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Septum-like structures in lipoma and liposarcoma: MR imaging and pathologic correlation.

OBJECTIVE: To investigate the septum-like structures in predominantly lipomatous tumors, by correlating fat-suppressed MR images with histopathologic findings. DESIGN AND PATIENTS: The MR findings of three cases of well-differentiated liposarcoma (atypical lipoma), one case of lipoma-like component of dedifferentiated liposarcoma, and nine cases of lipoma were analyzed. T1-, T2-, and fat-suppressed T1-weighted images after Gd-DTPA administration were obtained. Surgical specimens from five patients (four with liposarcoma and one with lipoma) were also scanned with a MR unit, and compared with the pathologic findings. RESULTS AND CONCLUSIONS: Enhancement features of lipoma and liposarcoma were well visualized on fat-suppressed T1-weighted images after Gd-DTPA administration. The septum-like structures of liposarcoma are thick and enhanced considerably, while septa of lipoma are thin and enhanced only slightly. Pathologically, the septum-like structures of liposarcoma contained muscle fibers and the septa of lipoma represented fibrous capsule. Identification of well-enhanced septa in a predominantly lipomatous tumor helps to differentiate malignant tumors from lipomas. As the septum-like structures of liposarcoma contain a skeletal muscle component the tumor might need more extensive surgical procedures including resection of adjacent muscles.

Aged↗

MDM2 amplification and loss of heterozygosity at Rb and p53 genes: no simultaneous alterations in the oncogenesis of liposarcomas.

PURPOSE: The present study aimed to investigate the status of alterations of the MDM2, Rb and p53 genes in a series of 45 liposarcomas. Furthermore, the possible correlation with histological and clinical parameters was studied. METHODS: MDM2 amplification was examined by non-radioactive Southern blot hybridization with a human MDM2 cDNA probe. Mutations in the p53 gene were screened by polymerase chain reaction/single-strand conformation polymorphism analysis and direct sequencing. To study loss of heterozygosity (LOH) at the tumor-suppressor genes Rb and p53, we used four polymorphic intragenic Rb markers (introns 1, 17, 20, and 25) and two p53 markers (intron 1 and exon 4). RESULTS: MDM2 amplification was found in 19 of 45 liposarcomas (42.2%). The frequency of LOH in Rb and p53 was nearly identical (22%). In 4 of 9 tumors (44.4%) with LOH, allelic loss was a concurrent event in both genes. Of 45 liposarcomas, 6 (13.3%) showed p53 mutations. Overall, alterations of the p53/MDM2/Rb pathway occurred in 30 of 45 liposarcomas (66.6%). In contrast to myxoid and pleomorphic variants, well-differentiated liposarcomas were characterized by a high frequency of MDM2 amplification, a lack of LOH of Rb and p53, and p53 mutations. CONCLUSIONS: Obviously MDM2 amplification and LOH at the Rh and p53 genes do not occur simultaneously in the oncogenesis of liposarcomas, as is the case for MDM2 amplification and p53 gene mutations (with one exception). We suggest that well-differentiated, myxoid and pleomorphic liposarcomas are characterized by a different pattern of molecular alterations.

Adult↗

Composition of fat in different types of liposarcomas in comparison with lipomas.

Different types of liposarcomas, and for comparison, lipomas were investigated for their lipid composition. Triglycerides were the main components of lipomas and lipoma-like liposarcomas. Myxoid liposarcomas had a high water content and contained considerable amounts of free cholesterol and phospholipids. One pleomorphic liposarcoma resembled a myxoid liposarcoma in its lipid composition and water content. In 4 liposarcomas of mixed type the lipid composition resembled the main subtype. A glycerol ether-like fraction was found in all lipoma-like (well differentiated) liposarcomas, in one myxoid type but not in the other types.

Chemical Fractionation↗

Differential sensitivity of liposarcoma subtypes to chemotherapy.

