title: Well-differentiated and dedifferentiated liposarcomas with prominent myxoid stroma: analysis of 56 cases.
abstract: OBJECTIVE
  Occasional cases of well-differentiated and dedifferentiated liposarcoma (LPS) contain myxoid stroma, leading to confusion with other sarcomas. The aim of this study was to analyse the clinicopathological and genetic features of well-differentiated/dedifferentiated LPS with prominent myxoid stroma.
  
  
  RESULTS
  Fifty-six cases of LPS (22 well-differentiated; 34 dedifferentiated) with prominent myxoid stroma were evaluated. Most arose in the retroperitoneum, abdominal cavity, or spermatic cord. The mean size was 170 mm. Myxoid LPS-like plexiform vessels were conspicuous in 11 cases of well-differentiated LPS. In 22 cases of dedifferentiated LPS, myxofibrosarcoma-like curvilinear vessels were prominent. In other cases, the myxoid component had variably bland or pleomorphic morphology. By immunohistochemistry, staining for MDM2 was positive in 95% of cases, and CDK4 in 78%. Cytogenetics in 13 cases showed ring and giant marker chromosomes. Fluorescence in-situ hybridization showed amplification of 12q13-15 in six cases evaluated. Of 30 patients with follow-up, all but one had local recurrences (up to four), but only one has so far had distant metastases.
  
  
  CONCLUSIONS
  Well-differentiated/dedifferentiated LPS with prominent myxoid stroma can closely resemble other sarcoma types, especially myxoid LPS and myxofibrosarcoma. The clinical presentation (large retroperitoneal or abdominal tumour) is a clue to the correct diagnosis; the degree of nuclear atypia helps to exclude myxoid LPS. Immunohistochemistry for MDM2 and CDK4 and genetic analysis can be useful to confirm the diagnosis.
authors.affiliation: Ludwig Center at Dana-Farber/Harvard Cancer Center, and Department of Pathology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA.
authors.forename: Stefano
authors.initials: S
authors.lastname: Sioletic
authors.forename: Paola
authors.initials: P
authors.lastname: Dal Cin
authors.forename: Christopher D M
authors.initials: CD
authors.lastname: Fletcher
authors.forename: Jason L
authors.initials: JL
authors.lastname: Hornick
mesh_terms: D000008:Abdominal Neoplasms / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D017667:Adipocytes / Q000378:metabolism / Q000473:pathology; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D014408:Biomarkers, Tumor / Q000378:metabolism; D002869:Chromosome Aberrations; D002881:Chromosomes, Human, Pair 12; D051358:Cyclin-Dependent Kinase 4 / Q000378:metabolism; D004273:DNA, Neoplasm / Q000032:analysis; D005260:Female; D005784:Gene Amplification; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D018208:Liposarcoma, Myxoid / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D009077:Mucins / Q000378:metabolism; D051736:Proto-Oncogene Proteins c-mdm2 / Q000378:metabolism; D012187:Retroperitoneal Space; D012983:Soft Tissue Neoplasms / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D017154:Stromal Cells / Q000378:metabolism / Q000473:pathology*; D055815:Young Adult
chemical_list: D014408:Biomarkers, Tumor; D004273:DNA, Neoplasm; D009077:Mucins; C497206:MDM2 protein, human; D051736:Proto-Oncogene Proteins c-mdm2; C495900:CDK4 protein, human; D051358:Cyclin-Dependent Kinase 4