Myxoid liposarcoma

Summary Liposarcoma is an important soft tissue sarcoma. It requires careful classification into types, since prognosis varies considerably with histological appearance. In this case a myxoid sarcoma is shown to contain cells resembling fetal fat with active pinocytosis, and some scanty signet-ring cells. Their ultrastructural appearances are described.The author is indebted to Priv.- Doz. Dr. K. Donath, Department of Pathology University Hamburg, for electron microscopic photographs     

Myxoid liposarcoma

Summary Ten myxoid liposarcomas (ML) were studied ultrastructurally in an attempt to determine the histogenesis of this neoplasm and structural associations which might contribute to their relatively benign clinical behavior. The findings were compared with normal and neoplastic adipose tissue.Three cell types were observed, i.e., primitive mesenchymal cells, intermediate cell types, and lipoblasts at various stages of development. The principle differences between the lipoblastic elements were the number and the size of intracytoplasmic fat vacuoles, the development of basement membrane-like material, micropinocytotic vesicles along the plasma membrane and the quantity and pleomorphism of mitochondria. The tumor vasculature was complex but consistently demonstrated a multilayered basal lamina. This finding has been described in neoplasms associated with a relatively good prognosis.This study demonstrates that the better differentiated lipoblasts in ML share some features with normal brown fetal fat and hibernoma. It is, thus, suggested that ML may be derived from brown adipose tissue.     

Myxoid malignant fibrous histiocytoma and pleomorphic liposarcoma share very similar genomic imbalances

Malignant fibrous histiocytoma (MFH) is the most common soft tissue sarcoma. Nevertheless, the validity of this heterogeneous pathological entity has been recurrently questioned by pathologists. Recently, analyses by comparative genomic hybridization (CGH) of a large series of MFHs suggested that MFHs consist of morphologic modulation of other poorly differentiated sarcomas like leiomyosarcomas (LMS) or dedifferentiated liposarcomas (DLPS). We report here an analysis by CGH of 22 myxoid MFHs (mMFH), one of the five histological subtypes of MFH, and of nine pleomorphic liposarcomas (pLPS), a rare poorly differentiated LPS. The chromosome imbalances encountered in the series of mMFH were very similar to those observed in the series of pLPS studied in the laboratory and in the series of 14 pLPS published in the literature. The most frequent gains involved chromosome subregions: pericentromeric regions of 1, 5p, 19p, 19q and 20q. Losses found in the chromosomal arms 1q, 2q, 3p, 4q, 10q, 11q and 13q were also recurrent. The use of a clustering software did not separate the two pathological groups (mMFH and pLPS) on the basis of genomic data. Moreover, pLPS-mMFH represented, according to the clustering software results, an entity clearly distinguished from other soft tissue sarcomas, LMS in particular, with which they share common genetic aberrations. Additional studies are needed to identify genes targeted by these genomic aberrations, and implicated in the oncogenesis of these tumor subtypes. The characterization of common gene alterations in both tumor groups would suggest a closer relationship between these two types of soft tissue sarcomas.     

Myxoid liposarcoma of the foot: a study of 8 cases

IntroductionMyxoid liposarcoma is the only translocation-associated liposarcoma subtype. It classically originates in the deep soft tissues of the thigh. At distal sites of the extremities, this tumor is exceedingly rare. We present a series of 8 cases occurring in the foot/ankle.ResultsTwo female and 6 male patients, aged between 32 and 77 years (mean, 54.3 years), were identified. Tumor size ranged from 1.1 to 10 cm (mean, 6.8 cm). Two lesions eroded bone. All tumors were treated by excision and 7 by (neo)adjuvant radiotherapy. R0 status was reached in 2 cases with 1 case followed by metastasis in the groin. All other cases were documented with R1 (n = 2) or R2 (n = 4) resection status. In 1 patient, the follow-up status was unknown. All other patients were alive 15-135 (mean, 55.8) months after initial diagnosis.We conclude that myxoid liposarcoma at acral sites are exceedingly rare, and in this series, prognosis was good irrespective of resection status. Clinicians and pathologists have to be aware because this sarcoma type shows a peculiar clinical behavior with high radio- and chemosensitivity and metastatic spread to extrapulmonary sites.     