Liposarcoma is one of the most common soft tissue sarcomas and has a number of different subtypes: well-differentiated; dedifferentiated; myxoid/round cell; and pleomorphic. However, the response of these subgroups to chemotherapy is not well documented. In this study, we have conducted a retrospective analysis of a prospectively maintained database of soft tissue sarcoma patients treated at the Royal Marsden Hospital. Eighty-eight liposarcoma patients who received chemotherapy between August 1989 and June 2004 were identified. The response rates to chemotherapy of the different histological subtypes and overall and progression free survival were investigated. Survival according to histological grade was also assessed. A statistically significant higher response rate to first-line chemotherapy was observed in patients with myxoid liposarcoma compared to de- and well-differentiated tumours, 48% (95%CI; 28-69) and 11% (95%CI; 2-29), P = 0.005. Similarly, those with myxoid liposarcoma had a significantly higher response rate compared to all other liposarcoma patients, 48% (95%CI; 28-69) and 18% (95%CI; 8-31). Patients with lower grade tumours had better overall survival. This retrospective analysis suggests that myxoid liposarcoma is relatively chemosensitive in comparison to a combination of other liposarcomas, and in particular de- and well-differentiated tumours. Further confirmation of these results should be sought by similar analyses of other databases.

Adult↗

Magnetic resonance imaging of lipoma and liposarcoma: potential of short tau inversion recovery as a technique of fat suppression.

The present limited retrospective study was performed to assess MR imaging of lipomatous tumours of the musculoskeletal system and to evaluate the potential of the T2 short tau inversion-recovery (STIR) technique for differentiating lipomas from liposarcomas. Magnetic resonance imaging of 12 patients with lipomatous tumours of the musculoskeletal system (eight benign lipomas, three well-differentiated liposarcomas and one myxoid liposarcoma) were reviewed. Benign lipomas were usually superficial and showed homogeneity on T1- and T2-weighted spin echo sequences. Full suppression at T2 STIR was readily demonstrated. In contrast, the liposarcomas in the present series were all deep-seated. Two well-differentiated liposaromas showed homogeneity at long and short relaxation time (TR) but failed to show complete suppression at T2 STIR. One case of well-differentiated liposarcoma (dedifferentiated liposarcoma) and one of myxoid liposarcoma showed mild and moderate heterogeneity at T1 and T2, respectively, and posed no difficulty in being diagnosed correctly. In conclusion, short and long TR in combination with T2 STIR show promise in differentiating benign from malignant lipomatous tumours of the musculoskeletal system, when taken in combination with the position of the tumour.

Adolescent↗

Primary liposarcoma of the orbit: a clinicopathologic study of seven cases.

Liposarcoma, the most common soft tissue sarcoma in adults, will rarely involve the orbit, either primarily or as a metastasis. We describe seven primary orbital liposarcomas, representing the largest documented series of primary orbital liposarcoma to date. Affected patients were three males and four females ranging in age from 28 to 69 years (median, 51 years). Five patients presented with painless proptosis, one patient had painful proptosis, and no details of presenting symptoms are available in one case. The site distribution was retrobulbar (3 cases), lateral orbital wall (2 cases), medial wall (1 case), and unspecified (1 case). Radiologic impression included hemangioma, lipoma, and an inflammatory process. Lesional size ranged from 2.8 to 4 cm. Five liposarcomas were purely well-differentiated, one was dedifferentiated, and one was pleomorphic in type. The well-differentiated cases comprised the following subtypes: spindle cell (2 cases), adipocytic (2 cases), and combined adipocytic/sclerosing/inflammatory (1 case). Five patients underwent orbital exenteration (one followed by radiation) and two had marginal/partial excision of their tumors. Follow-up was available for five patients, ranging from 13 to 204 months (median 65 months). Four patients showed no evidence of recurrence, including the patient with pleomorphic liposarcoma who had a long, disease-free survival (65 months) following marginal excision. One patient has had multiple recurrences following initial partial excision. One patient died of an unrelated cause with no clinical evidence of recurrence. Despite the difficulty in obtaining wide surgical margins, the small tumor size at presentation and the apparent predominance of the well-differentiated type means that the prognosis for orbital liposarcoma is generally good. In view of the various morphologic patterns that may occur, liposarcoma should be considered in the differential diagnosis of any histologically unusual mesenchymal lesion in the orbit.

