Usefulness of a Monoclonal ERG/FLI1 Antibody for Immunohistochemical Discrimination of Ewing Family Tumors
ABSTRACT Ewing family tumors (EFTs) and prostate carcinomas are characterized by rearrangement of ETS genes, most commonly FLI1 (EFTs) and ERG (prostate carcinomas). Previously, we characterized an antibody against ERG (EPR3864) for detecting ERG-rearranged prostate carcinoma. Because EPR3864 also cross-reacts with FLI1, we evaluated the usefulness of EPR3864 for discriminating EFTs from other small round blue cell tumors (SRBCTs) with immunohistochemistry. Of 57 evaluable EFTs, 47 (82%) demonstrated at least moderate, diffuse, nuclear ERG/FLI1 staining (including 89% and 100% of cases with confirmed EWSR1:FLI1 and EWSR1:ERG fusions, respectively), of which 1, 3, and 43 showed negative, cytoplasmic, or membranous CD99 staining, respectively. Among other SRBCTs (61 cases, 7 types), at least moderate, diffuse, nuclear EPR3864 staining was seen in all precursor B-lymphoblastic lymphomas/leukemias and subsets of Burkitt lymphomas (10%) and synovial sarcomas (45%). In summary, EPR3864 may be useful in detecting EWSR1:FLI1 and EWSR1:ERG rearranged EFTs in addition to prostate carcinomas.
SourceAvailable from: Rajiv Michael Patel[Show abstract] [Hide abstract]
ABSTRACT: Recent molecular advances have identified a novel, clinically aggressive subgroup of undifferentiated round cell sarcomas defined molecularly by oncogenic fusion of the gene, CIC, and either DUX4 or its paralog, DUX4L, herein termed CIC-DUX sarcomas. Morphologically, CIC-DUX sarcomas are round cell sarcomas with high-grade nuclear features, including vesicular chromatin and nucleoli, patchy clear cell foci, myxoid change, and necrosis. Here, we studied a cohort of 10 cases, including 6 newly identified cases, 2 with paired metastases. Given our prior observation of trisomy 8 in these tumors, we assayed for amplification and expression of MYC (c-Myc) and representative downstream targets. Trisomy 8 was detected in 5/7 testable cases, with further amplification of MYC locus in 6/7 testable cases and immunohistochemical expression of MYC in 10/10. The canonical MYC transcriptional target, p21, but not MTDH, was differentially expressed compared with Ewing sarcomas. Given prior observation of induction of ETS-family transcription factors by the fusion oncoprotein, we assayed and identified highly prevalent positivity for ERG (9/10) and FLI1 (8/8). These findings are cautionary regarding use of these immunostains in prospective case workup, whereas the prevalent MYC amplification may represent a therapeutically targetable oncogenic pathway in CIC-DUX sarcomas.Modern Pathology advance online publication, 20 June 2014; doi:10.1038/modpathol.2014.83.Modern Pathology 06/2014; 28(1). DOI:10.1038/modpathol.2014.83 · 6.36 Impact Factor
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ABSTRACT: The aim of the present study was to explore ERG immunoreactivity in a series of sarcomas, GIST and malignant rhabdoid tumor (MRT), considering the not fully elucidated specificity and sensitivity of this antibody. Paraffin-embedded tissue microarrays from those tumors were stained with anti-ERG against the C-terminus [(EPR3864(2)] and N-terminus (Clone 9FY). EPR3864(2) was positive in almost all angiosarcomas, and MRT.GIST were positive in a large proportion of cases (38.4%), and more than half the synovial sarcomas (52.7%) revealed EPR3864(2) staining. Several chondrosarcomas, osteosarcomas, rhabdomyosarcoma and Ewing's sarcoma family of tumors (ESFT) presented EPR3864(2) expression in a lower number of cases. 9FY was positive in most of the angiosarcomas; however, only sporadic ESFT and synovial sarcoma were positive and the other tumors tested were negative. Fourteen ESFT with EWSR1/Fli-1 gene fusion presented positive nuclear staining for EPR3864(2). Similarly, 5 ESFT with EWSR1/Fli-1 gene fusion presented positive staining for 9FY. We must stress that the difference between the present and previous studies may be due to the source of the anti-ERG employed, anti-ERG against C or N-terminus, protein cross-reactivity and dilution. In conclusion, specificity for ERG staining in sarcomas should be considered with caution apnd the immunoexpression is undoubtedly influenced by clone and antibody selection.Pathology - Research and Practice 08/2014; DOI:10.1016/j.prp.2014.04.005 · 1.56 Impact Factor
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ABSTRACT: Ewing sarcoma (ES) is a high-grade malignant neoplasm primarily affecting children and young adults. The diagnosis of ES is often difficult because of its broad differential diagnosis comprising a diverse group of small round cell tumors (SRCTs). Although the identification of tumor type-specific fusion genes by molecular testing is the gold standard for the diagnosis of ES, such approaches are not always available in a routine pathology practice. Thus, a reliable immunohistochemical marker is required. A recent study using a limited number of tumor samples has shown that NKX2.2, a putative transcriptional target of EWSR1-FLI1, is a useful marker for the diagnosis of ES. In the present study, the immunohistochemical expression of NKX2.2 was evaluated on 46 genetically confirmed ES and 85 non-ES SRCTs, together with comparative assessment of CD99 and other molecular targets of EWSR1-FLI1, including NR0B1, E2F3, and EZH2. NKX2.2 was expressed in 37 (80 %) of the ES samples with a mostly diffuse and strong staining pattern, and 14 (16 %) of the non-ES SRCTs, including olfactory neuroblastomas, extraskeletal myxoid chondrosarcoma, mesenchymal chondrosarcoma, small cell carcinomas, and Merkel cell carcinoma, also expressed this marker. The sensitivity and specificity of the NKX2.2 expression in this cohort were 80 and 84 %, respectively. The specificity when combined with CD99 was 98 %, with exceptional expression of both markers in only two non-ES SRCTs, including one case each of mesenchymal chondrosarcoma and small cell carcinoma. NR0B1, E2F3, and EZH2 were less sensitive for specific markers for ES when applied singly or in any combination. In conclusion, the study reinforces that NKX2.2 is a useful immunohistochemical marker for ES, and that the combination of CD99 and NKX2.2 is a powerful diagnostic tool that can differentiate ES from other SRCTs.Archiv für Pathologische Anatomie und Physiologie und für Klinische Medicin 07/2014; 465(5). DOI:10.1007/s00428-014-1627-1 · 2.56 Impact Factor