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PubMed1995

Lipomatous tumours of soft tissues: an update.

This review summarizes the clinicopathological features of recently characterized variants of lipomatous tumours of soft tissue, attempts to deal with some difficult conceptual issues relating to adipocytic neoplasms and aims to provide an update on cytogenetic aspects of fatty tumours. Myolipoma is a rare benign neoplasm, occurring most frequently in adults in the deep soft tissue of the abdomen or retroperitoneum, and is composed of irregularly admixed mature adipose and smooth muscle tissues. Chondroid lipoma represents an unusual benign lesion occurring mainly in adult females subcutaneously or in deep soft tissue; it is easily mistaken for myxoid liposarcoma or extraskeletal myxoid chondrosarcoma. Spindle-cell liposarcoma is a variant of well-differentiated liposarcoma quite commonly found in subcutaneous tissue of the shoulder region and upper limbs and is composed of relatively bland-appearing spindle cells mixed with a well-differentiated liposarcomatous component. Recently there has been considerable debate about classification of lipomatous tumours. The term atypical lipoma was proposed for a group of well-differentiated non-metastasizing liposarcomas arising in surgically amenable soft tissues and for deep-seated atypical adipocytic neoplasms that show variation in adipocytic size and atypical stromal cells but lack lipoblasts. However, these neoplasms recur repeatedly and may dedifferentiate and thereby acquire metastatic potential. We use the diagnosis atypical lipoma with caution and propose to use the terms well-differentiated liposarcoma and atypical lipoma interchangeably. The relationship between myxoid and round-cell liposarcoma, which constitutes the morphological spectrum of a single entity, has been clarified but there remain considerable problems in defining likely clinical behaviour. The recent advances in cytogenetic characterization and classification of lipomatous tumours, which is already proving to be of diagnostic importance, are reviewed, and the genetic importance of the distinct chromosomal translocation in myxoid/round cell liposarcoma is briefly discussed.

Adult↗
PubMed2001

Relationship between tumor suppressor gene p53 and tumors of adipose tissue.

OBJECTIVE: To investigate the relationship between p53 gene and tumors of adipose tissue at the level of protein and gene. METHODS: Immunohistochemical LSAB, PCR-SSCP and DNA sequencing were used in 82 cases. RESULTS: p53 protein is expressed only in liposarcomas, in which the positive staining rate was 48.08% (25/52). In different subtypes of liposarcomas, the positive staining rate in well differentiated liposarcomas was 30.00% (9/30), which is much lower than that of the poorly differentiated liposarcomas (P < 0.005). Abnormality in the single-stranded DNA pattern was determined in 2 samples (pleomophic liposarcomas) by PCR-SSCP analysis. Missense mutations in exon 8 codon 268 of p53 gene (AAC-->ATC) were detected by DNA sequencing. Another heterozygotic cosense mutation may exist at exon 6 codon 221 of p53 gene (GAG-->GAA). CONCLUSIONS: The data suggest that the p53 protein has a relationship with development, differentiation and malignancy of liposarcoma. Detecting the level of p53 protein expression may be valuable in evaluating the level of differentiation and malignancy of liposarcoma. There appear point mutation on exon 8, 6 of p53 gene.

Genes, p53↗
PubMed1997

Interphase cytogenetic analysis of myxoid soft tissue tumors by fluorescence in situ hybridization and DNA flow cytometry using paraffin-embedded tissue.