Adult↗

Dedifferentiated liposarcoma of the cheek.

Liposarcomas of the head and neck region are rare; only a few cases have been reported to arise in the cheek or buccal mucosa. Dedifferentiated liposarcoma has rarely been reported in the head and neck region and, to the best of our knowledge, this is the first reported case of dedifferentiated liposarcoma of the cheek. Dedifferentiated liposarcoma is a mixed histologic subtype defined by the association of an atypical lipomatous tumor or well-differentiated liposarcoma and a nonlipogenic sarcoma. The patient was a 61-year-old man who presented with a soft-tissue mass of the left cheek and a presumptive diagnosis of salivary neoplasm based on a fine needle aspiration. The tumor was excised and consisted histologically of an atypical lipomatous tumor/well-differentiated liposarcoma composed a well-differentiated lipomatous neoplasm with atypical cells and rare lipoblasts. The tumor recurred in the same location 5 months after surgery. The recurrent tumor was primarily composed of a nonlipogenic spindle sarcoma with focal rhabdomyoblastic differentiation associated with areas of an atypical lipomatous tumor/well-differentiated liposarcoma.

Biomarkers, Tumor↗

[Magnetic resonance tomography of liposarcoma].

PURPOSE: Liposarcoma is the most common soft tissue sarcoma in adults. The purpose of the study was to correlate MR imaging features with the four ICD subclasses. METHODS: 28 patients with liposarcoma were examined preoperatively on a 1.0 T MRI system, using spin echo sequences, gradient echo imaging and STIR sequences. In all patients, classification of the liposarcomas was made by histologic diagnosis (ICD-10-M-classification). RESULTS: Well differentiated liposarcomas (9 patients) showed a number of MRI features consistent with lipoma (well defined mass high signal intensity (SI) on T1 images, low signal on T2 images, no or only little signal increase of tumour tissue after contrast material application, no necrosis). Not well differentiated liposarcomas (myxoid 14 patients, pleomorphic three patients, round cell two patients) revealed the largest part of the mass to be of low SI on T1-weighted images. Only scattered fatty islands and septa (9 patients with myxoid liposarcoma had more SI in T1-weighted images. T2-weighted image showed most of the mass to be of intermediate to high SI are the fatty island of relatively low SI. The probability of tumor necrosis increased with lower tumour grading. CONCLUSION: MRI seems to be valuable to identify well differentiated liposarcomas.

Adult↗

Gene expression in mixed type liposarcoma.

AIMS: Mixed type liposarcomas are rare. Here, we analysed the characteristics of an unusual case of mixed type liposarcoma, which consisted of a well-differentiated liposarcoma (WDL) and a pleomorphic liposarcoma (PL), with a special emphasis on molecular alterations. METHODS: Microscopic and immunohistochemical approaches were used to investigate this case of mixed type liposarcoma, and to identify molecular alterations in this tumour, gene expression was examined in PL, WDL, and normal adipose tissue (NA) samples using a 17,000 cDNA microarray. RESULTS: The tumour mass, 9 x 5 x 5 cm, was located in the left upper arm of a 76-year-old man. Grossly, the proximal portion of the tumour was composed of a yellowish fatty lesion, whereas the distal portion of the tumour was whitish and necrotic in nature. Histologically, the tumour was composed of two distinct components. The proximal component of the tumour was a WDL and the distal component was a PL. Immunohistochemically, S100 protein immunoreactivity highlighted lipoblasts in both tumour portions. The Ki-67 proliferation index was <1% in the WDL and 20% in the PL. MDM2 was positive in the WDL, but negative in the PL. p53 was negative in both areas. Numerous differentially expressed genes were found, which included genes coding for signal transduction, transcription, cell cycle, enzyme, structural protein, immune system and others. CONCLUSIONS: Our data demonstrate that multiple genes are differentially expressed in mixed type liposarcoma and suggest that these genes are associated with the differences in the morphological characteristics and pathogenesis of mixed type liposarcoma.

