title: Dedifferentiated liposarcoma with meningothelial-like whorls, metaplastic bone formation, and CDK4, MDM2, and p16 expression: a morphologic and immunohistochemical study.
abstract: We studied 5 cases of dedifferentiated liposarcoma with meningothelial-like whorls and metaplastic bone formation, assessing morphology and immunohistochemical expression of a panel of antigens (CDK4, MDM2, and p16 proteins, desmin, smooth muscle actin, h-caldesmon, CD34, AE1/AE3, epithelial membrane antigen, claudin-1, S100 protein, CD21, CD35, CD117, β-catenin, vimentin, and MIB1). The specimens were from the retroperitoneum (3), pelvis (1) or paratesticular region (1), and all 5 specimens comprised exclusively or predominantly dedifferentiated liposarcoma. All 5 dedifferentiated liposarcomas showed prominent metaplastic bone, 3 produced cartilage, and 1 also had osteosarcomatous tissue. The whorls comprised concentric distributions of spindle or epithelioid cells. All cases expressed smooth muscle actin, 3 strongly, whereas 4 cases showed at least focal claudin-1 positivity. In all cases, the whorls expressed at least 2 of CDK4, MDM2, and p16. The presence of 2 morphologic subsets and the immunohistochemical findings suggest that the whorls in these dedifferentiated liposarcomas exhibit divergent myofibroblastic and possibly perineurial differentiation. The CDK4, MDM2, and p16 expression in the whorls suggests that they share a similar genetic background to well-differentiated and dedifferentiated liposarcoma, and that additional genetic events are causal to their distinct morphology.
authors.affiliation: Department of Histopathology, Royal Marsden NHS Foundation Trust, Institute of Cancer Research, London, UK. khin.thway@rmh.nhs.uk
authors.forename: Khin
authors.initials: K
authors.lastname: Thway
authors.forename: David
authors.initials: D
authors.lastname: Robertson
authors.forename: Yi
authors.initials: Y
authors.lastname: Thway
authors.forename: Cyril
authors.initials: C
authors.lastname: Fisher
mesh_terms: D000328:Adult; D000368:Aged; D014408:Biomarkers, Tumor / Q000032:analysis*; D002114:Calcinosis; D002454:Cell Differentiation; D051358:Cyclin-Dependent Kinase 4 / Q000096:biosynthesis*; D019941:Cyclin-Dependent Kinase Inhibitor p16; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D008080:Liposarcoma / Q000378:metabolism / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D009363:Neoplasm Proteins / Q000096:biosynthesis*; D051736:Proto-Oncogene Proteins c-mdm2 / Q000096:biosynthesis*; D012983:Soft Tissue Neoplasms / Q000378:metabolism / Q000473:pathology*
chemical_list: D014408:Biomarkers, Tumor; C000614131:CDKN2A protein, human; D019941:Cyclin-Dependent Kinase Inhibitor p16; D009363:Neoplasm Proteins; C497206:MDM2 protein, human; D051736:Proto-Oncogene Proteins c-mdm2; C495900:CDK4 protein, human; D051358:Cyclin-Dependent Kinase 4