BACKGROUND: Myxoid liposarcoma is one of the major myxoid malignancies of soft tissue and its histologic differentiation from other myxoid tumors is sometimes difficult. Recent cytogenetic analysis revealed that a characteristic reciprocal chromosomal translocation of t(12;16)(q13;p11) occurs in myxoid liposarcomas. In this study, retrospective cytogenetic analysis by means of fluorescence in situ hybridization (FISH) and DNA flow cytometry were performed on free nuclei isolated from paraffin embedded myxoid liposarcoma cells, and they were compared with myxoid malignant fibrous histiocytomas (MFHs), low grade fibromyxoid sarcomas, and intramuscular myxomas. METHODS: Nine myxoid liposarcomas, five myxoid MFHs, two low grade fibromyxoid sarcomas, and four intramuscular myxomas were examined. Chromosomal aberrations in chromosomes 12 and 16 were investigated by FISH, using both centromeric DNA probes and whole chromosome painting probes. Cellular DNA contents were determined by flow cytometry. RESULTS: All nine myxoid liposarcomas were shown to be diploid by DNA flow cytometry and exhibited the translocation t(12; 16), as shown by FISH. Four of the five myxoid MFHs exhibited aneuploidy, as shown by flow cytometry, and remarkable numeric aberrations of chromosomes 12 and 16. No abnormal DNA content or chromosomal aberrations were identified in the two low grade fibromyxoid sarcomas or the four intramuscular myxomas. CONCLUSIONS: FISH analysis performed on paraffin embedded materials can be used to differentiate myxoid liposarcomas from other myxoid soft tissue tumors.

Adult↗
PubMed1981

Lipomatous tumors of the abdominal cavity: CT appearance and pathologic correlation.

Twenty patients with pathologically confirmed extraparenchymal intraabdominal lipomatous tumors, including two lipomas, two cases of diffuse infiltrating lipomatosis, and 16 liposarcomas, were examined by computed tomography (CT). The CT appearance of these tumors closely correlated with their gross and microscopic pathologic anatomy. Distinctive CT features differentiated simple lipomas from diffuse infiltrating lipomatosis and from liposarcomas. The densities of these tumors, including the variable densities of liposarcomas, were explained by their tissue composition. Lipomas, diffuse infiltrating lipomatosis, and lipogenic liposarcomas were predominantly of fat density, whereas myxoid liposarcomas were of a higher range of densities. Liposarcomas often contained more than one type of tumor tissue, resulting in masses of distinctly different densities coexisting within the same tumor. CT accurately depicted the presence, location, and size of the tumors and provided information about their relation to adjacent structures.

Abdominal Neoplasms↗
PubMed2001

[Subfascial lipomatous tumors: management in a series of 37 consecutive cases].

PURPOSE OF THE STUDY: The prognosis of subfascial lipomatous soft tissue tumors depends greatly on their histological type ranging from benign lipomas that cause little local or general problems to the severe prognosis of liposarcomas that exhibit both local and distant extension. However, the clinical presentation of the two types of tumors may be similar and thus quite misleading, sometimes leading to inappropriate management and severe consequences. The main objective of this study was to determine whether the preoperative work-up in patients treated for musculoskeletal tumors within our recruitment zone is adequate, allowing appropriate therapeutic decisions. In addition, we wanted to know what explorations are most pertinent for the differential diagnosis between benign and malignant subfascial lipomatous soft tissue tumors. MATERIAL AND METHODS: Thirty-seven patients with subfascial tumors were included in this study. There were 16 with benign lipomas and 21 with liposarcomas. All the patients with benign lipomas but only 9 (43%) of those with liposarcoma had received initial care within our recruitment zone before final diagnosis. Two cases had been referred after biopsy and 1 after resection by morcellation; the 9 others were secondary referrals after tumor recurrence. Only 5 of these 12 referred patients had had an MRI exploration prior to surgery, 2 with an erroneous interpretation. An MRI series was obtained for all the patients with benign lipoma and for the 9 with liposarcomas who attended our units directly. A biopsy was also obtained in case of suspected liposarcoma. Two radiologists blinded to the final diagnosis reviewed the available MRI to assess their diagnostic value for subfascial lipomatous soft tissue tumors. RESULTS: No case of recurrence, after marginal resection (10 cases) was noted for lipomas. Six are under observation with regular MRI (with no change in size or signal). Four patients with liposarcoma died from their disease (19%) and 2 who had undergone "curative" resection had a recurrence (12%). Incorrect or imprecise (incomplete, incorrectly interpreted or no MRI) preoperative diagnosis led to additional morbidity with 3.4 surgical procedures (mean per patient) compared with 1 in patients who had had undergone a complete work-up and whose diagnosis was established after multidisciplinary discussions. Among the diagnostic elements available before pathology, only MRI findings had diagnostic value for subfascial lipomatous soft tissue tumors: for benign lipoma positive predictive value=92% and negative predictive value=93%. DISCUSSION: The clinical course of the benign lipomas and the sarcomas in this series confirm the radically different prognosis of these two tumors, both in terms of local extension and survival. Inadequate management in the initial diagnostic stages-i.e. lack of MRI with contrast injection, biopsy and multidisciplinary interpretation prior to treatment-raises the risk of higher morbidity, particularly a significantly greater number of reoperations, and progression to a higher grade of malignancy for two tumors. Our retrospective analysis enabled us to develop a decision making tree for patients with subfascial lipomatous tumors. Prospective validation will be necessary.

