Andrew L. Folpe , Michael T. Tetzlaff , Steven D. Billings , Jorge Torres-Mora , Alexander David Borowsky , Teresa C. Santiago , Baptiste Ameline , Daniel Baumhoer
{"title":"Superficial Neurocristic EWSR1::FLI1 Fusion Tumor: A Distinctive, Clinically Indolent, S100 Protein/SOX10-Positive Neoplasm","authors":"Andrew L. Folpe , Michael T. Tetzlaff , Steven D. Billings , Jorge Torres-Mora , Alexander David Borowsky , Teresa C. Santiago , Baptiste Ameline , Daniel Baumhoer","doi":"10.1016/j.modpat.2024.100537","DOIUrl":null,"url":null,"abstract":"<div><p>It is now understood that identical gene fusions may be shared by different entities. We report a distinctive neoplasm of the skin and subcutis, harboring the Ewing sarcoma-associated <em>EWSR1::FLI1</em> fusion but differing otherwise from Ewing sarcoma. Slides and blocks for 5 cutaneous neoplasms coded as other than Ewing sarcoma and harboring <em>EWSR1::FLI1</em> were retrieved. Immunohistochemical and molecular genetic results were abstracted from reports. Methylation profiling was performed. Clinical information was obtained. The tumors occurred in 4 men and 1 woman (median: 25 years of age; range: 19-69 years) and involved the skin/subcutis of the back (2), thigh, buttock, and chest wall (median: 2.4 cm; range: 1-11 cm). Two tumors were present “years” before coming to clinical attention. The lesions were multinodular and circumscribed and consisted of nests of bland, round cells admixed with hyalinized collagenous bands containing spindled cells. Hemorrhage and cystic change were often present; necrosis was absent. All were diffusely S100 protein/SOX10-positive; 4 of 5 were CD99-negative. One tested case was strongly positive for NKX2.2. A variety of other tested markers were either focally positive (glial fibrillary acidic protein, p63) or negative. Molecular genetic results were as follows: <em>EWSR1</em> exon 7::<em>FLI1</em> exon 8, <em>EWSR1</em> exon 11::<em>FLI1</em> exon 5, <em>EWSR1</em> exon 11::<em>FLI1</em> exon 6, <em>EWSR1</em> exon 7::<em>FLI1</em> exon 6, and <em>EWSR1</em> exon 10::<em>FLI1</em> exon 6. Methylation profiling (3 cases) showed these to form a unique cluster, distinct from Ewing sarcoma. All patients underwent excision with negative margins; one received 1 cycle of chemotherapy. Clinical follow-up showed all patients to be alive without disease (median: 17 months; range: 11-62 months). Despite similar gene fusions, the morphologic, immunohistochemical, epigenetic, and clinical features of these unique <em>EWSR1::FLI1</em>-fused neoplasms of the skin and subcutis differ substantially from Ewing sarcoma. Interestingly, <em>EWSR1</em> rearrangements involved exons 10 or 11, only rarely seen in Ewing sarcoma, in a majority of cases. Superficial neurocristic <em>EWSR1::FLI1</em> fusion tumors should be rigorously distinguished from true cutaneous Ewing sarcomas.</p></div>","PeriodicalId":18706,"journal":{"name":"Modern Pathology","volume":null,"pages":null},"PeriodicalIF":7.1000,"publicationDate":"2024-06-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Modern Pathology","FirstCategoryId":"3","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S0893395224001170","RegionNum":1,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"PATHOLOGY","Score":null,"Total":0}
引用次数: 0
Abstract
It is now understood that identical gene fusions may be shared by different entities. We report a distinctive neoplasm of the skin and subcutis, harboring the Ewing sarcoma-associated EWSR1::FLI1 fusion but differing otherwise from Ewing sarcoma. Slides and blocks for 5 cutaneous neoplasms coded as other than Ewing sarcoma and harboring EWSR1::FLI1 were retrieved. Immunohistochemical and molecular genetic results were abstracted from reports. Methylation profiling was performed. Clinical information was obtained. The tumors occurred in 4 men and 1 woman (median: 25 years of age; range: 19-69 years) and involved the skin/subcutis of the back (2), thigh, buttock, and chest wall (median: 2.4 cm; range: 1-11 cm). Two tumors were present “years” before coming to clinical attention. The lesions were multinodular and circumscribed and consisted of nests of bland, round cells admixed with hyalinized collagenous bands containing spindled cells. Hemorrhage and cystic change were often present; necrosis was absent. All were diffusely S100 protein/SOX10-positive; 4 of 5 were CD99-negative. One tested case was strongly positive for NKX2.2. A variety of other tested markers were either focally positive (glial fibrillary acidic protein, p63) or negative. Molecular genetic results were as follows: EWSR1 exon 7::FLI1 exon 8, EWSR1 exon 11::FLI1 exon 5, EWSR1 exon 11::FLI1 exon 6, EWSR1 exon 7::FLI1 exon 6, and EWSR1 exon 10::FLI1 exon 6. Methylation profiling (3 cases) showed these to form a unique cluster, distinct from Ewing sarcoma. All patients underwent excision with negative margins; one received 1 cycle of chemotherapy. Clinical follow-up showed all patients to be alive without disease (median: 17 months; range: 11-62 months). Despite similar gene fusions, the morphologic, immunohistochemical, epigenetic, and clinical features of these unique EWSR1::FLI1-fused neoplasms of the skin and subcutis differ substantially from Ewing sarcoma. Interestingly, EWSR1 rearrangements involved exons 10 or 11, only rarely seen in Ewing sarcoma, in a majority of cases. Superficial neurocristic EWSR1::FLI1 fusion tumors should be rigorously distinguished from true cutaneous Ewing sarcomas.
期刊介绍:
Modern Pathology, an international journal under the ownership of The United States & Canadian Academy of Pathology (USCAP), serves as an authoritative platform for publishing top-tier clinical and translational research studies in pathology.
Original manuscripts are the primary focus of Modern Pathology, complemented by impactful editorials, reviews, and practice guidelines covering all facets of precision diagnostics in human pathology. The journal's scope includes advancements in molecular diagnostics and genomic classifications of diseases, breakthroughs in immune-oncology, computational science, applied bioinformatics, and digital pathology.