Morphologic and Immunophenotypic Diversity in Ewing Family Tumors: A Study of 66 Genetically Confirmed Cases

More than 85% of Ewing sarcoma/primitive neuroectodermal tumor (ES/PNET), or “Ewing family of tumors” (EFTs), have the translocation, t (11;22) (q24;q12), with others having variant translocations. Identification of these by cytogenetic and/or molecular genetic techniques is specific for EFT and is increasingly recognized as the “gold standard” for diagnosis. However, these techniques are not universally available. We therefore studied a large group of genetically confirmed EFTs to more completely understand the morphologic and immunophenotypic spectrum of this rare sarcoma. Sixty-six cytogenetically, FISH or RT-PCR proven-EFTs were retrieved. In 56 cases, immunohistochemistry (IHC) was performed for pan-cytokeratins (PanCK), high molecular weight cytokeratins (HMWCK), desmin (DES), CD99, CD117, and FLI1 protein using heat-induced epitope retrieval and the Dako Envision system. The cases arose chiefly in children and young adults (median 18 years; range, 3-65 years) of both sexes (male, 32; female, 31; unknown, 3) in a variety of bone (N = 39) and soft tissue (N = 27) sites. Histologically, 46 cases (73%) showed only typical features of ES, 9 cases (16%) showed features of PNET, 3 cases (5%) showed “adamantinoma-like” features, 3 cases (5%) corresponded to “atypical Ewing sarcoma,” 3 cases (5%) showed principally intersecting fascicles of spindled cells, and 2 cases had abundant hyalinized matrix. IHC results were as follows: PanCK (18 of 56, 32%), HMWCK (3 of 55, 5%), DES (1 of 56, 2%), CD99 (52 of 52, 100%), CD117 (13 of 54, 24%), and FLI1 (44 of 47, 94%). HMWCK was expressed only in “adamantinoma-like” EFTs, none of which expressed DES. In conclusion, most, but not all, EFTs can be accurately diagnosed using time-honored morphologic criteria and ancillary immunohistochemistry. However, genetic confirmation remains essential for the diagnosis of unusual morphologic variants of EFT, including “adamantinoma-like,” spindled, sclerosing, and clear cell/anaplastic variants. Therefore, to exclude or confirm the diagnosis of Ewing's sarcoma in round cell sarcomas having a variety of patterns but not specifically conforming to a tumor of known lineage (eg, rhabdomyosarcoma), cytogenetics, and/or molecular analysis is required.

[1]  F. Kikuchi,et al.  Case report 727. Juxtacortical adamantinoma of humerus (simulating Ewing tumor). , 1992, Skeletal radiology.

[2]  W. Gerald,et al.  Primary desmoplastic small cell tumor of soft tissues and bone of the hand. , 1999, The American journal of surgical pathology.

[3]  W. Taylor,et al.  Ewing's sarcoma. A clinicopathological and statistical analysis of patients surviving five years or longer. , 1975, The Journal of bone and joint surgery. American volume.

[4]  G. Hübner,et al.  Malignant tumor of humerus with features of "adamantinoma" and Ewing's sarcoma. , 1979, Pathology, research and practice.

[5]  M. Fukunaga,et al.  Periosteal Ewing-like adamantinoma , 1998, Virchows Archiv.

[6]  F. Askin,et al.  Malignant small cell tumor of the thoracopulmonary region in childhood. A distinctive clinicopathologic entity of uncertain histogenesis , 1979, Cancer.

[7]  M. Santamaría,et al.  The neuroectodermal tumor of bone , 1984, The American journal of surgical pathology.

[8]  U. Van Haelst,et al.  A perplexing malignant bone tumor. Highly malignant so-called adamantinoma or non-typical Ewing's sarcoma. , 1975, Virchows Archiv. A, Pathological anatomy and histology.

[9]  L. Dehner.  Primitive Neuroectodermal Tumor and Ewing's Sarcoma , 1993, The American journal of surgical pathology.

[10]  C. Fletcher,et al.  Immunohistochemical staining for KIT (CD117) in soft tissue sarcomas is very limited in distribution. , 2002, American journal of clinical pathology.

[11]  R. Lloyd,et al.  Desmoplastic Small Round Cell Tumor: A Clinicopathologic, Immunohistochemical, and Molecular Study of 32 Tumors , 2002, The American journal of surgical pathology.