Decision Trees↗
PubMed2004

[Lipoma, lipoma-like, atypical lipoma: case report].

Lipoma, generally considered as a benign neoplasia, may occur as liposarcoma lipoma-like or atipycal lipoma, especially when of huge dimension. Pathological features of lipoma and liposarcoma lipoma-like are similar: the pattern is characterized by fatty lobules, with fibrosus septa. The presence of vartiable amount of atipical cell with hyperchromatic, solitary or multiple nuclei is suggestive of liposarcoma lipoma-like or atypical lipoma. The clinical features of these lesions are high rate of local recurrence and a low risk to metastasize. Preoperative work up, ultrasounds and MR have a poor diagnostic value, and no imaging features are so specific to differentiate between lipoma and liposarcoma lipoma-like, except site and size. The surgical treatment of the liposarcoma lipoma-like and atypical lipoma and the postoperative therapy, when required, should be performed in specialized centers. Only the combined approach, surgery and radiotherapy, can result in prevention of local recurrence and malignant transformation. The Authors report two cases of liposarcoma lipoma-like admitted to their Institution and review the Literature.

Adult↗
PubMed1994

Atypical and malignant lipomatous lesions of the head and neck.

Although liposarcoma is the second most common soft-tissue sarcoma in adults, the incidence of liposarcoma of the head and neck is low. There are only 83 reported cases of head and neck liposarcoma. We report four cases of atypical and malignant lipomatous lesions of the head and neck and discuss their histologic classification and treatment implications. The histologic nature of liposarcoma is correlated clinically with treatment outcome. Recently, many authors have adopted the term atypical lipoma to describe well-differentiated lipomatous lesions in superficial extremity locations because of their tendency toward local recurrence only, without metastases or patient mortality. Although we accept the classification atypical lipoma for superficial, well-differentiated lesions, we believe that histologically similar lesions in nonsuperficial locations in the head and neck are best designated "well-differentiated liposarcoma."

Adult↗
PubMed2002

Biochemical correlates of thiazolidinedione-induced adipocyte differentiation by high-resolution magic angle spinning NMR spectroscopy.

Thiazolidinediones, a class of synthetic ligands to the peroxisome proliferator-activated receptor-gamma, induce terminal adipocyte differentiation of 3T3 F442A cells, and have already been used as alternative therapeutic agents for the treatment of liposarcoma in clinical trials. The biochemical changes occurring in the 3T3 F442A cell line and well-differentiated liposarcoma following induction of adipocyte differentiation with the thiazolidinedione troglitazone were measured using high-resolution magic angle spinning (MAS) nuclear magnetic resonance (NMR) spectroscopy. 3T3 F442A cell differentiation was characterized by a large accumulation of intracellular triglyceride and withdrawal from the cell cycle. Phosphatidylcholine (PTC), phosphocholine (PC), myo-inositol, and glycerol were found to be possible biochemical markers for adipocyte differentiation induced by thiazolidenediones. The molar ratio of PTC to PC increased fourfold in differentiated 3T3 F442A cells compared to undifferentiated cells, suggesting a substantial increase in CTP:phosphocholine cytidylyltransferase activity with differentiation. A 2.8-fold increase in the PTC:PC ratio was observed in the lipoma-like well-differentiated liposarcoma of three patients who were treated with troglitazone when compared to liposarcoma from patients not treated with this drug. Thus, this ratio may be an NMR-detectable marker of troglitazone efficacy and response to differentiation therapy for liposarcoma.