Myxoid liposarcoma of the breast--report of a rare case

Breast sarcomas are very rare. A 40 year old lady presented with a well-defined hard lump, 6 cm in size, in the left breast. Patient underwent simple mastectomy with axillary clearance following a diagnosis of phylloides tumour on fine needle aspiration cytology. Grossly, it was a circumscribed myxoid tumour. Histopathologically, it fulfilled all the criteria for a diagnosis of myxoid liposarcoma. The absence of epithelial component excluded phylloides tumour.     

Myxoid and round cell liposarcoma: a spectrum of myxoid adipocytic neoplasia.

Myxoid and round cell liposarcoma accounts for about 30% to 35% of all liposarcomas and, even if still classified by the World Health Organization (WHO) as 2 distinct subtypes, share both clinical and morphologic features. Lesions combining both patterns are frequent and wide agreement exists in considering round cell liposarcoma as the high grade counterpart of myxoid liposarcoma. Furthermore, myxoid and round cell liposarcoma share the same characteristic chromosome change represented most frequently by a reciprocal translocation t(12;16)(q13;p11) that fuses the CHOP gene with the TLS gene. Clinically, myxoid and round cell liposarcoma tend to occur in the limbs with a peak incidence ranging between the third and the fifth decade and exhibit overall a metastatic rate of approximately 30%. A peculiar tendency to metastasize to the soft tissue is observed that should not be interpreted as multicentricity. Microscopically, purely myxoid liposarcoma is composed by a hypocellular spindle cell proliferation set in a myxoid background and associated with a varying number of monovacuolated lipoblasts. The most helpful morphologic clue is represented by the presence of a thin-walled capillary network organized in a plexiform pattern. The most important morphologic variation observed in myxoid liposarcoma is represented by the occurrence of hypercellular areas that may exhibits an undifferentiated round cell morphology. On the basis of the percentage of hypercellularity/round cell formation, a myxoid/round cell liposarcoma (more than 25% hypercellular/round cell areas) and a round cell liposarcoma (more than 75% hypercellular/round cell areas) are somewhat arbitrarily recognized. Both the recognition and the quantification of hypercellular/round cell areas represents a crucial step in the evaluation of this liposarcoma subtype because hypercellularity appears to correlate with the clinical outcome. In consideration of the intrinsic difficulty in establishing accurately the percentage of high grade areas as well as of application of different cut off values, it appears safer to consider any amount of hypercellularity as prognostically relevant. Careful as well as extensive sampling is mandatory to permit detection of the smallest amount of hypercellularity. The differential diagnosis of myxoid liposarcoma includes benign lesions, such as myxoid spindle cell lipoma, intramuscular myxoma and lipoblastoma, and malignant ones such as low grade myxofibrosarcoma, and extraskeletal myxoid chondrosarcoma. In consideration of the great morphologic variability, the application of both immunohistochemistry and genetics has proved helpful in sorting out the more challenging cases.     

Primary pleomorphic liposarcoma of breast: a rare case report

Sarcoma of the breast constitutes less than 1% of all malignant breast tumors and liposarcoma of the breast has an incidence of 0.3% of all the mammary sarcomas. A 47-year-old woman presented with a mass in the right breast and mammography was suggestive of a malignant lesion. Modified radical mastectomy was performed. The tumor was diagnosed histologically as a pleomorphic liposarcoma. The patient was discharged and her postoperative recovery was uneventful.     

Epithelioid variant of pleomorphic liposarcoma: report of a case

A case of an epithelioid variant of pleomorphic liposarcoma (PL) arising in the back of a 72-year old male is presented. The lesion was a well-circumscribed but unencapsulated, yellowish white mass measuring 11 x 10 x 9 cm in the subcutis and muscle. Histologically, the tumor consisted of three elements; an epithelioid cell element occupying about 50%, a lipogenic and mixed lipogenic and epithelioid cell element occupying 40%, and a malignant fibrous histiocytoma-like element. The lipogenic area was composed of uni- and multivacuolated pleomorphic lipoblasts. Immunohistochemically, the tumor was positive for vimentin, epithelial membrane antigen, and CD10. It was negative for desmin, alpha-smooth muscle actin, muscle actin, S-100 protein, and cytokeratins 8 and 18. The epithelioid variant of PL should be differentiated from metastatic renal cell carcinoma and adrenal cortical adenocarcinoma.     