[12]  A. Llombart‐Bosch,et al.  Atypical Pleomorphic Extraosseous Ewing Tumor/Peripheral Primitive Neuroectodermal Tumor with Unusual Phenotypic/Genotypic Profile , 2002, Diagnostic molecular pathology : the American journal of surgical pathology, part B.

[13]  E. Álava,et al.  Intraabdominal desmoplastic small round cell tumor with EWS/ERG fusion transcript. , 1998, The American journal of surgical pathology.

[14]  W. Gerald,et al.  EWS-FLI1 fusion transcript structure is an independent determinant of prognosis in Ewing's sarcoma. , 1998, Journal of clinical oncology : official journal of the American Society of Clinical Oncology.

[15]  E. Reddy,et al.  Analysis of the DNA-binding and transcriptional activation functions of human Fli-1 protein. , 1993, Oncogene.

[16]  J. Goldblum,et al.  Immunohistochemical Analysis of Neural Markers in Peripheral Primitive Neuroectodermal Tumors (pPNET) Without Light Microscopic Evidence of Neural Differentiation , 1997 .

[17]  P. Casali,et al.  Cytokeratin immunoreactivity in 41 cases of ES/PNET confirmed by molecular diagnostic studies. , 2001, The American journal of surgical pathology.

[18]  L. Kahn,et al.  Case report 235. Ewing-like adamantinoma of the left radial head and neck. , 1983, Skeletal radiology.

[19]  H. Dorfman,et al.  Adamantinoma-like Ewing's sarcoma: genomic confirmation, phenotypic drift. , 1999, The American journal of surgical pathology.

[20]  J. Squire,et al.  Is the EWS/FLI-1 fusion transcript specific for Ewing sarcoma and peripheral primitive neuroectodermal tumor? A report of four cases showing this transcript in a wider range of tumor types. , 1996, The American journal of pathology.

[21]  C. Coffin,et al.  Peripheral neurogenic tumors of the soft tissues in children and adolescents: a clinicopathologic study of 139 cases. , 1989, Pediatric pathology.

[22]  W. Gerald,et al.  Fusion of the EWS and WT1 genes in the desmoplastic small round cell tumor. , 1994, Cancer research.

[23]  M. Ladanyi,et al.  Cytokeratin immunoreactivity in Ewing's sarcoma: prevalence in 50 cases confirmed by molecular diagnostic studies. , 2000, The American journal of surgical pathology.

[24]  W. Gerald,et al.  Molecular biology of the Ewing's sarcoma/primitive neuroectodermal tumor family. , 2000, Journal of clinical oncology : official journal of the American Society of Clinical Oncology.

[25]  R. Carter,et al.  A comparative study of immunohistochemical staining for neuron‐specific enolase, protein gene product 9.5 and S‐100 protein in neuroblastoma, Ewing's sarcoma and other round cell tumours in children , 1990, Histopathology.

[26]  E. Andreu,et al.  Imatinib Inhibits Proliferation of Ewing Tumor Cells Mediated by the Stem Cell Factor/KIT Receptor Pathway, and Sensitizes Cells to Vincristine and Doxorubicin-Induced Apoptosis , 2004, Clinical Cancer Research.

[27]  A. Sharrocks.  The ETS-domain transcription factor family , 2001, Nature Reviews Molecular Cell Biology.

[28]  W. Newton,et al.  Extraskeletal Ewing's sarcoma: a preliminary review of 26 cases encountered in the Intergroup Rhabdomyosarcoma Study. , 1978, Cancer.

[29]  S. Steinberg,et al.  Neuroectodermal differentiation in Ewing's sarcoma family of tumors does not predict tumor behavior. , 1999, Human pathology.

[30]  G. Nilsson,et al.  Detection of EWS/FLI-1 by Immunostaining. An Adjunctive Tool in Diagnosis of Ewing's Sarcoma and Primitive Neuroectodermal Tumour on Cytological Samples and Paraffin-Embedded Archival Material , 1999, Sarcoma.

[31]  G. Basso,et al.  c-kit is expressed in soft tissue sarcoma of neuroectodermic origin and its ligand prevents apoptosis of neoplastic cells. , 1998, Blood.

[32]  P. D. Dhulipal.  Ets oncogene family. , 1997, Indian journal of experimental biology.