3T3 Cells↗
PubMed1997

Lipoleiomyosarcoma of the mediastinum.

A case is described of a mediastinal soft tissue sarcoma, in a 76-year-old man, characterized microscopically by the intimate combined features of liposarcoma and leiomyosarcoma. The lipomatous component consisted of well differentiated liposarcoma with myxoid areas. The smooth muscle component was characterized by fascicles of spindle cells showing nuclear atypia and scattered mitoses. The spindle cells displayed intense reactivity for alpha smooth muscle actin (ASMA), desmin and vimentin. Differential diagnoses included dedifferentiated liposarcoma, spindle cell liposarcoma, angiomyolipoma and myolipoma. To the best of our knowledge no case of sarcoma in the mediastinum with combined features of liposarcoma and leiomyosarcoma has been reported. The dual lineage differentiation of the lipoleiomyosarcoma may be difficult to identify in small biopsy samples which may not represent the tumor as a whole. Lipoleiomyosarcoma should be included in the differential diagnosis of soft tissue tumors arising in the mediastinum.

Actins↗
PubMed2004

Accuracy of cytology for diagnosis of lipomatous tumors: comparison with magnetic resonance and computed tomography findings in 175 cases.

PURPOSE: To assess the value of fine-needle aspiration cytology in the diagnostic work-up of lipomatous tumors of the extremities and trunk, and to identify specific radiological features that could aid in the preoperative evaluation. MATERIAL AND METHODS: 175 patients with subfascial lipomatous tumors who had undergone preoperative magnetic resonance imaging or computed tomography and fine-needle aspiration cytology were studied. The percentage of fat within the lesion was visually graded from the images as: none, 1-75%, 75-95%, or 95-100%. The histological and cytological diagnoses were compared and in discordant cases the radiological images were re-reviewed. RESULTS: There was cytological and histological concordance in 96% of lipomas and in 85% of atypical lipomatous tumors (ALT) and liposarcomas. Most discordant cases exhibited 1-75% fat. Radiological review suggested that cytological sampling problems due to tumor heterogeneity were the main cause of diagnostic difficulties. The majority of tumors with less than 75% fat were liposarcomas, and in no liposarcoma was the fat content higher than 75%. Both ALT and lipoma were found in the 95-100% group. CONCLUSION: Cytology can be highly accurate in the diagnosis of lipomatous tumors, including ALT; however, critical comparison with the radiological findings increases diagnostic security. In tumors with fat content visually assessed as less than 75% of the tumor volume, liposarcoma is the most likely diagnosis and a cytological diagnosis of ALT or lipoma should be questioned. In lesions with 75-95% fat, liposarcoma is unlikely, but FNAC is still indicated for safety. In lesions with 95-100% fat, FNAC is only indicated if the differentiation between lipoma and ALT influences the treatment strategy.

Adolescent↗
PubMed1986

Surgical treatment of 43 retroperitoneal sarcomas.