Adipose Tissue↗

Heterologous elements in the dedifferentiated component of dedifferentiated liposarcoma.

Five cases of dedifferentiated liposarcoma in which heterologous elements were present in the dedifferentiated component are presented. Two patients, men 54 and 66 years of age, had retroperitoneal atypical lipomatous tumors (well-differentiated liposarcomas) that recurred (after 2.5 and 12 years, respectively) as dedifferentiated liposarcomas with rhabdomyosarcomatous elements in the dedifferentiated components. The third patient, a 63-year-old woman, had a retroperitoneal dedifferentiated liposarcoma whose dedifferentiated component demonstrated focal osteoid formation. The fourth patient, a 36-year-old woman, had two seemingly separate retroperitoneal masses, one composed of atypical lipomatous tumor with foci of smooth muscle and the other of leiomyosarcoma; despite the apparent separation, it was thought more logical to consider this a dedifferentiated liposarcoma with leiomyosarcoma as the dedifferentiated component than two unrelated neoplasms. The fifth patient, a 45-year-old man, had a mediastinal dedifferentiated liposarcoma with angiosarcomatous areas in the dedifferentiated component. The relatively short follow-up thus far available on these cases has not demonstrated tumor behavior significantly different from that of dedifferentiated liposarcoma as a whole.

Adult↗

Upper aerodigestive tract liposarcoma: report on four cases and literature review.

OBJECTIVE: To report on the clinical behavior, histopathology, treatment, and prognosis of laryngeal, hypopharyngeal, and cervical esophageal liposarcomas. STUDY DESIGN: Retrospective reviews of pathology files and hospital records at a tertiary care hospital and a retrospective search of the English-language literature. METHODS: Cases of upper aerodigestive tract (UADT) liposarcoma with adequate histopathologic documentation and clinical information were included for review. RESULTS: Four cases of UADT liposarcomas were identified. The literature review revealed 26 cases of laryngeal liposarcomas, 7 cases of hypopharyngeal liposarcomas, and 6 cases of esophageal liposarcomas: the mean age at presentation was 55.8 years, the male:female ratio was 5:1, and 60% of the patients presented with dysphagia. Eighty-six percent of tumors had low-grade histologic findings. The recurrence rate after primary resection was 50%. Recurrence correlated with surgical procedure rather than with histologic subtype; 94.7% of recurrences happened after simple excision. Distant metastases occurred in three patients; two of them died of the disease. CONCLUSIONS: The literature supports that UADT liposarcomas are rare and usually of low-grade histologic type. The rate of metastatic disease and tumor-related mortality is low. However, high recurrence rates have been noted, particularly when less radical surgery is employed.

Adult↗

Biochemical uncovering of mdm2/p53 complexes in liposarcomas parallels their immunohistochemical detection.

