A1 Refereed original research article in a scientific journal

EWSR1::BEND2 fusion sarcoma of the urinary bladder – a case report and review of literature




AuthorsHalava, Vili; Tuominen, Jenni; Lindholm, Paula; Kyyrönen, Timo; Kallajoki, Markku; Orte, Katri

PublisherSpringer Science and Business Media LLC

Publication year2025

Journal: Diagnostic pathology

Article number116

Volume20

Issue1

eISSN1746-1596

DOIhttps://doi.org/10.1186/s13000-025-01721-3

Publication's open availability at the time of reportingOpen Access

Publication channel's open availability Open Access publication channel

Web address https://doi.org/10.1186/s13000-025-01721-3

Self-archived copy’s web addresshttps://research.utu.fi/converis/portal/detail/Publication/504740283


Abstract
In this case report we describe a Ewing-like high grade small round cell sarcoma of the urinary bladder in which an extremely rare EWSR1::BEND2 fusion was found. A 28-year-old male patient presented with hematuria and in the following examinations a large necrotic bladder tumor with spreading to adjacent prostatic tissue and multiple lung metastases were found. Histology showed a poorly differentiated small round cell tumor with perivascular rosettes and moderate membranous positivity for CD99. The methylation profile of the tumor did not match with any of the tumor entities grouped by the sarcoma classifier. With tumor agnostic methods, mainly next generation sequencing, novel fusions are being found at an accelerating rate. Our case adds to the expanding group of EWSR1 fusion neoplasms, and describes the effects of a Ewing sarcoma treatment protocol on this type of sarcoma. The relevance of traditional methods for detecting Ewing sarcoma with fluorescence in situ hybridization is decreasing as EWSR1 rearrangements are detected in tumors that show different clinical behavior and morphology. The classification of these tumors into WHO defined entities to guide treatment is a challenge.

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Last updated on 03/11/2025 03:28:07 PM