Forty-three cases of primary retroperitoneal sarcomas, observed and treated from 1970 to 1983 at this Institute, were analysed. The series consisted of 16 liposarcomas (37%), 10 leiomyosarcomas (23%), 7 rhabdomyosarcomas (16%), 5 fibrosarcomas (12%), 2 malignant histiocytomas (5%), 2 sarcomas NOS (5%) and 1 mesenchymoma (2%). All the patients underwent surgery. In order to evaluate the results of surgery, the patients were divided into three groups, according to the type of operation performed, that is open biopsy, resection and excision. Survival of the patients in the first group never exceeded 24 months. The symptom-free period for the patients treated by incomplete removal of the tumour (second group) lasted 3-24 months. Further surgery, in three cases for this group, did not result in a useful control of the disease. As regards radically treated cases, local recurrence was observed in 3 of the 7 liposarcomas, 2 of the 5 leiomyosarcomas, 1 of the 2 rhabdomyosarcomas and 1 fibrosarcoma. Out of 16 cases of the third group, regularly followed up, only 3 patients (liposarcomas) were alive and free of disease at 5 years from first operation. Overall 5-year survival for this group was 31.9%; disease-free survival was 18.7%. For the whole series of 43 cases, overall 5-year survival was 11.4%. As far as histology was concerned, liposarcomas showed the highest operability rate: out of 16, 7 were resected and 9 radically excised. There is a lack of convincing evidence for the utility of post-operative chemotherapy. On the contrary, post-operative radiotherapy seems to be worthwhile for liposarcomas, especially after non-radical operations.

Adult↗
PubMed1996

Distribution of basement membrane components in normal adipose tissue and in benign and malignant tumors of lipomatous origin.

Normal adipose tissue as well as 13 benign and 17 malignant lipomatous tumors (lipomas, hibernomas, lipoblastomas, and liposarcomas) were immunohistochemically analyzed for their expression of the basement membrane components collagen IV, laminin, heparan sulfate proteoglycan, and fibronectin. Monovacuolar cells in normal white fat tissue and in lipomas generally exhibited a distinctive pericellular basement membrane composed of collagen IV and laminin, whereas heparan sulfate proteoglycan and fibronectin were almost completely missing. In brown fat tissue and hibernomas the characteristic multivacuolated cells differed from the monovacuolated white fat cells by the additional content of heparan sulfate proteoglycan and fibronectin and the more intensive staining for the other components tested. In contrast, multi-/monovacuolated cells in lipoblastomas exhibited no characteristic immunohistochemical feature because they reacted irregularly and only faintly for collagen IV, laminin, and heparan sulfate proteoglycan. Spindle cell areas in benign lipomatous tumors displayed more fibronectin than laminin and heparan sulfate proteoglycan indicating a "preadipose" fibroblast-like cellular differentiation. In liposarcomas, only well-differentiated lipoma-like neoplasms revealed a basement membrane pattern resembling that of white fat tissue. Otherwise, in nonlipoma-like liposarcomas, a marked decrease particularly of collagen IV staining was evident. Poorly differentiated liposarcomas mostly failed to express any of the basement membrane components, but showed a relative increase of fibronectin. Our results provide evidence that the staining pattern of basement membrane components parallels the histogenetic derivation of benign lipomatous tumors from either brown or white adipose tissue and, additionally, may reflect such a derivation in liposarcomas.

Adipose Tissue↗
PubMed2002

Atypical lipomatous tumor in a 14-year-old patient: distinction from lipoblastoma using FISH analysis.

Liposarcomas are rare in young age. We present the rare case of an atypical lipomatous tumor (synonym: well-differentiated lipoma-like liposarcoma) in a 14-year-old girl with the differential diagnosis of lipoblastoma which was excluded by fluorescence in situ hybridization (FISH) analysis. The tumor presented as a soft tissue mass at the dorsal part of the right thigh measuring up to 18 cm. Microscopically the lesion consisted of atypical adipocytes with hyperchromatic nuclei and additional multivacuolated lipoblasts. Interphase dual-color FISH performed with chromosome 8 centromeric and YAC164H5 (mapping to exons 2-5 of the PLAG1 gene) probes revealed no rearrangement of PLAG1 oncogene or polysomy of chromosome 8. Additional FISH using an MDM2 gene probe and an BAC534N15 probe (containing sequences specific for the CDK4 gene) showed amplification of the CDK4 gene. These findings indicate that this tumor was no lipoblastoma but an atypical lipomatous tumor, which is of clinical relevance. In young individuals the distinction between lipoblastoma and liposarcoma is often impossible by light microscopy alone. This case shows that FISH can serve as a decisive tool in the differential diagnosis of lipoblastoma and lipoma-like liposarcoma apart from its role in distinction between lipoblastoma and myxoid/round cell liposarcoma.