Recent observations indicate the existence of pathogenetically distinct groups of well-differentiated (WD) dedifferentiated (DD) liposarcomas. In the retroperitoneal WD-DD liposarcomas, the predominant phenotype is represented by the aberrant (overexpressed) mdm2+/p53+ wild-type profile. At the nonretroperitoneal site, the WD liposarcomas present a wider association of MDM2/P53 gene expression; i.e., mdm2+/p53+, mdm2+/p53-, mdm2-/p53+ and mdm2-/p53-, and TP53 mutations seem to correlate with the dedifferentiation process. A biochemical study of mdm2-p53 association in 11 tumor samples characterized by the presence of different mdm2 and p53 immunophenotypes was performed. Immunoprecipitation assays using a p53-specific antibody were performed on tumor tissue and surrounding normal tissue; the immunoprecipitated material was then investigated for the presence of p53 (control) and of coimmunoprecipitated mdm2. This biochemical analysis showed that, in mdm2+/p53+/wild-type retroperitoneal liposarcomas, a band corresponded to mdm2 protein in the cellular lysates immunoprecipitated with a p53-directed antibody. In contrast, the mdm2+/p53- liposarcoma did not evidence the presence of mdm2 protein nor was p53 protein available to direct immunoprecipitation, as in the p53 mutant tumor samples with mdm2-/p53+ and mdm2-/p53- phenotypes. From the normal counterpart of retroperitoneal liposarcoma lysates, no p53 protein was immunoprecipitated. The findings in this study agree with the molecular data and they show the physical association of mdm2 and p53 in fresh liposarcoma surgical specimens.

Gene Amplification↗

Gene expression profile identifies a rare epithelioid variant case of pleomorphic liposarcoma carrying FUS-CHOP transcript.

AIMS: To describe a tumour with morphological and immunophenotypic characteristics of epithelioid variant of pleomorphic liposarcoma. Pleomorphic liposarcoma is a very rare variant of liposarcoma defined morphologically by the presence of pleomorphic lipoblasts showing peculiar epithelial-like features that can be confused with primary or metastatic carcinoma. METHODS AND RESULTS: Molecular analysis demonstrated for the first time the presence of FUS-CHOP transcript in this liposarcoma variant. Microarray analysis revealed a gene expression profile related to a more aggressive tumour type when compared with other myxoid/round cell liposarcomas. CONCLUSIONS: The present data show that the epithelioid variant of pleomorphic liposarcoma represents a further variant of myxoid liposarcoma sharing the FUS-CHOP fusion transcript but carrying a distinct expression profile, in keeping with its aggressive clinical course.

Antigens, CD34↗

Myxoid liposarcoma: appearance at MR imaging with histologic correlation.

Although myxoid liposarcoma is a subtype of liposarcoma, it may be difficult to establish the correct diagnosis with magnetic resonance (MR) imaging due to the lack of fat signal intensity. Without the administration of gadolinium contrast material, the tumor may even mimic a cystic tumor. A spectrum of MR imaging abnormalities occur in myxoid liposarcoma, depending on the amount of fat and myxoid material, the degree of cellularity and vascularity, and the presence of necrosis. Most myxoid liposarcomas have lacy or linear, amorphous foci of fat. Some myxoid liposarcomas appear to be cystic at nonenhanced MR imaging, although they enhance like other solid masses at contrast material-enhanced MR imaging. The enhancing areas within the tumor represent increased cellularity and vascularity; the nonenhancing areas represent necrosis, reduced cellularity, and accumulated mucinous material. Gadolinium-enhanced imaging is important in differentiating myxoid liposarcoma from benign cystic tumors. Characterization of the tumor with MR imaging plays an important role in the management of myxoid liposarcoma.

Adipose Tissue↗

Dedifferentiated liposarcoma of the pyriform sinus: report of a case and review of the literature.

Laryngeal and hypopharyngeal liposarcomas are extraordinarily infrequent tumors. To the best of our knowledge there are fewer than 40 well-documented cases reported to date. Almost all of them are well-differentiated liposarcomas, with only 2 laryngeal-hypopharyngeal dedifferentiated liposarcomas. Dedifferentiated liposarcoma is defined as a well-differentiated liposarcoma with areas of high-grade spindle cell nonlipogenic sarcoma. The well-differentiated areas may be of a lipoma-like, sclerosing, or mixed type, and the dedifferentiated areas most frequently are of malignant fibrous hystiocytoma-like type. Despite its commonly pleomorphic histology, dedifferentiated liposarcoma does not behave as aggressively as most pleomorphic sarcomas of adulthood; however, it has the capacity to metastasize, in contrast to its well-differentiated counterpart. We present a case of dedifferentiated liposarcoma arising in the pyriform sinus, an event only twice reported previously in the literature.

