title: Undifferentiated sarcoma: does it exist? A clinicopathologic study of 7 pediatric cases and review of literature.
abstract: Undifferentiated sarcomas are primitive mesenchymal tumors that cannot be classified among standardized histopathologic entities. Whether they represent a homogeneous group with common histogenesis and clinical behavior or comprise a variety of tumors able to differentiate along specific maturative lineages is still debated. To identify prognostic and histogenetic markers, we analyzed 7 undifferentiated sarcomas (4 in the trunk and 3 in the extremities). Mean patient age was 7.5 years, and mean follow-up was 18 months. Two clinicopathologic subtypes emerged from this study. Four primitive mesenchymal undifferentiated sarcomas arose mainly on the trunk and very proximal extremities, had an aggressive clinical course with poor outcome (3 deaths from disease, 1 with persistent disease), and displayed sheets of oval cells, with bland nuclei. Three spindle cell undifferentiated sarcomas arose on the extremities, had a favorable outcome, and showed elongated spindle cells with areas of primitive fibrosarcoma. All were negative for epithelial membrane antigen, cytokeratins, CD34, smooth muscle actin, desmin,Myf4, and HMB45 and showed nuclear staining for INI. Focal staining for S100 and CD99 was found in 3 and 4, respectively. Among stem cell markers, CD117 was positive in 3 cases (1 primitive, 2 spindle), nestin in 5 cases (4 primitive, 1 spindle), and CD105-stained tumor cells lining newly formed vascular spaces in 4 cases (1 primitive, 3 spindle). Survivin was weakly expressed in 6 cases and reflected low levels of mRNA (median survivin/GAPDH ratio, 1.096). Cytogenetic analysis revealed nonspecific translocations in 3 tumors. No translocations associated with Ewing sarcoma, synovial sarcoma, or alveolar rhabdomyosarcoma were found. In summary, primitive undifferentiated sarcomas occur in the trunk, behave aggressively, and express nestin. Spindle cell undifferentiated sarcomas occur in extremities, have a favorable outcome, resemble fibrosarcomas, and have similarly low survivin levels and display CD105-positive vascular spaces, which may represent an early hemangiopericytomatous pattern.
authors: Department of Diagnostic Medical Sciences and Special Therapies, General Surgical Pathology Unit, University of Padua, Padua 35121, Italy.
authors: Rita
authors: R
authors: Alaggio
authors: Gianni
authors: G
authors: Bisogno
authors: Antonio
authors: A
authors: Rosato
authors: Vito
authors: V
authors: Ninfo
authors: Cheryl M
authors: CM
authors: Coffin
mesh_terms: D000293:Adolescent; D014408:Biomarkers, Tumor / Q000032:analysis; D002648:Child; D002675:Child, Preschool; D005260:Female; D015870:Gene Expression; D006801:Humans; D007150:Immunohistochemistry; D007223:Infant; D007231:Infant, Newborn; D051034:Inhibitor of Apoptosis Proteins; D008297:Male; D008869:Microtubule-Associated Proteins / Q000096:biosynthesis; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012509:Sarcoma / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D012983:Soft Tissue Neoplasms / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D000077022:Survivin
chemical_list: C107489:BIRC5 protein, human; D014408:Biomarkers, Tumor; D051034:Inhibitor of Apoptosis Proteins; D008869:Microtubule-Associated Proteins; D000077022:Survivin