[33]  L. Angervall,et al.  Extraskeletal neoplasm resembling Ewing's sarcoma , 1975, Cancer.

[34]  A. Llombart‐Bosch,et al.  Ultrastructural study of 28 cases of Ewing's sarcoma: Typical and atypical forms , 1978, Cancer.

[35]  D. Parham,et al.  Desmin Positivity in Primitive Neuroectodermal Tumors of Childhood , 1992, The American journal of surgical pathology.

[36]  J. Goldblum,et al.  Enzinger and Weiss's Soft Tissue Tumors , 2001 .

[37]  H. Jacobson.  Bone Tumors: General Aspects and Data on 6,221 Cases , 1979 .

[38]  E. Mindell.  Enzinger and Weiss’s Soft Tissue Tumors. 4th ed. , 2001 .

[39]  A. D. Tos,et al.  Utility of the immunohistochemical detection of FLI-1 expression in round cell and vascular neoplasm using a monoclonal antibody , 2004, Modern Pathology.

[40]  P. Lollini,et al.  C-kit receptor expression in Ewing's sarcoma: lack of prognostic value but therapeutic targeting opportunities in appropriate conditions. , 2003, Journal of clinical oncology : official journal of the American Society of Clinical Oncology.

[41]  P. Stiegler,et al.  The avian fli gene is specifically expressed during embryogenesis in a subset of neural crest cells giving rise to mesenchyme. , 1998, The International journal of developmental biology.

[42]  K. Cooper,et al.  A clinicopathologic study of 20 cases of large‐cell (atypical) Ewing's sarcoma of bone , 1980, The American journal of surgical pathology.

[43]  P. Lollini,et al.  The metastatic ability of Ewing's sarcoma cells is modulated by stem cell factor and by its receptor c-kit. , 2000, The American journal of pathology.

[44]  C. Fisher,et al.  Ewing's sarcoma and primitive neuroectodermal tumor in adults: are they different from Ewing's sarcoma and primitive neuroectodermal tumor in children? , 1997, Journal of clinical oncology : official journal of the American Society of Clinical Oncology.

[45]  D. Dahlin.  Bone tumors : general aspects and data on 3,987 cases , 1967 .

[46]  A. Llombart‐Bosch,et al.  Does malignant small round cell tumor of the thoracopulmonary region (askin tumor) constitute a clinicopathologic entity?. An analysis of 30 cases with immunohistochemical and electron‐microscopic support treated at the institute gustave roussy , 1992, Cancer.

[47]  L. Kindblom,et al.  Sclerosing Epithelioid Fibrosarcoma: A Variant of Fibrosarcoma Simulating Carcinoma , 1995, The American journal of surgical pathology.

[48]  J. McKenney,et al.  Sclerosing Rhabdomyosarcoma in Adults: Report of Four Cases of a Hyalinizing, Matrix-Rich Variant of Rhabdomyosarcoma That May Be Confused With Osteosarcoma, Chondrosarcoma, or Angiosarcoma , 2002, The American journal of surgical pathology.

[49]  J. Downing,et al.  Detection of the (11;22)(q24;q12) translocation of Ewing's sarcoma and peripheral neuroectodermal tumor by reverse transcription polymerase chain reaction. , 1993, The American journal of pathology.

[50]  J. Ewing.  Diffuse endothelioma of bone , 1972 .

[51]  A. Llombart‐Bosch,et al.  Soft Tissue Ewing Sarcoma–Peripheral Primitive Neuroectodermal Tumor With Atypical Clear Cell Pattern Shows a New Type of EWS-FEV Fusion Transcript , 2000, Diagnostic molecular pathology : the American journal of surgical pathology, part B.

[52]  E. de Álava,et al.  Ewing Tumor: Tumor Biology and Clinical Applications , 2001, International journal of surgical pathology.

[53]  A. Pappo,et al.  c-kit Expression in Pediatric Solid Tumors: A Comparative Immunohistochemical Study , 2002, The American journal of surgical pathology.

[54]  A. Llombart‐Bosch,et al.  Immunohistochemical Detection of EWS and FLI-1 Proteins in Ewing Sarcoma and Primitive Neuroectodermal Tumors: Comparative Analysis With CD99 (MIC-2) Expression , 2001, Applied immunohistochemistry & molecular morphology : AIMM.