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Warmke LM, Perret R, Ledoux P, Michot A, Italiano A, Zou YS, Matoso A, Argani P, Ulbright TM, Baumhoer D, Ameline B, Gross JM. EWSR1::WT1 Fusions in Neoplasms Other Than Conventional Desmoplastic Small Round Cell Tumor: Three Tumors Occurring Outside the Female Genital Tract. Mod Pathol 2024; 37:100418. [PMID: 38158126 DOI: 10.1016/j.modpat.2023.100418] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2023] [Revised: 11/07/2023] [Accepted: 12/14/2023] [Indexed: 01/03/2024]
Abstract
Desmoplastic small round cell tumor (DSRCT) is a high-grade, primitive round cell sarcoma classically associated with prominent desmoplastic stroma, coexpression of keratin and desmin, and a characteristic EWSR1::WT1 gene fusion. DSRCT typically arises in the abdominopelvic cavity of young males with diffuse peritoneal spread and poor overall survival. Although originally considered to be pathognomonic for DSRCT, EWSR1::WT1 gene fusions have recently been detected in rare tumors lacking the characteristic morphologic and immunohistochemical features of DSRCT. Here, we report 3 additional cases of neoplasms other than conventional DSCRCT with EWSR1::WT1 gene fusions that occurred outside the female genital tract. Two occurred in the abdominopelvic cavities of a 27-year-old man and a 12-year-old girl, whereas the third arose in the axillary soft tissue of an 85-year-old man. All cases lacked prominent desmoplastic stroma and were instead solid and cystic with peripheral fibrous pseudocapsules and occasional intervening fibrous septa. Necrosis was either absent (1/3) or rare (2/3), and mitotic activity was low (<1 to 3 per 10 hpf). In immunohistochemical studies, there was expression of smooth muscle actin (3/3) and desmin (3/3), rare to focal reactivity for EMA (2/3), and variable expression of CK AE1/AE3 (1/3). Myogenin and MyoD1 were negative, and C-terminus-specific WT1 was positive in both cases tested (2/2). All 3 tumors followed a more indolent clinical course with 2 cases demonstrating no evidence of disease at 20 and 44 months after resection. The patient from case 3 died of other causes at 14 months with no evidence of recurrence. DNA methylation profiling showed that the 3 cases clustered with DSRCT; however, they demonstrated fewer copy number variations with 2 cases having a flat profile (0% copy number variation). Differential methylation analysis with hierarchical clustering further showed variation between the 3 cases and conventional DSRCT. Although further study is needed, our results, in addition to previous reports, suggest that EWSR1::WT1 gene fusions occur in rare and seemingly distinctive tumors other than conventional DSRCT with indolent behavior. Proper classification of these unusual soft tissue tumors with EWSR1::WT1 gene fusions requires direct correlation with tumor morphology and clinical behavior, which is essential to avoid overtreatment with aggressive chemotherapy.
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Affiliation(s)
- Laura M Warmke
- Department of Pathology, Indiana University School of Medicine, Indianapolis, Indiana.
| | - Raul Perret
- Department of Biopathology, Institut Bergonié, Comprehensive Cancer Center, Bordeaux, France; Bordeaux Institute of Oncology, BRIC, INSERM, Bordeaux University, Bergonié Institute, Bordeaux, France
| | - Pauline Ledoux
- Department of Diagnostic and Interventional Oncological Imaging, Institut Bergonié, Regional Comprehensive Cancer of Nouvelle-Aquitaine, Bordeaux, France
| | - Audrey Michot
- Plastic and Reconstructive Surgery Department, Bergonié Institute, Bordeaux, France
| | - Antoine Italiano
- Sarcoma Unit, Institut Bergonié, Bordeaux, Gironde, France; Faculty of Medicine, University of Bordeaux, Bordeaux, Gironde, France
| | - Ying S Zou
- Department of Pathology, The Johns Hopkins Hospital, Baltimore, Maryland
| | - Andres Matoso
- Department of Pathology, The Johns Hopkins Hospital, Baltimore, Maryland
| | - Pedram Argani
- Department of Pathology, The Johns Hopkins Hospital, Baltimore, Maryland
| | - Thomas M Ulbright
- Department of Pathology, Indiana University School of Medicine, Indianapolis, Indiana
| | - Daniel Baumhoer
- Bone Tumor Reference Center at the Institute of Pathology, University Hospital Basel and University of Basel, Basel, Switzerland
| | - Baptiste Ameline
- Bone Tumor Reference Center at the Institute of Pathology, University Hospital Basel and University of Basel, Basel, Switzerland
| | - John M Gross
- Department of Pathology, The Johns Hopkins Hospital, Baltimore, Maryland
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