liposarcomas may be detected during hernia repair operations. We assessed the incidence of liposarcomas presenting at hernia repair in our hospital. METHODS: We performed a clerical review of pathology reports on adult tissue accessioned during hernia repair operations and reviewed operating room logs to obtain information concerning the total number of hernia repair operations (since some operations afford no accessioned tissue). RESULTS: Between 1992 and 1997, 1,736 adult hernia repair specimens were accessioned from approximately 2,000 operations. Among these, 22% had an associated cord lipoma; 2 cases were well-differentiated liposarcomas. These were from males aged 56 and 64 years in contrast to the mean age of 35 years for cord lipoma and measured 13 and 10 cm, whereas the mean size for cord lipomas was 5.5 cm. One of the liposarcomas had radiographic evidence of extension from a retroperitoneal lesion; the other appeared confined to the groin. On surgical exploration, the lesion was restricted to the spermatic cord region in both cases despite the suggestion of retroperitoneal extension/involvement in one. CONCLUSIONS: Incidental liposarcomas identified during hernia operations are rare (<0.1% at our institution) but their presence merits histologic evaluation of adipose tissue from these cases. However, if efforts to contain costs are implemented and histologic review of such tissue is deemed generally unrewarding, large (>10 cm) fatty masses from this area should still be sampled.

Adult↗