Myxoid liposarcoma. An ultrastructural study of two cases.

Two cases in which myxoid liposarcomas were examined by use of light and electron microscopy are presented. The relationship of this tumor to the development of normal adipose tissue is discussed. Most of the ultrastructural features were identical to those of developing white adipose tissue. Features not typical of developing white adipose tissue, such as congeries of 60-Angstrom filaments and large masses of glycogen, are also illustrated and discussed.     

Epithelioid variant of pleomorphic liposarcoma in a heifer

A case of epithelioid variant of liposarcoma in a 31-month-old Japanese Black heifer is described. The tumour mass, which formed in the subcutis of the left cheek, was excised surgically, but this was followed by recurrence and metastasis to lymph nodes. The primary tumour was composed of sheets of lipid-laden cells, and anaplastic larger cells with eosinophilic or amphophilic cytoplasm were occasionally seen. In addition to vimentin and S-100 protein expression in the majority of tumour cells, squamous and non-squamous cytokeratins (CKs) were present, mainly in the larger cells, which predominated in the metastatic lesions. The expression of CKs was considered to be evidence of epithelioid differentiation.     

Epithelioid variant of pleomorphic liposarcoma: a study of 12 cases of a distinctive variant of high-grade liposarcoma.

We describe 12 patients with a distinctive variant of pleomorphic liposarcoma that histologically shows epithelioid features and focally resembles a solid carcinoma. The tumors occurred in nine men and three women (median age, 63 yr; range, 40-78 yr). Five tumors were in the thigh, two in the chest wall, two in the axilla, and one each in the retroperitoneum, groin, and calf. Most were 15 to 20 cm in maximal diameter. They consisted of sheets of epithelioid-appearing cells with ample, variably eosinophilic cytoplasm, often showing a honeycomb-like pattern of cell borders and little if any collagenous extracellular matrix. Their histologic features often resembled those of renal clear cell carcinoma or adrenal cortical carcinoma, but all showed evidence of adipocytic differentiation, and five also showed focal spindle cell components. One patient whose tumor in the thigh had been originally diagnosed as metastatic renal carcinoma had undergone nephrectomy without a finding of a kidney tumor. All of the cases were positive for vimentin; 6 of 11 cases were positive for S-100 protein, usually focally; 5 of 11 were focally positive for keratins; and all were negative for epithelial membrane antigen, muscle actins, desmin, and CD34. High mitotic activity (mean, 42 mitotic figures per 10 high power fields) and high MIB-1-positive proliferative fraction (>30%) were seen in all of the cases, and nuclear p53 immunoreactivity was detected in five of seven cases. Of the eight patients with complete follow-up, five died of disease (median survival, 6 mo), two died of unrelated causes 10 and 18 years later, and 1 was alive and well 24 years later. The epithelioid variant of pleomorphic liposarcoma is a high-grade tumor that must be distinguished from malignant epithelial tumors, especially in view of the keratin immunoreactivity of some of these neoplasms.     

Myxoid liposarcoma with cartilaginous differentiation: A case study with fish analysis and review of the literature

Cartilaginous differentiation is rarely encountered in myxoid liposarcomas. To date, a small number of such cases have been described, and molecular or cytogenetic analysis was performed only in few of them. In the present study, we describe a primary myxoid liposarcoma with cartilaginous differentiation which arised in the left thigh of a 37-year-old man. Miscroscopically, the tumor consisted of areas with typical myxoid liposarcoma morphology and areas of sharply demarcated hyaline cartilage nodules. Here, we present the results of Fluorescence In Situ Hybridization (FISH) analysis that revealed the presence of FUS and DDIT3 gene rearrangements in both the liposarcomatous and cartilaginous components of the tumor. These findings confirm the neoplastic nature of the cartilage component in this rare tumor.