Adolescent↗
PubMed2002

Reassessment and clinicopathological prognostic factors of malignant fibrous histiocytoma of soft parts.

Recently, the category of malignant fibrous histiocytoma (MFH) has been under discussion and new entities resembling MFH have appeared. To clarify the recent situation regarding MFH, we reassessed previously diagnosed MFH cases in accordance with the most up-to-date diagnostic criteria, which included allied tumors. We carefully reassessed 428 cases that had been diagnosed in our institute during the past 28 years. Moreover, we searched for clinicopathological prognostic factors among the cases that were finally diagnosed as MFH. Among the 428 cases, 138 cases had their diagnoses changed. The revised cases included 78 leiomyosarcomas (57%; ordinary leiomyosarcoma, 45 cases; pleomorphic leiomyosarcoma, 23 cases; myxoid leiomyosarcoma, 10 cases), 12 liposarcomas (9%; pleomorphic liposarcoma, 11 cases; dedifferentiated liposarcoma, one case), seven dermatofibrosarcoma protuberans (5%), six unclassified sarcomas (4%), five primary or metastatic carcinomas (4%), four low-grade fibromyxoid sarcomas (3%), four inflammatory myofibroblastic tumors (3%), three rhabdomyosarcomas (2%), three malignant peripheral nerve sheath tumors (2%), three acral myxoinflammatory fibroblastic sarcomas (2%) and two atypical fibroxanthomas (1.5%). Among the 1974 soft tissue sarcomas registered in our institute, MFH (428 cases) had been the most common sarcoma, followed by liposarcoma, leiomyosarcoma and rhabdomyosarcoma. However, after reassessment, leiomyosarcoma proved to be the most common soft tissue sarcoma (322 cases), followed by 290 MFH, 273 liposarcomas and 202 rhabdomyosarcomas. Among these 290 cases finally diagnosed as MFH, survival data were available in 189 cases. Tumor location in the abdominal cavity, the retroperitoneum or the head and neck (P = 0.0024), tumor size of 5 cm or more (P < 0.0001), deep tumor location (P < 0.0001), high histological grade (grade 3) based on the French Federation of Cancer Centers' grading system (P = 0.0007), and high stage (stage III or IV) based on the American Joint Committee on Cancer (AJCC) staging system (P < 0.0001) were significantly worse prognostic factors by univariate analysis. In multivariate analysis, deep tumor location and high AJCC stage were independent adverse prognostic factors. We conclude that leiomyosarcoma is the most important differential diagnosis for MFH, especially pleomorphic leiomyosarcoma from storiform-pleomorphic type and myxoid leiomyosarcoma from myxoid type. Tumor depth and AJCC stage are the most important predictive prognostic factors in MFH.

Data Interpretation, Statistical↗
PubMed2000

The value of fine-needle aspiration biopsy in the differential diagnosis of adult myxoid sarcoma.

BACKGROUND: The usefulness of fine-needle aspiration biopsy (FNAB) for the histologic subtyping of specific sarcomas still is somewhat controversial but is becoming increasingly popular in the U.S. METHODS: To determine the accuracy and usefulness of FNAB in the differential diagnosis of myxoid sarcoma, the authors retrospectively reviewed 18 FNAB specimens (16 primary tumors, 1 local recurrence, and 1 metastasis) in 18 patients. The study sample included myxoid/round cell liposarcoma in six patients, myxofibrosarcoma in six patients, myxoid chondrosarcoma in five patients, and myxoid leiomyosarcoma in one patient. RESULTS: All but one tumor were recognized correctly as malignant. With regard to primary tumors, a specific cytologic diagnosis was rendered in 13 of 16 patients (81%). Problematic areas included the diagnosis of high grade myxofibrosarcoma with minimal amounts of myxoid stroma, myxoid liposarcoma with a predominant round cell component, and the single case of myxoid leiomyosarcoma. CONCLUSIONS: FNAB represents a valuable diagnostic tool for the differential diagnosis of myxoid sarcoma, especially myxofibrosarcoma, low grade myxoid liposarcoma, and myxoid chondrosarcoma. Due to its prognostic and therapeutic significance, the presence of a predominant round cell component in myxoid liposarcoma should be documented adequately. Other sarcomas (e.g., leiomyosarcoma) rarely may exhibit a prominent myxoid stroma and therefore should be considered in the differential diagnosis of adult myxoid sarcoma.