Aged↗

Liposarcomas of the larynx and hypopharynx: a clinicopathologic study of eight new cases and a review of the literature.

Laryngeal and hypopharyngeal liposarcomas were studied in seven men and one woman. Patient age ranged from 25 to 81 years, with a median of 64 years. Symptoms included dysphagia, airway obstruction, and the sensation of a foreign body in the back of the throat. Histologically, seven of the tumors were of the biologically favorable types, either representing well-differentiated (lipoma-like) liposarcomas or myxoid liposarcomas. One tumor was a pleomorphic liposarcoma. Six of the eight patients had one or more episodes of recurrent tumor. Surgery is the treatment of choice and can include conservative (organ-sparing) procedures. However, to eradicate the tumor completely and thereby prevent recurrent disease, open surgical approaches (i.e., lateral pharyngotomy), rather than endoscopic techniques should be employed. The morbidity rate for laryngeal and hypopharyngeal liposarcomas is high because these tumors tend to recur over extended periods of time. In this study, however, there were no instances of metastatic disease, and no deaths were attributed to liposarcoma. Prospectively, laryngeal and hypopharyngeal well-differentiated (lipoma-like) liposarcoma is a difficult clinical and histopathologic diagnosis to establish. Often, this diagnosis is made only after one or more episodes of recurrent disease.

Adult↗

Liposarcoma in the nasal cavity of a cow.

Liposarcomas are rare neoplasms in domestic animals, but have been reported to occur in many species. In humans, liposarcoma is one of the most common malignant mesenchymal tumors. Classification of liposarcomas in humans has been well established and categorization by type can be of prognostic value; no such unique classification scheme has been established for liposarcomas in animals. Liposarcoma of the head and neck in humans are uncommon, and are rarely reported in the nasal cavity, sinuses, and nasopharynx. To our knowledge, a liposarcoma has never been reported in the nasal cavity of a domestic animal. In this report we describe a liposarcoma that developed in the nasal cavity of a cow, with local invasion into the oral cavity.

Animals↗

Dedifferentiated liposarcoma of the extremities: imaging findings in four patients.

OBJECTIVE: The term "dedifferentiated" liposarcoma is used to describe a distinctive lesion in which a well-differentiated liposarcoma is juxtaposed with a high-grade nonlipogenic sarcoma. Dedifferentiated liposarcoma is probably the most common of all the dedifferentiated sarcomas, occurring almost exclusively in the mediastinum, the retroperitoneum, and the inguinal/paratesticular regions. We report the imaging findings in four cases of dedifferentiated liposarcoma of the lower extremities. MATERIALS AND METHODS: The radiologic images and clinical histories of four patients with histologically verified dedifferentiated liposarcoma were retrospectively studied. The mean age of the patients was 61 years (range, 33-79 years). All lesions occurred in the thigh. Spin-echo MR images were available for review in two cases and CT scans in the two remaining cases. Plain radiographs were available in all cases. RESULTS: All lesions were large, with a mean maximum size of 24 cm (range, 12-30 cm), and had a significant fatty component radiologically. Both MR and CT showed a well-delineated fatty component of the lesions and a closely apposed nonfatty region. Radiographs showed well-defined bone within one lesion, bone and amorphous calcification in another, and a single punctate calcification in a third. Two patients had a history of excision of a lipomatous lesion in the region of the mass. One patient had pulmonary metastases. CONCLUSION: The potential for deep well-differentiated fatty tumors of the extremities to dedifferentiate is not generally recognized. Although the different types of liposarcoma cannot be reliably distinguished with imaging studies, a well-defined nonlipomatous mass juxtaposed with a predominantly fatty tumor is suggestive of a dedifferentiated liposarcoma.

Adult↗