Adult↗
PubMed1988

Imaging of atypical lipomas of the extremities: report of three cases.

Atypical lipomas are soft tissue neoplasms which differ from simple lipomas in that they consist of mature fat cells interspersed with occasional areas containing a variable admixture of multinucleated cells, collagen bundles, and adipocytes with large, hyperchromic nuclei. Although these histopathologic features resemble those of liposarcoma, atypical lipomas occurring in the extremities differ from liposarcoma because they have no tendency for distant metastases. Three patients with atypical lipomas involving the posterior compartment of the thigh are presented. The lipomas were imaged with computed tomography (CT) and magnetic resonance imaging (MRI), using a 0.15-T whole body imager. Although all lesions appeared largely lipomatous, the three lesions simulated liposarcoma on both CT and MRI. On CT, each lesion demonstrated small areas of confluent soft tissue density; these areas were hyperintense with adipose tissue on strongly T2-weighted MRI. We conclude that atypical lipoma of the extremities may not be distinguishable from liposarcoma on imaging and that biopsy is necessary for differentiation.

Adult↗
PubMed1982

CT-diagnosis of lipomatous tumors of the soft tissues.

Twenty-six patients with soft tissue lipoma and liposarcoma were evaluated by CT; 17 lipomas and 9 liposarcomas. All the lipomas except for one subcutaneous lesion were well-delineated. All but one partly calcified lipoma had homogeneous density with attenuation values in the range of the patients' own subcutaneous fat (-65 to -125 HU). The liposarcomas, on the other hand, were less well-delineated and less homogeneous with considerably higher attenuation values. Contrast enhancement may be seen as opposed to lipomas. The results indicate that it is quite possible by CT to differentiate between lipoma and liposarcoma, which is of great help in the preoperative planning.

Adult↗
PubMed1999

MRI findings in intramuscular lipomas.

OBJECTIVE: To investigate the spectrum of magnetic resonance (MR) findings of intramuscular lipoma. DESIGN AND PATIENTS: A retrospective review of 17 consecutive cases of intramuscular lipoma examined with MR imaging was undertaken. Features assessed included the size and margin of the mass; the homogeneity of the contents, including the presence or absence of intermingled muscle fibers; whether the mass was uninodular or multinodular; and the presence of linear structures between and within the tumor nodules. Three well-differentiated liposarcomas and one dedifferentiated liposarcoma associated with lipoma-like components were also studied to allow a comparison of the benign and malignant lesions. RESULTS: The diameter of the intramuscular lipomas varied from less than 3 cm to more than 10 cm. Ten of the intramuscular lipomas were homogeneous but the remaining seven were inhomogeneous with intermingled muscle fibers within the mass. The intramuscular lipomas were well defined in 12 cases, and infiltrative in five. In one case the margin of the lesion showed prominent infiltration of the surrounding muscle tissue. Of the 17 cases of intramuscular lipoma, 15 were composed of a single nodule, whereas three of four cases of liposarcoma were composed of multinodular masses. CONCLUSION: The MR findings of intramuscular lipoma varied from a small, single and homogeneous mass identical to ordinary (superficial) lipoma, to a large, inhomogeneous lesion with an infiltrative margin. The presence of infiltrative margins and intermingled muscle fibers in intramuscular lipoma indicates a benign lesion rather than malignancy. In addition, uninodularity of the mass is helpful in differentiating intramuscular lipoma from well-differentiated liposarcoma.

Adolescent↗